Add software LiPo UV protection with energy-save boot.

Detect under-voltage on GPIO1/11, persist UV state in NVS, enter a minimal
power mode without ESP-NOW, and recover after charge; expose LED mode 6
battery-low for host testing via goTool.

Co-authored-by: Cursor <cursoragent@cursor.com>

docs/ARCHITECTURE.md

@@ -0,0 +1,416 @@
+# Powerpod — Architektur-Spezifikation
+
+Dieses Dokument beschreibt die Firmware-Architektur des ESP32-S3-Projekts: Rollen, Schichten, Datenflüsse und die wichtigsten Implementierungsstellen. **goTool** (Host-CLI) ist bewusst ausgeschlossen — es nutzt nur das UART-Protokoll des Masters.
+
+---
+
+## 1. Systemüberblick
+
+Master und Slave laufen mit **demselben Binary**. Die Rolle wird beim Boot per DIP-Schalter und I2C-IO-Expander festgelegt; danach verzweigt die Initialisierung.
+
+```mermaid
+flowchart TB
+  subgraph host["Externer Host (UART)"]
+    PC[PC / beliebiger UART-Client]
+  end
+
+  subgraph master["Master ESP32-S3"]
+    UART_RX[uart_read_task]
+    Q[cmd_queue]
+    DISP[vCmdDispatcherTask]
+    HAND[cmd/*.c Handler]
+    REG[client_registry]
+    ENOW_M[esp_now_comm Master]
+  end
+
+  subgraph slaves["Slave ESP32-S3 × N"]
+    ENOW_S[esp_now_comm Slave]
+    BMA[BMA456 + LED Ring]
+  end
+
+  PC <-->|UART1 921600 framed + protobuf| UART_RX
+  UART_RX --> Q --> DISP --> HAND
+  HAND --> REG
+  HAND --> ENOW_M
+  ENOW_M <-->|ESP-NOW nanopb| ENOW_S
+  ENOW_S --> BMA
+  ENOW_S -->|Accel/Tap/Battery| ENOW_M
+  ENOW_M --> REG
+```
+
+| Rolle | UART | ESP-NOW | Zentrale Datenhaltung |
+|-------|------|---------|------------------------|
+| **Master** | Ja — einziger Befehlseingang von außen | Discover (Broadcast), Unicast zu Slaves | `client_registry.c` |
+| **Slave** | Nein | Antwort auf Discover, Heartbeat, Events zum Master | `esp_now_slave.c` |
+
+**Einstieg:** `main/powerpod.c` → `app_main()`.
+
+---
+
+## 2. Boot und Konfiguration
+
+### 2.1 Ablauf
+
+```mermaid
+sequenceDiagram
+  participant AM as app_main
+  participant NVS as pod_settings
+  participant I2C as I2C / IO-Expander
+  participant BMA as bosch456
+  participant EN as esp_now_comm
+  participant LR as led_ring
+  participant BI as board_input
+  participant CMD as cmd_handler + uart
+
+  AM->>NVS: pod_settings_init()
+  AM->>AM: GPIO DIP_MASTER → master/slave
+  AM->>I2C: Bus + Expander 0x20 → network 1–8
+  AM->>BMA: init_bma456() (Master + Slave)
+  AM->>AM: app_config_t füllen
+  AM->>BI: board_input_init()
+  AM->>EN: esp_now_comm_init(&app_config)
+  AM->>LR: led_ring_init()
+  alt master == true
+    AM->>CMD: Queue, Dispatcher, UART, Handler registrieren
+  end
+```
+
+### 2.2 `app_config_t`
+
+| Feld | Quelle | Bedeutung |
+|------|--------|-----------|
+| `master` | `DIP_MASTER` (GPIO 4): Low = Master | Steuert UART + Registry-Nutzung |
+| `network` | IO-Expander, Bits 5–8 (nibble reversed) | 1–8 → WiFi/ESP-NOW-Kanal |
+| `running_partition` | `esp_ota_get_running_partition()` | Aktives OTA-Label (`ota_0` / `ota_1`) |
+
+**Dateien:** `main/app_config.h`, `main/powerpod.c`, `main/powerpod.h` (Pins).
+
+---
+
+## 3. Schichtenmodell
+
+```
+┌─────────────────────────────────────────────────────────────┐
+│  Befehlshandler (main/cmd/cmd_*.c)                          │
+│  Decode/Encode: uart_cmd.c, Antwort: uart_proto.c           │
+├─────────────────────────────────────────────────────────────┤
+│  Dispatch: cmd_handler.c (Queue + vCmdDispatcherTask)       │
+├─────────────────────────────────────────────────────────────┤
+│  Transport UART: uart.c (Framing)  │  ESP-NOW: esp_now_comm │
+├─────────────────────────────────────────────────────────────┤
+│  Protokoll: uart_messages.proto    │  esp_now_messages.proto │
+│  Codec: nanopb (proto/*.pb.c)      │  esp_now_proto.c        │
+├─────────────────────────────────────────────────────────────┤
+│  Domäne: client_registry, bosch456, led_ring, ota_*, board  │
+├─────────────────────────────────────────────────────────────┤
+│  ESP-IDF: UART, WiFi, ESP-NOW, I2C, ADC, OTA, NVS, FreeRTOS │
+└─────────────────────────────────────────────────────────────┘
+```
+
+---
+
+## 4. Datenfluss: Commands (Befehle)
+
+Commands sind **asynchron über eine FreeRTOS-Queue** entkoppelt; der UART-Reader blockiert nicht auf Handler-Logik.
+
+### 4.1 Eingang (UART → Handler)
+
+```mermaid
+flowchart LR
+  A[Bytes UART1] --> B[parse_uart_byte]
+  B --> C{Frame vollständig?}
+  C -->|ja| D[uart_enqueue_packet]
+  D --> E["generic_msg_t<br/>msg_id = payload[0]<br/>payload = Rest"]
+  E --> F[cmd_queue xQueueSend]
+  F --> G[vCmdDispatcherTask]
+  G --> H{msg_register_handler}
+  H --> I[cmd_*.c callback]
+  I --> J[free payload]
+```
+
+**Wichtige Stellen:**
+
+| Schritt | Datei | Funktion |
+|---------|--------|----------|
+| Byte-Parser + Timeout 50 ms | `main/uart.c` | `parse_uart_byte()`, `uart_read_task()` |
+| Queue-Eintrag | `main/uart.c` | `uart_enqueue_packet()` |
+| Dispatcher | `main/cmd/cmd_handler.c` | `vCmdDispatcherTask()`, `msg_register_handler()` |
+| Registrierung Master | `main/powerpod.c` | `cmd_*_register()` nach `init_uart()` |
+
+**Nachrichten-ID:** Byte 0 des UART-Payloads = `alox_MessageType` (siehe `main/proto/uart_messages.proto`). Bytes 1… = nanopb-kodiertes `UartMessage` **ohne** wiederholtes Type-Feld — Handler erhalten nur den protobuf-Teil (`msg.payload` ab Offset 1).
+
+### 4.2 Ausgang (Handler → UART)
+
+```mermaid
+flowchart LR
+  H[Handler baut alox_UartMessage] --> U[uart_cmd_send]
+  U --> P[uart_send_uart_message]
+  P --> E[pb_encode + Byte0 = type]
+  E --> F[uart_send_framed]
+  F --> W[uart_write_bytes]
+```
+
+**Wichtige Stellen:**
+
+| Schritt | Datei | Funktion |
+|---------|--------|----------|
+| Handler-Hilfen | `main/uart_cmd.c` | `uart_cmd_decode()`, `uart_cmd_init_response()`, `uart_cmd_send()` |
+| Protobuf + Framing | `main/uart_proto.c` | `uart_send_uart_message()` |
+| XOR-Rahmen | `main/uart.c` | `uart_send_framed()` |
+
+### 4.3 OTA-Sperre (keine parallelen Befehle)
+
+Während einer OTA-Session (`ota_uart_is_active()` oder `ota_espnow_distribution_active()`) lehnt der Dispatcher alle UART-Befehle ab **außer**:
+
+- `OTA_START`, `OTA_PAYLOAD`, `OTA_END`, `OTA_START_ESPNOW`, `OTA_SLAVE_PROGRESS`
+
+Implementierung: `ota_session.c`, Prüfung in `vCmdDispatcherTask` vor Handler-Aufruf.
+
+Auf dem **Slave** verarbeitet `espnow_recv_cb` während `ota_uart_is_active()` nur noch OTA-Nachrichten vom joined Master (kein Discover, Stream, LED, …).
+
+Auf dem **Master** während ESP-NOW-Verteilung nur noch `ESPNOW_OTA_STATUS` aus dem recv_cb.
+
+### 4.4 UART-Request-Decode (strikt)
+
+| Regel | Beispiele |
+|-------|-----------|
+| Leerer protobuf-Body (`len == 0`) erlaubt | `VERSION`, `CLIENT_INFO`, `CACHE_STATUS`, `BATTERY_STATUS` (Defaults) |
+| `len > 0` → Decode muss gelingen, `which_payload` muss passen | `ACCEL_STREAM`, `TAP_NOTIFY`, `RESTART`, OTA, … |
+
+### 4.5 Bridge-Muster: UART-Befehl → ESP-NOW
+
+Viele Master-Handler folgen demselben Muster:
+
+1. `uart_cmd_decode()` → Request aus `UartMessage`
+2. Lokale Aktion und/oder `client_registry_*` aktualisieren
+3. `esp_now_comm_send_*()` mit MAC aus Registry
+4. `uart_cmd_send()` mit Response
+
+```mermaid
+sequenceDiagram
+  participant Host
+  participant UART as uart.c
+  participant CMD as cmd_accel_deadzone.c
+  participant REG as client_registry
+  participant EN as esp_now_comm.c
+  participant SL as Slave
+
+  Host->>UART: Frame ACCEL_DEADZONE
+  UART->>CMD: generic_msg_t
+  CMD->>REG: set_accel_deadzone / lookup MAC
+  CMD->>EN: esp_now_comm_send_accel_deadzone
+  EN->>SL: ESPNOW_SET_ACCEL_DEADZONE
+  SL->>SL: bma456 + NVS
+  CMD->>Host: uart_cmd_send Response
+```
+
+**Beispiel-Implementierung:** `main/cmd/cmd_accel_deadzone.c`  
+**Weitere Bridge-Handler:** `cmd_accel_stream.c`, `cmd_tap_notify.c`, `cmd_led_ring.c`, `cmd_espnow_find_me.c`, `cmd_restart.c`, `cmd_espnow_unicast_test.c`, `cmd_espnow_echo_ping.c`, `cmd/cmd_ota.c` (OTA + `ota_espnow.c`).
+
+**Nur Master / nur Cache (kein Slave-Roundtrip):** `cmd_client_info.c`, `cmd_battery.c`, `cmd_cache_status.c`, `cmd_version.c`, `cmd_set_log_level.c`.
+
+---
+
+## 5. Datenfluss: UART
+
+### 5.1 Rahmenformat (Transport)
+
+Unabhängig von Protobuf — reines Bytestream-Framing:
+
+| Feld | Wert |
+|------|------|
+| Start | `0xAA` |
+| Länge | 1 Byte (1–252) |
+| Payload | `length` Bytes |
+| Prüfsumme | XOR aller Payload-Bytes |
+| Stopp | `0xCC` |
+
+**Parameter:** `main/uart.h` — `UART_NUM_1`, `921600` Baud, TX GPIO **2**, RX GPIO **3**, `MAX_PAYLOAD_SIZE` 248.
+
+### 5.2 Nutzlast (Anwendung)
+
+```
+Payload[0]     = MessageType (enum, 1 Byte)
+Payload[1…]    = nanopb UartMessage (Felder ab type/payload oneof)
+```
+
+**Schema:** `main/proto/uart_messages.proto`  
+**Generiert:** `main/proto/uart_messages.pb.c/h` (`make proto_generate_uart`)
+
+### 5.3 Tasks und Prioritäten
+
+| Task | Stack | Priorität | Datei |
+|------|-------|-----------|--------|
+| `uart_rx` | 4096 | 5 | `uart.c` |
+| `cmd_dispatch` | 8192 | 5 | `cmd_handler.c` |
+
+Queue-Größe Master: **64** Einträge (`powerpod.c`); volle Queue → Warnung, Payload wird freigegeben.
+
+---
+
+## 6. Datenfluss: ESP-NOW
+
+### 6.1 Stack-Initialisierung
+
+`esp_now_comm_init()` (`esp_now_comm.c`) → `esp_now_core` (WiFi/Radio/Send) + Rolle:
+
+1. `client_registry_init()` (Master)
+2. `esp_now_init()`, recv_cb leitet an `esp_now_master_on_recv` / `esp_now_slave_on_recv`
+3. **Master** (`esp_now_master.c`): `espnow_disc`, `espnow_mon`
+4. **Slave** (`esp_now_slave.c`): `espnow_stx`, `espnow_hb`, `espnow_accel`, `ota_slave_work`
+
+**Codec:** Rohes Paket = ein nanopb `EspNowMessage` — **kein** zusätzliches Framing (`main/esp_now_proto.c`).
+
+### 6.2 Discovery und Join (Slave)
+
+```mermaid
+sequenceDiagram
+  participant M as Master espnow_disc
+  participant S as Slave recv_cb
+  participant TX as slave_tx_task
+
+  loop alle 500 ms
+    M->>M: ESPNOW_DISCOVER → FF:FF:…:FF
+  end
+  S->>S: handle_discover (network match)
+  S->>S: s_slave_joined, s_master_mac
+  Note over S,TX: Kein Send aus recv_cb!
+  S->>TX: SLAVE_TX_SLAVE_INFO
+  TX->>M: ESPNOW_SLAVE_INFO
+  S->>TX: SLAVE_TX_BATTERY
+  TX->>M: ESPNOW_BATTERY_REPORT
+  loop alle 1 s
+    S->>M: ESPNOW_HEARTBEAT
+  end
+```
+
+**Registry-Schlüssel:** immer `recv_info.src_addr` (WiFi-MAC des Senders), **nicht** optionales `mac`-Feld in der Protobuf-Nachricht.
+
+**Slave-ID:** `mac[5]` (letztes Oktett) — kann kollidieren; eindeutig ist die volle MAC in der Registry.
+
+**Master-Verlust:** Slave setzt Join zurück, wenn **5 s** kein Discover vom gleichen Master (`SLAVE_MASTER_LOST_MS`).
+
+**Join-Policy:** Master→Slave-Steuerung (Stream, Tap, LED, OTA, `UNICAST_TEST`, `SET_ACCEL_DEADZONE`, …) nur bei `s_slave_joined` und `src_addr == s_master_mac`. Während `ota_uart_is_active()` auf dem Slave verarbeitet der recv_cb nur OTA vom joined Master.
+
+**Slave OTA:** Payload/End/Status-Sends laufen über `ota_slave_work_task` (Queue), nicht im ESP-NOW-recv_cb.
+
+### 6.3 Master → Slave (Unicast)
+
+Alle Master-Sends laufen über `send_message()` / `send_message_ex()`:
+
+1. `esp_now_proto_encode()`
+2. `ensure_peer(dest_mac)`
+3. `esp_now_send()`
+
+Öffentliche API: `main/esp_now_comm.h` (`esp_now_comm_send_*`).
+
+**Empfang Slave:** `espnow_recv_cb()` → Switch auf `which_payload` → Handler (`handle_slave_*`).
+
+### 6.4 Slave → Master (Events)
+
+| Nachricht | Task / Trigger | Master-Ziel |
+|-----------|----------------|-------------|
+| `ESPNOW_ACCEL_SAMPLE` | `slave_accel_stream_task` 16 ms | `client_registry_update_accel()` |
+| `ESPNOW_TAP_EVENT` | BMA456-IRQ → `on_bma456_tap` | `client_registry_update_tap()` |
+| `ESPNOW_BATTERY_REPORT` | Heartbeat + nach Join | `client_registry_update_battery()` |
+| `ESPNOW_SLAVE_INFO` / `HEARTBEAT` | `slave_tx_task` / Heartbeat-Task | `client_registry_heartbeat()` |
+| `ESPNOW_OTA_STATUS` | `ota_espnow_slave_*` | `ota_espnow_master_on_status()` |
+
+**Master recv:** `espnow_recv_cb()` — Presence, Accel, Tap, Battery, OTA-Status.
+
+### 6.5 OTA über ESP-NOW
+
+Nach erfolgreichem UART-OTA auf dem Master (oder `OTA_START_ESPNOW`): `ota_espnow.c` liest gestagte Partition, sendet `OTA_START` / `PAYLOAD` (≤200 B, `send_message_ex` mit ACK-Semaphore) / `OTA_END` an alle **available** Slaves.
+
+Gemeinsamer Flash-Puffer: `ota_uart.c` (4 KiB Blockgröße).
+
+---
+
+## 7. Client Registry (Master-Datenhub)
+
+Die Registry ist die **zentrale Brücke** zwischen ESP-NOW-Echtzeitdaten und UART-Abfragen.
+
+```mermaid
+flowchart TB
+  EN_RX[espnow_recv_cb] --> REG[client_registry]
+  CMD_R[cmd_client_info / battery / cache_status] --> REG
+  CMD_W[cmd_* write paths] --> REG
+  REG --> CMD_R
+  EN_TX[esp_now_comm_send_*] --> MAC[MAC aus Registry]
+```
+
+| Daten | Aktualisiert durch | Gelesen durch UART |
+|-------|-------------------|-------------------|
+| Presence, Version | HEARTBEAT / SLAVE_INFO | `CLIENT_INFO` |
+| Accel-Stream-Samples | `ESPNOW_ACCEL_SAMPLE` | `CACHE_STATUS` |
+| Tap-Events (16 ms Cache) | `ESPNOW_TAP_EVENT` | `CACHE_STATUS` |
+| Batterie | `ESPNOW_BATTERY_REPORT` + Master-ADC | `BATTERY_STATUS` |
+| Konfig-Flags | Handler + ESP-NOW | `CLIENT_INFO`, diverse GET |
+
+**Datei:** `main/client_registry.c`, `main/client_registry.h` (max. 16 Clients, Timeout 3 s ohne Heartbeat).
+
+---
+
+## 8. FreeRTOS-Tasks (Übersicht)
+
+| Task | Rolle | Intervall / Trigger |
+|------|-------|---------------------|
+| `uart_rx` | Master | UART read 20 ms timeout |
+| `cmd_dispatch` | Master | Queue blocking |
+| `espnow_disc` | Master | 500 ms Discover |
+| `espnow_mon` | Master | 1 s Timeout + Master-Battery |
+| `espnow_stx` | Slave | Queue: SLAVE_INFO, Battery nach Join |
+| `espnow_hb` | Slave | 1 s Heartbeat + 30 s Battery |
+| `espnow_accel` | Slave | 16 ms Accel wenn Stream an |
+| `bma456_poll` | Beide | 10 Hz (`bosch456.c`) |
+| `vTaskLedRing` | Beide | LED-Ring-Befehle |
+
+`app_main` endet in `while(1) vTaskDelay(portMAX_DELAY)` — alle Arbeit läuft in Tasks.
+
+---
+
+## 9. Implementierungskarte (wichtige Dateien)
+
+| Bereich | Pfad | Verantwortung |
+|---------|------|----------------|
+| Einstieg / Init | `main/powerpod.c` | Boot-Reihenfolge, Master-Handler-Register |
+| UART Transport | `main/uart.c`, `main/uart.h` | Framing RX/TX |
+| UART Protobuf TX | `main/uart_proto.c` | `uart_send_uart_message` |
+| UART Handler-Boilerplate | `main/uart_cmd.c`, `main/uart_cmd.h` | Decode, Register, Send |
+| Command Dispatch | `main/cmd/cmd_handler.c` | Queue, Dispatcher |
+| UART Commands | `main/cmd/cmd_*.c` | Pro Befehl ein Modul |
+| ESP-NOW | `esp_now_comm.c` Init/Router; `esp_now_core.c` Send/Peer; `esp_now_master.c` / `esp_now_slave.c` Rollenlogik |
+| ESP-NOW Codec | `main/esp_now_proto.c` | nanopb encode/decode |
+| Registry | `main/client_registry.c` | Slave-Tabelle + Caches |
+| BMA456 | `main/bosch456.c` | Sensor, Tap, Deadzone-Filter |
+| LED | `main/led_ring.c` | 95 LEDs, Digit-Maps |
+| OTA UART | `main/ota_uart.c`, `cmd/cmd_ota.c` | A/B-Partition Upload |
+| OTA ESP-NOW | `main/ota_espnow.c` | Verteilung an Slaves |
+| Einstellungen NVS | `main/pod_settings.c` | Accel-Deadzone persistent |
+| Board | `main/board_input.c` | Taster, LiPo-ADC |
+| Protobuf Schemas | `main/proto/*.proto` | Vertrag UART / ESP-NOW |
+| Vendor BMA456 | `components/bma456/` | Nur `bma4.c` + `bma456h.c` gelinkt |
+
+---
+
+## 10. Protokoll-Verträge (Kurzreferenz)
+
+- **UART:** `main/proto/uart_messages.proto` — Host ↔ Master  
+- **ESP-NOW:** `main/proto/esp_now_messages.proto` — Master ↔ Slave  
+
+Regenerierung: `make proto_generate` (siehe `DOCUMENTATION.md`).
+
+---
+
+## 11. Design-Entscheidungen
+
+1. **Eine Queue für UART-Commands** — einziger Eingang vom Host; während OTA nur OTA-Befehle.  
+2. **Kein ESP-NOW-Send im `recv_cb`** — Slave antwortet auf Discover über `slave_tx_task` (Deadlock-/Stack-Risiko vermeiden).  
+3. **Registry-MAC = ESP-NOW-Quelladresse** — Protobuf-MAC ist optional/informativ.  
+4. **Gleiches Binary** — Konfiguration nur Hardware (DIP + Expander); reduziert Release-Komplexität.  
+5. **Nanopb statt vollem protobuf-c** — passend für ESP-RAM/Flash.  
+6. **Master aggregiert Sensor-Daten** — Slaves streamen; Host pollt Cache per UART (`CACHE_STATUS`), kein Durchreichen jedes Accel-Samples über UART.
+
+---
+
+Weitere Details (Befehlsliste, GPIO, Build, BMA456): [`DOCUMENTATION.md`](DOCUMENTATION.md).

docs/DOCUMENTATION.md

@@ -0,0 +1,564 @@
+# Powerpod ESP-Firmware — Dokumentation
+
+Vollständige Referenz für das ESP-IDF-Projekt unter `main/` und `components/`. Diese Doku beschreibt **nur die Firmware** — kein goTool, keine Host-Implementierung.
+
+- **Architektur & Datenflüsse:** [`ARCHITECTURE.md`](ARCHITECTURE.md)  
+- **Neues Feature end-to-end:** [`adding-a-feature.md`](adding-a-feature.md)
+
+---
+
+## Inhaltsverzeichnis
+
+1. [Projektziel](#1-projektziel)
+2. [Hardware und Pins](#2-hardware-und-pins)
+3. [Build und Flash](#3-build-und-flash)
+4. [Boot-Konfiguration](#4-boot-konfiguration)
+5. [UART-Protokoll](#5-uart-protokoll)
+6. [ESP-NOW-Protokoll](#6-esp-now-protokoll)
+7. [Befehlsreferenz (UART)](#7-befehlsreferenz-uart)
+8. [OTA](#8-ota)
+9. [BMA456 Beschleunigungssensor](#9-bma456-beschleunigungssensor)
+10. [LED-Ring](#10-led-ring)
+11. [Board-Input und Batterie](#11-board-input-und-batterie)
+12. [Persistenz (NVS)](#12-persistenz-nvs)
+13. [Protobuf und Code-Generierung](#13-protobuf-und-code-generierung)
+14. [Modulreferenz](#14-modulreferenz)
+15. [Logging-Tags](#15-logging-tags)
+
+---
+
+## 1. Projektziel
+
+**Powerpod** ist Firmware für ESP32-S3-Knoten in einem verteilten System:
+
+- Ein **Master** spricht per **UART** mit einem externen Host und verwaltet bis zu **16 Slaves** über **ESP-NOW**.
+- **Slaves** haben keinen UART-Befehlspfad; sie joinen über periodisches **Discover**, senden Heartbeats und liefern Sensor-/Statusdaten.
+- Master und Slave nutzen **identisches Firmware-Image**; Rolle und Funknetz werden beim Boot erkannt.
+
+Zielbild für den Host: Befehle an den Master senden; der Master steuert Slaves und **cached** deren Telemetrie (`client_registry`) für schnelle UART-Abfragen.
+
+---
+
+## 2. Hardware und Pins
+
+> Pinbelegung ist in `powerpod.h` als vorläufig markiert — mit Schaltplan abgleichen.
+
+| Signal | GPIO | Datei / Modul |
+|--------|------|----------------|
+| DIP Master/Slave | 4 | `powerpod.h` — Low = Master |
+| I2C SCL / SDA | 5 / 6 | IO-Expander `0x20`, BMA456 `0x18` |
+| UART1 TX / RX | **2 / 3** | `uart.h` (Adapter: ESP-TX → Host-RX) |
+| LED-Ring (WS2812) | 7 | `led_ring.c` |
+| BMA456 Interrupt | 10 | `bosch456.c` |
+| Taster | 12 | `board_input.c` |
+| LiPo ADC 1 | 1 | `board_input.c` |
+| LiPo ADC 2 | 11 | `board_input.c` |
+
+**UART (Host-Protokoll):** `UART_NUM_1`, **921600** Baud, 8N1, kein Flow-Control.
+
+**ESP-IDF-Log (Debug):** `esp_log_*` geht auf **UART0** (Standard-Konsole, typisch USB am Dev-Board, **115200** Baud, `CONFIG_ESP_CONSOLE_UART_NUM=0`). Das ist **getrennt** vom Host-UART1 — goTool liest keine `esp_log`-Ausgabe. Ohne angeschlossenes Debug-Kabel werden aktivierte Logs trotzdem formatiert und an UART0 gesendet (CPU-Overhead bleibt); nur `ESP_LOG_NONE` / Level-Filter vermeiden die Arbeit.
+
+**I2C:** 100 kHz, interne Pull-ups, gemeinsamer Bus für Expander und BMA456H.
+
+---
+
+## 3. Build und Flash
+
+**Ziel-Chip:** ESP32-S3 (ESP-IDF).
+
+```bash
+source ~/esp/esp-idf/export.sh   # oder export.fish
+cd /pfad/zu/powerpod
+idf.py build
+idf.py -p /dev/ttyUSB0 flash monitor
+```
+
+- **Git-Hash** wird beim Build in `POWERPOD_GIT_HASH` eingebettet (`main/CMakeLists.txt`).
+- **Firmware-Version:** `POWERPOD_FW_VERSION` (Default `1` in `esp_now_comm.c` / `cmd_version.c`).
+
+**Komponenten:**
+
+| Pfad | Inhalt |
+|------|--------|
+| `main/` | Anwendungslogik |
+| `components/bma456/` | Bosch BMA456H-Treiber (Vendor) |
+| `libs/nanopb/` | Protobuf-Codec für Embedded |
+
+---
+
+## 4. Boot-Konfiguration
+
+### 4.1 Initialisierungsreihenfolge (`powerpod.c`)
+
+1. `pod_settings_init()` — NVS
+2. `board_input_init_adc_only()` — LiPo-ADC
+3. Bei `POWERPOD_BATTERY_UV_ENABLE`: `battery_uv_evaluate_boot()` → ggf. Energiesparmodus (nur LED + ADC, **kein** weiterer Init)
+4. DIP → `app_config.master`
+5. I2C + IO-Expander → `app_config.network` (1–8)
+6. `init_bma456()` — optional, bei Fehler weiter ohne Sensor
+7. `pod_settings_apply_accel_deadzone()` wenn Sensor da
+8. OTA-Partition → `app_config.running_partition`
+9. `board_input_start_lipo_monitor()` + `board_input_init_button()`
+10. `esp_now_comm_init(&app_config)` — **normaler Pfad** (Master + Slave)
+11. `led_ring_init()`
+12. **Nur Master:** `cmd_queue` → `init_cmdHandler` → `init_uart` → alle `cmd_*_register()`
+
+### 4.2 Master vs. Slave
+
+| Funktion | Master | Slave |
+|----------|--------|-------|
+| UART Command-Handler | Ja | Nein |
+| ESP-NOW Discover senden | Ja (Broadcast) | Nein |
+| ESP-NOW auf Discover reagieren | Nein | Ja |
+| `client_registry` für Fremdknoten | Ja | Nein (nur eigener Join-State) |
+
+---
+
+## 5. UART-Protokoll
+
+*(Transport + Anwendung — Datenfluss-Diagramme in [`ARCHITECTURE.md`](ARCHITECTURE.md) §4–5.)*
+
+### 5.1 Rahmen
+
+| Byte | Inhalt |
+|------|--------|
+| 0 | `0xAA` Start |
+| 1 | Länge N (1–252) |
+| 2…N+1 | Payload |
+| N+2 | XOR-Checksum über Payload |
+| N+3 | `0xCC` Stopp |
+
+Implementierung: `uart.c` — `parse_uart_byte()`, `uart_send_framed()`.
+
+### 5.2 Anwendungs-Payload
+
+| Offset | Bedeutung |
+|--------|-----------|
+| 0 | `MessageType` (siehe Enum in `uart_messages.proto`) |
+| 1… | nanopb `UartMessage` (ohne separates type-Feld im protobuf-Teil) |
+
+**Antworten** nutzen dieselbe Struktur: Byte 0 = Response-Typ, Rest = kodierte `UartMessage`.
+
+### 5.3 Handler-Pipeline
+
+1. `uart_read_task` parst Frames → `uart_enqueue_packet`
+2. `generic_msg_t` → `cmd_queue`
+3. `vCmdDispatcherTask` → registrierter `msg_callback_t`
+4. Handler: `uart_cmd_decode(data, len, &msg)` — `data` ist **nur** protobuf-Teil; bei `len > 0` strikt (Decode/`which_payload`-Fehler → Fehlerantwort)
+5. `ota_session_uart_cmd_allowed()` — während OTA nur OTA-Befehle
+6. Antwort: `uart_cmd_init_response()` + Felder setzen + `uart_cmd_send()`
+
+Hilfsmakro für Request-Felder:
+
+```c
+UART_CMD_REQ(&uart_msg, alox_UartMessage_accel_deadzone_request_tag, accel_deadzone_request)
+```
+
+---
+
+## 6. ESP-NOW-Protokoll
+
+*(Join, Tasks, Registry — [`ARCHITECTURE.md`](ARCHITECTURE.md) §6.)*
+
+### 6.1 Grundlagen
+
+- WiFi **STA**, keine AP-Verbindung.
+- **Kanal** = `app_config.network` (1–13).
+- Payload = ein `EspNowMessage` (nanopb), max. `ESP_NOW_MAX_DATA_LEN`.
+- Schema: `main/proto/esp_now_messages.proto`.
+
+### 6.2 Nachrichtentypen
+
+| Type | Richtung | Payload | Zweck |
+|------|----------|---------|--------|
+| `ESPNOW_DISCOVER` | M→Broadcast | `discover.network` | Slaves finden Master |
+| `ESPNOW_SLAVE_INFO` | S→M | `slave_info` | Erste Registrierung |
+| `ESPNOW_HEARTBEAT` | S→M | `heartbeat` | Keepalive 1 s |
+| `ESPNOW_SET_ACCEL_DEADZONE` | M→S | `accel_deadzone` | Deadzone LSB |
+| `ESPNOW_SET_ACCEL_STREAM` | M→S | `accel_stream` | Stream ~16 ms |
+| `ESPNOW_ACCEL_SAMPLE` | S→M | `accel_sample` | x/y/z Roh-LSB |
+| `ESPNOW_SET_TAP_NOTIFY` | M→S | `tap_notify` | Tap-Arten filtern |
+| `ESPNOW_TAP_EVENT` | S→M | `tap_event` | kind 1/2/3 |
+| `ESPNOW_BATTERY_QUERY` | M→S | `battery_query` | On-demand |
+| `ESPNOW_BATTERY_REPORT` | S→M | `battery_report` | mV LiPo 1/2 |
+| `ESPNOW_LED_RING` | M→S | `led_ring` | Wie UART LED_RING |
+| `ESPNOW_FIND_ME` | M→S | `find_me` | LED-Locate |
+| `ESPNOW_RESTART` | M→S | `restart` | Reboot Slave |
+| `ESPNOW_UNICAST_TEST` | M→S | `unicast_test` | Link-Test |
+| `ESPNOW_ECHO_PING` | M→S | `echo_ping` | Latenztest (Host-Timestamp + `master_time_us`) |
+| `ESPNOW_ECHO_PONG` | S→M | `echo_pong` | Echo unverändert zurück zum Master |
+| `ESPNOW_OTA_*` | M↔S | `ota_*` | Firmware-Verteilung |
+
+### 6.3 Zeitkonstanten (`esp_now_comm.c`)
+
+| Konstante | Wert |
+|-----------|------|
+| Discover-Intervall | 500 ms |
+| Heartbeat | 1000 ms |
+| Client-Timeout (Master) | 3 × Heartbeat = 3 s → `available=false` |
+| Master-Verlust (Slave) | 5 s ohne Discover |
+| Accel-Stream | 16 ms |
+| Batterie-Report | 30 s (+ einmal 150 ms nach Join) |
+| Echo-Ping Timeout (Master) | 500 ms (`ESPNOW_ECHO_PING_TIMEOUT_MS`) |
+
+### 6.4 `EspNowSlavePresence`
+
+Felder: `network`, `mac` (6 B), `version`, `slave_id`, `available`, `used`.
+
+- `slave_id` = letztes Oktett der STA-MAC.
+- Registry auf dem Master indexiert über **Sender-MAC** der ESP-NOW-Callback.
+
+---
+
+## 7. Befehlsreferenz (UART)
+
+Nur auf dem **Master** registriert (`powerpod.c`). IDs aus `MessageType` in `uart_messages.proto`.
+
+| ID | Name | Modul | Kurzbeschreibung |
+|----|------|-------|------------------|
+| 1 | ACK | — | Reserviert |
+| 2 | ECHO | — | Reserviert |
+| 3 | VERSION | `cmd_version.c` | FW-Version, Git-Hash, OTA-Partition |
+| 4 | CLIENT_INFO | `cmd_client_info.c` | Liste `client_registry` |
+| 5 | CLIENT_INPUT | — | Geplant |
+| 6 | ACCEL_DEADZONE | `cmd_accel_deadzone.c` | Get/Set Deadzone lokal + ESP-NOW |
+| 7 | ESPNOW_UNICAST_TEST | `cmd_espnow_unicast_test.c` | Link-Test zu Slave |
+| 8 | LED_RING | `cmd_led_ring.c` | Ring lokal / ESP-NOW |
+| 16 | OTA_START | `cmd_ota.c` | UART-OTA beginnen |
+| 17 | OTA_PAYLOAD | `cmd_ota.c` | Chunk ≤200 B |
+| 18 | OTA_END | `cmd_ota.c` | Abschluss + ESP-NOW-Verteilung |
+| 19 | OTA_STATUS | `cmd_ota.c` | Gerät → Host Status |
+| 20 | OTA_START_ESPNOW | `cmd_ota.c` | Nur ESP-NOW aus Staging |
+| 21 | OTA_SLAVE_PROGRESS | `cmd_ota_slave_progress.c` | Fortschritt pro Slave |
+| 22 | FIND_ME | `cmd_espnow_find_me.c` | LED Locate |
+| 23 | RESTART | `cmd_restart.c` | Master oder Slave reboot |
+| 25 | ACCEL_STREAM | `cmd_accel_stream.c` | ESP-NOW Accel-Stream an/aus |
+| 26 | BATTERY_STATUS | `cmd_battery.c` | Cache LiPo Master + Slaves |
+| 27 | TAP_NOTIFY | `cmd_tap_notify.c` | Tap-Weiterleitung konfigurieren |
+| 29 | CACHE_STATUS | `cmd_cache_status.c` | Accel + Tap Cache (ein Round-Trip) |
+| 30 | ESPNOW_ECHO_PING | `cmd_espnow_echo_ping.c` | Timestamp-Echo über ESP-NOW (Latenztest) |
+| 31 | SET_LOG_LEVEL | `cmd_set_log_level.c` | ESP-IDF-Log-Level global (`"*"`) lesen/setzen |
+
+### 7.1 VERSION (3)
+
+- **Request:** nur Typ-Byte `0x03` oder leerer protobuf-Body.
+- **Response:** `version`, `git_hash`, `running_partition`.
+
+### 7.2 CLIENT_INFO (4)
+
+- **Response:** wiederholtes `ClientInfo` pro Registry-Eintrag: `id`, `mac`, `version`, `available`, `used`, `last_ping`, `last_success_ping`, Tap-/Stream-Flags.
+
+### 7.3 ACCEL_DEADZONE (6)
+
+- **Request:** `write`, `deadzone`, `client_id` (0=lokal), `all_clients`.
+- **Write Master:** Registry + `esp_now_comm_send_accel_deadzone` pro Slave; lokal `bma456` + NVS.
+- **Slave-Empfang:** `handle_slave_accel_deadzone` in `esp_now_comm.c`.
+
+### 7.4 ACCEL_STREAM (25)
+
+- Master setzt `client_registry_set_accel_stream` und sendet `ESPNOW_SET_ACCEL_STREAM`.
+- Slave-Task `slave_accel_stream_task` sendet `ESPNOW_ACCEL_SAMPLE` alle 16 ms.
+
+### 7.5 TAP_NOTIFY (27)
+
+- Konfiguriert auf Slave welche Tap-Arten `ESPNOW_TAP_EVENT` auslösen.
+- Tap-Quelle: BMA456-Interrupt → `on_bma456_tap` in `esp_now_comm.c`.
+
+### 7.6 CACHE_STATUS (29)
+
+- **Request:** leer.
+- **Response:** pro Slave mit Stream und/oder Tap-Notify: gecachte Accel-Werte (`age_ms`) und konsumierte Tap-Events (`client_registry_take_tap`).
+
+### 7.7 BATTERY_STATUS (26)
+
+- Liest **nur Cache** — keine ESP-NOW-Roundtrip-Pflicht pro Abfrage.
+- Master-Batterie: `client_registry_set_master_battery` (Monitor-Task).
+
+### 7.8 LED_RING (8)
+
+| mode | Bedeutung |
+|------|-----------|
+| 0 | Clear |
+| 1 | Progress 0–100 % |
+| 2 | Digit 0–10 |
+| 3 | Blink |
+| 4 | Find-me (RGB-Sequenz) |
+| 5 | Solid color |
+
+`client_id=0` nur Master-Ring; `>0` ESP-NOW; `all_clients` Broadcast über Registry.
+
+### 7.9 FIND_ME (22) / RESTART (23)
+
+- `client_id=0`: lokaler Master (`led_ring_find_me` / `pod_schedule_restart`).
+- `client_id>0`: ESP-NOW Unicast zum Slave.
+
+### 7.10 ESPNOW_UNICAST_TEST (7)
+
+Minimaler Master→Slave-Ping; Slave loggt `UNICAST TEST OK`.
+
+### 7.11 ESPNOW_ECHO_PING (30)
+
+Round-Trip-Latenztest zu einem **Slave** (`client_id` > 0, muss in der Registry sein).
+
+**Ablauf:**
+
+1. Host (goTool) setzt `timestamp_us` (Unix-µs) und sendet `EspNowEchoPingRequest` per UART.
+2. Master (`cmd_espnow_echo_ping.c`) löst MAC aus Registry auf, ruft `esp_now_comm_echo_ping()` auf.
+3. Master sendet `ESPNOW_ECHO_PING` mit `host_timestamp_us` und `master_time_us` (`esp_timer_get_time()` kurz vor Send).
+4. Slave (`handle_echo_ping`) antwortet mit `ESPNOW_ECHO_PONG` (Felder unverändert).
+5. Master empfängt Pong, berechnet `esp_rtt_us = esp_timer_get_time() - master_time_us`, antwortet per UART.
+
+**Request:** `client_id`, `timestamp_us` (vom Host gesetzt).
+
+**Response:** `success`, `client_id`, `timestamp_us` (echoed), `esp_rtt_us` (nur bei Erfolg).
+
+| Feld | Quelle | Bedeutung |
+|------|--------|-----------|
+| `timestamp_us` | Host → Slave → Host | Korrelations-ID; muss mit Request übereinstimmen |
+| `esp_rtt_us` | Master | Rohe µs-Differenz von `esp_timer_get_time()` (Ping-Send → Pong-Empfang im `recv_cb`) |
+
+**Implementierung:** `main/cmd/cmd_espnow_echo_ping.c`, `esp_now_comm_echo_ping()` in `esp_now_master.c`, Slave `handle_echo_ping` in `esp_now_slave.c`.
+
+**Host-seitig (goTool):** `rtt_ms` = volle UART-Kette (Send bis Response-Empfang); unabhängig von `esp_rtt_us`.
+
+### 7.12 SET_LOG_LEVEL (31)
+
+Laufzeit-Steuerung des **globalen** ESP-IDF-Log-Levels auf dem Master (`esp_log_level_set("*", …)`). Kein ESP-NOW, kein NVS — nur Master.
+
+**Request:** `write`, `level` (`esp_log_level_t`: 0=NONE, 1=ERROR, 2=WARN, 3=INFO, 4=DEBUG, 5=VERBOSE).
+
+| `write` | Verhalten |
+|---------|-----------|
+| `false` / leer | Aktuelles Level lesen (`esp_log_level_get("*")`) |
+| `true` | Level setzen; ungültige Werte (>5) → `success=false` |
+
+**Response:** `success`, `level` (aktuell bzw. gesetzt).
+
+**Boot-Default:** `CONFIG_LOG_DEFAULT_LEVEL` in `sdkconfig` (aktuell **INFO** = 3). Kann per UART/Web-UI zur Laufzeit geändert werden; nach Reboot gilt wieder der sdkconfig-Wert.
+
+**Ausgabe:** Logs erscheinen auf **UART0** (Debug-USB), nicht auf dem Host-UART1 (goTool).
+
+```bash
+go run . -port /dev/ttyUSB0 log-level
+go run . -port /dev/ttyUSB0 log-level -set -level 3
+```
+
+---
+
+## 8. OTA
+
+### 8.1 UART-OTA (nur Master)
+
+Implementierung: `ota_uart.c`, Steuerung `cmd/cmd_ota.c`.
+
+| Phase | Host → Master | Master → Host |
+|-------|---------------|---------------|
+| Start | `OTA_START` + `total_size` | `OTA_STATUS` preparing → ready |
+| Daten | `OTA_PAYLOAD` ≤200 B, `seq` | `block_ack` je 4096 B Flash |
+| Ende | `OTA_END` | success/failed; startet ESP-NOW-Verteilung |
+
+- Inaktive Partition: `esp_ota_get_next_update_partition()`.
+- LED-Ring zeigt Fortschritt (blau Schreiben, grün Verteilung).
+
+### 8.2 ESP-NOW-OTA (Master → Slaves)
+
+`ota_espnow.c` — gleiche Status-Codes wie UART.
+
+1. `ESPNOW_OTA_START` + `total_size` → Slave `ota_espnow_slave_on_start`
+2. `ESPNOW_OTA_PAYLOAD` bis 200 B → 4 KiB Buffer auf Slave
+3. `ESPNOW_OTA_END` → Boot-Partition setzen
+4. Slave antwortet `ESPNOW_OTA_STATUS` (mit `send_message_ex` + Semaphore auf Master)
+
+Nach Erfolg: **alle Knoten neu starten**.
+
+### 8.3 OTA_SLAVE_PROGRESS (21)
+
+Abfrage laufender oder letzter ESP-NOW-Verteilung: pro Slave `bytes_written`, `status`, `error`.
+
+---
+
+## 9. BMA456 Beschleunigungssensor
+
+| Thema | Detail |
+|-------|--------|
+| Wrapper | `bosch456.c` / `bosch456.h` |
+| Chip-Variante | BMA456**H** (`bma456h.c` im Component) |
+| I2C | Adresse 0x18, 100 kHz |
+| Polling | Task ~10 Hz |
+| Interrupt GPIO 10 | Single/Double/Triple Tap |
+| Deadzone | Software-Filter für Logs/Stream (Default 100 LSB) |
+| API | `bma456_read_accel`, `bma456_set_accel_deadzone`, `bma456_set_tap_handler` |
+
+Ohne Sensor: `bma456_is_ready() == false`, Firmware läuft weiter.
+
+---
+
+## 10. LED-Ring
+
+- **95 LEDs**, WS2812 über RMT (`led_ring.c`).
+- Segment-Karten für Ziffern 0–10 in `digit_lookup[]`.
+- **Kein** lokaler Demo-Loop — Anzeige nur über UART (`cmd_led_ring.c`) oder ESP-NOW `ESPNOW_LED_RING`.
+- Helligkeit: `intensity` 0 → Default ~5 % (`LED_RING_DEFAULT_INTENSITY`).
+- Modi: `0` clear … `5` color, `6` **battery-low** (erste 4 LEDs rot ~10 %, 5 s).
+
+---
+
+## 11. Board-Input und Batterie
+
+`board_input.c`:
+
+- **Taster** GPIO 12 — Logging bei Druck.
+- **LiPo-ADC** GPIO 1 und GPIO 11 (Pin-Spannung in mV).
+- Master: `master_monitor_task` aktualisiert Master-Batterie alle 30 s.
+- Slave: `slave_send_battery_report_to_master` nach Join, Heartbeat und Query.
+
+Spannungen in Millivolt in Registry und `BATTERY_STATUS`-UART.
+
+### Software-UV-Schutz (`battery_uv.c`)
+
+Aktivierbar mit `POWERPOD_BATTERY_UV_ENABLE` in `powerpod.h` (CMake-Override möglich).
+
+| Zustand | ADC-Schwelle | Logik |
+|---------|--------------|-------|
+| UV | < 2300 mV | Ein gültiger Kanal reicht |
+| Geladen | ≥ 3000 mV | Alle gültigen Kanäle |
+
+- NVS-Key `uv_latch` in `pod_settings.c`
+- Boot: ADC früh, bei UV nur LED + ADC-Poll (kein ESP-NOW/WiFi/UART/I2C/Button)
+- Runtime: `battery_uv_poll()` im LiPo-Monitor (2 Samples Debounce)
+- LED-Anzeige: Mode `6` battery-low (`led_ring_show_battery_low`)
+
+---
+
+## 12. Persistenz (NVS)
+
+`pod_settings.c` — Namespace `powerpod`:
+
+| Key | Inhalt |
+|-----|--------|
+| `accel_dz` | Accel-Deadzone LSB |
+| `uv_latch` | Software-UV-Zustand (`1` = Energiesparmodus) |
+
+Gespeichert bei lokalem Set (UART `client_id=0`, ESP-NOW auf Slave). Geladen nach `init_bma456()`.
+
+---
+
+## 13. Protobuf und Code-Generierung
+
+```bash
+make proto_generate        # beide Schemas
+make proto_generate_uart   # nur uart_messages.proto
+make proto_generate_espnow # nur esp_now_messages.proto
+```
+
+**Ausgabe:** `main/proto/*.pb.c`, `*.pb.h`  
+**Optionen:** `main/proto/uart_messages.options` (nanopb max_size etc.)
+
+Includes in generierten `.pb.c` müssen `"uart_messages.pb.h"` heißen (nicht `main/proto/...`).
+
+**Paketname protobuf:** `alox` → C-Prefix `alox_`.
+
+---
+
+## 14. Modulreferenz
+
+### 14.1 Kern
+
+| Datei | Rolle |
+|-------|--------|
+| `powerpod.c` | `app_main`, Init, Master-Register |
+| `app_config.h` | Laufzeit-Konfiguration |
+| `cmd_handler.c` | Queue + Dispatcher |
+| `uart.c` | Framing |
+| `uart_proto.c` | UartMessage send |
+| `uart_cmd.c` | Handler-Hilfen |
+
+### 14.2 Kommunikation
+
+| Datei | Rolle |
+|-------|--------|
+| `esp_now_comm.c` | Init, recv-Router |
+| `esp_now_core.c` | WiFi, Peer, gemeinsamer Send |
+| `esp_now_master.c` | Master-Tasks, Registry, Unicast send |
+| `esp_now_slave.c` | Join, Heartbeat, Accel/Tap send |
+| `esp_now_proto.c` | nanopb für EspNowMessage |
+| `client_registry.c` | Slave-Tabelle + Telemetrie-Cache |
+
+### 14.3 Befehle (`main/cmd/`)
+
+| Datei | UART-Typ |
+|-------|----------|
+| `cmd_version.c` | VERSION |
+| `cmd_client_info.c` | CLIENT_INFO |
+| `cmd_accel_deadzone.c` | ACCEL_DEADZONE |
+| `cmd_accel_stream.c` | ACCEL_STREAM |
+| `cmd_tap_notify.c` | TAP_NOTIFY |
+| `cmd_cache_status.c` | CACHE_STATUS |
+| `cmd_battery.c` | BATTERY_STATUS |
+| `cmd_led_ring.c` | LED_RING |
+| `cmd_espnow_find_me.c` | FIND_ME |
+| `cmd_restart.c` | RESTART |
+| `cmd_espnow_unicast_test.c` | ESPNOW_UNICAST_TEST |
+| `cmd_espnow_echo_ping.c` | ESPNOW_ECHO_PING |
+| `cmd_set_log_level.c` | SET_LOG_LEVEL |
+| `cmd_ota.c` | OTA_* |
+| `cmd_ota_slave_progress.c` | OTA_SLAVE_PROGRESS |
+
+### 14.4 Domäne
+
+| Datei | Rolle |
+|-------|--------|
+| `bosch456.c` | Accelerometer + Tap |
+| `led_ring.c` | LED-Anzeige |
+| `board_input.c` | Taster, ADC |
+| `battery_uv.c` | Software-UV-Schutz, Energiesparmodus |
+| `pod_settings.c` | NVS |
+| `pod_reboot.c` | Verzögerter Restart |
+| `ota_uart.c` | Flash-Puffer UART-OTA |
+| `ota_espnow.c` | OTA Master/Slave; Slave-Work-Queue |
+| `ota_session.c` | OTA-Sperre für UART-Dispatcher |
+
+### 14.5 Protobuf
+
+| Datei | Rolle |
+|-------|--------|
+| `proto/uart_messages.proto` | UART-Vertrag |
+| `proto/esp_now_messages.proto` | ESP-NOW-Vertrag |
+| `proto/pb_encode.c`, `pb_decode.c`, `pb_common.c` | nanopb Runtime |
+
+---
+
+## 15. Logging-Tags
+
+**Level zur Laufzeit:** UART `SET_LOG_LEVEL` (31) oder Dashboard „ESP Log-Level“ — steuert nur die Konsolen-Ausgabe auf UART0, nicht das Host-Protokoll.
+
+| Tag | Modul |
+|-----|--------|
+| `[Main]` | powerpod.c |
+| `[LOG_LVL]` | cmd_set_log_level.c |
+| `[UART]` | uart.c |
+| `[CMDH]` | cmd_handler.c |
+| `[UART_CMD]` | uart_cmd.c |
+| `[ESPNOW]` | esp_now_comm.c |
+| `[CLIENTS]` | client_registry.c |
+| `[BMA456]` | bosch456.c |
+| `[VERSION]` etc. | jeweiliger cmd_* |
+
+Typischer Ablauf bei UART-Befehl:
+
+```
+[UART] received message cmd=0x06 len=…
+[CMDH] trigger command ACCEL_DEADZONE (0x06)
+[ACCEL_DZ] …
+```
+
+---
+
+## Anhang: Neues UART-Kommando hinzufügen
+
+1. `uart_messages.proto` erweitern → `make proto_generate_uart`
+2. `cmd/cmd_neu.c` mit `handle_*` + `uart_cmd_register()`
+3. In `powerpod.c` `cmd_neu_register()` aufrufen (nur Master-Zweig)
+4. Bei Slave-Bedarf: `esp_now_messages.proto` + `esp_now_comm_send_*` + Slave-Zweig in `espnow_recv_cb`
+
+Siehe [`adding-a-feature.md`](adding-a-feature.md) für ein vollständiges Beispiel (Find Me).

docs/adding-a-feature.md

@@ -26,8 +26,8 @@ sequenceDiagram
 | Schema UART | `main/proto/uart_messages.proto` | `MessageType`, Request/Response für Host ↔ Master |
 | Schema ESP-NOW | `main/proto/esp_now_messages.proto` | Master ↔ Slave (ohne UART) |
 | Transport UART | `main/uart.c`, `goTool/uart/` | Rahmen `0xAA … 0xCC`, Byte 0 = Command-ID |
-| Dispatch | `main/cmd_handler.c`, `main/uart_cmd.c` | Queue + `uart_cmd_register()` |
-| Master-Logik | `main/cmd_*.c` | Decode, Registry, ESP-NOW senden |
+| Dispatch | `main/cmd/cmd_handler.c`, `main/uart_cmd.c` | Queue + `uart_cmd_register()` |
+| Master-Logik | `main/cmd/cmd_*.c` | Decode, Registry, ESP-NOW senden |
 | ESP-NOW | `main/esp_now_comm.c` | Encode/Decode, Send, Slave-`recv_cb` |
 | Geräte-Funktion | z.B. `main/led_ring.c` | Wiederverwendbare Aktion (Master + Slave) |
 | Host | `goTool/cmd_*.go`, `api_serve.go`, `webui/` | CLI, HTTP, UI |
@@ -46,8 +46,8 @@ sequenceDiagram
 
 **Find me:** UART `FIND_ME` mit `client_id`; `0` = Master-Ring, `>0` = Unicast `ESPNOW_FIND_ME` an die Slave-MAC aus der Registry.
 
-Referenz für **nur ESP-NOW-Weiterleitung ohne lokale Wirkung:** `cmd_espnow_unicast_test.c`  
-Referenz für **Master lokal + Slave + `client_id`:** `cmd_espnow_find_me.c`, `cmd_accel_deadzone.c`
+Referenz für **nur ESP-NOW-Weiterleitung ohne lokale Wirkung:** `main/cmd/cmd_espnow_unicast_test.c`  
+Referenz für **Master lokal + Slave + `client_id`:** `main/cmd/cmd_espnow_find_me.c`, `main/cmd/cmd_accel_deadzone.c`
 
 ---
 
@@ -129,13 +129,13 @@ Funktion, die auf **Master und Slave** gleich wirken soll, gehört **nicht** in
 Find me:
 
 - `led_ring_find_me()` in `led_ring.c` — sequenz `LED_CMD_FIND_ME` (3× rot/grün/blau, volle Helligkeit)
-- Optional separater UART-Pfad nur für Ring-Steuerung: `LED_RING` mode `4` in `cmd_led_ring.c` (ohne ESP-NOW)
+- Optional separater UART-Pfad nur für Ring-Steuerung: `LED_RING` mode `4` in `main/cmd/cmd_led_ring.c` (ohne ESP-NOW)
 
 ---
 
 ## Schritt 4 — UART-Command-Handler (nur Master)
 
-Neue Dateien: `main/cmd_espnow_find_me.c`, `main/cmd_espnow_find_me.h`
+Neue Dateien: `main/cmd/cmd_espnow_find_me.c`, `main/cmd/cmd_espnow_find_me.h`
 
 Muster (gekürzt):
 
@@ -191,8 +191,8 @@ Hilfs-APIs (`uart_cmd.h`):
 cmd_espnow_find_me_register();
 ```
 
-**Build:** `main/CMakeLists.txt` → `"cmd_espnow_find_me.c"`  
-**Logging-Namen:** `main/cmd_handler.c` → `case alox_MessageType_FIND_ME: return "FIND_ME";`
+**Build:** `main/CMakeLists.txt` → `"cmd/cmd_espnow_find_me.c"`  
+**Logging-Namen:** `main/cmd/cmd_handler.c` → `case alox_MessageType_FIND_ME: return "FIND_ME";`
 
 ### Ablauf UART intern
 
@@ -324,7 +324,7 @@ idf.py build
 - [ ] Geräte-Modul (z.B. `led_ring_*`)
 - [ ] `cmd_*.c` + `uart_cmd_register`
 - [ ] `esp_now_comm`: `send_*` + Slave-`recv` case
-- [ ] `CMakeLists.txt`, `powerpod.c`, `cmd_handler.c` Name
+- [ ] `CMakeLists.txt`, `powerpod.c`, `cmd/cmd_handler.c` Name
 - [ ] goTool: CLI, `client_api`, optional `api_serve` + WebUI
 - [ ] README aktualisieren
 - [ ] Master + Slave flashen bei ESP-NOW-Proto-Änderung
@@ -337,7 +337,7 @@ idf.py build
 |---------|--------|
 | UART Proto | `main/proto/uart_messages.proto` |
 | ESP-NOW Proto | `main/proto/esp_now_messages.proto` |
-| UART Handler | `main/cmd_espnow_find_me.c` |
+| UART Handler | `main/cmd/cmd_espnow_find_me.c` |
 | ESP-NOW | `main/esp_now_comm.c`, `main/esp_now_comm.h` |
 | LED | `main/led_ring.c`, `main/led_ring.h` |
 | Host CLI | `goTool/cmd_find_me.go` |
@@ -345,7 +345,7 @@ idf.py build
 
 Ähnliche Features zum Abgucken:
 
-- **Nur Master, kein ESP-NOW:** `cmd_version.c`, `cmd_led_ring.c`
-- **Nur Slave per ESP-NOW (Master leitet nur durch):** `cmd_espnow_unicast_test.c`
-- **Master + alle Slaves / Filter:** `cmd_accel_deadzone.c`
-- **Großer ESP-NOW-Fluss mit Status:** `ota_espnow.c`, `cmd_ota.c`
+- **Nur Master, kein ESP-NOW:** `main/cmd/cmd_version.c`, `main/cmd/cmd_led_ring.c`, `main/cmd/cmd_set_log_level.c`
+- **Nur Slave per ESP-NOW (Master leitet nur durch):** `main/cmd/cmd_espnow_unicast_test.c`
+- **Master + alle Slaves / Filter:** `main/cmd/cmd_accel_deadzone.c`
+- **Großer ESP-NOW-Fluss mit Status:** `ota_espnow.c`, `main/cmd/cmd_ota.c`

goTool/Makefile

@@ -0,0 +1,2 @@
+win:
+	GOOS=windows GOARCH=386 go build .

goTool/README.md

@@ -24,14 +24,19 @@ go run . -port /dev/ttyUSB0 clients
 |---------|--------------|-------------|
 | `version` | `0x03` | Prints `version` and `git_hash` from firmware |
 | `clients` | `0x04` | Lists slaves registered on the master via ESP-NOW |
+| `deadzone` | `0x06` | Get/set accelerometer deadzone LSB (`-set`, `-value`, `-client`, `-all`) |
+| `tap-notify` | `0x1b` | Get/set which tap kinds (single/double/triple) notify via ESP-NOW (`-set`, `-client`, `-all`, `-single`, `-double`, `-triple`) |
+| `cache-status` | `0x1d` | Subscribed accel + tap cache (`CACHE_STATUS`); one UART round-trip for 16 ms polling |
 | `unicast-test` | `0x07` | Sends ESP-NOW unicast test to one slave (`-client`, `-seq`) |
+| `echo-ping` | `0x1e` | ESP-NOW echo round-trip to one slave (`-client`); prints `rtt_ms` (host UART chain) and `esp_rtt_us` (master ESP-NOW, raw µs) |
 | `test` | — | Run an automated scenario (JSON configs under `testdata/`) |
 | `serve` | — | Web dashboard at `http://localhost:8080` (WebSocket live updates) |
 | `ota` | 16–19 | UART firmware upload to master; firmware then pushes to slaves via ESP-NOW |
 | `ota-progress` | 21 | Query per-slave ESP-NOW OTA progress on the master (`-client N`, default all) |
-| `led-ring` | 8 | LED ring: `-mode clear\|progress\|digit\|blink\|find-me`, … |
+| `led-ring` | 8 | LED ring: `-mode clear\|color\|progress\|digit\|blink\|find-me\|battery-low`, `-client`, `-all` |
 | `find-me` | 22 | Locate pod (`-client 0` master, `>0` slave via ESP-NOW) |
 | `restart` | 23 | Reboot master or slave (`-client 0` / `>0`) |
+| `log-level` | `0x1f` | Get/set master ESP-IDF log level for tag `"*"` (`-set`, `-level` 0–5); output on UART0 debug, not host UART |
 
 `clients` requires slaves to have responded to master discover broadcasts first.
 
@@ -60,28 +65,43 @@ Polls the master over UART and pushes state to the browser via WebSocket (Alpine
 ```bash
 go run . -port /dev/ttyUSB0 serve
 go run . -port /dev/ttyUSB0 serve -addr :8080 -interval 2s
+go run . -port /dev/ttyUSB0 serve -api-addr :8081 -accel-interval 16ms
 make gotool-serve PORT=/dev/ttyUSB0
 ```
 
 Open [http://localhost:8080](http://localhost:8080) — shows master firmware info and the ESP-NOW client table from `CLIENT_INFO`.
 
+**Tap (dashboard):** two independent controls per slave:
+
+| Column | Meaning |
+|--------|---------|
+| Tap-Notify (S/D/T) | Which tap kinds the **slave** sends to the master over ESP-NOW (UART `TAP_NOTIFY`) — does **not** poll UART |
+| Tap (An/Aus) | Host **receive**: poll master tap cache (~16 ms) and show last tap for **≥2 s** |
+
+Enable notify first, then turn receive on to see events. Same split as the external WebSocket API (`set_tap_notify` vs `set_tap_stream`).
+
 If the UART device is unplugged or the port disappears, `serve` keeps running and retries on each poll interval; the UI shows **UART off** until the port is available again.
 
-The dashboard can configure nodes using the same UART commands as the CLI:
+### HTTP / WebSocket API
 
-| UI action | CLI equivalent |
-|-----------|------------------|
-| Nur Master | `deadzone -set -value N -client 0` |
-| Einzelner Slave | `deadzone -set -value N -client ID` |
-| Alle Slaves | per-slave ESP-NOW (Master bleibt unverändert; CLI `-all` setzt auch den Master) |
-| Unicast test | `unicast-test -client ID` |
+`serve` also listens on **`:8081`** for external programs (`-api-addr`, empty to disable). Same UART as the dashboard.
 
-HTTP API (used by the web UI): `GET/POST /api/deadzone`, `POST /api/unicast-test`, `POST /api/find-me`, `POST /api/restart`, `POST /api/ota` (multipart field `firmware`, max 2 MiB).
+| Doc | Content |
+|-----|---------|
+| **[docs/API_WEBSOCKET.md](docs/API_WEBSOCKET.md)** | `ws://…:8081/ws` commands and **`input` push stream** (accel + tap) |
+| **[docs/API_REST.md](docs/API_REST.md)** | REST on `:8080` (dashboard) and `:8081` (battery, LED, service info) |
+
+CLI:
+
+```bash
+go run . -port /dev/ttyUSB0 tap-notify -client 16 -set -single
+go run . -port /dev/ttyUSB0 cache-status
+```
 
 | UI / API | Behaviour |
 |----------|-----------|
-| Firmware OTA card | Same as `ota` CLI; WebSocket `ota_progress` with `step` `master` (UART) then `slaves` (ESP-NOW) |
-| `POST /api/ota` | Upload `.bin` to master only — slaves are updated by firmware over ESP-NOW after `OTA_END` |
+| Firmware OTA card | Same as `ota` CLI; dashboard WebSocket `ota_progress` ([REST doc](docs/API_REST.md)) |
+| `POST /api/ota` | Upload `.bin` to master — slaves updated by firmware over ESP-NOW after `OTA_END` |
 
 ```bash
 go run . -port /dev/ttyUSB0 ota build/powerpod.bin
@@ -95,8 +115,24 @@ go run . -port /dev/ttyUSB0 unicast-test -client 16 -seq 42
 
 On success the slave serial log should show `UNICAST TEST OK from master … seq=42`.
 
+```bash
+go run . -port /dev/ttyUSB0 echo-ping -client 16
+go run . -port /dev/ttyUSB0 log-level
+go run . -port /dev/ttyUSB0 log-level -set -level 3
+```
+
+`log-level` controls `esp_log_*` on the master (UART0 USB console). The host protocol UART (GPIO 2/3) is unchanged.
+
+Measures latency to one slave. `rtt_ms` is the full host round-trip (UART + ESP-NOW + UART back). `esp_rtt_us` is the master-side ESP-NOW leg only (`esp_timer_get_time()` delta, raw microseconds from firmware).
+
 Example output:
 
+```
+echo ping: success=true client_id=16 rtt_ms=49.729 esp_rtt_us=18234
+```
+
+`clients` example:
+
 ```
 clients (2):
   [0] id=42 mac=aabbccddeeff ver=1 available=true used=false last_ping=250 last_success_ping=250

goTool/accel_stream_ctl.go

@@ -0,0 +1,40 @@
+package main
+
+import "sync"
+
+// accelStreamCtl tracks which slaves the host wants to poll for accel (mirrors firmware).
+type accelStreamCtl struct {
+	mu      sync.Mutex
+	enabled map[uint32]struct{}
+}
+
+func newAccelStreamCtl() *accelStreamCtl {
+	return &accelStreamCtl{enabled: make(map[uint32]struct{})}
+}
+
+func (c *accelStreamCtl) Set(clientID uint32, on bool) {
+	c.mu.Lock()
+	defer c.mu.Unlock()
+	if on {
+		c.enabled[clientID] = struct{}{}
+	} else {
+		delete(c.enabled, clientID)
+	}
+}
+
+func (c *accelStreamCtl) Any() bool {
+	c.mu.Lock()
+	defer c.mu.Unlock()
+	return len(c.enabled) > 0
+}
+
+func (c *accelStreamCtl) SyncFromClients(clients []ClientView) {
+	c.mu.Lock()
+	defer c.mu.Unlock()
+	c.enabled = make(map[uint32]struct{})
+	for _, cl := range clients {
+		if cl.AccelStream {
+			c.enabled[cl.ID] = struct{}{}
+		}
+	}
+}

goTool/api_accel_stream.go

@@ -0,0 +1,220 @@
+package main
+
+import (
+	"encoding/json"
+	"fmt"
+	"net/http"
+	"strconv"
+
+	"powerpod/gotool/pb"
+)
+
+type accelStreamAPIRequest struct {
+	Write      bool   `json:"write"`
+	Enable     bool   `json:"enable"`
+	ClientID   uint32 `json:"client_id"`
+	AllClients bool   `json:"all_clients"`
+}
+
+type accelStreamAPIResponse struct {
+	Enabled       bool   `json:"enabled"`
+	ClientID      uint32 `json:"client_id"`
+	Success       bool   `json:"success"`
+	SlavesUpdated uint32 `json:"slaves_updated"`
+	Error         string `json:"error,omitempty"`
+}
+
+type clientAccelStreamBody struct {
+	Enable bool `json:"enable"`
+}
+
+func mountAccelStreamAPI(mux *http.ServeMux, link *managedSerial, hub *wsHub, ctl *accelStreamCtl) {
+	mux.HandleFunc("GET /api/clients/{clientID}/accel-stream", func(w http.ResponseWriter, r *http.Request) {
+		clientID, err := parsePathClientID(r)
+		if err != nil {
+			writeJSON(w, http.StatusBadRequest, accelStreamAPIResponse{Error: err.Error()})
+			return
+		}
+		serveAccelStreamGet(w, clientID, link, hub, ctl)
+	})
+	mux.HandleFunc("PUT /api/clients/{clientID}/accel-stream", func(w http.ResponseWriter, r *http.Request) {
+		clientID, err := parsePathClientID(r)
+		if err != nil {
+			writeJSON(w, http.StatusBadRequest, accelStreamAPIResponse{Error: err.Error()})
+			return
+		}
+		serveClientAccelStreamPut(w, r, clientID, link, hub, ctl)
+	})
+
+	mux.HandleFunc("/api/accel-stream", func(w http.ResponseWriter, r *http.Request) {
+		switch r.Method {
+		case http.MethodGet:
+			serveAccelStreamGetQuery(w, r, link, hub, ctl)
+		case http.MethodPost:
+			serveAccelStreamPost(w, r, link, hub, ctl)
+		default:
+			http.Error(w, "method not allowed", http.StatusMethodNotAllowed)
+		}
+	})
+}
+
+func parsePathClientID(r *http.Request) (uint32, error) {
+	s := r.PathValue("clientID")
+	if s == "" {
+		return 0, fmt.Errorf("client_id required")
+	}
+	v, err := strconv.ParseUint(s, 10, 32)
+	if err != nil || v == 0 {
+		return 0, fmt.Errorf("invalid client_id")
+	}
+	return uint32(v), nil
+}
+
+func applyAccelStreamClient(link *managedSerial, hub *wsHub, ctl *accelStreamCtl, clientID uint32, enable bool) accelStreamAPIResponse {
+	resp, err := link.AccelStream(&pb.AccelStreamRequest{
+		Write:    true,
+		Enable:   enable,
+		ClientId: clientID,
+	})
+	if err != nil {
+		return accelStreamAPIResponse{
+			ClientID: clientID,
+			Error:    err.Error(),
+		}
+	}
+	out := accelStreamAPIResponse{
+		Enabled:       enable,
+		ClientID:      resp.GetClientId(),
+		Success:       resp.GetSuccess(),
+		SlavesUpdated: resp.GetSlavesUpdated(),
+	}
+	if resp.GetSuccess() {
+		if ctl != nil {
+			ctl.Set(clientID, enable)
+		}
+		if hub != nil {
+			hub.patchClientAccelStream(clientID, enable)
+		}
+	} else {
+		out.Enabled = resp.GetEnabled()
+	}
+	return out
+}
+
+func serveAccelStreamGet(w http.ResponseWriter, clientID uint32, link *managedSerial, hub *wsHub, ctl *accelStreamCtl) {
+	resp, err := link.AccelStreamPoll(&pb.AccelStreamRequest{
+		Write:    false,
+		ClientId: clientID,
+	})
+	if err != nil {
+		writeJSON(w, http.StatusServiceUnavailable, accelStreamAPIResponse{
+			ClientID: clientID,
+			Error:    err.Error(),
+		})
+		return
+	}
+	if ctl != nil {
+		ctl.Set(clientID, resp.GetEnabled())
+	}
+	writeJSON(w, http.StatusOK, accelStreamAPIResponse{
+		Enabled:  resp.GetEnabled(),
+		ClientID: resp.GetClientId(),
+		Success:  resp.GetSuccess(),
+	})
+}
+
+func serveAccelStreamGetQuery(w http.ResponseWriter, r *http.Request, link *managedSerial, hub *wsHub, ctl *accelStreamCtl) {
+	clientID, err := parseUintQuery(r, "client_id", 0)
+	if err != nil || clientID == 0 {
+		writeJSON(w, http.StatusBadRequest, accelStreamAPIResponse{Error: "client_id required"})
+		return
+	}
+	serveAccelStreamGet(w, clientID, link, hub, ctl)
+}
+
+func serveClientAccelStreamPut(w http.ResponseWriter, r *http.Request, clientID uint32, link *managedSerial, hub *wsHub, ctl *accelStreamCtl) {
+	var body clientAccelStreamBody
+	if err := json.NewDecoder(r.Body).Decode(&body); err != nil {
+		writeJSON(w, http.StatusBadRequest, accelStreamAPIResponse{Error: "invalid JSON"})
+		return
+	}
+	out := applyAccelStreamClient(link, hub, ctl, clientID, body.Enable)
+	status := http.StatusOK
+	if out.Error != "" {
+		status = http.StatusServiceUnavailable
+	} else if !out.Success {
+		status = http.StatusServiceUnavailable
+	}
+	writeJSON(w, status, out)
+}
+
+func serveAccelStreamPost(w http.ResponseWriter, r *http.Request, link *managedSerial, hub *wsHub, ctl *accelStreamCtl) {
+	var body accelStreamAPIRequest
+	if err := json.NewDecoder(r.Body).Decode(&body); err != nil {
+		writeJSON(w, http.StatusBadRequest, accelStreamAPIResponse{Error: "invalid JSON"})
+		return
+	}
+
+	if body.AllClients {
+		updated, err := applyAccelStreamAll(link, body.Enable)
+		if err != nil {
+			writeJSON(w, http.StatusServiceUnavailable, accelStreamAPIResponse{Error: err.Error()})
+			return
+		}
+		clients, _ := link.listClientsPoll()
+		for _, c := range clients {
+			if ctl != nil {
+				ctl.Set(c.GetId(), body.Enable)
+			}
+			if hub != nil {
+				hub.patchClientAccelStream(c.GetId(), body.Enable)
+			}
+		}
+		writeJSON(w, http.StatusOK, accelStreamAPIResponse{
+			Enabled:       body.Enable,
+			Success:       updated > 0,
+			SlavesUpdated: updated,
+		})
+		return
+	}
+
+	if body.ClientID == 0 {
+		writeJSON(w, http.StatusBadRequest, accelStreamAPIResponse{Error: "client_id required"})
+		return
+	}
+
+	out := applyAccelStreamClient(link, hub, ctl, body.ClientID, body.Enable)
+	status := http.StatusOK
+	if out.Error != "" || !out.Success {
+		status = http.StatusServiceUnavailable
+	}
+	writeJSON(w, status, out)
+}
+
+func applyAccelStreamAll(link *managedSerial, enable bool) (uint32, error) {
+	clients, err := link.listClients()
+	if err != nil {
+		return 0, err
+	}
+	var updated uint32
+	for _, c := range clients {
+		resp, err := link.AccelStream(&pb.AccelStreamRequest{
+			Write:    true,
+			Enable:   enable,
+			ClientId: c.GetId(),
+		})
+		if err != nil {
+			continue
+		}
+		if resp.GetSuccess() {
+			updated++
+		}
+	}
+	if len(clients) == 0 {
+		return 0, fmt.Errorf("no slaves registered")
+	}
+	if updated == 0 {
+		return 0, fmt.Errorf("accel stream not applied to any slave")
+	}
+	return updated, nil
+}

goTool/api_battery.go

@@ -0,0 +1,60 @@
+package main
+
+import (
+	"encoding/json"
+	"net/http"
+	"strconv"
+)
+
+func mountBatteryAPI(mux *http.ServeMux, link *managedSerial) {
+	mux.HandleFunc("/api/battery", func(w http.ResponseWriter, r *http.Request) {
+		switch r.Method {
+		case http.MethodGet:
+			serveBatteryGet(w, r, link)
+		case http.MethodPost:
+			serveBatteryPost(w, r, link)
+		default:
+			http.Error(w, "method not allowed", http.StatusMethodNotAllowed)
+		}
+	})
+}
+
+func serveBatteryGet(w http.ResponseWriter, r *http.Request, link *managedSerial) {
+	req := batteryAPIRequest{}
+	if v := r.URL.Query().Get("all_clients"); v == "1" || v == "true" {
+		req.AllClients = true
+	}
+	if s := r.URL.Query().Get("client_id"); s != "" {
+		id, err := strconv.ParseUint(s, 10, 32)
+		if err != nil {
+			writeJSON(w, http.StatusBadRequest, batteryAPIResponse{Error: "invalid client_id"})
+			return
+		}
+		req.ClientID = uint32(id)
+	} else if !req.AllClients {
+		req.AllClients = true
+	}
+	out := applyBatteryStatus(link, req)
+	status := http.StatusOK
+	if out.Error != "" || !out.Success {
+		status = http.StatusServiceUnavailable
+	}
+	writeJSON(w, status, out)
+}
+
+func serveBatteryPost(w http.ResponseWriter, r *http.Request, link *managedSerial) {
+	var body batteryAPIRequest
+	if err := json.NewDecoder(r.Body).Decode(&body); err != nil {
+		writeJSON(w, http.StatusBadRequest, batteryAPIResponse{Error: "invalid JSON"})
+		return
+	}
+	if !body.AllClients && body.ClientID == 0 {
+		body.AllClients = true
+	}
+	out := applyBatteryStatus(link, body)
+	status := http.StatusOK
+	if out.Error != "" || !out.Success {
+		status = http.StatusServiceUnavailable
+	}
+	writeJSON(w, status, out)
+}

goTool/api_led_ring.go

@@ -0,0 +1,36 @@
+package main
+
+import (
+	"encoding/json"
+	"net/http"
+)
+
+func mountLedRingAPI(mux *http.ServeMux, link *managedSerial) {
+	mux.HandleFunc("/api/led-ring", func(w http.ResponseWriter, r *http.Request) {
+		if r.Method != http.MethodPost {
+			http.Error(w, "method not allowed", http.StatusMethodNotAllowed)
+			return
+		}
+		serveLedRingPost(w, r, link)
+	})
+}
+
+func serveLedRingPost(w http.ResponseWriter, r *http.Request, link *managedSerial) {
+	var body ledRingAPIRequest
+	if err := json.NewDecoder(r.Body).Decode(&body); err != nil {
+		writeJSON(w, http.StatusBadRequest, ledRingAPIResponse{Error: "invalid JSON"})
+		return
+	}
+	if body.Mode == "" {
+		writeJSON(w, http.StatusBadRequest, ledRingAPIResponse{Error: "mode required"})
+		return
+	}
+	out := applyLedRing(link, body)
+	status := http.StatusOK
+	if out.Error != "" {
+		status = http.StatusServiceUnavailable
+	} else if !out.Success {
+		status = http.StatusServiceUnavailable
+	}
+	writeJSON(w, status, out)
+}

goTool/api_live_stream.go

@@ -0,0 +1,52 @@
+package main
+
+import (
+	"encoding/json"
+	"net/http"
+)
+
+type liveStreamAPIResponse struct {
+	Enabled bool   `json:"enabled"`
+	Success bool   `json:"success"`
+	Error   string `json:"error,omitempty"`
+}
+
+func mountLiveStreamAPI(mux *http.ServeMux, hub *wsHub) {
+	mux.HandleFunc("/api/live-stream", func(w http.ResponseWriter, r *http.Request) {
+		switch r.Method {
+		case http.MethodGet:
+			serveLiveStreamGet(w, hub)
+		case http.MethodPut:
+			serveLiveStreamPut(w, r, hub)
+		default:
+			http.Error(w, "method not allowed", http.StatusMethodNotAllowed)
+		}
+	})
+}
+
+func serveLiveStreamGet(w http.ResponseWriter, hub *wsHub) {
+	enabled := false
+	if hub != nil {
+		enabled = hub.liveStreamEnabled()
+	}
+	writeJSON(w, http.StatusOK, liveStreamAPIResponse{Enabled: enabled, Success: true})
+}
+
+func serveLiveStreamPut(w http.ResponseWriter, r *http.Request, hub *wsHub) {
+	var body struct {
+		Enable bool `json:"enable"`
+	}
+	if err := json.NewDecoder(r.Body).Decode(&body); err != nil {
+		writeJSON(w, http.StatusBadRequest, liveStreamAPIResponse{Error: "invalid JSON"})
+		return
+	}
+
+	if hub != nil {
+		hub.patchLiveStream(body.Enable)
+	}
+
+	writeJSON(w, http.StatusOK, liveStreamAPIResponse{
+		Enabled: body.Enable,
+		Success: true,
+	})
+}

goTool/api_serve.go

@@ -2,6 +2,7 @@ package main
 
 import (
 	"encoding/json"
+	"errors"
 	"fmt"
 	"io"
 	"net/http"
@@ -40,6 +41,19 @@ type unicastAPIResponse struct {
 	Error   string `json:"error,omitempty"`
 }
 
+type echoPingAPIRequest struct {
+	ClientID uint32 `json:"client_id"`
+}
+
+type echoPingAPIResponse struct {
+	Success     bool    `json:"success"`
+	ClientID    uint32  `json:"client_id,omitempty"`
+	TimestampUs uint64  `json:"timestamp_us,omitempty"`
+	RttMs       float64 `json:"rtt_ms"`
+	EspRttUs    uint32  `json:"esp_rtt_us"`
+	Error       string  `json:"error,omitempty"`
+}
+
 type findMeAPIRequest struct {
 	ClientID uint32 `json:"client_id"`
 }
@@ -60,6 +74,17 @@ type restartAPIResponse struct {
 	Error    string `json:"error,omitempty"`
 }
 
+type logLevelAPIResponse struct {
+	Success bool   `json:"success"`
+	Level   uint32 `json:"level"`
+	Error   string `json:"error,omitempty"`
+}
+
+type logLevelAPIRequest struct {
+	Write bool   `json:"write"`
+	Level uint32 `json:"level"`
+}
+
 type otaAPIResponse struct {
 	Success       bool   `json:"success"`
 	BytesWritten  uint32 `json:"bytes_written,omitempty"`
@@ -67,7 +92,12 @@ type otaAPIResponse struct {
 	Error         string `json:"error,omitempty"`
 }
 
-func mountServeAPI(mux *http.ServeMux, link *managedSerial, hub *wsHub) {
+func mountServeAPI(mux *http.ServeMux, link *managedSerial, hub *wsHub, streamCtl *accelStreamCtl, tapCtl *tapNotifyCtl) {
+	mountLiveStreamAPI(mux, hub)
+	mountAccelStreamAPI(mux, link, hub, streamCtl)
+	mountTapAPI(mux, link, hub, tapCtl)
+	mountLedRingAPI(mux, link)
+	mountBatteryAPI(mux, link)
 	mux.HandleFunc("/api/deadzone", func(w http.ResponseWriter, r *http.Request) {
 		switch r.Method {
 		case http.MethodGet:
@@ -85,6 +115,13 @@ func mountServeAPI(mux *http.ServeMux, link *managedSerial, hub *wsHub) {
 		}
 		serveUnicastTest(w, r, link)
 	})
+	mux.HandleFunc("/api/echo-ping", func(w http.ResponseWriter, r *http.Request) {
+		if r.Method != http.MethodPost {
+			http.Error(w, "method not allowed", http.StatusMethodNotAllowed)
+			return
+		}
+		serveEchoPing(w, r, link)
+	})
 	mux.HandleFunc("/api/find-me", func(w http.ResponseWriter, r *http.Request) {
 		if r.Method != http.MethodPost {
 			http.Error(w, "method not allowed", http.StatusMethodNotAllowed)
@@ -99,6 +136,16 @@ func mountServeAPI(mux *http.ServeMux, link *managedSerial, hub *wsHub) {
 		}
 		serveRestart(w, r, link)
 	})
+	mux.HandleFunc("/api/log-level", func(w http.ResponseWriter, r *http.Request) {
+		switch r.Method {
+		case http.MethodGet:
+			serveLogLevelGet(w, r, link)
+		case http.MethodPost:
+			serveLogLevelPost(w, r, link)
+		default:
+			http.Error(w, "method not allowed", http.StatusMethodNotAllowed)
+		}
+	})
 	mux.HandleFunc("/api/ota", func(w http.ResponseWriter, r *http.Request) {
 		if r.Method != http.MethodPost {
 			http.Error(w, "method not allowed", http.StatusMethodNotAllowed)
@@ -141,7 +188,11 @@ func serveOTAUpload(w http.ResponseWriter, r *http.Request, link *managedSerial,
 		if hub != nil {
 			hub.broadcastRaw(OTAProgress{Type: "ota_progress", Phase: "error", Message: err.Error()})
 		}
-		writeJSON(w, http.StatusServiceUnavailable, otaAPIResponse{Error: err.Error()})
+		status := http.StatusServiceUnavailable
+		if errors.Is(err, errOTAInProgress) {
+			status = http.StatusConflict
+		}
+		writeJSON(w, status, otaAPIResponse{Error: err.Error()})
 		return
 	}
 	writeJSON(w, http.StatusOK, otaAPIResponse{
@@ -250,6 +301,43 @@ func applyDeadzoneToSlaves(link *managedSerial, deadzone uint32) (uint32, error)
 	return updated, nil
 }
 
+func serveLogLevelGet(w http.ResponseWriter, r *http.Request, link *managedSerial) {
+	resp, err := link.SetLogLevel(false, 0)
+	if err != nil {
+		writeJSON(w, http.StatusServiceUnavailable, logLevelAPIResponse{Error: err.Error()})
+		return
+	}
+	writeJSON(w, http.StatusOK, logLevelAPIResponse{
+		Success: resp.GetSuccess(),
+		Level:   resp.GetLevel(),
+	})
+}
+
+func serveLogLevelPost(w http.ResponseWriter, r *http.Request, link *managedSerial) {
+	var body logLevelAPIRequest
+	if err := json.NewDecoder(r.Body).Decode(&body); err != nil {
+		writeJSON(w, http.StatusBadRequest, logLevelAPIResponse{Error: "invalid JSON"})
+		return
+	}
+	if !body.Write {
+		writeJSON(w, http.StatusBadRequest, logLevelAPIResponse{Error: "write must be true"})
+		return
+	}
+	if body.Level > 5 {
+		writeJSON(w, http.StatusBadRequest, logLevelAPIResponse{Error: "level must be 0–5"})
+		return
+	}
+	resp, err := link.SetLogLevel(true, body.Level)
+	if err != nil {
+		writeJSON(w, http.StatusServiceUnavailable, logLevelAPIResponse{Error: err.Error()})
+		return
+	}
+	writeJSON(w, http.StatusOK, logLevelAPIResponse{
+		Success: resp.GetSuccess(),
+		Level:   resp.GetLevel(),
+	})
+}
+
 func serveRestart(w http.ResponseWriter, r *http.Request, link *managedSerial) {
 	var body restartAPIRequest
 	if err := json.NewDecoder(r.Body).Decode(&body); err != nil {
@@ -306,6 +394,30 @@ func serveUnicastTest(w http.ResponseWriter, r *http.Request, link *managedSeria
 	})
 }
 
+func serveEchoPing(w http.ResponseWriter, r *http.Request, link *managedSerial) {
+	var body echoPingAPIRequest
+	if err := json.NewDecoder(r.Body).Decode(&body); err != nil {
+		writeJSON(w, http.StatusBadRequest, echoPingAPIResponse{Error: "invalid JSON"})
+		return
+	}
+	if body.ClientID == 0 {
+		writeJSON(w, http.StatusBadRequest, echoPingAPIResponse{Error: "client_id required"})
+		return
+	}
+	result, err := link.EchoPing(body.ClientID)
+	if err != nil {
+		writeJSON(w, http.StatusServiceUnavailable, echoPingAPIResponse{Error: err.Error()})
+		return
+	}
+	writeJSON(w, http.StatusOK, echoPingAPIResponse{
+		Success:     result.Success,
+		ClientID:    result.ClientID,
+		TimestampUs: result.TimestampUs,
+		RttMs:       result.RttMs,
+		EspRttUs:    result.EspRttUs,
+	})
+}
+
 func parseUintQuery(r *http.Request, key string, def uint32) (uint32, error) {
 	s := r.URL.Query().Get(key)
 	if s == "" {

goTool/api_stream.go

@@ -0,0 +1,875 @@
+package main
+
+import (
+	"context"
+	"encoding/json"
+	"errors"
+	"log"
+	"net/http"
+	"sync"
+	"time"
+
+	"powerpod/gotool/pb"
+
+	"github.com/gorilla/websocket"
+)
+
+const (
+	defaultAccelStreamInterval = 16 * time.Millisecond
+	defaultPreFetchMs          = 2
+	minAPIStreamInterval       = 1 * time.Millisecond
+	maxAPIStreamInterval       = 10 * time.Second
+	// How long tap events stay in API push/cache after first sight (matches dashboard).
+	apiTapDisplayMinMs = 2000
+)
+
+// InputClientSample is one slave's cached accel + tap state on the master.
+type InputClientSample struct {
+	ClientID   uint32 `json:"client_id"`
+	Valid      bool   `json:"valid"`
+	X          int32  `json:"x,omitempty"`
+	Y          int32  `json:"y,omitempty"`
+	Z          int32  `json:"z,omitempty"`
+	AccelAgeMs uint32 `json:"accel_age_ms,omitempty"`
+	TapKind    string `json:"tap_kind,omitempty"`
+	TapAgeMs   uint32 `json:"tap_age_ms,omitempty"`
+}
+
+// InputStreamMessage is sent to external WebSocket clients (hello + input samples).
+type InputStreamMessage struct {
+	Type            string   `json:"type"` // "hello" | "input"
+	Serial          string   `json:"serial_port,omitempty"`
+	IntervalMs      int      `json:"interval_ms,omitempty"`
+	PreFetchMs      int      `json:"pre_fetch_ms,omitempty"`
+	TapDisplayMinMs int      `json:"tap_display_min_ms,omitempty"`
+	Commands        []string `json:"commands,omitempty"`
+	Note            string   `json:"note,omitempty"`
+
+	T       int64               `json:"t,omitempty"` // Unix nanoseconds
+	Success bool                `json:"success,omitempty"`
+	Clients []InputClientSample `json:"clients,omitempty"`
+	Error   string              `json:"error,omitempty"`
+}
+
+// StreamStatusMessage is the reply to set_stream / get_stream (this connection).
+type StreamStatusMessage struct {
+	Type          string `json:"type"` // "stream_status"
+	ReceiveInput  bool   `json:"receive_input"`
+	IntervalMs    int    `json:"interval_ms"`
+	PreFetch      int    `json:"pre_fetch"`
+	Success       bool   `json:"success"`
+	Error         string `json:"error,omitempty"`
+}
+
+// InputStreamStatusMessage is the reply to set_input_stream / get_input_stream (slave).
+type InputStreamStatusMessage struct {
+	Type          string `json:"type"` // "input_stream_status"
+	ClientID      uint32 `json:"client_id"`
+	Enabled       bool   `json:"enabled"`
+	Success       bool   `json:"success"`
+	SlavesUpdated uint32 `json:"slaves_updated,omitempty"`
+	Error         string `json:"error,omitempty"`
+}
+
+// APIClientInfo is one registered slave (or slot) from CLIENT_INFO.
+type APIClientInfo struct {
+	ID              uint32 `json:"id"`
+	MAC             string `json:"mac"`
+	Version         uint32 `json:"version"`
+	Available       bool   `json:"available"`
+	Used            bool   `json:"used"`
+	LastPing        uint32 `json:"last_ping"`
+	LastSuccessPing uint32 `json:"last_success_ping"`
+	InputStream     bool   `json:"input_stream"`
+	TapNotifySingle bool   `json:"tap_notify_single"`
+	TapNotifyDouble bool   `json:"tap_notify_double"`
+	TapNotifyTriple bool   `json:"tap_notify_triple"`
+}
+
+// ClientListMessage is the reply to list_clients.
+type ClientListMessage struct {
+	Type    string          `json:"type"` // "client_list"
+	Success bool            `json:"success"`
+	Clients []APIClientInfo `json:"clients,omitempty"`
+	Error   string          `json:"error,omitempty"`
+}
+
+// TapNotifyStatusMessage is the reply to set_tap_notify / get_tap_notify (slave).
+type TapNotifyStatusMessage struct {
+	Type          string `json:"type"` // "tap_notify_status"
+	ClientID      uint32 `json:"client_id"`
+	Single        bool   `json:"single"`
+	DoubleTap     bool   `json:"double_tap"`
+	Triple        bool   `json:"triple"`
+	Success       bool   `json:"success"`
+	SlavesUpdated uint32 `json:"slaves_updated,omitempty"`
+	Error         string `json:"error,omitempty"`
+}
+
+type accelWSCommand struct {
+	Type       string `json:"type"`
+	ClientID   uint32 `json:"client_id"`
+	Enable     *bool  `json:"enable"`
+	IntervalMs *int   `json:"interval_ms"`
+	PreFetch   *int   `json:"pre_fetch"`
+	Single     *bool  `json:"single"`
+	DoubleTap  *bool  `json:"double_tap"`
+	Triple     *bool  `json:"triple"`
+	AllClients bool   `json:"all_clients"`
+}
+
+type APIInfoResponse struct {
+	Name              string `json:"name"`
+	Version           string `json:"version"`
+	SerialPort        string `json:"serial_port"`
+	WebSocket         string `json:"websocket"`
+	DefaultIntervalMs int    `json:"default_interval_ms"`
+	DefaultPreFetchMs int    `json:"default_pre_fetch_ms"`
+	MinIntervalMs     int    `json:"min_interval_ms"`
+	MaxIntervalMs     int    `json:"max_interval_ms"`
+	TapDisplayMinMs   int    `json:"tap_display_min_ms"`
+	Description       string `json:"description"`
+}
+
+type cachedTapEvent struct {
+	kind    string
+	shownAt time.Time
+	ageMs   uint32
+}
+
+type wsSubscriber struct {
+	conn          *websocket.Conn
+	receiveInput  bool
+	interval      time.Duration
+	preFetch      time.Duration
+	lastInputSent time.Time
+}
+
+type pendingInputCache struct {
+	cache   *pb.CacheStatusResponse
+	readAt  time.Time
+	readErr error
+}
+
+type accelStreamHub struct {
+	mu              sync.RWMutex
+	clients         map[*websocket.Conn]*wsSubscriber
+	defaultInterval time.Duration
+	defaultPreFetch time.Duration
+	configChanged   chan struct{}
+	recentTaps      map[uint32]cachedTapEvent
+}
+
+func newAccelStreamHub(defaultInterval time.Duration) *accelStreamHub {
+	return &accelStreamHub{
+		clients:         make(map[*websocket.Conn]*wsSubscriber),
+		defaultInterval: defaultInterval,
+		defaultPreFetch: defaultPreFetchMs * time.Millisecond,
+		configChanged:   make(chan struct{}, 1),
+	}
+}
+
+func (h *accelStreamHub) notifyConfigChanged() {
+	select {
+	case h.configChanged <- struct{}{}:
+	default:
+	}
+}
+
+func clampAPIInterval(d time.Duration) time.Duration {
+	if d < minAPIStreamInterval {
+		return minAPIStreamInterval
+	}
+	if d > maxAPIStreamInterval {
+		return maxAPIStreamInterval
+	}
+	return d
+}
+
+func clampPreFetch(d time.Duration) time.Duration {
+	if d < 0 {
+		return 0
+	}
+	if d > maxAPIStreamInterval {
+		return maxAPIStreamInterval
+	}
+	return d
+}
+
+func (h *accelStreamHub) register(conn *websocket.Conn, portName string) *wsSubscriber {
+	sub := &wsSubscriber{
+		conn:         conn,
+		receiveInput: false,
+		interval:     h.defaultInterval,
+		preFetch:     h.defaultPreFetch,
+	}
+	h.mu.Lock()
+	h.clients[conn] = sub
+	h.mu.Unlock()
+
+	hello := InputStreamMessage{
+		Type:            "hello",
+		Serial:          portName,
+		IntervalMs:      int(h.defaultInterval / time.Millisecond),
+		PreFetchMs:      int(h.defaultPreFetch / time.Millisecond),
+		TapDisplayMinMs: apiTapDisplayMinMs,
+		Note:            "set_tap_notify configures slave S/D/T only; set_stream enables input polling/push on this connection",
+		Commands: []string{
+			"list_clients",
+			"set_stream", "get_stream",
+			"set_input_stream", "get_input_stream",
+			"set_tap_notify", "get_tap_notify",
+			"set_led_ring", "get_battery",
+		},
+	}
+	if data, err := json.Marshal(hello); err == nil {
+		_ = conn.WriteMessage(websocket.TextMessage, data)
+	}
+	return sub
+}
+
+func (h *accelStreamHub) unregister(conn *websocket.Conn) {
+	h.mu.Lock()
+	delete(h.clients, conn)
+	anyInput := false
+	for _, sub := range h.clients {
+		if sub.receiveInput {
+			anyInput = true
+			break
+		}
+	}
+	if !anyInput {
+		h.recentTaps = nil
+	}
+	h.mu.Unlock()
+	h.notifyConfigChanged()
+}
+
+func (h *accelStreamHub) anyWantsInput() bool {
+	h.mu.RLock()
+	defer h.mu.RUnlock()
+	for _, sub := range h.clients {
+		if sub.receiveInput {
+			return true
+		}
+	}
+	return false
+}
+
+func (h *accelStreamHub) minWantedInterval() time.Duration {
+	h.mu.RLock()
+	defer h.mu.RUnlock()
+	var min time.Duration
+	for _, sub := range h.clients {
+		if !sub.receiveInput {
+			continue
+		}
+		if min == 0 || sub.interval < min {
+			min = sub.interval
+		}
+	}
+	if min == 0 {
+		return h.defaultInterval
+	}
+	return min
+}
+
+func (h *accelStreamHub) setStream(sub *wsSubscriber, enable bool, intervalMs, preFetchMs *int) StreamStatusMessage {
+	h.mu.Lock()
+	sub.receiveInput = enable
+	if !enable {
+		h.recentTaps = nil
+	}
+	if intervalMs != nil {
+		sub.interval = clampAPIInterval(time.Duration(*intervalMs) * time.Millisecond)
+	}
+	if preFetchMs != nil {
+		sub.preFetch = clampPreFetch(time.Duration(*preFetchMs) * time.Millisecond)
+	}
+	ms := int(sub.interval / time.Millisecond)
+	pf := int(sub.preFetch / time.Millisecond)
+	h.mu.Unlock()
+	h.notifyConfigChanged()
+
+	return StreamStatusMessage{
+		Type:         "stream_status",
+		ReceiveInput: enable,
+		IntervalMs:   ms,
+		PreFetch:     pf,
+		Success:      true,
+	}
+}
+
+func (h *accelStreamHub) getStream(sub *wsSubscriber) StreamStatusMessage {
+	h.mu.RLock()
+	defer h.mu.RUnlock()
+	return StreamStatusMessage{
+		Type:         "stream_status",
+		ReceiveInput: sub.receiveInput,
+		IntervalMs:   int(sub.interval / time.Millisecond),
+		PreFetch:     int(sub.preFetch / time.Millisecond),
+		Success:      true,
+	}
+}
+
+func (h *accelStreamHub) streamTiming(now time.Time) (needRead, needDeliver bool, waitPreFetch time.Duration) {
+	h.mu.RLock()
+	defer h.mu.RUnlock()
+	for _, sub := range h.clients {
+		if !sub.receiveInput {
+			continue
+		}
+		if sub.lastInputSent.IsZero() {
+			needRead = true
+			needDeliver = true
+			if sub.preFetch > waitPreFetch {
+				waitPreFetch = sub.preFetch
+			}
+			continue
+		}
+		nextPush := sub.lastInputSent.Add(sub.interval)
+		readAt := nextPush.Add(-sub.preFetch)
+		if !now.Before(readAt) {
+			needRead = true
+		}
+		if !now.Before(nextPush) {
+			needDeliver = true
+			if sub.preFetch > waitPreFetch {
+				waitPreFetch = sub.preFetch
+			}
+		}
+	}
+	return needRead, needDeliver, waitPreFetch
+}
+
+func (h *accelStreamHub) ingestTapFromCache(cache *pb.CacheStatusResponse) {
+	if cache == nil {
+		return
+	}
+	h.mu.Lock()
+	defer h.mu.Unlock()
+
+	now := time.Now()
+	if h.recentTaps == nil {
+		h.recentTaps = make(map[uint32]cachedTapEvent)
+	}
+	for _, c := range cache.GetClients() {
+		t := c.GetTap()
+		if t == nil {
+			continue
+		}
+		kind := tapKindLabelPB(t.GetKind())
+		if kind == "" {
+			continue
+		}
+		h.recentTaps[c.GetClientId()] = cachedTapEvent{
+			kind:    kind,
+			shownAt: now,
+			ageMs:   t.GetAgeMs(),
+		}
+	}
+	h.pruneRecentTapsLocked(now)
+}
+
+func (h *accelStreamHub) pruneRecentTapsLocked(now time.Time) {
+	if len(h.recentTaps) == 0 {
+		return
+	}
+	cutoff := now.Add(-apiTapDisplayMinMs * time.Millisecond)
+	for id, ev := range h.recentTaps {
+		if ev.shownAt.Before(cutoff) {
+			delete(h.recentTaps, id)
+		}
+	}
+}
+
+func (h *accelStreamHub) inputClientsFromCacheLocked(cache *pb.CacheStatusResponse, now time.Time) []InputClientSample {
+	h.pruneRecentTapsLocked(now)
+	out := make([]InputClientSample, 0, len(cache.GetClients()))
+	for _, c := range cache.GetClients() {
+		sample := InputClientSample{
+			ClientID: c.GetClientId(),
+		}
+		if a := c.GetAccel(); a != nil {
+			sample.Valid = a.GetValid()
+			if a.GetValid() {
+				sample.X = a.GetX()
+				sample.Y = a.GetY()
+				sample.Z = a.GetZ()
+				sample.AccelAgeMs = a.GetAgeMs()
+			}
+		}
+		if ev, ok := h.recentTaps[c.GetClientId()]; ok {
+			sample.TapKind = ev.kind
+			if t := c.GetTap(); t != nil && tapKindLabelPB(t.GetKind()) == ev.kind {
+				sample.TapAgeMs = t.GetAgeMs()
+			} else {
+				sample.TapAgeMs = ev.ageMs + uint32(now.Sub(ev.shownAt).Milliseconds())
+			}
+		}
+		out = append(out, sample)
+	}
+	return out
+}
+
+func (h *accelStreamHub) deliverInput(msg InputStreamMessage) {
+	data, err := json.Marshal(msg)
+	if err != nil {
+		return
+	}
+
+	now := time.Now()
+	h.mu.Lock()
+	defer h.mu.Unlock()
+	for conn, sub := range h.clients {
+		if !sub.receiveInput {
+			continue
+		}
+		if !sub.lastInputSent.IsZero() && now.Sub(sub.lastInputSent) < sub.interval {
+			continue
+		}
+		sub.lastInputSent = now
+		if err := conn.WriteMessage(websocket.TextMessage, data); err != nil {
+			delete(h.clients, conn)
+			_ = conn.Close()
+		}
+	}
+}
+
+func runInputStreamer(link *managedSerial, hub *accelStreamHub, dash *wsHub, ctl *accelStreamCtl, tapCtl *tapNotifyCtl, stop <-chan struct{}) {
+	ticker := time.NewTicker(minAPIStreamInterval)
+	defer ticker.Stop()
+
+	var pending *pendingInputCache
+
+	for {
+		select {
+		case <-stop:
+			return
+		case <-hub.configChanged:
+			pending = nil
+		case now := <-ticker.C:
+			if !hub.anyWantsInput() || !inputPollingActive(dash, ctl, tapCtl) {
+				pending = nil
+				continue
+			}
+
+			needRead, needDeliver, waitPreFetch := hub.streamTiming(now)
+
+			if needRead && pending == nil {
+				cache, err := link.readCacheStatusPoll()
+				if err != nil {
+					pending = &pendingInputCache{readErr: err, readAt: now}
+				} else {
+					hub.ingestTapFromCache(cache)
+					pending = &pendingInputCache{cache: cache, readAt: now}
+				}
+			}
+
+			if !needDeliver || pending == nil {
+				continue
+			}
+
+			ts := now.UnixNano()
+			if pending.readErr != nil {
+				errMsg := pending.readErr.Error()
+				if errors.Is(pending.readErr, errUARTBusy) {
+					errMsg = "uart busy"
+				}
+				hub.deliverInput(InputStreamMessage{
+					Type:    "input",
+					T:       ts,
+					Success: false,
+					Error:   errMsg,
+				})
+				pending = nil
+				continue
+			}
+
+			if pending.cache != nil && now.Sub(pending.readAt) >= waitPreFetch {
+				hub.mu.RLock()
+				clients := hub.inputClientsFromCacheLocked(pending.cache, now)
+				hub.mu.RUnlock()
+				hub.deliverInput(InputStreamMessage{
+					Type:    "input",
+					T:       ts,
+					Success: true,
+					Clients: clients,
+				})
+				pending = nil
+			}
+		}
+	}
+}
+
+func inputPollingActive(dash *wsHub, ctl *accelStreamCtl, tapCtl *tapNotifyCtl) bool {
+	if ctl != nil && ctl.Any() {
+		return true
+	}
+	if tapCtl != nil && tapCtl.Any() {
+		return true
+	}
+	return dash != nil && dash.anyAccelStreamEnabled()
+}
+
+func writeStreamStatus(conn *websocket.Conn, msg StreamStatusMessage) {
+	data, err := json.Marshal(msg)
+	if err != nil {
+		return
+	}
+	_ = conn.WriteMessage(websocket.TextMessage, data)
+}
+
+func writeBatteryStatus(conn *websocket.Conn, out batteryAPIResponse) {
+	out.Type = "battery_status"
+	data, err := json.Marshal(out)
+	if err != nil {
+		return
+	}
+	_ = conn.WriteMessage(websocket.TextMessage, data)
+}
+
+func writeLedRingStatus(conn *websocket.Conn, out ledRingAPIResponse) {
+	out.Type = "led_ring_status"
+	data, err := json.Marshal(out)
+	if err != nil {
+		return
+	}
+	_ = conn.WriteMessage(websocket.TextMessage, data)
+}
+
+func writeInputStreamStatus(conn *websocket.Conn, out accelStreamAPIResponse) {
+	msg := InputStreamStatusMessage{
+		Type:          "input_stream_status",
+		ClientID:      out.ClientID,
+		Enabled:       out.Enabled,
+		Success:       out.Success,
+		SlavesUpdated: out.SlavesUpdated,
+		Error:         out.Error,
+	}
+	data, err := json.Marshal(msg)
+	if err != nil {
+		return
+	}
+	_ = conn.WriteMessage(websocket.TextMessage, data)
+}
+
+func clientInfoToAPI(c *pb.ClientInfo) APIClientInfo {
+	return APIClientInfo{
+		ID:              c.GetId(),
+		MAC:             formatMAC(c.GetMac()),
+		Version:         c.GetVersion(),
+		Available:       c.GetAvailable(),
+		Used:            c.GetUsed(),
+		LastPing:        c.GetLastPing(),
+		LastSuccessPing: c.GetLastSuccessPing(),
+		InputStream:     c.GetAccelStreamEnabled(),
+		TapNotifySingle: c.GetTapNotifySingle(),
+		TapNotifyDouble: c.GetTapNotifyDouble(),
+		TapNotifyTriple: c.GetTapNotifyTriple(),
+	}
+}
+
+func writeClientList(conn *websocket.Conn, msg ClientListMessage) {
+	data, err := json.Marshal(msg)
+	if err != nil {
+		return
+	}
+	_ = conn.WriteMessage(websocket.TextMessage, data)
+}
+
+func writeTapNotifyStatus(conn *websocket.Conn, out tapNotifyAPIResponse) {
+	msg := TapNotifyStatusMessage{
+		Type:          "tap_notify_status",
+		ClientID:      out.ClientID,
+		Single:        out.Single,
+		DoubleTap:     out.DoubleTap,
+		Triple:        out.Triple,
+		Success:       out.Success,
+		SlavesUpdated: out.SlavesUpdated,
+		Error:         out.Error,
+	}
+	data, err := json.Marshal(msg)
+	if err != nil {
+		return
+	}
+	_ = conn.WriteMessage(websocket.TextMessage, data)
+}
+
+func applyTapNotifyClientWS(link *managedSerial, dash *wsHub, tapCtl *tapNotifyCtl, clientID uint32, single, doubleTap, triple bool) tapNotifyAPIResponse {
+	resp, err := link.TapNotify(&pb.TapNotifyRequest{
+		Write:     true,
+		ClientId:  clientID,
+		Single:    single,
+		DoubleTap: doubleTap,
+		Triple:    triple,
+	})
+	if err != nil {
+		return tapNotifyAPIResponse{ClientID: clientID, Error: err.Error()}
+	}
+	out := tapNotifyAPIResponse{
+		ClientID:      resp.GetClientId(),
+		Success:       resp.GetSuccess(),
+		SlavesUpdated: resp.GetSlavesUpdated(),
+		Single:        resp.GetSingle(),
+		DoubleTap:     resp.GetDoubleTap(),
+		Triple:        resp.GetTriple(),
+	}
+	if resp.GetSuccess() {
+		if tapCtl != nil {
+			tapCtl.Set(clientID, single, doubleTap, triple)
+		}
+		if dash != nil {
+			dash.patchClientTapNotify(clientID, single, doubleTap, triple)
+		}
+	}
+	return out
+}
+
+func handleAccelWSCommand(conn *websocket.Conn, sub *wsSubscriber, data []byte, link *managedSerial, dash *wsHub, ctl *accelStreamCtl, tapCtl *tapNotifyCtl, hub *accelStreamHub) {
+	var cmd accelWSCommand
+	if err := json.Unmarshal(data, &cmd); err != nil {
+		writeStreamStatus(conn, StreamStatusMessage{Type: "stream_status", Error: "invalid JSON"})
+		return
+	}
+
+	switch cmd.Type {
+	case "list_clients":
+		clients, err := link.listClientsPoll()
+		if err != nil {
+			writeClientList(conn, ClientListMessage{
+				Type:  "client_list",
+				Error: err.Error(),
+			})
+			return
+		}
+		out := make([]APIClientInfo, 0, len(clients))
+		for _, c := range clients {
+			out = append(out, clientInfoToAPI(c))
+		}
+		writeClientList(conn, ClientListMessage{
+			Type:    "client_list",
+			Success: true,
+			Clients: out,
+		})
+
+	case "set_stream":
+		if cmd.Enable == nil {
+			writeStreamStatus(conn, StreamStatusMessage{
+				Type:  "stream_status",
+				Error: "enable required",
+			})
+			return
+		}
+		writeStreamStatus(conn, hub.setStream(sub, *cmd.Enable, cmd.IntervalMs, cmd.PreFetch))
+
+	case "get_stream":
+		writeStreamStatus(conn, hub.getStream(sub))
+
+	case "set_input_stream":
+		if cmd.ClientID == 0 {
+			writeInputStreamStatus(conn, accelStreamAPIResponse{Error: "client_id required"})
+			return
+		}
+		if cmd.Enable == nil {
+			writeInputStreamStatus(conn, accelStreamAPIResponse{
+				ClientID: cmd.ClientID,
+				Error:    "enable required",
+			})
+			return
+		}
+		writeInputStreamStatus(conn, applyAccelStreamClient(link, dash, ctl, cmd.ClientID, *cmd.Enable))
+
+	case "get_input_stream":
+		if cmd.ClientID == 0 {
+			writeInputStreamStatus(conn, accelStreamAPIResponse{Error: "client_id required"})
+			return
+		}
+		resp, err := link.AccelStreamPoll(&pb.AccelStreamRequest{
+			Write:    false,
+			ClientId: cmd.ClientID,
+		})
+		if err != nil {
+			writeInputStreamStatus(conn, accelStreamAPIResponse{
+				ClientID: cmd.ClientID,
+				Error:    err.Error(),
+			})
+			return
+		}
+		if ctl != nil {
+			ctl.Set(cmd.ClientID, resp.GetEnabled())
+		}
+		writeInputStreamStatus(conn, accelStreamAPIResponse{
+			Enabled:  resp.GetEnabled(),
+			ClientID: resp.GetClientId(),
+			Success:  resp.GetSuccess(),
+		})
+
+	case "set_tap_notify":
+		if cmd.AllClients {
+			if cmd.Single == nil || cmd.DoubleTap == nil || cmd.Triple == nil {
+				writeTapNotifyStatus(conn, tapNotifyAPIResponse{Error: "single, double_tap, triple required"})
+				return
+			}
+			updated, err := applyTapNotifyAll(link, dash, tapCtl, *cmd.Single, *cmd.DoubleTap, *cmd.Triple)
+			if err != nil {
+				writeTapNotifyStatus(conn, tapNotifyAPIResponse{Error: err.Error()})
+				return
+			}
+			writeTapNotifyStatus(conn, tapNotifyAPIResponse{
+				Success:       updated > 0,
+				SlavesUpdated: updated,
+				Single:        *cmd.Single,
+				DoubleTap:     *cmd.DoubleTap,
+				Triple:        *cmd.Triple,
+			})
+			return
+		}
+		if cmd.ClientID == 0 {
+			writeTapNotifyStatus(conn, tapNotifyAPIResponse{Error: "client_id required"})
+			return
+		}
+		if cmd.Single == nil || cmd.DoubleTap == nil || cmd.Triple == nil {
+			writeTapNotifyStatus(conn, tapNotifyAPIResponse{
+				ClientID: cmd.ClientID,
+				Error:    "single, double_tap, triple required",
+			})
+			return
+		}
+		writeTapNotifyStatus(conn, applyTapNotifyClientWS(link, dash, tapCtl, cmd.ClientID, *cmd.Single, *cmd.DoubleTap, *cmd.Triple))
+
+	case "get_tap_notify":
+		if cmd.ClientID == 0 {
+			writeTapNotifyStatus(conn, tapNotifyAPIResponse{Error: "client_id required"})
+			return
+		}
+		resp, err := link.TapNotifyPoll(&pb.TapNotifyRequest{
+			Write:    false,
+			ClientId: cmd.ClientID,
+		})
+		if err != nil {
+			writeTapNotifyStatus(conn, tapNotifyAPIResponse{
+				ClientID: cmd.ClientID,
+				Error:    err.Error(),
+			})
+			return
+		}
+		if tapCtl != nil {
+			tapCtl.Set(cmd.ClientID, resp.GetSingle(), resp.GetDoubleTap(), resp.GetTriple())
+		}
+		writeTapNotifyStatus(conn, tapNotifyAPIResponse{
+			ClientID:  cmd.ClientID,
+			Success:   resp.GetSuccess(),
+			Single:    resp.GetSingle(),
+			DoubleTap: resp.GetDoubleTap(),
+			Triple:    resp.GetTriple(),
+		})
+
+	case "set_led_ring":
+		var body ledRingAPIRequest
+		if err := json.Unmarshal(data, &body); err != nil {
+			writeLedRingStatus(conn, ledRingAPIResponse{Error: "invalid JSON"})
+			return
+		}
+		if body.Mode == "" {
+			writeLedRingStatus(conn, ledRingAPIResponse{Error: "mode required"})
+			return
+		}
+		writeLedRingStatus(conn, applyLedRing(link, body))
+
+	case "get_battery":
+		var body batteryAPIRequest
+		if err := json.Unmarshal(data, &body); err != nil {
+			writeBatteryStatus(conn, batteryAPIResponse{Error: "invalid JSON"})
+			return
+		}
+		if !body.AllClients && body.ClientID == 0 {
+			body.AllClients = true
+		}
+		writeBatteryStatus(conn, applyBatteryStatus(link, body))
+
+	default:
+		writeStreamStatus(conn, StreamStatusMessage{
+			Type: "stream_status",
+			Error: "unknown type (list_clients, set_stream, get_stream, set_input_stream, get_input_stream, set_tap_notify, get_tap_notify, set_led_ring, get_battery)",
+		})
+	}
+}
+
+func serveExternalWS(conn *websocket.Conn, link *managedSerial, dash *wsHub, ctl *accelStreamCtl, tapCtl *tapNotifyCtl, portName string, hub *accelStreamHub) {
+	sub := hub.register(conn, portName)
+	defer hub.unregister(conn)
+	defer conn.Close()
+
+	for {
+		_, data, err := conn.ReadMessage()
+		if err != nil {
+			return
+		}
+		handleAccelWSCommand(conn, sub, data, link, dash, ctl, tapCtl, hub)
+	}
+}
+
+func mountExternalAPI(mux *http.ServeMux, portName string, defaultInterval time.Duration, hub *accelStreamHub, link *managedSerial, dash *wsHub, ctl *accelStreamCtl, tapCtl *tapNotifyCtl) {
+	defMs := int(defaultInterval / time.Millisecond)
+	mux.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
+		if r.URL.Path != "/" && r.URL.Path != "/api/v1" && r.URL.Path != "/api/v1/" {
+			http.NotFound(w, r)
+			return
+		}
+		if r.Method != http.MethodGet {
+			http.Error(w, "method not allowed", http.StatusMethodNotAllowed)
+			return
+		}
+		writeJSON(w, http.StatusOK, APIInfoResponse{
+			Name:              "powerpod-external-api",
+			Version:           "1",
+			SerialPort:        portName,
+			WebSocket:         "/ws",
+			DefaultIntervalMs: defMs,
+			DefaultPreFetchMs: defaultPreFetchMs,
+			MinIntervalMs:     int(minAPIStreamInterval / time.Millisecond),
+			MaxIntervalMs:     int(maxAPIStreamInterval / time.Millisecond),
+			TapDisplayMinMs:   apiTapDisplayMinMs,
+			Description:       "WebSocket: set_input_stream + set_stream for input (accel + tap); set_tap_notify configures slave tap kinds",
+		})
+	})
+
+	mux.HandleFunc("/ws", func(w http.ResponseWriter, r *http.Request) {
+		conn, err := wsUpgrader.Upgrade(w, r, nil)
+		if err != nil {
+			log.Printf("api websocket upgrade: %v", err)
+			return
+		}
+		serveExternalWS(conn, link, dash, ctl, tapCtl, portName, hub)
+	})
+}
+
+func runAPIServer(portName string, link *managedSerial, addr string, defaultInterval time.Duration, dash *wsHub, ctl *accelStreamCtl, tapCtl *tapNotifyCtl, stop <-chan struct{}) *http.Server {
+	hub := newAccelStreamHub(defaultInterval)
+	go runInputStreamer(link, hub, dash, ctl, tapCtl, stop)
+
+	mux := http.NewServeMux()
+	mountExternalAPI(mux, portName, defaultInterval, hub, link, dash, ctl, tapCtl)
+	mountLedRingAPI(mux, link)
+	mountBatteryAPI(mux, link)
+
+	srv := &http.Server{Addr: addr, Handler: mux}
+	go func() {
+		log.Printf("external API http://localhost%s  WebSocket ws://localhost%s/ws  (default stream interval %s, per-client via set_stream)",
+			addr, addr, defaultInterval.String())
+		if err := srv.ListenAndServe(); err != nil && !errors.Is(err, http.ErrServerClosed) {
+			log.Printf("external API server: %v", err)
+		}
+	}()
+	return srv
+}
+
+func shutdownAPIServer(srv *http.Server) {
+	if srv == nil {
+		return
+	}
+	ctx, cancel := context.WithTimeout(context.Background(), 2*time.Second)
+	defer cancel()
+	_ = srv.Shutdown(ctx)
+}

goTool/api_tap.go

@@ -0,0 +1,219 @@
+package main
+
+import (
+	"encoding/json"
+	"fmt"
+	"net/http"
+
+	"powerpod/gotool/pb"
+)
+
+type tapNotifyAPIRequest struct {
+	Write      bool   `json:"write"`
+	ClientID   uint32 `json:"client_id"`
+	AllClients bool   `json:"all_clients"`
+	Single     bool   `json:"single"`
+	DoubleTap  bool   `json:"double_tap"`
+	Triple     bool   `json:"triple"`
+}
+
+type tapNotifyAPIResponse struct {
+	ClientID      uint32 `json:"client_id"`
+	Success       bool   `json:"success"`
+	SlavesUpdated uint32 `json:"slaves_updated"`
+	Single        bool   `json:"single"`
+	DoubleTap     bool   `json:"double_tap"`
+	Triple        bool   `json:"triple"`
+	Error         string `json:"error,omitempty"`
+}
+
+type tapSnapshotAPIResponse struct {
+	Events []tapEventView `json:"events"`
+	Error  string         `json:"error,omitempty"`
+}
+
+type tapEventView struct {
+	ClientID uint32 `json:"client_id"`
+	Kind     string `json:"kind"`
+	AgeMs    uint32 `json:"age_ms"`
+}
+
+func mountTapAPI(mux *http.ServeMux, link *managedSerial, hub *wsHub, tapCtl *tapNotifyCtl) {
+	mux.HandleFunc("GET /api/clients/{clientID}/tap-notify", func(w http.ResponseWriter, r *http.Request) {
+		clientID, err := parsePathClientID(r)
+		if err != nil {
+			writeJSON(w, http.StatusBadRequest, tapNotifyAPIResponse{Error: err.Error()})
+			return
+		}
+		serveTapNotifyGet(w, clientID, link)
+	})
+	mux.HandleFunc("PUT /api/clients/{clientID}/tap-notify", func(w http.ResponseWriter, r *http.Request) {
+		clientID, err := parsePathClientID(r)
+		if err != nil {
+			writeJSON(w, http.StatusBadRequest, tapNotifyAPIResponse{Error: err.Error()})
+			return
+		}
+		serveClientTapNotifyPut(w, r, clientID, link, hub, tapCtl)
+	})
+	mux.HandleFunc("/api/tap-notify", func(w http.ResponseWriter, r *http.Request) {
+		switch r.Method {
+		case http.MethodGet:
+			serveTapNotifyGetQuery(w, r, link)
+		case http.MethodPost:
+			serveTapNotifyPost(w, r, link, hub, tapCtl)
+		default:
+			http.Error(w, "method not allowed", http.StatusMethodNotAllowed)
+		}
+	})
+
+	mux.HandleFunc("/api/tap-snapshot", func(w http.ResponseWriter, r *http.Request) {
+		if r.Method != http.MethodGet {
+			http.Error(w, "method not allowed", http.StatusMethodNotAllowed)
+			return
+		}
+		serveTapSnapshotGet(w, r, link)
+	})
+}
+
+func applyTapNotifyClient(link *managedSerial, hub *wsHub, tapCtl *tapNotifyCtl, clientID uint32, single, doubleTap, triple bool) tapNotifyAPIResponse {
+	return applyTapNotifyClientWS(link, hub, tapCtl, clientID, single, doubleTap, triple)
+}
+
+func serveTapNotifyGet(w http.ResponseWriter, clientID uint32, link *managedSerial) {
+	resp, err := link.TapNotifyPoll(&pb.TapNotifyRequest{
+		Write:    false,
+		ClientId: clientID,
+	})
+	if err != nil {
+		writeJSON(w, http.StatusServiceUnavailable, tapNotifyAPIResponse{
+			ClientID: clientID,
+			Error:    err.Error(),
+		})
+		return
+	}
+	writeJSON(w, http.StatusOK, tapNotifyAPIResponse{
+		ClientID: resp.GetClientId(),
+		Success:  resp.GetSuccess(),
+		Single:   resp.GetSingle(),
+		DoubleTap: resp.GetDoubleTap(),
+		Triple:   resp.GetTriple(),
+	})
+}
+
+func serveTapNotifyGetQuery(w http.ResponseWriter, r *http.Request, link *managedSerial) {
+	clientID, err := parseUintQuery(r, "client_id", 0)
+	if err != nil || clientID == 0 {
+		writeJSON(w, http.StatusBadRequest, tapNotifyAPIResponse{Error: "client_id required"})
+		return
+	}
+	serveTapNotifyGet(w, clientID, link)
+}
+
+type clientTapNotifyBody struct {
+	Single    bool `json:"single"`
+	DoubleTap bool `json:"double_tap"`
+	Triple    bool `json:"triple"`
+}
+
+func serveClientTapNotifyPut(w http.ResponseWriter, r *http.Request, clientID uint32, link *managedSerial, hub *wsHub, tapCtl *tapNotifyCtl) {
+	var body clientTapNotifyBody
+	if err := json.NewDecoder(r.Body).Decode(&body); err != nil {
+		writeJSON(w, http.StatusBadRequest, tapNotifyAPIResponse{Error: "invalid JSON"})
+		return
+	}
+	out := applyTapNotifyClient(link, hub, tapCtl, clientID, body.Single, body.DoubleTap, body.Triple)
+	status := http.StatusOK
+	if out.Error != "" || !out.Success {
+		status = http.StatusServiceUnavailable
+	}
+	writeJSON(w, status, out)
+}
+
+func serveTapNotifyPost(w http.ResponseWriter, r *http.Request, link *managedSerial, hub *wsHub, tapCtl *tapNotifyCtl) {
+	var body tapNotifyAPIRequest
+	if err := json.NewDecoder(r.Body).Decode(&body); err != nil {
+		writeJSON(w, http.StatusBadRequest, tapNotifyAPIResponse{Error: "invalid JSON"})
+		return
+	}
+
+	if body.AllClients {
+		updated, err := applyTapNotifyAll(link, hub, tapCtl, body.Single, body.DoubleTap, body.Triple)
+		if err != nil {
+			writeJSON(w, http.StatusServiceUnavailable, tapNotifyAPIResponse{Error: err.Error()})
+			return
+		}
+		writeJSON(w, http.StatusOK, tapNotifyAPIResponse{
+			Success:       updated > 0,
+			SlavesUpdated: updated,
+			Single:        body.Single,
+			DoubleTap:     body.DoubleTap,
+			Triple:        body.Triple,
+		})
+		return
+	}
+
+	if body.ClientID == 0 {
+		writeJSON(w, http.StatusBadRequest, tapNotifyAPIResponse{Error: "client_id required"})
+		return
+	}
+
+	out := applyTapNotifyClient(link, hub, tapCtl, body.ClientID, body.Single, body.DoubleTap, body.Triple)
+	status := http.StatusOK
+	if out.Error != "" || !out.Success {
+		status = http.StatusServiceUnavailable
+	}
+	writeJSON(w, status, out)
+}
+
+func applyTapNotifyAll(link *managedSerial, hub *wsHub, tapCtl *tapNotifyCtl, single, doubleTap, triple bool) (uint32, error) {
+	resp, err := link.TapNotify(&pb.TapNotifyRequest{
+		Write:      true,
+		AllClients: true,
+		Single:     single,
+		DoubleTap:  doubleTap,
+		Triple:     triple,
+	})
+	if err != nil {
+		return 0, err
+	}
+	if !resp.GetSuccess() {
+		return 0, fmt.Errorf("tap notify not applied to any slave")
+	}
+	if hub != nil || tapCtl != nil {
+		clients, _ := link.listClientsPoll()
+		for _, c := range clients {
+			if tapCtl != nil {
+				tapCtl.Set(c.GetId(), single, doubleTap, triple)
+			}
+			if hub != nil {
+				hub.patchClientTapNotify(c.GetId(), single, doubleTap, triple)
+			}
+		}
+	}
+	return resp.GetSlavesUpdated(), nil
+}
+
+func serveTapSnapshotGet(w http.ResponseWriter, r *http.Request, link *managedSerial) {
+	clientID, err := parseUintQuery(r, "client_id", 0)
+	if err != nil {
+		writeJSON(w, http.StatusBadRequest, tapSnapshotAPIResponse{Error: err.Error()})
+		return
+	}
+	cache, err := link.readCacheStatusPoll()
+	if err != nil {
+		writeJSON(w, http.StatusServiceUnavailable, tapSnapshotAPIResponse{Error: err.Error()})
+		return
+	}
+	out := tapSnapshotAPIResponse{Events: make([]tapEventView, 0)}
+	for _, e := range tapEventsFromCacheStatus(cache) {
+		if clientID != 0 && e.GetClientId() != clientID {
+			continue
+		}
+		out.Events = append(out.Events, tapEventView{
+			ClientID: e.GetClientId(),
+			Kind:     tapKindLabel(e.GetKind()),
+			AgeMs:    e.GetAgeMs(),
+		})
+	}
+	writeJSON(w, http.StatusOK, out)
+}

goTool/autotest/runner.go

@@ -347,6 +347,10 @@ func ledRingModeValue(mode string) (uint32, error) {
 		return 3, nil
 	case "find_me", "findme":
 		return 4, nil
+	case "battery_low", "batterylow":
+		return 6, nil
+	case "color", "solid", "fill":
+		return 5, nil
 	default:
 		return 0, fmt.Errorf("unknown led_ring mode %q", mode)
 	}

goTool/autotest/runner_test.go

@@ -12,6 +12,7 @@ func TestLedRingModeValue(t *testing.T) {
 		{"digit", 2},
 		{"blink", 3},
 		{"find-me", 4},
+		{"battery-low", 6},
 	}
 	for _, tc := range tests {
 		got, err := ledRingModeValue(tc.mode)

goTool/battery_api.go

@@ -0,0 +1,120 @@
+package main
+
+import (
+	"powerpod/gotool/pb"
+)
+
+const (
+	lipoMinMv = 3000
+	lipoMaxMv = 4200
+)
+
+type lipoReadingJSON struct {
+	Valid     bool   `json:"valid"`
+	VoltageMv uint32 `json:"voltage_mv"`
+	Percent   int    `json:"percent,omitempty"`
+}
+
+type batterySampleJSON struct {
+	ClientID uint32          `json:"client_id"`
+	Lipo1    lipoReadingJSON `json:"lipo1"`
+	Lipo2    lipoReadingJSON `json:"lipo2"`
+	AgeMs    uint32          `json:"age_ms,omitempty"`
+}
+
+type batteryAPIRequest struct {
+	ClientID   uint32 `json:"client_id"`
+	AllClients bool   `json:"all_clients"`
+}
+
+type batteryAPIResponse struct {
+	Type     string              `json:"type,omitempty"` // battery_status (WebSocket)
+	Success  bool                `json:"success"`
+	Samples  []batterySampleJSON `json:"samples,omitempty"`
+	Error    string              `json:"error,omitempty"`
+}
+
+func lipoPercent(mv uint32) int {
+	if mv <= lipoMinMv {
+		return 0
+	}
+	if mv >= lipoMaxMv {
+		return 100
+	}
+	return int((mv - lipoMinMv) * 100 / (lipoMaxMv - lipoMinMv))
+}
+
+func lipoFromPBMsg(l *pb.LipoReading) lipoReadingJSON {
+	if l == nil {
+		return lipoReadingJSON{}
+	}
+	return lipoFromPB(l.GetValid(), l.GetVoltageMv())
+}
+
+func lipoFromPB(valid bool, mv uint32) lipoReadingJSON {
+	out := lipoReadingJSON{Valid: valid, VoltageMv: mv}
+	if valid {
+		out.Percent = lipoPercent(mv)
+	}
+	return out
+}
+
+func batterySamplesFromPB(samples []*pb.BatterySample) []batterySampleJSON {
+	out := make([]batterySampleJSON, 0, len(samples))
+	for _, s := range samples {
+		out = append(out, batterySampleJSON{
+			ClientID: s.GetClientId(),
+			Lipo1:    lipoFromPBMsg(s.GetLipo1()),
+			Lipo2:    lipoFromPBMsg(s.GetLipo2()),
+			AgeMs:    s.GetAgeMs(),
+		})
+	}
+	return out
+}
+
+func applyBatteryStatus(link *managedSerial, in batteryAPIRequest) batteryAPIResponse {
+	resp, err := link.BatteryStatus(&pb.BatteryStatusRequest{
+		ClientId:   in.ClientID,
+		AllClients: in.AllClients,
+	})
+	if err != nil {
+		return batteryAPIResponse{Error: err.Error()}
+	}
+	samples := batterySamplesFromPB(resp.GetSamples())
+	out := batteryAPIResponse{
+		Success: resp.GetSuccess() || len(samples) > 0,
+		Samples: samples,
+	}
+	if len(samples) == 0 && out.Error == "" {
+		out.Error = "battery status unavailable"
+	}
+	return out
+}
+
+func findBatterySample(samples []batterySampleJSON, clientID uint32) (batterySampleJSON, bool) {
+	for _, s := range samples {
+		if s.ClientID == clientID {
+			return s, true
+		}
+	}
+	return batterySampleJSON{}, false
+}
+
+// applyBatterySamplesToState merges UART/REST battery samples into dashboard views.
+func applyBatterySamplesToState(st *DashboardState, samples []batterySampleJSON) {
+	if st == nil || len(samples) == 0 {
+		return
+	}
+	if m, ok := findBatterySample(samples, 0); ok {
+		st.Master.Lipo1 = m.Lipo1
+		st.Master.Lipo2 = m.Lipo2
+		st.Master.BatteryAgeMs = m.AgeMs
+	}
+	for i := range st.Clients {
+		if s, ok := findBatterySample(samples, st.Clients[i].ID); ok {
+			st.Clients[i].Lipo1 = s.Lipo1
+			st.Clients[i].Lipo2 = s.Lipo2
+			st.Clients[i].BatteryAgeMs = s.AgeMs
+		}
+	}
+}

goTool/cache_status.go

@@ -0,0 +1,49 @@
+package main
+
+import "powerpod/gotool/pb"
+
+// accelSamplesFromCacheStatus maps combined CACHE_STATUS entries to AccelSample
+// (for dashboard / WebSocket accel push).
+func accelSamplesFromCacheStatus(r *pb.CacheStatusResponse) []*pb.AccelSample {
+	if r == nil {
+		return nil
+	}
+	out := make([]*pb.AccelSample, 0, len(r.GetClients()))
+	for _, c := range r.GetClients() {
+		if c.GetAccel() == nil {
+			continue
+		}
+		a := c.GetAccel()
+		out = append(out, &pb.AccelSample{
+			ClientId: c.GetClientId(),
+			Valid:    a.GetValid(),
+			X:        a.GetX(),
+			Y:        a.GetY(),
+			Z:        a.GetZ(),
+			AgeMs:    a.GetAgeMs(),
+		})
+	}
+	return out
+}
+
+// tapEventsFromCacheStatus maps combined CACHE_STATUS entries to TapEvent
+// (only clients with a consumed pending tap).
+func tapEventsFromCacheStatus(r *pb.CacheStatusResponse) []*pb.TapEvent {
+	if r == nil {
+		return nil
+	}
+	out := make([]*pb.TapEvent, 0, len(r.GetClients()))
+	for _, c := range r.GetClients() {
+		if c.GetTap() == nil {
+			continue
+		}
+		t := c.GetTap()
+		out = append(out, &pb.TapEvent{
+			ClientId: c.GetClientId(),
+			Valid:    true,
+			Kind:     t.GetKind(),
+			AgeMs:    t.GetAgeMs(),
+		})
+	}
+	return out
+}

goTool/client_api.go

@@ -2,6 +2,7 @@ package main
 
 import (
 	"fmt"
+	"time"
 
 	"google.golang.org/protobuf/proto"
 
@@ -40,6 +41,182 @@ func (m *managedSerial) listClientsPoll() ([]*pb.ClientInfo, error) {
 	return decodeClientsPayload(payload)
 }
 
+func decodeBatteryStatusPayload(payload []byte) (*pb.BatteryStatusResponse, error) {
+	if len(payload) < 2 {
+		return nil, fmt.Errorf("short battery response")
+	}
+	if payload[0] != byte(pb.MessageType_BATTERY_STATUS) {
+		return nil, fmt.Errorf("unexpected command id 0x%02x (want 0x%02x)",
+			payload[0], byte(pb.MessageType_BATTERY_STATUS))
+	}
+	var msg pb.UartMessage
+	if err := proto.Unmarshal(payload[1:], &msg); err != nil {
+		return nil, fmt.Errorf("decode: %w", err)
+	}
+	if msg.GetType() != pb.MessageType_BATTERY_STATUS {
+		return nil, fmt.Errorf("unexpected type %v", msg.GetType())
+	}
+	r := msg.GetBatteryStatusResponse()
+	if r == nil {
+		return nil, fmt.Errorf("missing battery_status_response")
+	}
+	return r, nil
+}
+
+func (m *managedSerial) BatteryStatus(req *pb.BatteryStatusRequest) (*pb.BatteryStatusResponse, error) {
+	var resp *pb.BatteryStatusResponse
+	err := m.withPort(func(sp *serialPort) error {
+		var e error
+		resp, e = sp.batteryStatus(req)
+		return e
+	})
+	return resp, err
+}
+
+func (m *managedSerial) BatteryStatusPoll(req *pb.BatteryStatusRequest) (*pb.BatteryStatusResponse, error) {
+	msg := &pb.UartMessage{
+		Type: pb.MessageType_BATTERY_STATUS,
+		Payload: &pb.UartMessage_BatteryStatusRequest{
+			BatteryStatusRequest: req,
+		},
+	}
+	body, err := proto.Marshal(msg)
+	if err != nil {
+		return nil, fmt.Errorf("encode: %w", err)
+	}
+	payload := append([]byte{byte(pb.MessageType_BATTERY_STATUS)}, body...)
+	respPayload, err := m.batteryStatusPayloadPoll(payload)
+	if err != nil {
+		return nil, err
+	}
+	return decodeBatteryStatusPayload(respPayload)
+}
+
+func (m *managedSerial) batteryStatusPayloadPoll(payload []byte) ([]byte, error) {
+	var resp []byte
+	err := m.withPortPoll(func(sp *serialPort) error {
+		var e error
+		resp, e = sp.exchangePayloadForBattery(payload, "BATTERY_STATUS")
+		return e
+	})
+	return resp, err
+}
+
+func (s *serialPort) batteryStatus(req *pb.BatteryStatusRequest) (*pb.BatteryStatusResponse, error) {
+	msg := &pb.UartMessage{
+		Type: pb.MessageType_BATTERY_STATUS,
+		Payload: &pb.UartMessage_BatteryStatusRequest{
+			BatteryStatusRequest: req,
+		},
+	}
+	body, err := proto.Marshal(msg)
+	if err != nil {
+		return nil, fmt.Errorf("encode: %w", err)
+	}
+	payload := append([]byte{byte(pb.MessageType_BATTERY_STATUS)}, body...)
+	respPayload, err := s.exchangePayloadForBattery(payload, "BATTERY_STATUS")
+	if err != nil {
+		return nil, err
+	}
+	return decodeBatteryStatusPayload(respPayload)
+}
+
+func (m *managedSerial) AccelStream(req *pb.AccelStreamRequest) (*pb.AccelStreamResponse, error) {
+	return m.accelStreamVia(m.withPort, req)
+}
+
+func (m *managedSerial) AccelStreamPoll(req *pb.AccelStreamRequest) (*pb.AccelStreamResponse, error) {
+	return m.accelStreamVia(m.withPortPoll, req)
+}
+
+// SetAccelStream enables or disables the ESP-NOW accel stream for one slave (master UART).
+func (m *managedSerial) SetAccelStream(clientID uint32, enable bool) (*pb.AccelStreamResponse, error) {
+	return m.AccelStream(&pb.AccelStreamRequest{
+		Write:    true,
+		Enable:   enable,
+		ClientId: clientID,
+	})
+}
+
+// GetAccelStream returns whether the accel stream is enabled for a slave on the master.
+func (m *managedSerial) GetAccelStream(clientID uint32) (bool, error) {
+	resp, err := m.AccelStreamPoll(&pb.AccelStreamRequest{
+		Write:    false,
+		ClientId: clientID,
+	})
+	if err != nil {
+		return false, err
+	}
+	if !resp.GetSuccess() {
+		return false, fmt.Errorf("accel stream read failed for client %d", clientID)
+	}
+	return resp.GetEnabled(), nil
+}
+
+func (m *managedSerial) TapNotify(req *pb.TapNotifyRequest) (*pb.TapNotifyResponse, error) {
+	return m.tapNotifyVia(m.withPort, req)
+}
+
+func (m *managedSerial) TapNotifyPoll(req *pb.TapNotifyRequest) (*pb.TapNotifyResponse, error) {
+	return m.tapNotifyVia(m.withPortPoll, req)
+}
+
+func (m *managedSerial) tapNotifyVia(
+	portFn func(func(*serialPort) error) error,
+	req *pb.TapNotifyRequest,
+) (*pb.TapNotifyResponse, error) {
+	var resp *pb.TapNotifyResponse
+	err := portFn(func(sp *serialPort) error {
+		var e error
+		resp, e = sp.TapNotify(req)
+		return e
+	})
+	return resp, err
+}
+
+func (m *managedSerial) readCacheStatusPoll() (*pb.CacheStatusResponse, error) {
+	payload, err := m.exchangePoll(byte(pb.MessageType_CACHE_STATUS), "CACHE_STATUS")
+	if err != nil {
+		return nil, err
+	}
+	return decodeCacheStatusPayload(payload)
+}
+
+func decodeCacheStatusPayload(payload []byte) (*pb.CacheStatusResponse, error) {
+	if len(payload) < 1 {
+		return nil, fmt.Errorf("empty response payload")
+	}
+	if payload[0] != byte(pb.MessageType_CACHE_STATUS) {
+		return nil, fmt.Errorf("unexpected command id 0x%02x (want 0x%02x)",
+			payload[0], byte(pb.MessageType_CACHE_STATUS))
+	}
+	var msg pb.UartMessage
+	if err := proto.Unmarshal(payload[1:], &msg); err != nil {
+		return nil, fmt.Errorf("decode: %w", err)
+	}
+	if msg.GetType() != pb.MessageType_CACHE_STATUS {
+		return nil, fmt.Errorf("unexpected type %v", msg.GetType())
+	}
+	r := msg.GetCacheStatusResponse()
+	if r == nil {
+		return nil, fmt.Errorf("missing cache_status_response")
+	}
+	return r, nil
+}
+
+func (m *managedSerial) accelStreamVia(
+	portFn func(func(*serialPort) error) error,
+	req *pb.AccelStreamRequest,
+) (*pb.AccelStreamResponse, error) {
+	var resp *pb.AccelStreamResponse
+	err := portFn(func(sp *serialPort) error {
+		var e error
+		resp, e = sp.AccelStream(req)
+		return e
+	})
+	return resp, err
+}
+
 func (m *managedSerial) AccelDeadzone(req *pb.AccelDeadzoneRequest) (*pb.AccelDeadzoneResponse, error) {
 	return m.accelDeadzoneVia(m.withPort, req)
 }
@@ -117,6 +294,68 @@ func (s *serialPort) listClients() ([]*pb.ClientInfo, error) {
 	return decodeClientsPayload(payload)
 }
 
+func (s *serialPort) AccelStream(req *pb.AccelStreamRequest) (*pb.AccelStreamResponse, error) {
+	msg := &pb.UartMessage{
+		Type: pb.MessageType_ACCEL_STREAM,
+		Payload: &pb.UartMessage_AccelStreamRequest{
+			AccelStreamRequest: req,
+		},
+	}
+	body, err := proto.Marshal(msg)
+	if err != nil {
+		return nil, fmt.Errorf("encode: %w", err)
+	}
+	payload := append([]byte{byte(pb.MessageType_ACCEL_STREAM)}, body...)
+	respPayload, err := s.exchangePayload(payload, "ACCEL_STREAM")
+	if err != nil {
+		return nil, err
+	}
+	var respMsg pb.UartMessage
+	if err := proto.Unmarshal(respPayload[1:], &respMsg); err != nil {
+		return nil, fmt.Errorf("decode: %w", err)
+	}
+	r := respMsg.GetAccelStreamResponse()
+	if r == nil {
+		return nil, fmt.Errorf("missing accel_stream_response")
+	}
+	return r, nil
+}
+
+func (s *serialPort) TapNotify(req *pb.TapNotifyRequest) (*pb.TapNotifyResponse, error) {
+	msg := &pb.UartMessage{
+		Type: pb.MessageType_TAP_NOTIFY,
+		Payload: &pb.UartMessage_TapNotifyRequest{
+			TapNotifyRequest: req,
+		},
+	}
+	body, err := proto.Marshal(msg)
+	if err != nil {
+		return nil, fmt.Errorf("encode: %w", err)
+	}
+	payload := append([]byte{byte(pb.MessageType_TAP_NOTIFY)}, body...)
+	respPayload, err := s.exchangePayload(payload, "TAP_NOTIFY")
+	if err != nil {
+		return nil, err
+	}
+	var respMsg pb.UartMessage
+	if err := proto.Unmarshal(respPayload[1:], &respMsg); err != nil {
+		return nil, fmt.Errorf("decode: %w", err)
+	}
+	r := respMsg.GetTapNotifyResponse()
+	if r == nil {
+		return nil, fmt.Errorf("missing tap_notify_response")
+	}
+	return r, nil
+}
+
+func (s *serialPort) readCacheStatus() (*pb.CacheStatusResponse, error) {
+	payload, err := s.exchange(byte(pb.MessageType_CACHE_STATUS), "CACHE_STATUS")
+	if err != nil {
+		return nil, err
+	}
+	return decodeCacheStatusPayload(payload)
+}
+
 func (s *serialPort) accelDeadzone(req *pb.AccelDeadzoneRequest) (*pb.AccelDeadzoneResponse, error) {
 	msg := &pb.UartMessage{
 		Type: pb.MessageType_ACCEL_DEADZONE,
@@ -172,16 +411,93 @@ func (s *serialPort) espnowUnicastTest(clientID, seq uint32) (*pb.EspNowUnicastT
 	return r, nil
 }
 
+// EchoPingResult is the host-side round-trip for ESP-NOW echo ping.
+type EchoPingResult struct {
+	Success     bool    `json:"success"`
+	ClientID    uint32  `json:"client_id"`
+	TimestampUs uint64  `json:"timestamp_us"`
+	RttMs       float64 `json:"rtt_ms"`     // goTool: full UART round-trip
+	EspRttUs    uint32  `json:"esp_rtt_us"` // master: µs delta ping send → pong recv
+}
+
+func (s *serialPort) echoPing(clientID uint32) (*EchoPingResult, error) {
+	t0 := time.Now()
+	timestampUs := uint64(t0.UnixMicro())
+	req := &pb.EspNowEchoPingRequest{
+		ClientId:    clientID,
+		TimestampUs: timestampUs,
+	}
+	msg := &pb.UartMessage{
+		Type: pb.MessageType_ESPNOW_ECHO_PING,
+		Payload: &pb.UartMessage_EspnowEchoPingRequest{
+			EspnowEchoPingRequest: req,
+		},
+	}
+	body, err := proto.Marshal(msg)
+	if err != nil {
+		return nil, fmt.Errorf("encode: %w", err)
+	}
+	payload := append([]byte{byte(pb.MessageType_ESPNOW_ECHO_PING)}, body...)
+	respPayload, err := s.exchangePayload(payload, "ESPNOW_ECHO_PING")
+	if err != nil {
+		return nil, err
+	}
+	rttMs := float64(time.Since(t0).Microseconds()) / 1000.0
+
+	var respMsg pb.UartMessage
+	if err := proto.Unmarshal(respPayload[1:], &respMsg); err != nil {
+		return nil, fmt.Errorf("decode: %w", err)
+	}
+	r := respMsg.GetEspnowEchoPingResponse()
+	if r == nil {
+		return nil, fmt.Errorf("missing espnow_echo_ping_response")
+	}
+	if !r.GetSuccess() {
+		return &EchoPingResult{
+			Success:  false,
+			ClientID: r.GetClientId(),
+			RttMs:    rttMs,
+		}, nil
+	}
+	if r.GetTimestampUs() != timestampUs {
+		return nil, fmt.Errorf("timestamp mismatch: sent %d got %d", timestampUs, r.GetTimestampUs())
+	}
+	return &EchoPingResult{
+		Success:     true,
+		ClientID:    r.GetClientId(),
+		TimestampUs: r.GetTimestampUs(),
+		RttMs:       rttMs,
+		EspRttUs:    r.GetEspRttUs(),
+	}, nil
+}
+
 func (m *managedSerial) FindMe(clientID uint32) error {
 	return m.withPort(func(sp *serialPort) error {
 		return runFindMeClient(sp, clientID)
 	})
 }
 
+func (m *managedSerial) SetLogLevel(write bool, level uint32) (*pb.SetLogLevelResponse, error) {
+	var resp *pb.SetLogLevelResponse
+	err := m.withPort(func(sp *serialPort) error {
+		var e error
+		resp, e = runSetLogLevelClient(sp, write, level)
+		return e
+	})
+	return resp, err
+}
+
 func (m *managedSerial) Restart(clientID uint32) error {
-	return m.withPort(func(sp *serialPort) error {
+	err := m.withPort(func(sp *serialPort) error {
 		return runRestartClient(sp, clientID)
 	})
+	if err != nil {
+		return err
+	}
+	if clientID == 0 {
+		m.recoverAfterMasterRestart()
+	}
+	return nil
 }
 
 func (s *serialPort) ledRingProgress(req *pb.LedRingProgressRequest) (*pb.LedRingProgressResponse, error) {
@@ -215,6 +531,28 @@ func (s *serialPort) GetVersion() (*pb.VersionResponse, error) { return s.getVer
 
 func (s *serialPort) ListClients() ([]*pb.ClientInfo, error) { return s.listClients() }
 
+func (s *serialPort) SetAccelStream(clientID uint32, enable bool) (*pb.AccelStreamResponse, error) {
+	return s.AccelStream(&pb.AccelStreamRequest{
+		Write:    true,
+		Enable:   enable,
+		ClientId: clientID,
+	})
+}
+
+func (s *serialPort) GetAccelStream(clientID uint32) (bool, error) {
+	resp, err := s.AccelStream(&pb.AccelStreamRequest{
+		Write:    false,
+		ClientId: clientID,
+	})
+	if err != nil {
+		return false, err
+	}
+	if !resp.GetSuccess() {
+		return false, fmt.Errorf("accel stream read failed for client %d", clientID)
+	}
+	return resp.GetEnabled(), nil
+}
+
 func (s *serialPort) AccelDeadzone(req *pb.AccelDeadzoneRequest) (*pb.AccelDeadzoneResponse, error) {
 	return s.accelDeadzone(req)
 }
@@ -223,10 +561,34 @@ func (s *serialPort) EspnowUnicastTest(clientID, seq uint32) (*pb.EspNowUnicastT
 	return s.espnowUnicastTest(clientID, seq)
 }
 
+func (s *serialPort) EchoPing(clientID uint32) (*EchoPingResult, error) {
+	return s.echoPing(clientID)
+}
+
+func (m *managedSerial) EchoPing(clientID uint32) (*EchoPingResult, error) {
+	var result *EchoPingResult
+	err := m.withPort(func(sp *serialPort) error {
+		var e error
+		result, e = sp.echoPing(clientID)
+		return e
+	})
+	return result, err
+}
+
 func (s *serialPort) LedRing(req *pb.LedRingProgressRequest) (*pb.LedRingProgressResponse, error) {
 	return s.ledRingProgress(req)
 }
 
+func (m *managedSerial) LedRing(req *pb.LedRingProgressRequest) (*pb.LedRingProgressResponse, error) {
+	var resp *pb.LedRingProgressResponse
+	err := m.withPort(func(sp *serialPort) error {
+		var e error
+		resp, e = sp.LedRing(req)
+		return e
+	})
+	return resp, err
+}
+
 func (s *serialPort) FindMe(clientID uint32) (*pb.EspNowFindMeResponse, error) {
 	return s.espnowFindMe(clientID)
 }

goTool/cmd_autotest.go

@@ -62,6 +62,8 @@ func runTest(portOverride string, baudOverride int, args []string) error {
 	if err != nil {
 		return fmt.Errorf("open %s: %w", port, err)
 	}
+	registerShutdown(func() { _ = sp.Close() })
+	enableShutdownOnInterrupt()
 	defer sp.Close()
 
 	if !*verbose {

goTool/cmd_cache_status.go

@@ -0,0 +1,33 @@
+package main
+
+import (
+	"fmt"
+)
+
+func runCacheStatus(sp *serialPort) error {
+	r, err := sp.readCacheStatus()
+	if err != nil {
+		return err
+	}
+	clients := r.GetClients()
+	if len(clients) == 0 {
+		fmt.Println("(no slaves with accel stream or tap notify enabled)")
+		return nil
+	}
+	for _, c := range clients {
+		id := c.GetClientId()
+		if a := c.GetAccel(); a != nil {
+			if !a.GetValid() {
+				fmt.Printf("client %d accel: no sample yet\n", id)
+			} else {
+				fmt.Printf("client %d accel: x=%d y=%d z=%d (age %d ms)\n",
+					id, a.GetX(), a.GetY(), a.GetZ(), a.GetAgeMs())
+			}
+		}
+		if t := c.GetTap(); t != nil {
+			fmt.Printf("client %d tap: %s (age %d ms)\n",
+				id, tapKindLabel(t.GetKind()), t.GetAgeMs())
+		}
+	}
+	return nil
+}

goTool/cmd_clients.go

@@ -18,9 +18,17 @@ func runClients(sp *serialPort) error {
 	fmt.Printf("clients (%d):\n", len(clients))
 	for i, c := range clients {
 		mac := hex.EncodeToString(c.GetMac())
-		fmt.Printf("  [%d] id=%d mac=%s ver=%d available=%v used=%v last_ping=%d last_success_ping=%d\n",
+		fmt.Printf("  [%d] id=%d mac=%s ver=%d available=%v used=%v last_ping=%d last_success_ping=%d tap=%s/%s/%s\n",
 			i, c.GetId(), mac, c.GetVersion(), c.GetAvailable(), c.GetUsed(),
-			c.GetLastPing(), c.GetLastSuccessPing())
+			c.GetLastPing(), c.GetLastSuccessPing(),
+			boolFlag(c.GetTapNotifySingle()), boolFlag(c.GetTapNotifyDouble()), boolFlag(c.GetTapNotifyTriple()))
 	}
 	return nil
 }
+
+func boolFlag(v bool) string {
+	if v {
+		return "on"
+	}
+	return "off"
+}

goTool/cmd_echo_ping.go

@@ -0,0 +1,26 @@
+package main
+
+import (
+	"flag"
+	"fmt"
+)
+
+func runEchoPing(sp *serialPort, args []string) error {
+	fs := flag.NewFlagSet("echo-ping", flag.ExitOnError)
+	clientID := fs.Uint("client", 0, "slave client id from `clients`")
+	if err := fs.Parse(args); err != nil {
+		return err
+	}
+	if *clientID == 0 {
+		return fmt.Errorf("client id required (see `gotool clients`)")
+	}
+
+	r, err := sp.echoPing(uint32(*clientID))
+	if err != nil {
+		return err
+	}
+
+	fmt.Printf("echo ping: success=%v client_id=%d rtt_ms=%.3f esp_rtt_us=%d\n",
+		r.Success, r.ClientID, r.RttMs, r.EspRttUs)
+	return nil
+}

goTool/cmd_led_ring.go

@@ -7,17 +7,12 @@ import (
 	"powerpod/gotool/pb"
 )
 
-const (
-	ledRingModeClear    = 0
-	ledRingModeProgress = 1
-	ledRingModeDigit    = 2
-	ledRingModeBlink    = 3
-	ledRingModeFindMe   = 4
-)
-
 func runLedRing(sp *serialPort, args []string) error {
 	fs := flag.NewFlagSet("led-ring", flag.ExitOnError)
-	mode := fs.String("mode", "progress", "clear, progress, digit, blink, or find-me")
+	mode := fs.String("mode", "progress", "clear, color, progress, digit, blink, find-me, or battery-low")
+	clientID := fs.Uint("client", 0, "0=master ring, >0=slave via ESP-NOW")
+	allClients := fs.Bool("all", false, "broadcast to all slaves")
+	slavesOnly := fs.Bool("slaves-only", false, "with -all: do not change master ring")
 	progress := fs.Uint("progress", 0, "fill level 0–100 (mode=progress)")
 	digit := fs.Uint("digit", 0, "digit 0–10 (mode=digit)")
 	r := fs.Uint("r", 0, "red 0–255")
@@ -30,20 +25,9 @@ func runLedRing(sp *serialPort, args []string) error {
 		return err
 	}
 
-	var modeVal uint32
-	switch *mode {
-	case "clear":
-		modeVal = ledRingModeClear
-	case "progress":
-		modeVal = ledRingModeProgress
-	case "digit":
-		modeVal = ledRingModeDigit
-	case "blink":
-		modeVal = ledRingModeBlink
-	case "find-me", "find_me", "findme":
-		modeVal = ledRingModeFindMe
-	default:
-		return fmt.Errorf("unknown -mode %q (clear, progress, digit, blink, find-me)", *mode)
+	modeVal, err := ledRingModeFromString(*mode)
+	if err != nil {
+		return err
 	}
 
 	resp, err := sp.ledRingProgress(&pb.LedRingProgressRequest{
@@ -56,11 +40,15 @@ func runLedRing(sp *serialPort, args []string) error {
 		Intensity:  uint32(*intensity),
 		BlinkMs:    uint32(*blinkMs),
 		BlinkCount: uint32(*blinkCount),
+		ClientId:   uint32(*clientID),
+		AllClients: *allClients,
+		SlavesOnly: *slavesOnly,
 	})
 	if err != nil {
 		return err
 	}
-	fmt.Printf("success=%v mode=%d progress=%d digit=%d\n",
-		resp.GetSuccess(), resp.GetMode(), resp.GetProgress(), resp.GetDigit())
+	fmt.Printf("success=%v mode=%d progress=%d digit=%d client_id=%d slaves_updated=%d\n",
+		resp.GetSuccess(), resp.GetMode(), resp.GetProgress(), resp.GetDigit(),
+		resp.GetClientId(), resp.GetSlavesUpdated())
 	return nil
 }

goTool/cmd_log_level.go

@@ -0,0 +1,61 @@
+package main
+
+import (
+	"flag"
+	"fmt"
+
+	"google.golang.org/protobuf/proto"
+	"powerpod/gotool/pb"
+)
+
+func runLogLevel(sp *serialPort, args []string) error {
+	fs := flag.NewFlagSet("log-level", flag.ExitOnError)
+	write := fs.Bool("set", false, "write log level (default: read)")
+	level := fs.Uint("level", 0, "esp_log_level_t 0–5 (with -set)")
+	if err := fs.Parse(args); err != nil {
+		return err
+	}
+	resp, err := sp.setLogLevel(*write, uint32(*level))
+	if err != nil {
+		return err
+	}
+	if !resp.GetSuccess() {
+		return fmt.Errorf("set_log_level rejected (level=%d)", resp.GetLevel())
+	}
+	fmt.Printf("log_level=%d success=%v\n", resp.GetLevel(), resp.GetSuccess())
+	return nil
+}
+
+func runSetLogLevelClient(sp *serialPort, write bool, level uint32) (*pb.SetLogLevelResponse, error) {
+	return sp.setLogLevel(write, level)
+}
+
+func (s *serialPort) setLogLevel(write bool, level uint32) (*pb.SetLogLevelResponse, error) {
+	msg := &pb.UartMessage{
+		Type: pb.MessageType_SET_LOG_LEVEL,
+		Payload: &pb.UartMessage_SetLogLevelRequest{
+			SetLogLevelRequest: &pb.SetLogLevelRequest{
+				Write: write,
+				Level: level,
+			},
+		},
+	}
+	body, err := proto.Marshal(msg)
+	if err != nil {
+		return nil, fmt.Errorf("encode: %w", err)
+	}
+	payload := append([]byte{byte(pb.MessageType_SET_LOG_LEVEL)}, body...)
+	respPayload, err := s.exchangePayload(payload, "SET_LOG_LEVEL")
+	if err != nil {
+		return nil, err
+	}
+	var respMsg pb.UartMessage
+	if err := proto.Unmarshal(respPayload[1:], &respMsg); err != nil {
+		return nil, fmt.Errorf("decode: %w", err)
+	}
+	r := respMsg.GetSetLogLevelResponse()
+	if r == nil {
+		return nil, fmt.Errorf("missing set_log_level_response")
+	}
+	return r, nil
+}

goTool/cmd_ota.go

@@ -16,8 +16,7 @@ func runOTA(sp *serialPort, args []string) error {
 
 	sp.mu.Lock()
 	defer sp.mu.Unlock()
-	m := &managedSerial{quiet: false, sp: sp}
-	return runOTAOnPortUnlocked(m, data, func(p OTAProgress) {
+	return runOTAOnPortUnlocked(sp, data, func(p OTAProgress) {
 		switch p.Phase {
 		case "preparing", "ready":
 			fmt.Println(p.Message)

goTool/cmd_serve.go

@@ -2,6 +2,7 @@ package main
 
 import (
 	"embed"
+	"errors"
 	"flag"
 	"fmt"
 	"io/fs"
@@ -21,7 +22,9 @@ var wsUpgrader = websocket.Upgrader{
 
 func runServe(portName string, baud int, args []string) error {
 	serveFlags := flag.NewFlagSet("serve", flag.ExitOnError)
-	addr := serveFlags.String("addr", ":8080", "HTTP listen address")
+	addr := serveFlags.String("addr", ":8080", "dashboard HTTP listen address")
+	apiAddr := serveFlags.String("api-addr", ":8081", "external API HTTP listen address (empty to disable)")
+	accelInterval := serveFlags.Duration("accel-interval", defaultAccelStreamInterval, "accel WebSocket sample period on API server")
 	interval := serveFlags.Duration("interval", 2*time.Second, "UART poll interval")
 	if err := serveFlags.Parse(args); err != nil {
 		return err
@@ -32,15 +35,33 @@ func runServe(portName string, baud int, args []string) error {
 
 	link := newManagedSerial(portName, baud)
 	link.quiet = true
-	defer link.Close()
 
 	hub := newWSHub()
+	streamCtl := newAccelStreamCtl()
+	tapCtl := newTapNotifyCtl()
 	stop := make(chan struct{})
-	defer close(stop)
-	go runPoller(link, portName, hub, *interval, stop)
+
+	var dashSrv *http.Server
+	var apiSrv *http.Server
+	registerShutdown(func() {
+		close(stop)
+		shutdownHTTPServer(dashSrv)
+		shutdownAPIServer(apiSrv)
+		if err := link.Close(); err != nil {
+			log.Printf("UART close: %v", err)
+		}
+	})
+
+	go runPoller(link, portName, hub, streamCtl, tapCtl, *interval, stop)
+	go runBatteryPoller(link, hub, 5*time.Second, stop)
+	go runCacheStatusDashboardPoller(link, hub, *accelInterval, stop)
+
+	if *apiAddr != "" {
+		apiSrv = runAPIServer(portName, link, *apiAddr, *accelInterval, hub, streamCtl, tapCtl, stop)
+	}
 
 	mux := http.NewServeMux()
-	mountServeAPI(mux, link, hub)
+	mountServeAPI(mux, link, hub, streamCtl, tapCtl)
 	mux.HandleFunc("/ws", func(w http.ResponseWriter, r *http.Request) {
 		conn, err := wsUpgrader.Upgrade(w, r, nil)
 		if err != nil {
@@ -64,7 +85,19 @@ func runServe(portName string, baud int, args []string) error {
 	}
 	mux.Handle("/", http.FileServer(http.FS(ui)))
 
-	log.Printf("dashboard http://localhost%s  (UART %s @ %d baud, poll %s, auto-reconnect)",
-		*addr, portName, baud, interval.String())
-	return http.ListenAndServe(*addr, mux)
+	log.Printf("dashboard http://localhost%s  (UART %s @ %d baud, poll %s, live-stream %s, auto-reconnect)",
+		*addr, portName, baud, interval.String(), accelInterval.String())
+	if *apiAddr == "" {
+		log.Printf("external API disabled (-api-addr \"\")")
+	}
+
+	dashSrv = &http.Server{Addr: *addr, Handler: mux}
+	go func() {
+		if err := dashSrv.ListenAndServe(); err != nil && !errors.Is(err, http.ErrServerClosed) {
+			log.Printf("dashboard server: %v", err)
+		}
+	}()
+
+	waitForShutdown()
+	return nil
 }

goTool/cmd_tap.go

@@ -0,0 +1,58 @@
+package main
+
+import (
+	"flag"
+	"fmt"
+
+	"powerpod/gotool/pb"
+)
+
+func runTapNotify(sp *serialPort, args []string) error {
+	fs := flag.NewFlagSet("tap-notify", flag.ExitOnError)
+	write := fs.Bool("set", false, "write tap notify flags (default: read)")
+	clientID := fs.Uint("client", 0, "client id (>0 required for read/set one slave)")
+	all := fs.Bool("all", false, "apply to all registered slaves (with -set)")
+	single := fs.Bool("single", false, "notify on single tap")
+	doubleTap := fs.Bool("double", false, "notify on double tap")
+	triple := fs.Bool("triple", false, "notify on triple tap")
+	if err := fs.Parse(args); err != nil {
+		return err
+	}
+
+	if !*write && (*all || *clientID == 0) {
+		return fmt.Errorf("read requires -client <id>")
+	}
+	if *write && !*all && *clientID == 0 {
+		return fmt.Errorf("set requires -client <id> or -all")
+	}
+
+	r, err := sp.TapNotify(&pb.TapNotifyRequest{
+		Write:      *write,
+		ClientId:   uint32(*clientID),
+		AllClients: *all,
+		Single:     *single,
+		DoubleTap:  *doubleTap,
+		Triple:     *triple,
+	})
+	if err != nil {
+		return err
+	}
+
+	fmt.Printf("client_id=%d success=%v slaves_updated=%d single=%v double=%v triple=%v\n",
+		r.GetClientId(), r.GetSuccess(), r.GetSlavesUpdated(),
+		r.GetSingle(), r.GetDoubleTap(), r.GetTriple())
+	return nil
+}
+
+func tapKindLabel(k pb.TapKind) string {
+	switch k {
+	case pb.TapKind_TAP_SINGLE:
+		return "single"
+	case pb.TapKind_TAP_DOUBLE:
+		return "double"
+	case pb.TapKind_TAP_TRIPLE:
+		return "triple"
+	default:
+		return "none"
+	}
+}

goTool/dashboard.go

@@ -19,7 +19,10 @@ type MasterView struct {
 	GitHash           string `json:"git_hash"`
 	RunningPartition  string `json:"running_partition,omitempty"`
 	Deadzone          uint32 `json:"deadzone,omitempty"`
-	OK                bool   `json:"ok"`
+	Lipo1             lipoReadingJSON `json:"lipo1"`
+	Lipo2             lipoReadingJSON `json:"lipo2"`
+	BatteryAgeMs      uint32          `json:"battery_age_ms,omitempty"`
+	OK                bool            `json:"ok"`
 	Error             string `json:"error,omitempty"`
 }
 
@@ -32,6 +35,20 @@ type ClientView struct {
 	Used            bool   `json:"used"`
 	LastPing        uint32 `json:"last_ping"`
 	LastSuccessPing uint32 `json:"last_success_ping"`
+	AccelValid      bool   `json:"accel_valid"`
+	AccelX          int32  `json:"accel_x"`
+	AccelY          int32  `json:"accel_y"`
+	AccelZ          int32  `json:"accel_z"`
+	AccelAgeMs      uint32 `json:"accel_age_ms"`
+	AccelStream     bool            `json:"accel_stream"`
+	TapNotifySingle bool            `json:"tap_notify_single"`
+	TapNotifyDouble bool            `json:"tap_notify_double"`
+	TapNotifyTriple bool            `json:"tap_notify_triple"`
+	LastTap         string          `json:"last_tap,omitempty"`
+	LastTapAt       int64           `json:"last_tap_at,omitempty"`
+	Lipo1           lipoReadingJSON `json:"lipo1"`
+	Lipo2           lipoReadingJSON `json:"lipo2"`
+	BatteryAgeMs    uint32          `json:"battery_age_ms,omitempty"`
 }
 
 type DashboardState struct {
@@ -40,14 +57,17 @@ type DashboardState struct {
 	UARTConnected bool         `json:"uart_connected"`
 	SerialOK      bool         `json:"serial_ok"`
 	SerialError   string       `json:"serial_error,omitempty"`
+	/** Host: fast CACHE_STATUS poll (~16 ms) for accel + tap. */
+	LiveStream    bool         `json:"live_stream"`
 	Master        MasterView   `json:"master"`
 	Clients       []ClientView `json:"clients"`
 }
 
 type wsHub struct {
-	mu      sync.RWMutex
-	clients map[*websocket.Conn]struct{}
-	state   DashboardState
+	mu         sync.RWMutex
+	clients    map[*websocket.Conn]struct{}
+	state      DashboardState
+	liveStream bool
 }
 
 func newWSHub() *wsHub {
@@ -56,6 +76,19 @@ func newWSHub() *wsHub {
 
 func (h *wsHub) setState(st DashboardState) {
 	h.mu.Lock()
+	prev := h.state
+	st.LiveStream = prev.LiveStream
+	st.Clients = preserveClientAccel(st.Clients, prev.Clients, st.LiveStream)
+	st.Clients = preserveClientBattery(st.Clients, prev.Clients)
+	st.Clients = preserveClientTap(st.Clients, prev.Clients)
+	if !st.Master.Lipo1.Valid && !st.Master.Lipo2.Valid {
+		if prev.Master.Lipo1.Valid || prev.Master.Lipo2.Valid {
+			st.Master.Lipo1 = prev.Master.Lipo1
+			st.Master.Lipo2 = prev.Master.Lipo2
+			st.Master.BatteryAgeMs = prev.Master.BatteryAgeMs
+		}
+	}
+	h.liveStream = st.LiveStream
 	h.state = st
 	conns := make([]*websocket.Conn, 0, len(h.clients))
 	for c := range h.clients {
@@ -68,7 +101,7 @@ func (h *wsHub) setState(st DashboardState) {
 		return
 	}
 	for _, c := range conns {
-		_ = c.WriteMessage(websocket.TextMessage, data)
+		h.writeJSON(c, data)
 	}
 }
 
@@ -79,7 +112,7 @@ func (h *wsHub) register(c *websocket.Conn) {
 	h.mu.Unlock()
 
 	if data, err := json.Marshal(snap); err == nil {
-		_ = c.WriteMessage(websocket.TextMessage, data)
+		h.writeJSON(c, data)
 	}
 }
 
@@ -89,24 +122,400 @@ func (h *wsHub) unregister(c *websocket.Conn) {
 	h.mu.Unlock()
 }
 
-func (h *wsHub) broadcastRaw(v any) {
+// writeJSON sends to one client; removes it on error or panic (closed connection).
+func (h *wsHub) writeJSON(c *websocket.Conn, data []byte) {
+	defer func() {
+		if recover() != nil {
+			h.unregister(c)
+		}
+	}()
+	if err := c.WriteMessage(websocket.TextMessage, data); err != nil {
+		h.unregister(c)
+	}
+}
+
+func (h *wsHub) broadcastJSON(data []byte) {
 	h.mu.RLock()
 	conns := make([]*websocket.Conn, 0, len(h.clients))
 	for c := range h.clients {
 		conns = append(conns, c)
 	}
 	h.mu.RUnlock()
+	for _, c := range conns {
+		h.writeJSON(c, data)
+	}
+}
 
-	data, err := json.Marshal(v)
+func applyAccelSamples(clients []ClientView, samples []*pb.AccelSample) []ClientView {
+	if len(samples) == 0 {
+		return clients
+	}
+	byID := make(map[uint32]*pb.AccelSample, len(samples))
+	for _, s := range samples {
+		byID[s.GetClientId()] = s
+	}
+	out := make([]ClientView, len(clients))
+	for i, c := range clients {
+		out[i] = c
+		if !c.AccelStream {
+			out[i].AccelValid = false
+			continue
+		}
+		s, ok := byID[c.ID]
+		if !ok {
+			continue
+		}
+		out[i].AccelValid = s.GetValid()
+		if s.GetValid() {
+			out[i].AccelX = s.GetX()
+			out[i].AccelY = s.GetY()
+			out[i].AccelZ = s.GetZ()
+			out[i].AccelAgeMs = s.GetAgeMs()
+		}
+	}
+	return out
+}
+
+func preserveClientAccel(newClients, oldClients []ClientView, liveStream bool) []ClientView {
+	if len(oldClients) == 0 {
+		return newClients
+	}
+	oldByID := make(map[uint32]ClientView, len(oldClients))
+	for _, c := range oldClients {
+		oldByID[c.ID] = c
+	}
+	out := make([]ClientView, len(newClients))
+	for i, c := range newClients {
+		out[i] = c
+		if !liveStream && !c.AccelStream {
+			continue
+		}
+		if liveStream && !c.AccelStream {
+			out[i].AccelValid = false
+			out[i].AccelX = 0
+			out[i].AccelY = 0
+			out[i].AccelZ = 0
+			out[i].AccelAgeMs = 0
+			continue
+		}
+		prev, ok := oldByID[c.ID]
+		if !ok || !prev.AccelValid {
+			continue
+		}
+		if !c.AccelValid {
+			out[i].AccelValid = prev.AccelValid
+			out[i].AccelX = prev.AccelX
+			out[i].AccelY = prev.AccelY
+			out[i].AccelZ = prev.AccelZ
+			out[i].AccelAgeMs = prev.AccelAgeMs
+		}
+	}
+	return out
+}
+
+func preserveClientBattery(newClients, oldClients []ClientView) []ClientView {
+	if len(oldClients) == 0 {
+		return newClients
+	}
+	oldByID := make(map[uint32]ClientView, len(oldClients))
+	for _, c := range oldClients {
+		oldByID[c.ID] = c
+	}
+	out := make([]ClientView, len(newClients))
+	for i, c := range newClients {
+		out[i] = c
+		if c.Lipo1.Valid || c.Lipo2.Valid {
+			continue
+		}
+		prev, ok := oldByID[c.ID]
+		if !ok {
+			continue
+		}
+		if prev.Lipo1.Valid || prev.Lipo2.Valid {
+			out[i].Lipo1 = prev.Lipo1
+			out[i].Lipo2 = prev.Lipo2
+			out[i].BatteryAgeMs = prev.BatteryAgeMs
+		}
+	}
+	return out
+}
+
+func anyClientAccelStream(clients []ClientView) bool {
+	for _, c := range clients {
+		if c.AccelStream {
+			return true
+		}
+	}
+	return false
+}
+
+func anyClientTapNotify(clients []ClientView) bool {
+	for _, c := range clients {
+		if c.TapNotifySingle || c.TapNotifyDouble || c.TapNotifyTriple {
+			return true
+		}
+	}
+	return false
+}
+
+func tapKindLabelPB(k pb.TapKind) string {
+	switch k {
+	case pb.TapKind_TAP_SINGLE:
+		return "single"
+	case pb.TapKind_TAP_DOUBLE:
+		return "double"
+	case pb.TapKind_TAP_TRIPLE:
+		return "triple"
+	default:
+		return ""
+	}
+}
+
+func applyTapEvents(clients []ClientView, events []*pb.TapEvent) []ClientView {
+	if len(events) == 0 {
+		return clients
+	}
+	byID := make(map[uint32]*pb.TapEvent, len(events))
+	for _, e := range events {
+		if e.GetValid() {
+			byID[e.GetClientId()] = e
+		}
+	}
+	if len(byID) == 0 {
+		return clients
+	}
+	now := time.Now().UnixMilli()
+	out := make([]ClientView, len(clients))
+	for i, c := range clients {
+		out[i] = c
+		if !clientTapNotifyAny(c) {
+			continue
+		}
+		e, ok := byID[c.ID]
+		if !ok {
+			continue
+		}
+		out[i].LastTap = tapKindLabelPB(e.GetKind())
+		out[i].LastTapAt = now
+	}
+	return out
+}
+
+const clientTapDisplayMinMs = 2000
+
+func clientTapNotifyAny(c ClientView) bool {
+	return c.TapNotifySingle || c.TapNotifyDouble || c.TapNotifyTriple
+}
+
+func preserveClientTap(newClients, oldClients []ClientView) []ClientView {
+	if len(oldClients) == 0 {
+		return newClients
+	}
+	oldByID := make(map[uint32]ClientView, len(oldClients))
+	for _, c := range oldClients {
+		oldByID[c.ID] = c
+	}
+	cutoff := time.Now().Add(-clientTapDisplayMinMs * time.Millisecond).UnixMilli()
+	out := make([]ClientView, len(newClients))
+	for i, c := range newClients {
+		out[i] = c
+		if c.LastTap != "" {
+			continue
+		}
+		prev, ok := oldByID[c.ID]
+		if !ok || prev.LastTap == "" || prev.LastTapAt < cutoff {
+			continue
+		}
+		out[i].LastTap = prev.LastTap
+		out[i].LastTapAt = prev.LastTapAt
+	}
+	return out
+}
+
+// patchClientAccelStream updates stream flag immediately (e.g. after REST) and pushes WS.
+func (h *wsHub) patchClientAccelStream(clientID uint32, enabled bool) {
+	h.mu.Lock()
+	for i := range h.state.Clients {
+		if h.state.Clients[i].ID != clientID {
+			continue
+		}
+		h.state.Clients[i].AccelStream = enabled
+		if !enabled {
+			h.state.Clients[i].AccelValid = false
+			h.state.Clients[i].AccelX = 0
+			h.state.Clients[i].AccelY = 0
+			h.state.Clients[i].AccelZ = 0
+			h.state.Clients[i].AccelAgeMs = 0
+		}
+		break
+	}
+	st := h.state
+	st.UpdatedAt = time.Now().Format(time.RFC3339)
+	conns := make([]*websocket.Conn, 0, len(h.clients))
+	for c := range h.clients {
+		conns = append(conns, c)
+	}
+	h.mu.Unlock()
+
+	data, err := json.Marshal(st)
 	if err != nil {
 		return
 	}
 	for _, c := range conns {
-		_ = c.WriteMessage(websocket.TextMessage, data)
+		h.writeJSON(c, data)
 	}
 }
 
-func pollDashboard(link *managedSerial, portName string, last *DashboardState) DashboardState {
+func (h *wsHub) anyAccelStreamEnabled() bool {
+	h.mu.RLock()
+	defer h.mu.RUnlock()
+	return anyClientAccelStream(h.state.Clients)
+}
+
+func (h *wsHub) anyTapNotifyEnabled() bool {
+	h.mu.RLock()
+	defer h.mu.RUnlock()
+	return anyClientTapNotify(h.state.Clients)
+}
+
+func (h *wsHub) liveStreamEnabled() bool {
+	h.mu.RLock()
+	defer h.mu.RUnlock()
+	return h.liveStream
+}
+
+func (h *wsHub) snapshotClients() []ClientView {
+	h.mu.RLock()
+	defer h.mu.RUnlock()
+	out := make([]ClientView, len(h.state.Clients))
+	copy(out, h.state.Clients)
+	return out
+}
+
+// patchLiveStream toggles host CACHE_STATUS polling (~16 ms).
+func (h *wsHub) patchLiveStream(enabled bool) {
+	h.mu.Lock()
+	h.liveStream = enabled
+	st := h.state
+	st.LiveStream = enabled
+	if !enabled {
+		for i := range st.Clients {
+			st.Clients[i].AccelValid = false
+			st.Clients[i].AccelX = 0
+			st.Clients[i].AccelY = 0
+			st.Clients[i].AccelZ = 0
+			st.Clients[i].AccelAgeMs = 0
+			st.Clients[i].LastTap = ""
+			st.Clients[i].LastTapAt = 0
+		}
+	}
+	h.state = st
+	conns := make([]*websocket.Conn, 0, len(h.clients))
+	for c := range h.clients {
+		conns = append(conns, c)
+	}
+	h.mu.Unlock()
+
+	data, err := json.Marshal(st)
+	if err != nil {
+		return
+	}
+	for _, c := range conns {
+		h.writeJSON(c, data)
+	}
+}
+
+// patchClientTapNotify updates tap notify flags immediately (e.g. after REST) and pushes WS.
+func (h *wsHub) patchClientTapNotify(clientID uint32, single, doubleTap, triple bool) {
+	h.mu.Lock()
+	for i := range h.state.Clients {
+		if h.state.Clients[i].ID != clientID {
+			continue
+		}
+		h.state.Clients[i].TapNotifySingle = single
+		h.state.Clients[i].TapNotifyDouble = doubleTap
+		h.state.Clients[i].TapNotifyTriple = triple
+		if !single && !doubleTap && !triple {
+			h.state.Clients[i].LastTap = ""
+			h.state.Clients[i].LastTapAt = 0
+		}
+		break
+	}
+	st := h.state
+	st.UpdatedAt = time.Now().Format(time.RFC3339)
+	conns := make([]*websocket.Conn, 0, len(h.clients))
+	for c := range h.clients {
+		conns = append(conns, c)
+	}
+	h.mu.Unlock()
+
+	data, err := json.Marshal(st)
+	if err != nil {
+		return
+	}
+	for _, c := range conns {
+		h.writeJSON(c, data)
+	}
+}
+
+// mergeAccel updates cached accel on clients and pushes state to dashboard WebSockets.
+func (h *wsHub) mergeAccel(samples []*pb.AccelSample) {
+	if !h.liveStreamEnabled() {
+		return
+	}
+	h.mu.Lock()
+	st := h.state
+	st.Clients = applyAccelSamples(st.Clients, samples)
+	st.UpdatedAt = time.Now().Format(time.RFC3339)
+	h.state = st
+	conns := make([]*websocket.Conn, 0, len(h.clients))
+	for c := range h.clients {
+		conns = append(conns, c)
+	}
+	h.mu.Unlock()
+
+	data, err := json.Marshal(st)
+	if err != nil {
+		return
+	}
+	for _, c := range conns {
+		h.writeJSON(c, data)
+	}
+}
+
+func (h *wsHub) mergeTap(events []*pb.TapEvent) {
+	if len(events) == 0 || !h.liveStreamEnabled() {
+		return
+	}
+	h.mu.Lock()
+	st := h.state
+	st.Clients = applyTapEvents(st.Clients, events)
+	st.UpdatedAt = time.Now().Format(time.RFC3339)
+	h.state = st
+	conns := make([]*websocket.Conn, 0, len(h.clients))
+	for c := range h.clients {
+		conns = append(conns, c)
+	}
+	h.mu.Unlock()
+
+	data, err := json.Marshal(st)
+	if err != nil {
+		return
+	}
+	for _, c := range conns {
+		h.writeJSON(c, data)
+	}
+}
+
+func (h *wsHub) broadcastRaw(v any) {
+	data, err := json.Marshal(v)
+	if err != nil {
+		return
+	}
+	h.broadcastJSON(data)
+}
+
+func pollDashboard(link *managedSerial, portName string, last *DashboardState, streamCtl *accelStreamCtl, tapCtl *tapNotifyCtl) DashboardState {
 	st := DashboardState{
 		UpdatedAt:  time.Now().Format(time.RFC3339),
 		SerialPort: portName,
@@ -152,15 +561,119 @@ func pollDashboard(link *managedSerial, portName string, last *DashboardState) D
 			Used:            c.GetUsed(),
 			LastPing:        c.GetLastPing(),
 			LastSuccessPing: c.GetLastSuccessPing(),
-		}
-		if dz, err := readDeadzonePoll(link, c.GetId()); err == nil {
-			cv.Deadzone = dz
+			AccelStream:     c.GetAccelStreamEnabled(),
+			TapNotifySingle: c.GetTapNotifySingle(),
+			TapNotifyDouble: c.GetTapNotifyDouble(),
+			TapNotifyTriple: c.GetTapNotifyTriple(),
 		}
 		st.Clients = append(st.Clients, cv)
 	}
+	applyBatteryToState(link, &st)
+	if last == nil || !last.LiveStream {
+		for i, c := range clients {
+			if dz, err := readDeadzonePoll(link, c.GetId()); err == nil {
+				st.Clients[i].Deadzone = dz
+			}
+		}
+	}
+	if last != nil {
+		st.LiveStream = last.LiveStream
+	}
+	if streamCtl != nil {
+		streamCtl.SyncFromClients(st.Clients)
+	}
+	if tapCtl != nil {
+		tapCtl.SyncFromClients(st.Clients)
+	}
 	return st
 }
 
+func applyBatteryToState(link *managedSerial, st *DashboardState) {
+	bat, err := link.BatteryStatusPoll(&pb.BatteryStatusRequest{AllClients: true})
+	if errors.Is(err, errUARTBusy) {
+		return
+	}
+	if err != nil {
+		log.Printf("battery poll: %v", err)
+		return
+	}
+	applyBatterySamplesToState(st, batterySamplesFromPB(bat.GetSamples()))
+}
+
+func (h *wsHub) mergeBattery(samples []batterySampleJSON) {
+	if len(samples) == 0 {
+		return
+	}
+	h.mu.Lock()
+	st := h.state
+	applyBatterySamplesToState(&st, samples)
+	st.UpdatedAt = time.Now().Format(time.RFC3339)
+	h.state = st
+	conns := make([]*websocket.Conn, 0, len(h.clients))
+	for c := range h.clients {
+		conns = append(conns, c)
+	}
+	h.mu.Unlock()
+
+	data, err := json.Marshal(st)
+	if err != nil {
+		return
+	}
+	for _, c := range conns {
+		h.writeJSON(c, data)
+	}
+}
+
+func runBatteryPoller(link *managedSerial, hub *wsHub, interval time.Duration, stop <-chan struct{}) {
+	ticker := time.NewTicker(interval)
+	defer ticker.Stop()
+
+	for {
+		select {
+		case <-stop:
+			return
+		case <-ticker.C:
+			if !link.IsConnected() {
+				continue
+			}
+			bat, err := link.BatteryStatusPoll(&pb.BatteryStatusRequest{AllClients: true})
+			if errors.Is(err, errUARTBusy) || err != nil {
+				continue
+			}
+			hub.mergeBattery(batterySamplesFromPB(bat.GetSamples()))
+		}
+	}
+}
+
+func runCacheStatusDashboardPoller(link *managedSerial, hub *wsHub, interval time.Duration, stop <-chan struct{}) {
+	ticker := time.NewTicker(interval)
+	defer ticker.Stop()
+
+	for {
+		select {
+		case <-stop:
+			return
+		case <-ticker.C:
+			if !hub.liveStreamEnabled() {
+				continue
+			}
+			cache, err := link.readCacheStatusPoll()
+			if err != nil {
+				continue
+			}
+			hub.mergeAccel(accelSamplesFromCacheStatus(cache))
+			hub.mergeTap(tapEventsFromCacheStatus(cache))
+		}
+	}
+}
+
+func (h *wsHub) clientCount() int {
+	h.mu.RLock()
+	n := len(h.clients)
+	h.mu.RUnlock()
+	return n
+}
+
 func pausedPollState(portName string, last *DashboardState) DashboardState {
 	if last != nil && last.UARTConnected {
 		st := *last
@@ -208,22 +721,25 @@ func formatMAC(mac []byte) string {
 	return hex.EncodeToString(mac)
 }
 
-func runPoller(link *managedSerial, portName string, hub *wsHub, interval time.Duration, stop <-chan struct{}) {
+func runPoller(link *managedSerial, portName string, hub *wsHub, streamCtl *accelStreamCtl, tapCtl *tapNotifyCtl, interval time.Duration, stop <-chan struct{}) {
+	// streamCtl / tapCtl kept for external API; dashboard uses hub.state flags.
 	ticker := time.NewTicker(interval)
 	defer ticker.Stop()
 
 	uartUp := false
 	var lastGood DashboardState
 	publish := func() {
-		st := pollDashboard(link, portName, &lastGood)
+		st := pollDashboard(link, portName, &lastGood, streamCtl, tapCtl)
+		hub.setState(st)
 		if st.UARTConnected && st.SerialOK {
-			lastGood = st
+			hub.mu.RLock()
+			lastGood = hub.state
+			hub.mu.RUnlock()
 		}
 		if st.UARTConnected && !uartUp {
 			log.Printf("UART %s connected", portName)
 		}
 		uartUp = st.UARTConnected
-		hub.setState(st)
 	}
 
 	publish()

goTool/docs/API_REST.md

@@ -0,0 +1,368 @@
+# REST API
+
+`go run . -port /dev/ttyUSB0 serve` starts two HTTP servers on the same UART link:
+
+| Base URL | Flag | Used by |
+|----------|------|---------|
+| `http://localhost:8080` | `-addr` (default `:8080`) | Web dashboard + automation on the UI routes |
+| `http://localhost:8081` | `-api-addr` (default `:8081`, `""` disables) | External programs; subset of routes + service info |
+
+WebSocket streaming (accel/tap push): [`API_WEBSOCKET.md`](API_WEBSOCKET.md).
+
+All JSON responses use `Content-Type: application/json`. On UART errors many routes return **503** with `"error"` in the body.
+
+---
+
+## External API (`:8081`)
+
+### Service info
+
+```http
+GET /
+GET /api/v1/
+```
+
+```json
+{
+  "name": "powerpod-external-api",
+  "version": "1",
+  "serial_port": "/dev/ttyUSB0",
+  "websocket": "/ws",
+  "default_interval_ms": 16,
+  "min_interval_ms": 1,
+  "max_interval_ms": 10000,
+  "tap_display_min_ms": 2000,
+  "description": "..."
+}
+```
+
+### Battery
+
+```http
+GET /api/battery?all_clients=true
+GET /api/battery?client_id=16
+POST /api/battery
+Content-Type: application/json
+```
+
+POST body:
+
+```json
+{"all_clients": true}
+{"client_id": 0}
+{"client_id": 16}
+```
+
+Response:
+
+```json
+{
+  "success": true,
+  "samples": [
+    {
+      "client_id": 16,
+      "lipo1": {"valid": true, "voltage_mv": 3850, "percent": 71},
+      "lipo2": {"valid": false},
+      "age_ms": 1200
+    }
+  ]
+}
+```
+
+Slaves push battery to the master every **30 s**; these routes read the master cache.
+
+WebSocket equivalent: `get_battery` on `ws://localhost:8081/ws` (reply type `battery_status`).
+
+### LED ring
+
+```http
+POST /api/led-ring
+Content-Type: application/json
+```
+
+Body:
+
+```json
+{"mode":"color","client_id":16,"r":255,"g":0,"b":0,"intensity":128}
+{"mode":"digit","client_id":0,"digit":3,"r":0,"g":255,"b":0}
+{"mode":"find-me","all_clients":true,"slaves_only":true}
+```
+
+| `mode` | Notes |
+|--------|--------|
+| `clear` | Turn off |
+| `color` | Full ring RGB + `intensity` |
+| `progress` | `progress` 0–100 |
+| `digit` | `digit` 0–10 |
+| `blink` | `blink_ms`, `blink_count` |
+| `find-me` | Locate pod |
+| `battery-low` | First 4 LEDs red at ~10 % for 5 s (UV indicator test) |
+
+Use `client_id` (`0` = master) or `all_clients` (+ optional `slaves_only`) for broadcast.
+
+Response: `success`, `slaves_updated`, optional `error`.
+
+WebSocket: `set_led_ring` with the same fields plus `"type":"set_led_ring"` → `led_ring_status`.
+
+---
+
+## Dashboard API (`:8080`)
+
+Used by the web UI; safe for scripts that drive the same features.
+
+### Live stream (host `CACHE_STATUS` poll ~16 ms)
+
+```http
+GET /api/live-stream
+PUT /api/live-stream
+Content-Type: application/json
+{"enable": true}
+```
+
+```json
+{"enabled": true, "success": true}
+```
+
+Enables fast UART polling for dashboard accel/tap display. Per-slave accel still requires accel-stream (below).
+
+### Accel stream (firmware ESP-NOW, per slave)
+
+```http
+GET /api/clients/16/accel-stream
+PUT /api/clients/16/accel-stream
+Content-Type: application/json
+{"enable": true}
+```
+
+```json
+{"enabled": true, "client_id": 16, "success": true}
+```
+
+All slaves:
+
+```http
+POST /api/accel-stream
+Content-Type: application/json
+{"write": true, "enable": true, "all_clients": true}
+```
+
+Polling on the host runs only while at least one slave has streaming enabled (here or via external WebSocket / dashboard).
+
+### Tap notify (firmware; does not start host tap polling)
+
+```http
+GET /api/clients/16/tap-notify
+PUT /api/clients/16/tap-notify
+Content-Type: application/json
+{"single": true, "double_tap": false, "triple": false}
+```
+
+```json
+{
+  "client_id": 16,
+  "success": true,
+  "slaves_updated": 1,
+  "single": true,
+  "double_tap": false,
+  "triple": false
+}
+```
+
+All slaves:
+
+```http
+POST /api/tap-notify
+Content-Type: application/json
+{"single": true, "double_tap": false, "triple": false, "all_clients": true}
+```
+
+Host tap display / external `set_tap_stream` is separate.
+
+### Tap snapshot (one-shot, via `CACHE_STATUS`)
+
+```http
+GET /api/tap-snapshot?client_id=16
+```
+
+Reads the combined cache (`CACHE_STATUS`); optional `client_id` filters pending tap events. Pending taps are consumed on read.
+
+```json
+{
+  "events": [
+    {"client_id": 16, "kind": "single", "age_ms": 4}
+  ]
+}
+```
+
+### Deadzone
+
+```http
+GET /api/deadzone?client_id=0
+POST /api/deadzone
+Content-Type: application/json
+{"write": true, "deadzone": 128, "client_id": 0}
+```
+
+With `all_clients` + `slaves_only`: push to ESP-NOW slaves only (master BMA456 unchanged).
+
+```json
+{"deadzone": 128, "client_id": 0, "success": true, "slaves_updated": 2}
+```
+
+### Unicast test
+
+```http
+POST /api/unicast-test
+Content-Type: application/json
+{"client_id": 16, "seq": 42}
+```
+
+### Echo ping (ESP-NOW round-trip latency)
+
+```http
+POST /api/echo-ping
+Content-Type: application/json
+{"client_id": 16}
+```
+
+`client_id` must be a registered slave id (`> 0`). The host sends a microsecond timestamp; the master forwards it over ESP-NOW and the slave echoes it back unchanged.
+
+**Flow:** Host → UART → `cmd_espnow_echo_ping` → `ESPNOW_ECHO_PING` (with `master_time_us` from `esp_timer_get_time()`) → Slave → `ESPNOW_ECHO_PONG` → Master `recv_cb` → UART response.
+
+**Response fields:**
+
+| Field | Unit | Meaning |
+|-------|------|---------|
+| `success` | — | `true` if pong received within 500 ms |
+| `client_id` | — | Echo of request |
+| `timestamp_us` | µs (Unix) | Echoed host timestamp; must match request on success |
+| `rtt_ms` | ms | **Host-side** round-trip: goTool send → UART response (full chain incl. USB serial) |
+| `esp_rtt_us` | µs | **Master-side** ESP-NOW only: `esp_timer_get_time()` delta from ping send to pong recv |
+
+`esp_rtt_us` is the raw firmware value (microseconds, not converted). The web dashboard displays it converted to milliseconds for readability (`esp_rtt_us / 1000`, 3 decimal places). The success banner stays visible for at least 5 seconds.
+
+```json
+{
+  "success": true,
+  "client_id": 16,
+  "timestamp_us": 1717654321123456,
+  "rtt_ms": 49.729,
+  "esp_rtt_us": 18234
+}
+```
+
+On failure (`success: false`), `esp_rtt_us` is omitted; `rtt_ms` still reflects the host round-trip. HTTP 503 if UART exchange fails (e.g. timeout, client not in registry).
+
+**CLI:**
+
+```bash
+go run . -port /dev/ttyUSB0 echo-ping -client 16
+```
+
+Example output:
+
+```
+echo ping: success=true client_id=16 rtt_ms=49.729 esp_rtt_us=18234
+```
+
+### Find me
+
+```http
+POST /api/find-me
+Content-Type: application/json
+{"client_id": 16}
+```
+
+`client_id` `0` = master LED ring.
+
+### Restart
+
+```http
+POST /api/restart
+Content-Type: application/json
+{"client_id": 16}
+```
+
+### Log level (master ESP-IDF console)
+
+Runtime get/set of the **global** log filter on the master (`esp_log_level_set("*", …)`). Output goes to **UART0** (USB debug, 115200), not the host protocol UART (GPIO 2/3, 921600).
+
+```http
+GET /api/log-level
+POST /api/log-level
+Content-Type: application/json
+{"write": true, "level": 3}
+```
+
+| `level` | Meaning |
+|---------|---------|
+| 0 | None (no log output) |
+| 1 | Error |
+| 2 | Warn |
+| 3 | Info |
+| 4 | Debug |
+| 5 | Verbose |
+
+```json
+{"success": true, "level": 3}
+```
+
+**CLI:**
+
+```bash
+go run . -port /dev/ttyUSB0 log-level
+go run . -port /dev/ttyUSB0 log-level -set -level 3
+```
+
+Dashboard: Master card → dropdown **ESP Log-Level** with **Lesen** / **Setzen**.
+
+### OTA (master UART upload)
+
+```http
+POST /api/ota
+Content-Type: multipart/form-data
+```
+
+Form field **`firmware`**: binary image, max **2 MiB**.
+
+```json
+{"success": true, "bytes_written": 123456, "target_slot": 1}
+```
+
+Firmware distributes to slaves over ESP-NOW after `OTA_END`. Progress also appears on dashboard WebSocket as `ota_progress` messages.
+
+CLI equivalent: `go run . -port /dev/ttyUSB0 ota build/powerpod.bin`
+
+### LED ring and battery
+
+Same as external API:
+
+- `POST /api/led-ring`
+- `GET` / `POST` `/api/battery`
+
+---
+
+## Dashboard vs external
+
+| Feature | Dashboard `:8080` | External `:8081` |
+|---------|-------------------|------------------|
+| Client list | Via dashboard WebSocket state / CLI `clients` | WebSocket `list_clients` |
+| Accel/tap **push stream** | WebSocket state when live-stream on | WebSocket `set_stream` / `set_tap_stream` |
+| Accel stream enable | REST `PUT .../accel-stream` | WebSocket `set_accel_stream` |
+| Tap notify | REST `PUT .../tap-notify` | WebSocket `set_tap_notify` |
+| LED / battery | REST | REST + WebSocket on `:8081` |
+
+---
+
+## UI mapping
+
+| UI action | REST / CLI |
+|-----------|------------|
+| Nur Master deadzone | `POST /api/deadzone` `client_id: 0` or CLI `deadzone -set -client 0` |
+| Einzelner Slave | `client_id: <id>` |
+| Alle Slaves deadzone | `all_clients` + `slaves_only` on POST |
+| Unicast test | `POST /api/unicast-test` |
+| Echo ping | `POST /api/echo-ping` (per-slave latency; UI shows Host ms + ESP ms) |
+| Master log level | `GET` / `POST /api/log-level` or CLI `log-level` |
+| Tap notify S/D/T | `PUT /api/clients/{id}/tap-notify` |
+| Tap receive (UI) | Live stream + tap notify; see WebSocket doc for external API |

goTool/docs/API_WEBSOCKET.md

@@ -0,0 +1,253 @@
+# WebSocket API
+
+External API: `ws://localhost:8081/ws` (default `-api-addr`, disable with empty string).
+
+Start with `go run . -port /dev/ttyUSB0 serve`.
+
+---
+
+## Connection flow
+
+1. Connect → server sends `hello` (push off; defaults and command list).
+2. Send JSON commands → one reply per message (`*_status` or `client_list`).
+3. After `set_stream` with `enable: true`, server may push `input` messages without a prior command.
+
+Commands and pushes share one socket — always branch on `type`.
+
+On disconnect, `set_stream` state for that socket is dropped. Firmware settings (`set_input_stream`, `set_tap_notify`) stay on the master until changed.
+
+---
+
+## Two layers (firmware vs host)
+
+
+| Layer              | Commands                             | Effect                                                             |
+| ------------------ | ------------------------------------ | ------------------------------------------------------------------ |
+| Firmware (ESP-NOW) | `set_input_stream`, `set_tap_notify` | Per `client_id`: slave sends accel and/or tap events to the master |
+| This connection    | `set_stream`                         | Whether you receive push JSON on this socket                       |
+
+
+UART polling runs only when at least one connection has `receive_input: true` **and** at least one slave streams input or has tap notify enabled. `set_tap_notify` alone does not enable push — you still need `set_stream`.
+
+### Push timing (per connection)
+
+
+| Field         | Where                                  | Meaning                                                      |
+| ------------- | -------------------------------------- | ------------------------------------------------------------ |
+| `interval_ms` | `hello`, `set_stream`, `stream_status` | Minimum ms between `input` pushes on this socket (1 … 10000) |
+| `pre_fetch`   | `set_stream`, `stream_status`          | Ms before each push when the host starts the UART cache read |
+
+
+Global UART poll interval = minimum `interval_ms` among all connections with push enabled.
+
+Typical sequence:
+
+1. `list_clients` → slave IDs
+2. Per slave: `set_input_stream` and/or `set_tap_notify`
+3. `set_stream` with `"enable": true`
+4. Read `input` messages; filter by `client_id` in your app (no per-slave filter on the wire)
+
+---
+
+## Push: `input`
+
+Combines latest accel cache and visible tap state for every slave slot on the master.
+
+**Success:**
+
+```json
+{
+  "type": "input",
+  "t": 1716900123456789012,
+  "success": true,
+  "clients": [
+    {
+      "client_id": 16,
+      "valid": true,
+      "x": 12,
+      "y": -34,
+      "z": 16384,
+      "accel_age_ms": 8,
+      "tap_kind": "single",
+      "tap_age_ms": 3
+    },
+    {
+      "client_id": 42,
+      "valid": false
+    }
+  ]
+}
+```
+
+
+| Field          | Meaning                                                              |
+| -------------- | -------------------------------------------------------------------- |
+| `t`            | Unix timestamp in nanoseconds when the host read the cache           |
+| `success`      | `true` if `CACHE_STATUS` succeeded                                   |
+| `clients[]`    | One entry per slave slot (includes invalid/stale entries)            |
+| `client_id`    | Same id as in `list_clients`                                         |
+| `valid`        | `false` if no accel sample yet or stale; omit `x`/`y`/`z` when false |
+| `x`, `y`, `z`  | Raw accelerometer LSB (BMA456, ±2 g)                                 |
+| `accel_age_ms` | Ms since the master received this accel sample                       |
+| `tap_kind`     | `"single"`, `"double"`, or `"triple"`; omit when no recent tap       |
+| `tap_age_ms`   | Ms since tap in master cache; omit with `tap_kind`                   |
+
+
+Tap events stay visible for `tap_display_min_ms` (2000, in `hello`) after the API first saw them.
+
+**Failure** (no `clients` array):
+
+```json
+{"type":"input","t":1716900123456789012,"success":false,"error":"uart busy"}
+```
+
+---
+
+## Commands
+
+One JSON object per message; field `type` selects the command.
+
+**Errors:** Replies use the matching response `type`. On failure: `success: false` (or omitted) and `"error": "…"`. Malformed JSON or unknown `type` → `stream_status` with `error`.
+
+### `hello` (server → client)
+
+```json
+{
+  "type": "hello",
+  "serial_port": "/dev/ttyUSB0",
+  "interval_ms": 16,
+  "pre_fetch_ms": 2,
+  "tap_display_min_ms": 2000,
+  "commands": [
+    "list_clients",
+    "set_stream", "get_stream",
+    "set_input_stream", "get_input_stream",
+    "set_tap_notify", "get_tap_notify",
+    "set_led_ring", "get_battery"
+  ]
+}
+```
+
+### `list_clients`
+
+Request: `{"type":"list_clients"}`
+
+Response `client_list`:
+
+```json
+{
+  "type": "client_list",
+  "success": true,
+  "clients": [
+    {
+      "id": 16,
+      "mac": "aa:bb:cc:dd:ee:10",
+      "available": true,
+      "input_stream": false,
+      "tap_notify_single": false,
+      "tap_notify_double": false,
+      "tap_notify_triple": false
+    }
+  ]
+}
+```
+
+Also per client: `version`, `used`, `last_ping`, `last_success_ping`.
+
+### `set_stream` / `get_stream`
+
+```json
+{"type":"set_stream","enable":true,"interval_ms":32,"pre_fetch":2}
+{"type":"get_stream"}
+```
+
+Response `stream_status`:
+
+```json
+{"type":"stream_status","receive_input":true,"interval_ms":32,"pre_fetch":2,"success":true}
+```
+
+### `set_input_stream` / `get_input_stream` (firmware)
+
+`client_id` required (> 0).
+
+```json
+{"type":"set_input_stream","client_id":16,"enable":true}
+{"type":"get_input_stream","client_id":16}
+```
+
+Response `input_stream_status`:
+
+```json
+{"type":"input_stream_status","client_id":16,"enabled":true,"success":true}
+```
+
+### `set_tap_notify` / `get_tap_notify` (firmware)
+
+Set requires `single`, `double_tap`, `triple` per client, or `"all_clients": true` for broadcast.
+
+```json
+{"type":"set_tap_notify","client_id":16,"single":true,"double_tap":false,"triple":false}
+{"type":"get_tap_notify","client_id":16}
+```
+
+Response `tap_notify_status`:
+
+```json
+{"type":"tap_notify_status","client_id":16,"success":true,"single":true,"double_tap":false,"triple":false}
+```
+
+### `set_led_ring`
+
+```json
+{"type":"set_led_ring","mode":"color","client_id":16,"r":255,"g":0,"b":0,"intensity":128}
+{"type":"set_led_ring","mode":"digit","client_id":0,"digit":3,"r":0,"g":255,"b":0}
+{"type":"set_led_ring","mode":"find-me","all_clients":true,"slaves_only":true}
+```
+
+
+| Request `mode` | Notes                       |
+| -------------- | --------------------------- |
+| `clear`        | Turn off                    |
+| `color`        | Full ring RGB + `intensity` |
+| `progress`     | `progress` 0–100            |
+| `digit`        | `digit` 0–10                |
+| `blink`        | `blink_ms`, `blink_count`   |
+| `find-me`      | Locate pod                  |
+| `battery-low`  | UV indicator (4 LEDs, 5 s)  |
+
+
+Target: `client_id` (`0` = master) or `all_clients` (+ optional `slaves_only`).
+
+Response `led_ring_status` — `mode` is numeric: 0=clear, 1=progress, 2=digit, 3=blink, 4=find-me, 5=color, 6=battery-low.
+
+```json
+{"type":"led_ring_status","success":true,"mode":5,"client_id":16,"slaves_updated":1}
+```
+
+### `get_battery`
+
+Slaves push battery every 30 s; this reads the master cache. Default: all clients.
+
+```json
+{"type":"get_battery","all_clients":true}
+{"type":"get_battery","client_id":16}
+```
+
+Response `battery_status`:
+
+```json
+{
+  "type": "battery_status",
+  "success": true,
+  "samples": [
+    {
+      "client_id": 16,
+      "lipo1": {"valid": true, "voltage_mv": 3850, "percent": 71},
+      "lipo2": {"valid": false},
+      "age_ms": 1200
+    }
+  ]
+}
+```
+

goTool/led_ring_api.go

@@ -0,0 +1,109 @@
+package main
+
+import (
+	"fmt"
+	"strings"
+
+	"powerpod/gotool/pb"
+)
+
+const (
+	ledRingModeClear    = 0
+	ledRingModeProgress = 1
+	ledRingModeDigit    = 2
+	ledRingModeBlink    = 3
+	ledRingModeFindMe   = 4
+	ledRingModeColor    = 5
+	ledRingModeBatteryLow = 6
+)
+
+type ledRingAPIRequest struct {
+	Mode       string `json:"mode"`
+	ClientID   uint32 `json:"client_id"`
+	AllClients bool   `json:"all_clients"`
+	SlavesOnly bool   `json:"slaves_only"`
+	Progress   uint32 `json:"progress"`
+	Digit      uint32 `json:"digit"`
+	R          uint32 `json:"r"`
+	G          uint32 `json:"g"`
+	B          uint32 `json:"b"`
+	Intensity  uint32 `json:"intensity"`
+	BlinkMs    uint32 `json:"blink_ms"`
+	BlinkCount uint32 `json:"blink_count"`
+}
+
+type ledRingAPIResponse struct {
+	Type          string `json:"type,omitempty"` // led_ring_status (WebSocket)
+	Success       bool   `json:"success"`
+	Mode          uint32 `json:"mode,omitempty"`
+	Progress      uint32 `json:"progress,omitempty"`
+	Digit         uint32 `json:"digit,omitempty"`
+	ClientID      uint32 `json:"client_id,omitempty"`
+	SlavesUpdated uint32 `json:"slaves_updated,omitempty"`
+	Error         string `json:"error,omitempty"`
+}
+
+func ledRingModeFromString(s string) (uint32, error) {
+	switch strings.ToLower(strings.TrimSpace(s)) {
+	case "clear", "":
+		return ledRingModeClear, nil
+	case "color", "solid", "fill":
+		return ledRingModeColor, nil
+	case "progress":
+		return ledRingModeProgress, nil
+	case "digit":
+		return ledRingModeDigit, nil
+	case "blink":
+		return ledRingModeBlink, nil
+	case "find-me", "find_me", "findme":
+		return ledRingModeFindMe, nil
+	case "battery-low", "battery_low", "batterylow":
+		return ledRingModeBatteryLow, nil
+	default:
+		return 0, fmt.Errorf("unknown mode %q (clear, color, progress, digit, blink, find-me, battery-low)", s)
+	}
+}
+
+func ledRingPBFromAPI(in ledRingAPIRequest) (*pb.LedRingProgressRequest, error) {
+	mode, err := ledRingModeFromString(in.Mode)
+	if err != nil {
+		return nil, err
+	}
+	return &pb.LedRingProgressRequest{
+		Mode:       mode,
+		Progress:   in.Progress,
+		Digit:      in.Digit,
+		R:          in.R,
+		G:          in.G,
+		B:          in.B,
+		Intensity:  in.Intensity,
+		BlinkMs:    in.BlinkMs,
+		BlinkCount: in.BlinkCount,
+		ClientId:   in.ClientID,
+		AllClients: in.AllClients,
+		SlavesOnly: in.SlavesOnly,
+	}, nil
+}
+
+func applyLedRing(link *managedSerial, in ledRingAPIRequest) ledRingAPIResponse {
+	req, err := ledRingPBFromAPI(in)
+	if err != nil {
+		return ledRingAPIResponse{Error: err.Error()}
+	}
+	resp, err := link.LedRing(req)
+	if err != nil {
+		return ledRingAPIResponse{Error: err.Error()}
+	}
+	out := ledRingAPIResponse{
+		Success:       resp.GetSuccess(),
+		Mode:          resp.GetMode(),
+		Progress:      resp.GetProgress(),
+		Digit:         resp.GetDigit(),
+		ClientID:      resp.GetClientId(),
+		SlavesUpdated: resp.GetSlavesUpdated(),
+	}
+	if !out.Success && out.Error == "" {
+		out.Error = "led ring command rejected"
+	}
+	return out
+}

goTool/main.go

@@ -16,14 +16,18 @@ func usage() {
 	fmt.Fprintf(os.Stderr, "  version   firmware version and git hash\n")
 	fmt.Fprintf(os.Stderr, "  clients   registered ESP-NOW slaves on the master\n")
 	fmt.Fprintf(os.Stderr, "  deadzone      get/set accelerometer deadzone (LSB)\n")
+	fmt.Fprintf(os.Stderr, "  tap-notify    get/set which tap kinds notify via ESP-NOW\n")
+	fmt.Fprintf(os.Stderr, "  cache-status  subscribed accel + tap cache (one UART round-trip)\n")
 	fmt.Fprintf(os.Stderr, "  unicast-test  send ESP-NOW unicast test to one slave\n")
+	fmt.Fprintf(os.Stderr, "  echo-ping     ESP-NOW timestamp echo round-trip to one slave\n")
 	fmt.Fprintf(os.Stderr, "  test          run automated scenario (see testdata/)\n")
 	fmt.Fprintf(os.Stderr, "  serve         web dashboard (Bootstrap + WebSocket)\n")
 	fmt.Fprintf(os.Stderr, "  ota           UART OTA upload (A/B partitions)\n")
 	fmt.Fprintf(os.Stderr, "  ota-progress  query per-slave ESP-NOW OTA progress on master\n")
 	fmt.Fprintf(os.Stderr, "  led-ring      set LED ring progress bar (0–100%%, rgb, intensity)\n")
 	fmt.Fprintf(os.Stderr, "  find-me       blink LED ring red/green/blue (3× each, full brightness)\n")
-	fmt.Fprintf(os.Stderr, "  restart       reboot master or slave (ESP-NOW)\n\n")
+	fmt.Fprintf(os.Stderr, "  restart       reboot master or slave (ESP-NOW)\n")
+	fmt.Fprintf(os.Stderr, "  log-level     get/set master ESP-IDF log level (global)\n\n")
 	flag.PrintDefaults()
 }
 
@@ -50,7 +54,7 @@ func main() {
 			os.Exit(2)
 		}
 		runErr = runServe(*portName, *baud, flag.Args()[1:])
-	case "version", "clients", "client-info", "deadzone", "accel-deadzone", "unicast-test", "unicast_test", "led-ring", "led_ring", "find-me", "find_me", "restart", "ota", "ota-progress", "ota_progress":
+	case "version", "clients", "client-info", "deadzone", "accel-deadzone", "tap-notify", "tap_notify", "cache-status", "cache_status", "unicast-test", "unicast_test", "echo-ping", "echo_ping", "led-ring", "led_ring", "find-me", "find_me", "restart", "log-level", "log_level", "ota", "ota-progress", "ota_progress":
 		if *portName == "" {
 			fmt.Fprintf(os.Stderr, "command %q requires -port\n\n", cmd)
 			usage()
@@ -60,6 +64,8 @@ func main() {
 		if err != nil {
 			log.Fatalf("open serial: %v", err)
 		}
+		registerShutdown(func() { _ = sp.Close() })
+		enableShutdownOnInterrupt()
 		defer sp.Close()
 		switch cmd {
 		case "version":
@@ -68,14 +74,22 @@ func main() {
 			runErr = runClients(sp)
 		case "deadzone", "accel-deadzone":
 			runErr = runDeadzone(sp, flag.Args()[1:])
+		case "tap-notify", "tap_notify":
+			runErr = runTapNotify(sp, flag.Args()[1:])
+		case "cache-status", "cache_status":
+			runErr = runCacheStatus(sp)
 		case "unicast-test", "unicast_test":
 			runErr = runUnicastTest(sp, flag.Args()[1:])
+		case "echo-ping", "echo_ping":
+			runErr = runEchoPing(sp, flag.Args()[1:])
 		case "led-ring", "led_ring":
 			runErr = runLedRing(sp, flag.Args()[1:])
 		case "find-me", "find_me":
 			runErr = runFindMe(sp, flag.Args()[1:])
 		case "restart":
 			runErr = runRestart(sp, flag.Args()[1:])
+		case "log-level", "log_level":
+			runErr = runLogLevel(sp, flag.Args()[1:])
 		case "ota":
 			runErr = runOTA(sp, flag.Args()[1:])
 		case "ota-progress", "ota_progress":

goTool/ota_upload.go

@@ -2,7 +2,6 @@ package main
 
 import (
 	"fmt"
-	"log"
 	"time"
 
 	"google.golang.org/protobuf/proto"
@@ -21,6 +20,9 @@ const (
 	otaDistQueryInterval   = 500 * time.Millisecond
 	otaDistQueryTimeout    = 2 * time.Second
 	otaDistEmitMinInterval = 150 * time.Millisecond
+	// Pace host chunks so the master UART RX ring is not overrun (~20 frames/block).
+	otaHostChunkPace = 3 * time.Millisecond
+	otaBlockMaxRetries = 3
 )
 
 const (
@@ -69,16 +71,45 @@ const (
 )
 
 func runOTAUpload(m *managedSerial, firmware []byte, onProgress otaProgressFn) error {
+	push := func(phase, msg string) {
+		if onProgress == nil {
+			return
+		}
+		onProgress(OTAProgress{
+			Type: "ota_progress", Phase: phase, Step: otaStepMaster,
+			Percent: 0, Message: msg, MasterMessage: msg,
+		})
+	}
+	push("preparing", "UART wird vorbereitet…")
+
+	// Block until the UART is free, then hold m.mu for the entire upload so
+	// dashboard/API polling cannot interleave on the serial port.
 	m.mu.Lock()
-	defer m.mu.Unlock()
-	err := runOTAOnPortUnlocked(m, firmware, onProgress)
+	if m.otaActive {
+		m.mu.Unlock()
+		return errOTAInProgress
+	}
+	m.otaActive = true
+	if m.sp == nil {
+		if err := m.openLocked(); err != nil {
+			m.otaActive = false
+			m.mu.Unlock()
+			push("error", err.Error())
+			return err
+		}
+	}
+	sp := m.sp
+
+	err := runOTAOnPortUnlocked(sp, firmware, onProgress)
 	if err != nil {
 		m.invalidateLocked(err)
 	}
+	m.otaActive = false
+	m.mu.Unlock()
 	return err
 }
 
-func runOTAOnPortUnlocked(m *managedSerial, firmware []byte, onProgress otaProgressFn) error {
+func runOTAOnPortUnlocked(sp *serialPort, firmware []byte, onProgress otaProgressFn) error {
 	if len(firmware) == 0 {
 		return fmt.Errorf("empty firmware")
 	}
@@ -120,32 +151,31 @@ func runOTAOnPortUnlocked(m *managedSerial, firmware []byte, onProgress otaProgr
 		onProgress(p)
 	}
 
-	if m.sp == nil {
-		if err := m.openLocked(); err != nil {
-			notify("error", "", 0, err.Error())
-			return err
-		}
-	}
-
-	sp := m.sp
-	if err := sp.port.SetReadTimeout(otaPrepareTimeout); err != nil {
+	if err := sp.port.SetReadTimeout(readTimeout); err != nil {
 		notify("error", "", 0, err.Error())
 		return err
 	}
-	defer sp.port.SetReadTimeout(readTimeout)
 
 	notify("preparing", otaStepMaster, 0, fmt.Sprintf("Master: OTA start (%d bytes)…", imageSize))
 
+	flushSerialInput(sp)
+
 	if err := writeUartMessage(sp, &pb.UartMessage{
 		Type: pb.MessageType_OTA_START,
 		Payload: &pb.UartMessage_OtaStart{
 			OtaStart: &pb.OtaStartPayload{TotalSize: uint32(imageSize)},
 		},
-	}, false); err != nil {
+	}); err != nil {
 		notify("error", "", 0, err.Error())
 		return err
 	}
 
+	if err := sp.port.SetReadTimeout(otaPrepareTimeout); err != nil {
+		notify("error", "", 0, err.Error())
+		return err
+	}
+	defer func() { _ = sp.port.SetReadTimeout(readTimeout) }()
+
 	ready, err := waitOtaStatus(sp, otaStReady, otaPrepareTimeout, func(msg string) {
 		notify("preparing", otaStepMaster, 2, msg)
 	})
@@ -162,52 +192,83 @@ func runOTAOnPortUnlocked(m *managedSerial, firmware []byte, onProgress otaProgr
 
 	var seq uint32
 	for offset := 0; offset < imageSize; {
-		bytesInBlock := 0
-		for bytesInBlock < otaFlashBlockSize && offset < imageSize {
-			n := otaHostChunkSize
-			room := otaFlashBlockSize - bytesInBlock
-			if n > room {
-				n = room
-			}
-			if offset+n > imageSize {
-				n = imageSize - offset
-			}
-			chunk := firmware[offset : offset+n]
+		blockStart := offset
+		blockStartSeq := seq
 
-			if err := writeUartMessage(sp, &pb.UartMessage{
-				Type: pb.MessageType_OTA_PAYLOAD,
-				Payload: &pb.UartMessage_OtaPayload{
-					OtaPayload: &pb.OtaPayload{Seq: seq, Data: chunk},
-				},
-			}, false); err != nil {
-				notify("error", "", 0, err.Error())
-				return err
-			}
-			seq++
-			offset += n
-			bytesInBlock += n
+		sendBlock := func() (fullBlock bool, err error) {
+			bytesInBlock := 0
+			for bytesInBlock < otaFlashBlockSize && offset < imageSize {
+				n := otaHostChunkSize
+				room := otaFlashBlockSize - bytesInBlock
+				if n > room {
+					n = room
+				}
+				if offset+n > imageSize {
+					n = imageSize - offset
+				}
+				chunk := firmware[offset : offset+n]
 
-			pct := offset * 100 / imageSize
-			if pct > 99 {
-				pct = 99
+				if err := writeUartMessage(sp, &pb.UartMessage{
+					Type: pb.MessageType_OTA_PAYLOAD,
+					Payload: &pb.UartMessage_OtaPayload{
+						OtaPayload: &pb.OtaPayload{Seq: seq, Data: chunk},
+					},
+				}); err != nil {
+					return false, err
+				}
+				time.Sleep(otaHostChunkPace)
+				seq++
+				offset += n
+				bytesInBlock += n
+
+				pct := offset * 100 / imageSize
+				if pct > 99 {
+					pct = 99
+				}
+				notify("uploading", otaStepMaster, pct,
+					fmt.Sprintf("Master: %d / %d bytes", offset, imageSize))
 			}
-			notify("uploading", otaStepMaster, pct, fmt.Sprintf("Master: %d / %d bytes", offset, imageSize))
+			return bytesInBlock == otaFlashBlockSize, nil
 		}
 
-		if bytesInBlock == otaFlashBlockSize {
-			st, err := waitOtaStatus(sp, otaStBlockAck, otaDefaultTimeout, nil)
-			if err != nil {
-				notify("error", "", 0, err.Error())
-				return err
-			}
-			pct := offset * 100 / imageSize
-			if pct > 99 {
-				pct = 99
-			}
-			notify("uploading", otaStepMaster, pct,
-				fmt.Sprintf("Master: Block geschrieben (%d bytes)", st.GetBytesWritten()),
-				OTAProgress{Bytes: st.GetBytesWritten()})
+		fullBlock, err := sendBlock()
+		if err != nil {
+			notify("error", "", 0, err.Error())
+			return err
 		}
+
+		if !fullBlock {
+			continue
+		}
+
+		var st *pb.OtaStatusPayload
+		var ackErr error
+		for attempt := 0; attempt < otaBlockMaxRetries; attempt++ {
+			if attempt > 0 {
+				offset = blockStart
+				seq = blockStartSeq
+				if _, err := sendBlock(); err != nil {
+					notify("error", "", 0, err.Error())
+					return err
+				}
+			}
+			st, ackErr = waitOtaStatus(sp, otaStBlockAck, otaDefaultTimeout, nil)
+			if ackErr == nil {
+				break
+			}
+		}
+		if ackErr != nil {
+			notify("error", "", 0, ackErr.Error())
+			return ackErr
+		}
+
+		pct := offset * 100 / imageSize
+		if pct > 99 {
+			pct = 99
+		}
+		notify("uploading", otaStepMaster, pct,
+			fmt.Sprintf("Master: Block geschrieben (%d bytes)", st.GetBytesWritten()),
+			OTAProgress{Bytes: st.GetBytesWritten()})
 	}
 
 	masterPct = 100
@@ -219,7 +280,7 @@ func runOTAOnPortUnlocked(m *managedSerial, firmware []byte, onProgress otaProgr
 		Payload: &pb.UartMessage_OtaEnd{
 			OtaEnd: &pb.OtaEndPayload{},
 		},
-	}, false); err != nil {
+	}); err != nil {
 		notify("error", "", 0, err.Error())
 		return err
 	}
@@ -333,7 +394,7 @@ func queryOtaSlaveProgressLocked(sp *serialPort, clientID uint32,
 			},
 		},
 	}
-	if err := writeUartMessage(sp, req, false); err != nil {
+	if err := writeUartMessage(sp, req); err != nil {
 		return nil, err
 	}
 	if queryTimeout <= 0 {
@@ -389,7 +450,7 @@ func readUartMessageUntil(sp *serialPort, deadline time.Time, want pb.MessageTyp
 		if err := sp.port.SetReadTimeout(wait); err != nil {
 			return nil, err
 		}
-		payload, err := uartframe.ReadFrame(sp.port, nil)
+		payload, err := uartframe.ReadFrame(sp.port, nil, wait)
 		if err != nil {
 			return nil, err
 		}
@@ -487,14 +548,11 @@ func waitOtaComplete(sp *serialPort, timeout time.Duration,
 	}
 }
 
-func writeUartMessage(sp *serialPort, msg *pb.UartMessage, logFrame bool) error {
+func writeUartMessage(sp *serialPort, msg *pb.UartMessage) error {
 	frame, err := encodeUartMessage(msg)
 	if err != nil {
 		return err
 	}
-	if logFrame {
-		log.Printf("sending %s (%d frame bytes)", msg.Type, len(frame))
-	}
 	_, err = sp.port.Write(frame)
 	return err
 }
@@ -505,12 +563,24 @@ func waitOtaStatus(sp *serialPort, want uint32, timeout time.Duration, onPrepari
 		if time.Now().After(deadline) {
 			return nil, fmt.Errorf("timeout waiting for OTA status %d", want)
 		}
-		if err := sp.port.SetReadTimeout(time.Until(deadline)); err != nil {
+		readWait := time.Until(deadline)
+		if readWait > otaStatusPollTimeout {
+			readWait = otaStatusPollTimeout
+		}
+		if err := sp.port.SetReadTimeout(readWait); err != nil {
 			return nil, err
 		}
-		st, err := readOtaStatus(sp)
+		payload, err := uartframe.ReadFrame(sp.port, nil, readWait)
 		if err != nil {
-			return nil, err
+			continue
+		}
+		msg, err := decodeUartPayload(payload)
+		if err != nil || msg.GetType() != pb.MessageType_OTA_STATUS {
+			continue
+		}
+		st := msg.GetOtaStatus()
+		if st == nil {
+			continue
 		}
 		switch st.GetStatus() {
 		case want:
@@ -526,7 +596,7 @@ func waitOtaStatus(sp *serialPort, want uint32, timeout time.Duration, onPrepari
 }
 
 func readOtaStatus(sp *serialPort) (*pb.OtaStatusPayload, error) {
-	payload, err := uartframe.ReadFrame(sp.port, nil)
+	payload, err := uartframe.ReadFrame(sp.port, nil, readTimeout)
 	if err != nil {
 		return nil, fmt.Errorf("read response: %w", err)
 	}
@@ -553,6 +623,22 @@ func encodeUartMessage(msg *pb.UartMessage) ([]byte, error) {
 	return uartframe.EncodeFrame(payload)
 }
 
+// flushSerialInput drops stale RX bytes (not full frames — avoids ReadFrame blocking).
+func flushSerialInput(sp *serialPort) {
+	if sp == nil {
+		return
+	}
+	_ = sp.port.SetReadTimeout(10 * time.Millisecond)
+	buf := make([]byte, 256)
+	deadline := time.Now().Add(50 * time.Millisecond)
+	for time.Now().Before(deadline) {
+		n, err := sp.port.Read(buf)
+		if n == 0 || err != nil {
+			return
+		}
+	}
+}
+
 func decodeUartPayload(payload []byte) (*pb.UartMessage, error) {
 	if len(payload) == 0 {
 		return nil, fmt.Errorf("empty response")

goTool/serial_link.go

@@ -11,14 +11,18 @@ import (
 // errUARTBusy is returned when the port is held for OTA (poller should not treat as unplug).
 var errUARTBusy = errors.New("uart busy (OTA in progress)")
 
+// errOTAInProgress is returned when a second OTA upload is attempted while one is running.
+var errOTAInProgress = errors.New("OTA upload already in progress")
+
 // managedSerial keeps the UART open and reconnects after I/O failures or unplug.
 type managedSerial struct {
 	portName string
 	baud     int
 	quiet    bool
 
-	mu sync.Mutex
-	sp *serialPort
+	mu        sync.Mutex
+	sp        *serialPort
+	otaActive bool // UART held for firmware upload; poll/API must not interleave
 }
 
 func newManagedSerial(portName string, baud int) *managedSerial {
@@ -76,20 +80,17 @@ func (m *managedSerial) withPort(fn func(*serialPort) error) error {
 	return m.withPortLocked(false, fn)
 }
 
-// withPortPoll is like withPort but returns errUARTBusy instead of blocking during OTA.
+// withPortPoll is like withPort but returns errUARTBusy during OTA (no TryLock race).
 func (m *managedSerial) withPortPoll(fn func(*serialPort) error) error {
 	return m.withPortLocked(true, fn)
 }
 
-func (m *managedSerial) withPortLocked(try bool, fn func(*serialPort) error) error {
-	if try {
-		if !m.mu.TryLock() {
-			return errUARTBusy
-		}
-	} else {
-		m.mu.Lock()
-	}
+func (m *managedSerial) withPortLocked(poll bool, fn func(*serialPort) error) error {
+	m.mu.Lock()
 	defer m.mu.Unlock()
+	if m.otaActive {
+		return errUARTBusy
+	}
 
 	if m.sp == nil {
 		if err := m.openLocked(); err != nil {
@@ -104,6 +105,26 @@ func (m *managedSerial) withPortLocked(try bool, fn func(*serialPort) error) err
 	return err
 }
 
+func (m *managedSerial) recoverAfterMasterRestart() {
+	const bootWait = 6 * time.Second
+
+	m.mu.Lock()
+	m.closeLocked()
+	m.mu.Unlock()
+
+	log.Printf("UART: master restart — waiting %s for boot", bootWait)
+	time.Sleep(bootWait)
+
+	m.mu.Lock()
+	defer m.mu.Unlock()
+	if err := m.openLocked(); err != nil {
+		log.Printf("UART reconnect after master restart: %v", err)
+		return
+	}
+	flushSerialInput(m.sp)
+	log.Printf("UART %s ready after master restart", m.portName)
+}
+
 func (m *managedSerial) exchangePayload(payload []byte, cmdName string) ([]byte, error) {
 	return m.exchangePayloadVia(m.withPort, payload, cmdName)
 }
@@ -119,7 +140,7 @@ func (m *managedSerial) exchangePayloadVia(
 	var resp []byte
 	err := portFn(func(sp *serialPort) error {
 		var e error
-		resp, e = sp.exchangePayloadLocked(payload, cmdName)
+		resp, e = sp.exchangePayloadLocked(payload, cmdName, readTimeout)
 		return e
 	})
 	return resp, err

goTool/serialport.go

@@ -12,6 +12,9 @@ import (
 
 const readTimeout = 3 * time.Second
 
+// batteryReadTimeout: master may query each slave over ESP-NOW (~400 ms each).
+const batteryReadTimeout = 12 * time.Second
+
 type serialPort struct {
 	port  serial.Port
 	mu    sync.Mutex
@@ -44,10 +47,16 @@ func (s *serialPort) Close() error {
 func (s *serialPort) exchangePayload(payload []byte, cmdName string) ([]byte, error) {
 	s.mu.Lock()
 	defer s.mu.Unlock()
-	return s.exchangePayloadLocked(payload, cmdName)
+	return s.exchangePayloadLocked(payload, cmdName, readTimeout)
 }
 
-func (s *serialPort) exchangePayloadLocked(payload []byte, cmdName string) ([]byte, error) {
+func (s *serialPort) exchangePayloadForBattery(payload []byte, cmdName string) ([]byte, error) {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+	return s.exchangePayloadLocked(payload, cmdName, batteryReadTimeout)
+}
+
+func (s *serialPort) exchangePayloadLocked(payload []byte, cmdName string, timeout time.Duration) ([]byte, error) {
 	if len(payload) == 0 {
 		return nil, fmt.Errorf("empty payload")
 	}
@@ -63,7 +72,15 @@ func (s *serialPort) exchangePayloadLocked(payload []byte, cmdName string) ([]by
 		return nil, fmt.Errorf("write: %w", err)
 	}
 
-	respPayload, err := uartframe.ReadFrame(s.port, nil)
+	if timeout <= 0 {
+		timeout = readTimeout
+	}
+	if err := s.port.SetReadTimeout(timeout); err != nil {
+		return nil, fmt.Errorf("set read timeout: %w", err)
+	}
+	defer func() { _ = s.port.SetReadTimeout(readTimeout) }()
+
+	respPayload, err := uartframe.ReadFrame(s.port, nil, timeout)
 	if err != nil {
 		return nil, fmt.Errorf("read response: %w", err)
 	}
@@ -96,7 +113,7 @@ func (s *serialPort) exchangeLocked(cmdID byte, cmdName string) ([]byte, error)
 		return nil, fmt.Errorf("write: %w", err)
 	}
 
-	payload, err := uartframe.ReadFrame(s.port, nil)
+	payload, err := uartframe.ReadFrame(s.port, nil, readTimeout)
 	if err != nil {
 		return nil, fmt.Errorf("read response: %w", err)
 	}

goTool/shutdown.go

@@ -0,0 +1,75 @@
+package main
+
+import (
+	"context"
+	"log"
+	"net/http"
+	"os"
+	"os/signal"
+	"sync"
+	"syscall"
+	"time"
+)
+
+var (
+	shutdownMu   sync.Mutex
+	shutdownFns  []func()
+	hooksOnce    sync.Once
+	bgHandlerOnce sync.Once
+)
+
+// registerShutdown runs fn on SIGINT/SIGTERM (LIFO order).
+func registerShutdown(fn func()) {
+	shutdownMu.Lock()
+	shutdownFns = append(shutdownFns, fn)
+	shutdownMu.Unlock()
+}
+
+func runShutdownHooks() {
+	hooksOnce.Do(func() {
+		shutdownMu.Lock()
+		fns := shutdownFns
+		shutdownMu.Unlock()
+		for i := len(fns) - 1; i >= 0; i-- {
+			fns[i]()
+		}
+	})
+}
+
+// enableShutdownOnInterrupt listens for SIGINT/SIGTERM in the background and exits
+// after running shutdown hooks. Use for one-shot CLI commands (OTA, etc.).
+func enableShutdownOnInterrupt() {
+	bgHandlerOnce.Do(func() {
+		ch := make(chan os.Signal, 1)
+		signal.Notify(ch, os.Interrupt, syscall.SIGTERM)
+		go func() {
+			sig := <-ch
+			signal.Stop(ch)
+			log.Printf("received %v, shutting down…", sig)
+			runShutdownHooks()
+			os.Exit(0)
+		}()
+	})
+}
+
+// waitForShutdown blocks until SIGINT/SIGTERM, runs hooks, and returns.
+// Use for long-running servers (serve/dashboard).
+func waitForShutdown() {
+	ch := make(chan os.Signal, 1)
+	signal.Notify(ch, os.Interrupt, syscall.SIGTERM)
+	sig := <-ch
+	signal.Stop(ch)
+	log.Printf("received %v, shutting down…", sig)
+	runShutdownHooks()
+}
+
+func shutdownHTTPServer(srv *http.Server) {
+	if srv == nil {
+		return
+	}
+	ctx, cancel := context.WithTimeout(context.Background(), 2*time.Second)
+	defer cancel()
+	if err := srv.Shutdown(ctx); err != nil {
+		log.Printf("HTTP shutdown: %v", err)
+	}
+}

goTool/tap_notify_ctl.go

@@ -0,0 +1,50 @@
+package main
+
+import "sync"
+
+// tapNotifyCtl tracks which slaves have tap notify enabled (mirrors firmware / dashboard).
+type tapNotifyCtl struct {
+	mu    sync.Mutex
+	flags map[uint32]tapNotifyFlags
+}
+
+type tapNotifyFlags struct {
+	single    bool
+	doubleTap bool
+	triple    bool
+}
+
+func newTapNotifyCtl() *tapNotifyCtl {
+	return &tapNotifyCtl{flags: make(map[uint32]tapNotifyFlags)}
+}
+
+func (c *tapNotifyCtl) Set(clientID uint32, single, doubleTap, triple bool) {
+	c.mu.Lock()
+	defer c.mu.Unlock()
+	if !single && !doubleTap && !triple {
+		delete(c.flags, clientID)
+		return
+	}
+	c.flags[clientID] = tapNotifyFlags{single: single, doubleTap: doubleTap, triple: triple}
+}
+
+func (c *tapNotifyCtl) Any() bool {
+	c.mu.Lock()
+	defer c.mu.Unlock()
+	return len(c.flags) > 0
+}
+
+func (c *tapNotifyCtl) SyncFromClients(clients []ClientView) {
+	c.mu.Lock()
+	defer c.mu.Unlock()
+	c.flags = make(map[uint32]tapNotifyFlags)
+	for _, cl := range clients {
+		if cl.TapNotifySingle || cl.TapNotifyDouble || cl.TapNotifyTriple {
+			c.flags[cl.ID] = tapNotifyFlags{
+				single:    cl.TapNotifySingle,
+				doubleTap: cl.TapNotifyDouble,
+				triple:    cl.TapNotifyTriple,
+			}
+		}
+	}
+}

goTool/testdata/README.md

@@ -44,7 +44,7 @@ Ordered steps: UART commands, delays, or esptool reset.
 **unicast_test** — `input`: `slave` or `client_id`, `seq`  
 `expect`: `success`, `seq`
 
-**led_ring** — `input`: `mode` (`clear`, `progress`, `digit`, `blink`, `find_me`), `progress`, `digit`, `r`/`g`/`b`, `intensity`, `blink_ms`, `blink_count`  
+**led_ring** — `input`: `mode` (`clear`, `progress`, `digit`, `blink`, `find_me`, `battery_low`), `progress`, `digit`, `r`/`g`/`b`, `intensity`, `blink_ms`, `blink_count`  
 `expect`: `success`, `mode`, `progress`, `digit`
 
 **find_me** — `input`: `client` / `client_id` or `slave` (`0` = master ring)  

goTool/uart/frame.go

@@ -4,12 +4,14 @@ import (
 	"errors"
 	"fmt"
 	"io"
+	"time"
 )
 
 const (
 	StartMarker = 0xAA
 	StopMarker  = 0xCC
-	MaxPayload  = 252
+	// Must match main/uart.h MAX_PAYLOAD_SIZE (MAX_BUF_SIZE - 4).
+	MaxPayload = 248
 )
 
 var (
@@ -97,13 +99,22 @@ func (p *Parser) Feed(b byte) (payload []byte, ok bool, err error) {
 }
 
 // ReadFrame reads bytes from r until one full frame is parsed or an error occurs.
-func ReadFrame(r io.Reader, buf []byte) ([]byte, error) {
+// maxWait bounds total wait time; zero means no limit (serial read timeouts retry forever).
+func ReadFrame(r io.Reader, buf []byte, maxWait time.Duration) ([]byte, error) {
 	if buf == nil {
 		buf = make([]byte, 256)
 	}
 	parser := NewParser()
 
+	var deadline time.Time
+	if maxWait > 0 {
+		deadline = time.Now().Add(maxWait)
+	}
+
 	for {
+		if !deadline.IsZero() && !time.Now().Before(deadline) {
+			return nil, ErrTimeout
+		}
 		n, err := r.Read(buf)
 		if n > 0 {
 			for i := 0; i < n; i++ {

goTool/webui/index.html

@@ -55,11 +55,31 @@
     .badge-offline { background: #5c6570; color: #f0f3f5; }
     .badge.bg-secondary { background: #4a5560 !important; color: #f0f3f5; }
 
-    .mac {
+    .mac, .accel {
       font-family: ui-monospace, monospace;
       font-size: 0.85rem;
       color: var(--pp-accent);
     }
+    .accel-stale { color: var(--pp-text-muted); }
+
+    .tap-toggle {
+      display: inline-flex;
+      align-items: center;
+      gap: 0.15rem;
+      font-size: 0.72rem;
+      color: var(--pp-text-secondary);
+      white-space: nowrap;
+    }
+    .tap-toggle input { margin: 0; }
+    .tap-hit {
+      color: #ffd166;
+      font-weight: 600;
+      animation: tap-flash 2s ease-out;
+    }
+    @keyframes tap-flash {
+      from { color: #fff; transform: scale(1.08); }
+      to { color: #ffd166; transform: scale(1); }
+    }
 
     .pp-table {
       --bs-table-color: var(--pp-text);
@@ -199,6 +219,12 @@
                 <dd class="col-7" x-text="state.master.running_partition || '—'"></dd>
                 <dt class="col-5 text-muted">Deadzone</dt>
                 <dd class="col-7" x-text="state.master.deadzone != null ? state.master.deadzone + ' LSB' : '—'"></dd>
+                <dt class="col-5 text-muted">Log-Level</dt>
+                <dd class="col-7" x-text="formatLogLevel(masterLogLevel)"></dd>
+                <dt class="col-5 text-muted">LiPo 1</dt>
+                <dd class="col-7" x-text="formatLipo(state.master?.lipo1)"></dd>
+                <dt class="col-5 text-muted">LiPo 2</dt>
+                <dd class="col-7" x-text="formatLipo(state.master?.lipo2)"></dd>
               </dl>
             </template>
             <template x-if="state.master && !state.master.ok">
@@ -240,6 +266,31 @@
                   Restart
                 </button>
               </div>
+              <label class="form-label text-muted small mb-1 mt-3" for="master-log-level">
+                ESP Log-Level (global)
+              </label>
+              <div class="d-flex flex-wrap gap-2 align-items-end">
+                <select id="master-log-level" class="form-select form-select-sm config-input"
+                        x-model.number="masterLogLevel"
+                        :disabled="busy || !state.uart_connected">
+                  <option value="0">None (aus)</option>
+                  <option value="1">Error</option>
+                  <option value="2">Warn</option>
+                  <option value="3">Info</option>
+                  <option value="4">Debug</option>
+                  <option value="5">Verbose</option>
+                </select>
+                <button type="button" class="btn btn-outline-secondary btn-sm"
+                        @click="readMasterLogLevel()"
+                        :disabled="busy || !state.uart_connected">
+                  Lesen
+                </button>
+                <button type="button" class="btn btn-primary btn-sm"
+                        @click="setMasterLogLevel()"
+                        :disabled="busy || !state.uart_connected">
+                  Setzen
+                </button>
+              </div>
               <p class="text-muted small mt-2 mb-0" x-show="!state.uart_connected">
                 UART nicht verbunden — Eingabe gesperrt.
               </p>
@@ -265,8 +316,29 @@
               <span class="badge bg-secondary" x-text="(state.clients || []).length + ' registered'"></span>
             </div>
           </div>
-          <p class="text-muted small px-3 pt-2 mb-0">Slaves per ESP-NOW — Master-Deadzone bleibt separat.</p>
-          <div class="card-body p-0 pt-2">
+          <p class="text-muted small px-3 pt-2 mb-0">
+            <strong>Live-Stream</strong> startet die schnelle <code>CACHE_STATUS</code>-Abfrage (~16&nbsp;ms).
+            Pro Slave <strong>Accel</strong> aktiviert den ESP-NOW-Accel-Stream; Tap-Notify (S/D/T) steuert
+            die Tap-Arten auf dem Slave.
+          </p>
+          <div class="px-3 pb-2 d-flex flex-wrap gap-2 align-items-center">
+            <button type="button"
+                    class="btn btn-sm"
+                    :class="state.live_stream ? 'btn-warning' : 'btn-success'"
+                    @click="setLiveStream(!state.live_stream)"
+                    :disabled="busy || !state.uart_connected || !(state.clients || []).length"
+                    x-text="state.live_stream ? 'Live-Stream aus' : 'Live-Stream an'"></button>
+            <span class="text-muted small">Tap alle Slaves:</span>
+            <label class="tap-toggle"><input type="checkbox" x-model="allTapSingle" :disabled="busy"> S</label>
+            <label class="tap-toggle"><input type="checkbox" x-model="allTapDouble" :disabled="busy"> D</label>
+            <label class="tap-toggle"><input type="checkbox" x-model="allTapTriple" :disabled="busy"> T</label>
+            <button type="button" class="btn btn-outline-secondary btn-sm"
+                    @click="setTapNotifyAll(allTapSingle, allTapDouble, allTapTriple)"
+                    :disabled="busy || !state.uart_connected">
+              Tap setzen
+            </button>
+          </div>
+          <div class="card-body p-0 pt-1">
             <div class="table-responsive">
               <table class="table pp-table table-hover">
                 <thead>
@@ -276,12 +348,17 @@
                     <th>Ver</th>
                     <th>Status</th>
                     <th>Deadzone</th>
+                    <th>Accel (LSB)</th>
+                    <th>Akku</th>
+                    <th>Accel</th>
+                    <th>Tap-Notify</th>
+                    <th>Tap</th>
                     <th>Aktion</th>
                   </tr>
                 </thead>
                 <tbody>
                   <template x-if="!(state.clients || []).length">
-                    <tr><td colspan="6" class="text-muted text-center py-4">No clients</td></tr>
+                    <tr><td colspan="11" class="text-muted text-center py-4">No clients</td></tr>
                   </template>
                   <template x-for="c in (state.clients || [])" :key="c.id + c.mac">
                     <tr>
@@ -294,6 +371,47 @@
                               x-text="c.available ? 'available' : 'inactive'"></span>
                       </td>
                       <td x-text="c.deadzone != null ? c.deadzone : '—'"></td>
+                      <td>
+                        <span class="accel"
+                              :class="accelCellClass(c)"
+                              x-text="formatAccel(c)"
+                              :title="accelTitle(c)"></span>
+                      </td>
+                      <td class="small" x-text="formatLipoPair(c)" :title="lipoTitle(c)"></td>
+                      <td>
+                        <button type="button"
+                                class="btn btn-sm"
+                                :class="c.accel_stream ? 'btn-warning' : 'btn-outline-success'"
+                                @click="setAccelStream(c.id, !c.accel_stream)"
+                                :disabled="busy || !state.uart_connected || !c.available"
+                                x-text="c.accel_stream ? 'Aus' : 'An'"
+                                title="ESP-NOW Accel-Stream auf Slave"></button>
+                      </td>
+                      <td>
+                        <div class="d-flex flex-wrap gap-1 align-items-center">
+                          <label class="tap-toggle" title="Single tap">
+                            <input type="checkbox"
+                                   :checked="c.tap_notify_single"
+                                   @change="setTapNotify(c.id, $event.target.checked, c.tap_notify_double, c.tap_notify_triple)"
+                                   :disabled="busy || !state.uart_connected || !c.available"> S
+                          </label>
+                          <label class="tap-toggle" title="Double tap">
+                            <input type="checkbox"
+                                   :checked="c.tap_notify_double"
+                                   @change="setTapNotify(c.id, c.tap_notify_single, $event.target.checked, c.tap_notify_triple)"
+                                   :disabled="busy || !state.uart_connected || !c.available"> D
+                          </label>
+                          <label class="tap-toggle" title="Triple tap">
+                            <input type="checkbox"
+                                   :checked="c.tap_notify_triple"
+                                   @change="setTapNotify(c.id, c.tap_notify_single, c.tap_notify_double, $event.target.checked)"
+                                   :disabled="busy || !state.uart_connected || !c.available"> T
+                          </label>
+                        </div>
+                      </td>
+                      <td>
+                        <span :class="tapCellClass(c)" x-text="formatLastTap(c)" :title="tapTitle(c)"></span>
+                      </td>
                       <td>
                         <div class="d-flex flex-wrap gap-1 align-items-center">
                           <input type="number" class="form-control form-control-sm dz-input"
@@ -312,11 +430,23 @@
                                   title="ESP-NOW Unicast-Test">
                             Test
                           </button>
-                          <button type="button" class="btn btn-outline-warning btn-sm"
-                                  @click="findMe(c.id)"
+                          <button type="button" class="btn btn-outline-info btn-sm"
+                                  @click="echoPing(c.id)"
                                   :disabled="busy || !state.uart_connected || !c.available"
-                                  title="LED-Ring Find me (ESP-NOW)">
-                            Find me
+                                  title="ESP-NOW Timestamp-Echo (Round-Trip-Latenz)">
+                            Ping
+                          </button>
+                          <button type="button" class="btn btn-outline-info btn-sm"
+                                  @click="ledRing({ clientId: c.id })"
+                                  :disabled="busy || !state.uart_connected || !c.available"
+                                  title="LED-Ring (aktueller Modus)">
+                            LED
+                          </button>
+                          <button type="button" class="btn btn-outline-warning btn-sm"
+                                  @click="ledRing({ clientId: c.id, mode: 'find-me' })"
+                                  :disabled="busy || !state.uart_connected || !c.available"
+                                  title="Find me">
+                            Find
                           </button>
                           <button type="button" class="btn btn-outline-secondary btn-sm"
                                   @click="restart(c.id)"
@@ -335,6 +465,83 @@
         </div>
       </section>
 
+      <section class="col-12">
+        <div class="card">
+          <div class="card-header">LED-Ring</div>
+          <div class="card-body">
+            <p class="text-muted small mb-3">
+              Modi: <code>clear</code>, <code>color</code> (ganzer Ring), <code>progress</code> (0–100&nbsp;%),
+              <code>digit</code> (0–10), <code>blink</code>, <code>find-me</code>, <code>battery-low</code>.
+              Ziel: Master (<code>client_id=0</code>), ein Slave oder alle Slaves (Broadcast).
+            </p>
+            <div class="row g-3 align-items-end">
+              <div class="col-md-2">
+                <label class="form-label small text-muted">Modus</label>
+                <select class="form-select form-select-sm" x-model="led.mode" :disabled="busy">
+                  <option value="color">Farbe (alle LEDs)</option>
+                  <option value="clear">Aus (clear)</option>
+                  <option value="progress">Progress</option>
+                  <option value="digit">Ziffer/Symbol</option>
+                  <option value="blink">Blink</option>
+                  <option value="find-me">Find me</option>
+                  <option value="battery-low">Battery low</option>
+                </select>
+              </div>
+              <div class="col-md-4">
+                <label class="form-label small text-muted">RGB / Intensität</label>
+                <div class="d-flex flex-wrap gap-2">
+                  <input type="number" class="form-control form-control-sm" style="width:4rem" min="0" max="255"
+                         placeholder="R" x-model.number="led.r" :disabled="busy">
+                  <input type="number" class="form-control form-control-sm" style="width:4rem" min="0" max="255"
+                         placeholder="G" x-model.number="led.g" :disabled="busy">
+                  <input type="number" class="form-control form-control-sm" style="width:4rem" min="0" max="255"
+                         placeholder="B" x-model.number="led.b" :disabled="busy">
+                  <input type="number" class="form-control form-control-sm" style="width:5rem" min="0" max="255"
+                         title="0 = Geräte-Default (~5 %)"
+                         placeholder="Int." x-model.number="led.intensity" :disabled="busy">
+                </div>
+              </div>
+              <div class="col-md-2" x-show="led.mode === 'progress'">
+                <label class="form-label small text-muted">Progress %</label>
+                <input type="number" class="form-control form-control-sm" min="0" max="100"
+                       x-model.number="led.progress" :disabled="busy">
+              </div>
+              <div class="col-md-2" x-show="led.mode === 'digit'">
+                <label class="form-label small text-muted">Ziffer 0–10</label>
+                <input type="number" class="form-control form-control-sm" min="0" max="10"
+                       x-model.number="led.digit" :disabled="busy">
+              </div>
+              <div class="col-md-2" x-show="led.mode === 'blink'">
+                <label class="form-label small text-muted">Blink ms × Anzahl</label>
+                <div class="d-flex gap-1">
+                  <input type="number" class="form-control form-control-sm" min="1"
+                         x-model.number="led.blinkMs" :disabled="busy">
+                  <input type="number" class="form-control form-control-sm" min="1"
+                         x-model.number="led.blinkCount" :disabled="busy">
+                </div>
+              </div>
+              <div class="col-md-4 d-flex flex-wrap gap-2">
+                <button type="button" class="btn btn-primary btn-sm"
+                        @click="ledRing({ clientId: 0 })"
+                        :disabled="busy || !state.uart_connected">
+                  Master
+                </button>
+                <button type="button" class="btn btn-outline-primary btn-sm"
+                        @click="ledRing({ allClients: true, slavesOnly: true })"
+                        :disabled="busy || !state.uart_connected">
+                  Alle Slaves
+                </button>
+                <button type="button" class="btn btn-outline-secondary btn-sm"
+                        @click="ledRing({ allClients: true })"
+                        :disabled="busy || !state.uart_connected">
+                  Alle + Master
+                </button>
+              </div>
+            </div>
+          </div>
+        </div>
+      </section>
+
       <section class="col-12">
         <div class="card">
           <div class="card-header">Firmware OTA (A/B)</div>
@@ -448,8 +655,15 @@
         ws: null,
         wsConnected: false,
         masterDz: 100,
+        masterLogLevel: 0,
         allDz: 100,
+        allTapSingle: false,
+        allTapDouble: false,
+        allTapTriple: false,
         slaveDz: {},
+        TAP_DISPLAY_MS: 2000,
+        tapDisplay: {},
+        _tapClock: 0,
         otaFile: null,
         ota: {
           active: false, phase: '', step: '', percent: 0,
@@ -461,12 +675,31 @@
         busy: false,
         configMsg: '',
         configMsgOk: false,
+        _flashTimer: null,
+        led: {
+          mode: 'color',
+          r: 0,
+          g: 120,
+          b: 255,
+          intensity: 0,
+          progress: 50,
+          digit: 0,
+          blinkMs: 350,
+          blinkCount: 1
+        },
         connect() {
           const proto = location.protocol === 'https:' ? 'wss:' : 'ws:';
           const url = proto + '//' + location.host + '/ws';
+          if (this._batteryTimer) clearInterval(this._batteryTimer);
+          this._batteryTimer = setInterval(() => this.refreshBattery(), 5000);
+          if (this._tapTimer) clearInterval(this._tapTimer);
+          this._tapTimer = setInterval(() => { this._tapClock++; }, 250);
           const connect = () => {
             this.ws = new WebSocket(url);
-            this.ws.onopen = () => { this.wsConnected = true; };
+            this.ws.onopen = () => {
+              this.wsConnected = true;
+              this.refreshBattery();
+            };
             this.ws.onclose = () => {
               this.wsConnected = false;
               setTimeout(connect, 2000);
@@ -478,7 +711,14 @@
                   this.applyOTAProgress(msg);
                   return;
                 }
+                if (msg.type === 'battery_status') {
+                  if (msg.samples?.length) this.applyBatterySamples(msg.samples);
+                  return;
+                }
+                const prev = this.state;
                 this.state = msg;
+                this.preserveBatteryInState(prev, this.state);
+                this.syncTapDisplay(msg.clients || []);
                 if (msg.master?.deadzone != null) {
                   this.masterDz = msg.master.deadzone;
                 }
@@ -492,10 +732,173 @@
           };
           connect();
         },
+        preserveBatteryInState(prev, next) {
+          if (!prev || !next) return;
+          const keepLipo = (oldL, newL) => {
+            if (newL?.valid) return newL;
+            if (oldL?.valid) return oldL;
+            return newL ?? oldL;
+          };
+          const keepAge = (oldAge, newAge, hasValid) => {
+            if (hasValid && newAge != null) return newAge;
+            if (oldAge != null && !hasValid) return oldAge;
+            return newAge ?? oldAge;
+          };
+          if (next.master) {
+            const pm = prev.master || {};
+            const l1 = keepLipo(pm.lipo1, next.master.lipo1);
+            const l2 = keepLipo(pm.lipo2, next.master.lipo2);
+            next.master.lipo1 = l1;
+            next.master.lipo2 = l2;
+            next.master.battery_age_ms = keepAge(
+              pm.battery_age_ms, next.master.battery_age_ms, !!(l1?.valid || l2?.valid));
+          }
+          if (!Array.isArray(next.clients)) return;
+          const prevById = Object.fromEntries((prev.clients || []).map((c) => [c.id, c]));
+          next.clients = next.clients.map((c) => {
+            const p = prevById[c.id];
+            if (!p) return c;
+            const l1 = keepLipo(p.lipo1, c.lipo1);
+            const l2 = keepLipo(p.lipo2, c.lipo2);
+            return {
+              ...c,
+              lipo1: l1,
+              lipo2: l2,
+              battery_age_ms: keepAge(p.battery_age_ms, c.battery_age_ms, !!(l1?.valid || l2?.valid))
+            };
+          });
+        },
+        applyBatterySamples(samples) {
+          if (!samples?.length) return;
+          const master = { ...(this.state.master || {}) };
+          const clients = [...(this.state.clients || [])];
+          let masterChanged = false;
+          let clientsChanged = false;
+          for (const s of samples) {
+            if (s.client_id === 0) {
+              master.lipo1 = s.lipo1;
+              master.lipo2 = s.lipo2;
+              master.battery_age_ms = s.age_ms;
+              masterChanged = true;
+              continue;
+            }
+            const idx = clients.findIndex((x) => x.id === s.client_id);
+            if (idx >= 0) {
+              clients[idx] = {
+                ...clients[idx],
+                lipo1: s.lipo1,
+                lipo2: s.lipo2,
+                battery_age_ms: s.age_ms,
+              };
+              clientsChanged = true;
+            }
+          }
+          if (!masterChanged && !clientsChanged) return;
+          this.state = {
+            ...this.state,
+            ...(masterChanged ? { master } : {}),
+            ...(clientsChanged ? { clients } : {}),
+          };
+        },
+        async refreshBattery() {
+          if (!this.state?.uart_connected) return;
+          try {
+            const r = await fetch('/api/battery?all_clients=1');
+            if (!r.ok) return;
+            const data = await r.json();
+            if (data.samples?.length) this.applyBatterySamples(data.samples);
+          } catch (_) {}
+        },
+        formatLogLevel(level) {
+          const labels = ['None', 'Error', 'Warn', 'Info', 'Debug', 'Verbose'];
+          if (level == null || level < 0 || level > 5) return '—';
+          return `${labels[level]} (${level})`;
+        },
         formatMac(hex) {
           if (!hex || hex.length !== 12) return hex || '';
           return hex.match(/.{2}/g).join(':');
         },
+        formatLipo(l) {
+          if (!l?.valid) return '—';
+          const v = (l.voltage_mv / 1000).toFixed(2);
+          return l.percent != null ? `${v} V (${l.percent}%)` : `${v} V`;
+        },
+        formatLipoPair(c) {
+          return `1: ${this.formatLipo(c?.lipo1)} · 2: ${this.formatLipo(c?.lipo2)}`;
+        },
+        lipoTitle(c) {
+          if (!c?.lipo1?.valid && !c?.lipo2?.valid) return 'Keine ADC-Daten (Cache ~30 s)';
+          let t = `LiPo1 ${c.lipo1?.voltage_mv ?? '—'} mV, LiPo2 ${c.lipo2?.voltage_mv ?? '—'} mV`;
+          if (c.battery_age_ms != null) t += `, Alter ${c.battery_age_ms} ms`;
+          return t;
+        },
+        formatAccel(c) {
+          if (!this.state?.live_stream) return '—';
+          if (!c?.accel_stream) return '—';
+          if (!c?.accel_valid) return '…';
+          return `${c.accel_x} / ${c.accel_y} / ${c.accel_z}`;
+        },
+        accelTitle(c) {
+          if (!this.state?.live_stream) return 'Live-Stream aus — oben einschalten';
+          if (!c?.accel_stream) return 'Accel-Stream für diesen Slave nicht aktiv';
+          if (!c?.accel_valid) return 'Warte auf erste ESP-NOW Samples…';
+          const age = c.accel_age_ms != null ? `${c.accel_age_ms} ms alt` : '';
+          return `x=${c.accel_x} y=${c.accel_y} z=${c.accel_z} (raw LSB, ±2g)${age ? ' · ' + age : ''}`;
+        },
+        accelCellClass(c) {
+          if (!c?.accel_valid) return 'accel-stale';
+          if (c.accel_age_ms != null && c.accel_age_ms > 200) return 'accel-stale';
+          return '';
+        },
+        tapNotifyAny(c) {
+          return !!(c?.tap_notify_single || c?.tap_notify_double || c?.tap_notify_triple);
+        },
+        syncTapDisplay(clients) {
+          const now = Date.now();
+          for (const c of clients) {
+            if (!c?.last_tap || !c?.last_tap_at) continue;
+            const prev = this.tapDisplay[c.id];
+            if (!prev || c.last_tap_at >= prev.shownAt) {
+              this.tapDisplay[c.id] = { kind: c.last_tap, shownAt: c.last_tap_at };
+            }
+          }
+          for (const id of Object.keys(this.tapDisplay)) {
+            if (now - this.tapDisplay[id].shownAt > this.TAP_DISPLAY_MS + 500) {
+              delete this.tapDisplay[id];
+            }
+          }
+        },
+        activeTapDisplay(c) {
+          void this._tapClock;
+          const d = this.tapDisplay[c?.id];
+          if (!d) return null;
+          if (Date.now() - d.shownAt >= this.TAP_DISPLAY_MS) return null;
+          return d;
+        },
+        formatLastTap(c) {
+          if (!this.state?.live_stream) return '—';
+          if (!this.tapNotifyAny(c)) return '—';
+          const labels = { single: 'Single', double: 'Double', triple: 'Triple' };
+          const d = this.activeTapDisplay(c);
+          if (d) return labels[d.kind] || d.kind;
+          if (!c?.last_tap) return '…';
+          return '—';
+        },
+        tapTitle(c) {
+          if (!this.state?.live_stream) return 'Live-Stream aus';
+          if (!this.tapNotifyAny(c)) return 'Tap-Notify nicht konfiguriert (S/D/T)';
+          const d = this.activeTapDisplay(c);
+          if (d) {
+            const age = (Date.now() - d.shownAt) + ' ms her';
+            return `Tap: ${d.kind} · ${age}`;
+          }
+          if (!c?.last_tap) return 'Warte auf Tap-Event…';
+          return 'Bereit — letzter Tap ausgeblendet';
+        },
+        tapCellClass(c) {
+          if (this.activeTapDisplay(c)) return 'tap-hit';
+          return 'text-muted';
+        },
         formatSize(n) {
           if (n == null) return '';
           if (n < 1024) return n + ' B';
@@ -590,8 +993,21 @@
           return rows;
         },
         applyOTAProgress(p) {
-          this.ota.phase = p.phase || '';
-          this.ota.step = p.step || this.ota.step || '';
+          const prevPhase = this.ota.phase;
+          const prevStep = this.ota.step;
+          if (p.phase) {
+            // Ignore out-of-order master upload updates after distribution started.
+            if (!(p.phase === 'uploading' && prevPhase === 'distributing')) {
+              this.ota.phase = p.phase;
+            }
+          }
+          if (p.step) {
+            if (!(p.step === 'master' && (prevStep === 'slaves' || prevPhase === 'distributing'))) {
+              this.ota.step = p.step;
+            }
+          } else if (!this.ota.step) {
+            this.ota.step = '';
+          }
           this.ota.percent = p.percent ?? this.ota.percent;
           this.ota.message = p.message || '';
           if (p.image_size) this.ota.imageSize = p.image_size;
@@ -670,10 +1086,14 @@
             this.busy = false;
           }
         },
-        flash(msg, ok) {
+        flash(msg, ok, durationMs = 5000) {
           this.configMsg = msg;
           this.configMsgOk = ok;
-          setTimeout(() => { this.configMsg = ''; }, 5000);
+          if (this._flashTimer) clearTimeout(this._flashTimer);
+          this._flashTimer = setTimeout(() => {
+            this.configMsg = '';
+            this._flashTimer = null;
+          }, durationMs);
         },
         async setDeadzone(clientId, deadzone, opts = {}) {
           if (deadzone == null || deadzone < 0) {
@@ -732,6 +1152,182 @@
         async setMasterDeadzone() {
           await this.setDeadzone(0, this.masterDz);
         },
+        async readMasterLogLevel() {
+          this.busy = true;
+          try {
+            const r = await fetch('/api/log-level');
+            const data = await r.json();
+            if (!r.ok || !data.success) {
+              this.flash(data.error || 'Log-Level lesen fehlgeschlagen', false);
+              return;
+            }
+            this.masterLogLevel = data.level;
+            this.flash(`Master: Log-Level ${this.formatLogLevel(data.level)}`, true);
+          } catch (e) {
+            this.flash(String(e), false);
+          } finally {
+            this.busy = false;
+          }
+        },
+        async setMasterLogLevel() {
+          this.busy = true;
+          try {
+            const r = await fetch('/api/log-level', {
+              method: 'POST',
+              headers: { 'Content-Type': 'application/json' },
+              body: JSON.stringify({ write: true, level: this.masterLogLevel })
+            });
+            const data = await r.json();
+            if (!r.ok || !data.success) {
+              this.flash(data.error || 'Log-Level setzen fehlgeschlagen', false);
+              return;
+            }
+            this.masterLogLevel = data.level;
+            this.flash(`Master: Log-Level ${this.formatLogLevel(data.level)} gesetzt`, true);
+          } catch (e) {
+            this.flash(String(e), false);
+          } finally {
+            this.busy = false;
+          }
+        },
+        patchLiveStream(enabled) {
+          let clients = this.state.clients || [];
+          if (!enabled) {
+            clients = clients.map((c) => ({
+              ...c,
+              accel_valid: false,
+              accel_x: 0,
+              accel_y: 0,
+              accel_z: 0,
+              accel_age_ms: 0,
+              last_tap: '',
+              last_tap_at: 0
+            }));
+            this.tapDisplay = {};
+          }
+          this.state = { ...this.state, live_stream: enabled, clients };
+        },
+        async setLiveStream(enable) {
+          this.busy = true;
+          try {
+            const r = await fetch('/api/live-stream', {
+              method: 'PUT',
+              headers: { 'Content-Type': 'application/json' },
+              body: JSON.stringify({ enable })
+            });
+            const data = await r.json();
+            if (!r.ok || !data.success) {
+              this.flash(data.error || 'Live-Stream fehlgeschlagen', false);
+              return;
+            }
+            this.patchLiveStream(!!data.enabled);
+            this.flash(`Live-Stream ${data.enabled ? 'an' : 'aus'}`, true);
+          } catch (e) {
+            this.flash(String(e), false);
+          } finally {
+            this.busy = false;
+          }
+        },
+        patchClientAccelStream(clientId, enabled) {
+          const clients = (this.state.clients || []).map((c) => {
+            if (c.id !== clientId) return c;
+            const next = { ...c, accel_stream: enabled };
+            if (!enabled) {
+              next.accel_valid = false;
+              next.accel_x = 0;
+              next.accel_y = 0;
+              next.accel_z = 0;
+              next.accel_age_ms = 0;
+            }
+            return next;
+          });
+          this.state = { ...this.state, clients };
+        },
+        async setAccelStream(clientId, enable) {
+          this.busy = true;
+          try {
+            const r = await fetch(`/api/clients/${clientId}/accel-stream`, {
+              method: 'PUT',
+              headers: { 'Content-Type': 'application/json' },
+              body: JSON.stringify({ enable })
+            });
+            const data = await r.json();
+            if (!r.ok || !data.success) {
+              this.flash(data.error || `Accel-Stream Slave ${clientId} fehlgeschlagen`, false);
+              return;
+            }
+            this.patchClientAccelStream(clientId, !!data.enabled);
+            this.flash(`Slave ${clientId}: Accel-Stream ${data.enabled ? 'an' : 'aus'}`, true);
+          } catch (e) {
+            this.flash(String(e), false);
+          } finally {
+            this.busy = false;
+          }
+        },
+        patchClientTapNotify(clientId, single, doubleTap, triple) {
+          const clients = (this.state.clients || []).map((c) => {
+            if (c.id !== clientId) return c;
+            const next = {
+              ...c,
+              tap_notify_single: single,
+              tap_notify_double: doubleTap,
+              tap_notify_triple: triple
+            };
+            if (!single && !doubleTap && !triple) {
+              next.last_tap = '';
+              next.last_tap_at = 0;
+              delete this.tapDisplay[c.id];
+            }
+            return next;
+          });
+          this.state = { ...this.state, clients };
+        },
+        async setTapNotify(clientId, single, doubleTap, triple) {
+          this.busy = true;
+          try {
+            const r = await fetch(`/api/clients/${clientId}/tap-notify`, {
+              method: 'PUT',
+              headers: { 'Content-Type': 'application/json' },
+              body: JSON.stringify({ single, double_tap: doubleTap, triple })
+            });
+            const data = await r.json();
+            if (!r.ok || !data.success) {
+              this.flash(data.error || `Tap-Notify Slave ${clientId} fehlgeschlagen`, false);
+              return;
+            }
+            this.patchClientTapNotify(clientId, !!data.single, !!data.double_tap, !!data.triple);
+            const on = [data.single && 'S', data.double_tap && 'D', data.triple && 'T'].filter(Boolean).join('/') || 'aus';
+            this.flash(`Slave ${clientId}: Tap-Notify ${on}`, true);
+          } catch (e) {
+            this.flash(String(e), false);
+          } finally {
+            this.busy = false;
+          }
+        },
+        async setTapNotifyAll(single, doubleTap, triple) {
+          this.busy = true;
+          try {
+            const r = await fetch('/api/tap-notify', {
+              method: 'POST',
+              headers: { 'Content-Type': 'application/json' },
+              body: JSON.stringify({ all_clients: true, single, double_tap: doubleTap, triple })
+            });
+            const data = await r.json();
+            if (!r.ok || !data.success) {
+              this.flash(data.error || 'Tap-Notify für alle Slaves fehlgeschlagen', false);
+              return;
+            }
+            for (const c of (this.state.clients || [])) {
+              this.patchClientTapNotify(c.id, !!single, !!doubleTap, !!triple);
+            }
+            const on = [single && 'S', doubleTap && 'D', triple && 'T'].filter(Boolean).join('/') || 'aus';
+            this.flash(`Alle Slaves: Tap-Notify ${on} (${data.slaves_updated} aktualisiert)`, true);
+          } catch (e) {
+            this.flash(String(e), false);
+          } finally {
+            this.busy = false;
+          }
+        },
         async setDeadzoneAll(deadzone) {
           if (deadzone == null || deadzone < 0) {
             this.flash('Ungültiger Deadzone-Wert', false);
@@ -759,6 +1355,43 @@
             this.busy = false;
           }
         },
+        formatMs(v) {
+          return v != null && Number.isFinite(Number(v)) ? Number(v).toFixed(3) : '—';
+        },
+        formatUsAsMs(us) {
+          return us != null && Number.isFinite(Number(us))
+            ? (Number(us) / 1000).toFixed(3)
+            : '—';
+        },
+        async echoPing(clientId) {
+          this.busy = true;
+          try {
+            const r = await fetch('/api/echo-ping', {
+              method: 'POST',
+              headers: { 'Content-Type': 'application/json' },
+              body: JSON.stringify({ client_id: clientId })
+            });
+            const data = await r.json();
+            if (!r.ok) {
+              this.flash(data.error || `Echo-Ping Slave ${clientId} fehlgeschlagen`, false);
+              return;
+            }
+            if (!data.success) {
+              this.flash(`Echo-Ping Slave ${clientId} fehlgeschlagen (${this.formatMs(data.rtt_ms)} ms)`, false);
+              return;
+            }
+            this.flash(
+              `Echo-Ping Slave ${clientId}: Host ${this.formatMs(data.rtt_ms)} ms, ` +
+              `ESP ${this.formatUsAsMs(data.esp_rtt_us)} ms`,
+              true,
+              5000
+            );
+          } catch (e) {
+            this.flash(String(e), false);
+          } finally {
+            this.busy = false;
+          }
+        },
         async restart(clientId = 0) {
           this.busy = true;
           try {
@@ -780,6 +1413,49 @@
             this.busy = false;
           }
         },
+        async ledRing(opts = {}) {
+          const clientId = opts.clientId ?? 0;
+          const mode = opts.mode ?? this.led.mode;
+          this.busy = true;
+          try {
+            const r = await fetch('/api/led-ring', {
+              method: 'POST',
+              headers: { 'Content-Type': 'application/json' },
+              body: JSON.stringify({
+                mode,
+                client_id: clientId,
+                all_clients: !!opts.allClients,
+                slaves_only: !!opts.slavesOnly,
+                r: this.led.r,
+                g: this.led.g,
+                b: this.led.b,
+                intensity: this.led.intensity,
+                progress: this.led.progress,
+                digit: this.led.digit,
+                blink_ms: this.led.blinkMs,
+                blink_count: this.led.blinkCount
+              })
+            });
+            const data = await r.json();
+            if (!r.ok || !data.success) {
+              this.flash(data.error || 'LED-Ring fehlgeschlagen', false);
+              return;
+            }
+            let label = 'Master';
+            if (opts.allClients) {
+              label = opts.slavesOnly
+                ? `Alle Slaves (${data.slaves_updated})`
+                : `Alle + Master (${data.slaves_updated} Slaves)`;
+            } else if (clientId > 0) {
+              label = `Slave ${clientId}`;
+            }
+            this.flash(`LED ${mode} → ${label}`, true);
+          } catch (e) {
+            this.flash(String(e), false);
+          } finally {
+            this.busy = false;
+          }
+        },
         async findMe(clientId = 0) {
           this.busy = true;
           try {

main/CMakeLists.txt

@@ -14,24 +14,35 @@ idf_component_register(
   "uart.c"
   "uart_proto.c"
   "uart_cmd.c"
-  "cmd_handler.c"
-  "cmd_version.c"
-  "cmd_client_info.c"
-  "cmd_accel_deadzone.c"
-  "cmd_espnow_unicast_test.c"
-  "cmd_espnow_find_me.c"
-  "cmd_restart.c"
+  "cmd/cmd_handler.c"
+  "cmd/cmd_version.c"
+  "cmd/cmd_client_info.c"
+  "cmd/cmd_accel_deadzone.c"
+  "cmd/cmd_accel_stream.c"
+  "cmd/cmd_tap_notify.c"
+  "cmd/cmd_cache_status.c"
+  "cmd/cmd_espnow_unicast_test.c"
+  "cmd/cmd_espnow_echo_ping.c"
+  "cmd/cmd_espnow_find_me.c"
+  "cmd/cmd_restart.c"
   "pod_reboot.c"
-  "cmd_led_ring.c"
-  "cmd_ota.c"
-  "cmd_ota_slave_progress.c"
+  "cmd/cmd_led_ring.c"
+  "cmd/cmd_battery.c"
+  "cmd/cmd_set_log_level.c"
+  "cmd/cmd_ota.c"
+  "cmd/cmd_ota_slave_progress.c"
   "ota_uart.c"
   "ota_espnow.c"
+  "ota_session.c"
   "client_registry.c"
   "esp_now_comm.c"
+  "esp_now_core.c"
+  "esp_now_master.c"
+  "esp_now_slave.c"
   "esp_now_proto.c"
   "bosch456.c"
   "board_input.c"
+  "battery_uv.c"
   "pod_settings.c"
   "proto/uart_messages.pb.c"
   "proto/esp_now_messages.pb.c"
@@ -40,6 +51,7 @@ idf_component_register(
   "proto/pb_common.c"
   INCLUDE_DIRS
   "."
+  "cmd"
   "proto"
   REQUIRES
   esp_wifi
@@ -52,7 +64,10 @@ idf_component_register(
   esp_driver_i2c
   esp_adc
   app_update
+  esp_timer
   bma456)
 
 target_compile_definitions(${COMPONENT_LIB}
                            PRIVATE "POWERPOD_GIT_HASH=\"${POWERPOD_GIT_HASH}\"")
+# Optional: disable software UV protection
+# target_compile_definitions(${COMPONENT_LIB} PRIVATE POWERPOD_BATTERY_UV_ENABLE=0)

main/README.md

@@ -2,6 +2,8 @@
 
 ESP32-S3 firmware for Powerpod nodes. Master and slave devices run the **same binary**; role and ESP-NOW network are selected at boot via DIP switches and an I2C IO expander.
 
+**Architektur & ESP-only Doku (ohne goTool):** [`../docs/ARCHITECTURE.md`](../docs/ARCHITECTURE.md) (Datenflüsse UART/Commands/ESP-NOW), [`../docs/DOCUMENTATION.md`](../docs/DOCUMENTATION.md) (vollständige Referenz).
+
 ## System overview
 
 ```
@@ -53,18 +55,20 @@ Pins (`powerpod.h`):
 | BMA456 INT | 10 |
 | Button (Taster) | 12 |
 | LiPo sense 1 (ADC) | 1 |
-| LiPo sense 2 (ADC) | 12 (skipped if same as button) |
+| LiPo sense 2 (ADC) | 11 |
 
 > **TODO:** GPIO assignments above are provisional; confirm pinning against the real board before release.
 
-Startup order:
+Startup order (normal path; UV energy-save skips I2C/BMA456/ESP-NOW/UART/button — see **Software UV protection**):
 
-1. Read DIP + IO expander → `app_config`
-2. **I2C bus** — IO expander `0x20`; optional **BMA456H** (`init_bma456`, same bus)
-3. `esp_now_comm_init(&app_config)` — WiFi + ESP-NOW
-4. `led_ring_init()`
-5. `board_input_init()` — button press logs, LiPo ADC logs every **10 s**
-6. **Master only:** command queue, UART, registered commands (e.g. VERSION)
+1. `pod_settings_init()` — NVS
+2. LiPo ADC init + optional UV boot check (`battery_uv.c`)
+3. Read DIP + IO expander → `app_config`
+4. **I2C bus** — IO expander `0x20`; optional **BMA456H** (`init_bma456`, same bus)
+5. `esp_now_comm_init(&app_config)` — WiFi + ESP-NOW
+6. `led_ring_init()`
+7. LiPo monitor task + button (`board_input.c`)
+8. **Master only:** command queue, UART, registered commands (e.g. VERSION)
 
 ## BMA456 accelerometer (`bosch456.c`)
 
@@ -115,6 +119,10 @@ Schema: `proto/esp_now_messages.proto`. Encode/decode: `esp_now_proto.c`. The ES
 | `ESPNOW_UNICAST_TEST` | Master → slave | `EspNowUnicastTest` (`seq`) |
 | `ESPNOW_FIND_ME` | Master → slave | `EspNowFindMe` (`client_id` filter) — LED locate sequence |
 | `ESPNOW_RESTART` | Master → slave | `EspNowRestart` (`client_id` filter) — reboot slave |
+| `ESPNOW_ACCEL_SAMPLE` | Slave → master | `EspNowAccelSample` (`slave_id`, `x`, `y`, `z` raw LSB) — ~every 16 ms |
+| `ESPNOW_SET_TAP_NOTIFY` | Master → slave | `EspNowTapNotify` (`client_id`, `single`, `double_tap`, `triple`) — which tap kinds to forward |
+| `ESPNOW_TAP_EVENT` | Slave → master | `EspNowTapEvent` (`client_id`, `kind`) — on BMA456 tap interrupt if notify enabled |
+| `ESPNOW_BATTERY_REPORT` | Slave → master | `EspNowBatteryReport` (`client_id`, `lipo1/2` mV) — ~every 30 s; cached in `client_registry` |
 | `ESPNOW_OTA_START` | Master → slave (unicast) | `EspNowOtaStart` (`total_size`) |
 | `ESPNOW_OTA_PAYLOAD` | Master → slave | `EspNowOtaPayload` (`seq`, up to 200 B `data`) |
 | `ESPNOW_OTA_END` | Master → slave | `EspNowOtaEnd` |
@@ -172,7 +180,7 @@ Logging:
 
 ## Command handler
 
-Generic dispatch for host commands (UART today; `msg_post()` for in-firmware sources later).
+Generic dispatch for host commands over UART only.
 
 ```
 UART  →  generic_msg_t queue  →  vCmdDispatcherTask  →  registered handler
@@ -182,7 +190,8 @@ UART  →  generic_msg_t queue  →  vCmdDispatcherTask  →  registered handler
 |-----|-------------|
 | `init_cmdHandler(queue)` | Start dispatcher task (priority 5) |
 | `msg_register_handler(id, cb)` | Register callback; max 32 handlers |
-| `msg_post(id, data, len)` | Enqueue from firmware (e.g. future ESP-NOW → PC path) |
+
+During an OTA session (`ota_session_busy()`), the dispatcher rejects all UART commands except OTA_* and `OTA_SLAVE_PROGRESS` (see `ota_session.c`).
 
 ```c
 typedef void (*msg_callback_t)(const uint8_t *data, size_t len);
@@ -203,20 +212,26 @@ Host and master speak nanopb-encoded `UartMessage` inside UART frames (byte 0 =
 
 | ID | Name | Status |
 |----|------|--------|
-| 3 | `VERSION` | Implemented (`cmd_version.c`) |
-| 4 | `CLIENT_INFO` | Implemented (`cmd_client_info.c`) — slave list from registry |
+| 3 | `VERSION` | Implemented (`cmd/cmd_version.c`) |
+| 4 | `CLIENT_INFO` | Implemented (`cmd/cmd_client_info.c`) — slave list from registry |
 | 5 | `CLIENT_INPUT` | Planned |
-| 6 | `ACCEL_DEADZONE` | Implemented (`cmd_accel_deadzone.c`) — get/set accel filter LSB |
-| 7 | `ESPNOW_UNICAST_TEST` | Implemented (`cmd_espnow_unicast_test.c`) |
-| 8 | `LED_RING` | Implemented (`cmd_led_ring.c`) — ring progress bar (0–100 %, RGB, intensity) |
-| 16 | `OTA_START` | Implemented (`cmd_ota.c`) — begin UART OTA on inactive slot |
+| 6 | `ACCEL_DEADZONE` | Implemented (`cmd/cmd_accel_deadzone.c`) — get/set accel filter LSB |
+| 7 | `ESPNOW_UNICAST_TEST` | Implemented (`cmd/cmd_espnow_unicast_test.c`) |
+| 8 | `LED_RING` | Implemented (`cmd/cmd_led_ring.c`) — ring progress bar (0–100 %, RGB, intensity) |
+| 26 | `BATTERY_STATUS` | Implemented (`cmd/cmd_battery.c`) — cached LiPo 1/2 per pod from `client_registry` (UART read, no slave round-trip) |
+| 16 | `OTA_START` | Implemented (`cmd/cmd_ota.c`) — begin UART OTA on inactive slot |
 | 17 | `OTA_PAYLOAD` | Implemented — up to 200 B per frame; device buffers 4 KiB |
 | 18 | `OTA_END` | Implemented — flush, `esp_ota_end`, push image to slaves via ESP-NOW, set boot |
 | 19 | `OTA_STATUS` | Device → host (prepare/ready/block ACK/success/failed) |
 | 20 | `OTA_START_ESPNOW` | Implemented — re-distribute staged image to slaves only |
-| 21 | `OTA_SLAVE_PROGRESS` | Implemented (`cmd_ota_slave_progress.c`) — query per-slave ESP-NOW OTA progress |
-| 22 | `FIND_ME` | Implemented (`cmd_espnow_find_me.c`) — `client_id=0` local ring, `>0` ESP-NOW to slave |
-| 23 | `RESTART` | Implemented (`cmd_restart.c`) — `client_id=0` reboot master, `>0` ESP-NOW reboot slave |
+| 21 | `OTA_SLAVE_PROGRESS` | Implemented (`cmd/cmd_ota_slave_progress.c`) — query per-slave ESP-NOW OTA progress |
+| 22 | `FIND_ME` | Implemented (`cmd/cmd_espnow_find_me.c`) — `client_id=0` local ring, `>0` ESP-NOW to slave |
+| 23 | `RESTART` | Implemented (`cmd/cmd_restart.c`) — `client_id=0` reboot master, `>0` ESP-NOW reboot slave |
+| 25 | `ACCEL_STREAM` | Implemented — enable/disable slave ESP-NOW accel stream to master |
+| 27 | `TAP_NOTIFY` | Implemented (`cmd/cmd_tap_notify.c`) — get/set which tap kinds notify via ESP-NOW |
+| 29 | `CACHE_STATUS` | Implemented (`cmd/cmd_cache_status.c`) — subscribed accel + tap cache (one UART round-trip) |
+| 30 | `ESPNOW_ECHO_PING` | Implemented (`cmd/cmd_espnow_echo_ping.c`) — ESP-NOW timestamp echo (latency test) |
+| 31 | `SET_LOG_LEVEL` | Implemented (`cmd/cmd_set_log_level.c`) — get/set global `esp_log_level_set("*", …)` on master |
 
 Regenerate C code:
 
@@ -264,7 +279,7 @@ During OTA the LED ring shows progress at ~5 % brightness: **blue** while the im
 
 `OTA_START_ESPNOW` (type `20`): re-run ESP-NOW distribution from the last staged image without a new UART upload (no-op if nothing staged).
 
-Implementation: `ota_uart.c` (4 KiB buffer, `esp_ota_write`), `ota_espnow.c`, `cmd_ota.c`.
+Implementation: `ota_uart.c` (4 KiB buffer, `esp_ota_write`), `ota_espnow.c`, `cmd/cmd_ota.c`.
 
 Host upload:
 
@@ -310,6 +325,52 @@ Sets the **software** deadzone used by `bosch456.c` when logging accel (see [BMA
 
 **Response:** `accel_deadzone_response` with applied `deadzone`, `success`, and `slaves_updated` (ESP-NOW count).
 
+### TAP_NOTIFY command
+
+Configure which BMA456 tap kinds a **slave** forwards to the master over ESP-NOW. The slave only sends `ESPNOW_TAP_EVENT` when the matching notify flag is enabled (set locally on the slave via ESP-NOW).
+
+**Request:** framed `1b` (`0x1b`) + `tap_notify_request`:
+
+| Field | Meaning |
+|-------|---------|
+| `write` | `false` = read, `true` = write |
+| `single`, `double_tap`, `triple` | Which tap kinds to notify (write) |
+| `client_id` | Slave id (read/write one slave) |
+| `all_clients` | Master: ESP-NOW unicast to every registered slave |
+
+**Response:** `tap_notify_response` (`client_id`, `success`, `slaves_updated`, `single`, `double_tap`, `triple`).
+
+Notify flags are mirrored in `ClientInfo` (`tap_notify_single/double/triple`) for the dashboard.
+
+```bash
+go run . -port /dev/ttyUSB0 tap-notify -client 16 -set -single
+go run . -port /dev/ttyUSB0 tap-notify -client 16
+```
+
+### CACHE_STATUS command
+
+Read **cached** accel and/or tap data on the **master** in one UART round-trip. Slaves send `ESPNOW_ACCEL_SAMPLE` every **16 ms** when streaming; tap events arrive via `ESPNOW_TAP_EVENT` and are held up to **16 ms** (`CLIENT_REGISTRY_TAP_MAX_AGE_MS`). Pending taps are **consumed** on read (like the former `TAP_SNAPSHOT`).
+
+**Request:** framed `1d` (`0x1d`) only — no body (`CacheStatusRequest` empty).
+
+**Response:** `cache_status_response.clients[]` — one entry per slave with `accel_stream_enabled` and/or any tap-notify flag:
+
+| Field | When present |
+|-------|----------------|
+| `client_id` | Always (for listed slaves) |
+| `accel` | Slave has accel stream on (`valid`, `x`/`y`/`z`, `age_ms` when sample fresh) |
+| `tap` | Tap notify on **and** a pending tap was consumed (`kind`, `age_ms`) |
+
+Unsubscribed submessages are omitted on the wire (proto3 defaults). The master walks `client_registry` once per request (`cmd/cmd_cache_status.c`).
+
+Host tools poll this at **16 ms** when live-stream / WebSocket receive is enabled. Tap events stay visible for **2 s** in the UI/API after first sight.
+
+```bash
+go run . -port /dev/ttyUSB0 cache-status
+```
+
+External API (`serve -api-addr :8081`) uses the same command for WebSocket `accel` / `tap` push.
+
 ### ESPNOW_UNICAST_TEST command
 
 Minimal master→slave ESP-NOW unicast check (no BMA456). Use this before debugging `ACCEL_DEADZONE` unicast.
@@ -333,6 +394,30 @@ go run . -port /dev/ttyUSB0 find-me
 go run . -port /dev/ttyUSB0 find-me -client 16
 ```
 
+### SET_LOG_LEVEL command
+
+Read or set the **global** ESP-IDF log filter on the master (`esp_log_level_set("*", level)`). Does not affect the host UART protocol (UART1); `esp_log_*` output goes to the **debug console UART0** (USB, 115200).
+
+**Request:** framed `31` (`0x1f`) + `set_log_level_request` (`write`, `level` 0–5).
+
+**Response:** `set_log_level_response` (`success`, `level`).
+
+| `level` | `esp_log_level_t` |
+|---------|-------------------|
+| 0 | NONE |
+| 1 | ERROR |
+| 2 | WARN |
+| 3 | INFO |
+| 4 | DEBUG |
+| 5 | VERBOSE |
+
+Boot default follows `CONFIG_LOG_DEFAULT_LEVEL` in `sdkconfig` (not persisted across reboot).
+
+```bash
+go run . -port /dev/ttyUSB0 log-level
+go run . -port /dev/ttyUSB0 log-level -set -level 0
+```
+
 ### RESTART command
 
 Reboot the master (`client_id=0`) or one slave via ESP-NOW (`client_id` = registry id). The device sends the UART response, then restarts after ~150 ms.
@@ -345,6 +430,31 @@ go run . -port /dev/ttyUSB0 restart
 go run . -port /dev/ttyUSB0 restart -client 16
 ```
 
+### BATTERY_STATUS command
+
+Read **cached** LiPo ADC values on the **master** (master local + one entry per registered slave). Slaves push `ESPNOW_BATTERY_REPORT` every **30 s**; the master stores them in `client_registry` (`lipo1/2_valid`, `lipo1/2_mv`, `battery_updated_at`). The master refreshes its own pack on the same interval in `master_monitor_task`.
+
+**Request:** framed `26` + optional `battery_status_request` (`client_id`, `all_clients`).
+
+**Response:** `battery_status_response` with `samples[]` (`client_id`, `lipo1`, `lipo2`, `age_ms`).
+
+```bash
+# Host / goTool: all_clients returns master (id 0) + slaves from cache
+```
+
+### Software UV protection (LiPo)
+
+When `POWERPOD_BATTERY_UV_ENABLE` is `1` (default in `powerpod.h`, disable via CMake), the firmware monitors ADC pin voltages on GPIO 1 and 11:
+
+| Condition | ADC threshold | Action |
+|-----------|---------------|--------|
+| Under-voltage | any valid channel < **2300 mV** (3.0 V pack) | NVS latch `uv_latch`, restart into energy-save mode |
+| Charged | all valid channels ≥ **3000 mV** (4.0 V pack) | Clear latch, restart into normal boot |
+
+**Energy-save boot:** LED mode `6` (first 4 LEDs red ~10 % for 5 s), then no WiFi/ESP-NOW, UART, I2C, BMA456, or button — only LiPo ADC polling every 30 s until charged.
+
+**Test LED pattern from host:** `led-ring -mode battery-low` (works even when UV feature is disabled).
+
 ### LED_RING command
 
 Control the 95-LED ring from the host. The firmware **does not** animate digits locally; only UART updates the display.
@@ -353,14 +463,19 @@ Control the 95-LED ring from the host. The firmware **does not** animate digits
 
 | Field | Meaning |
 |-------|---------|
-| `mode` | `0` = clear, `1` = progress bar, `2` = digit, `3` = blink full ring, `4` = find-me (R/G/B ×3 @ full brightness) |
+| `mode` | `0` = clear, `1` = progress, `2` = digit (0–10), `3` = blink, `4` = find-me, `5` = solid color (all LEDs), `6` = battery-low (first 4 LEDs red ~10 % for 5 s) |
 | `progress` | 0–100 (% of ring lit, mode `1`) |
-| `digit` | 0–10 (mode `2`, same segment maps as built-in digits) |
+| `digit` | 0–10 (mode `2`, segment maps in `led_ring.c`) |
 | `r`, `g`, `b` | Color 0–255 |
 | `intensity` | Brightness 0–255 (scaled into RGB; `0` → firmware default ~5 %) |
 | `blink_ms`, `blink_count` | Pulse length and count (mode `3`; defaults 350 ms, 1) |
+| `client_id` | `0` = master ring only; `>0` = ESP-NOW unicast to one slave |
+| `all_clients` | Broadcast to all registered slaves |
+| `slaves_only` | With `all_clients`: do not change master ring |
 
-**Response:** `led_ring_progress_response` (`success`, `mode`, `progress`, `digit`).
+**Response:** `led_ring_progress_response` (`success`, `mode`, `progress`, `digit`, `client_id`, `slaves_updated`).
+
+Slaves receive the same command via ESP-NOW `ESPNOW_LED_RING` and run it locally.
 
 ```bash
 go run . -port /dev/ttyUSB0 led-ring -mode progress -progress 75 -g 80 -b 255
@@ -370,6 +485,9 @@ go run . -port /dev/ttyUSB0 led-ring -mode blink -g 255 -blink-count 2
 go run . -port /dev/ttyUSB0 find-me
 go run . -port /dev/ttyUSB0 find-me -client 16
 go run . -port /dev/ttyUSB0 led-ring -mode find-me
+go run . -port /dev/ttyUSB0 led-ring -mode battery-low -client 0
+go run . -port /dev/ttyUSB0 led-ring -mode color -r 255 -g 0 -b 0 -client 16
+go run . -port /dev/ttyUSB0 led-ring -mode digit -digit 5 -all
 ```
 
 ### CLIENT_INFO command
@@ -378,7 +496,7 @@ go run . -port /dev/ttyUSB0 led-ring -mode find-me
 
 **Response:** payload `04` + nanopb `UartMessage` with `client_info_response.clients` — one `ClientInfo` per registered slave (from ESP-NOW `SLAVE_INFO`).
 
-Fields per client: `id`, `mac`, `version`, `available`, `used`, `last_ping`, `last_success_ping` — **milliseconds since** the last packet / last successful heartbeat (computed when `CLIENT_INFO` is answered; typically 0–1000 while the slave is heartbeating every 1 s).
+Fields per client: `id`, `mac`, `version`, `available`, `used`, `last_ping`, `last_success_ping`, `tap_notify_single`, `tap_notify_double`, `tap_notify_triple` — **milliseconds since** the last packet / last successful heartbeat (computed when `CLIENT_INFO` is answered; typically 0–1000 while the slave is heartbeating every 1 s).
 
 ## Client registry
 
@@ -389,6 +507,7 @@ Fields per client: `id`, `mac`, `version`, `available`, `used`, `last_ping`, `la
 | `client_registry_heartbeat(mac, id, version, …)` | Same as upsert for heartbeats; reactivates inactive clients |
 | `client_registry_check_timeouts(timeout_ms)` | Mark stale clients inactive (master monitor task) |
 | `client_registry_count()` / `client_registry_at(i)` | Iterate for UART encoding |
+| `client_registry_set_tap_notify()` / `client_registry_take_tap()` | Tap notify flags + short-lived tap cache (16 ms) |
 
 Slaves register when the master receives `SLAVE_INFO` on the matching network; `HEARTBEAT` keeps them marked available. The registry **MAC is always the ESP-NOW source address** (`recv_info.src_addr`), not the optional `mac` bytes in the protobuf (used only on the wire for debugging).
 
@@ -443,22 +562,29 @@ Target: ESP32-S3. Close serial monitor on the UART adapter port before running `
 | `powerpod.c` | `app_main`, DIP/network config, init order |
 | `powerpod.h` | Pin defines |
 | `app_config.h` | `app_config_t` |
-| `esp_now_comm.c/h` | WiFi, ESP-NOW, discover / slave info / OTA send |
+| `esp_now_comm.c/h` | ESP-NOW init and recv router |
+| `esp_now_core.c/h` | Shared WiFi, peer, send |
+| `esp_now_master.c/h` | Master discover, monitor, unicast |
+| `esp_now_slave.c/h` | Slave join, heartbeat, telemetry |
 | `ota_uart.c/h` | Shared 4 KiB OTA flash buffer (UART + ESP-NOW) |
 | `ota_espnow.c/h` | Master: distribute staged image to slaves |
-| `cmd_ota.c/h` | UART OTA command handlers (master only) |
+| `cmd/cmd_ota.c/h` | UART OTA command handlers (master only) |
 | `uart.c/h` | Framed UART RX/TX |
 | `uart_proto.c/h` | Encode/send `UartMessage` |
-| `cmd_handler.c/h` | Command queue and dispatch |
+| `cmd/cmd_handler.c/h` | Command queue and dispatch |
 | `uart_cmd.c/h` | Shared UART decode/send helpers for handlers |
-| `cmd_version.c/h` | VERSION handler |
-| `cmd_client_info.c/h` | CLIENT_INFO handler |
+| `cmd/cmd_version.c/h` | VERSION handler |
+| `cmd/cmd_client_info.c/h` | CLIENT_INFO handler |
 | `client_registry.c/h` | Registered slave table |
-| `bosch456.c/h` | BMA456H I2C driver, accel poll, tap INT, deadzone filter |
-| `board_input.c/h` | Taster GPIO12, LiPo ADC on GPIO1 / GPIO12 |
-| `pod_settings.c/h` | NVS persistence (accel deadzone, …) |
+| `bosch456.c/h` | BMA456H I2C driver, accel poll, on-demand read, tap INT, deadzone filter |
+| `cmd/cmd_tap_notify.c` | UART `TAP_NOTIFY` — ESP-NOW tap notify config |
+| `cmd/cmd_cache_status.c` | UART `CACHE_STATUS` — subscribed accel + tap cache poll |
+| `board_input.c/h` | Taster GPIO12, LiPo ADC on GPIO1 / GPIO11 |
+| `battery_uv.c/h` | Software LiPo UV latch, energy-save boot (`POWERPOD_BATTERY_UV_ENABLE`) |
+| `pod_settings.c/h` | NVS persistence (accel deadzone, UV latch, …) |
 | `led_ring.c/h` | LED ring (digit display, progress bar) |
-| `cmd_led_ring.c` | UART `LED_RING` progress command |
+| `cmd/cmd_led_ring.c` | UART `LED_RING` progress command |
+| `cmd/cmd_set_log_level.c` | UART `SET_LOG_LEVEL` — runtime ESP-IDF log level |
 | `proto/uart_messages.proto` | UART protocol schema |
 | `proto/esp_now_messages.proto` | ESP-NOW protocol schema |
 | `esp_now_proto.c/h` | Encode/decode `EspNowMessage` |
@@ -475,7 +601,7 @@ Short checklist:
 
 1. Add or extend messages in `uart_messages.proto` (and `esp_now_messages.proto` if slaves are involved); run `make proto_generate` and `make gotool-proto`.
 2. Implement device logic in a shared module (e.g. `led_ring.c`), not only in the UART handler.
-3. Create `cmd_*.c`, register with `uart_cmd_register()`; decode with `uart_cmd_decode()` / `UART_CMD_REQ()`; reply with `uart_cmd_init_response()` + `uart_cmd_send()`.
+3. Create `cmd/cmd_*.c`, register with `uart_cmd_register()`; decode with `uart_cmd_decode()` / `UART_CMD_REQ()`; reply with `uart_cmd_init_response()` + `uart_cmd_send()`.
 4. Master → slave: `esp_now_comm_send_*()` + slave branch in `espnow_recv_cb`.
 5. Extend `goTool` (CLI, optional `/api/…` and web UI).
 

main/battery_uv.c

@@ -0,0 +1,130 @@
+#include "battery_uv.h"
+
+#if POWERPOD_BATTERY_UV_ENABLE
+
+#include "led_ring.h"
+#include "pod_reboot.h"
+#include "pod_settings.h"
+#include "esp_log.h"
+#include "freertos/FreeRTOS.h"
+#include "freertos/task.h"
+
+static const char *TAG = "[BATTERY_UV]";
+
+#define UV_DEBOUNCE_SAMPLES 2u
+#define UV_POLL_INTERVAL_MS 30000u
+
+static uint8_t s_uv_streak;
+static uint8_t s_charge_streak;
+
+bool battery_uv_is_latched(void) { return pod_settings_is_uv_latched(); }
+
+bool battery_uv_reading_is_under(const board_lipo_reading_t *reading) {
+  if (reading == NULL) {
+    return false;
+  }
+
+  if (reading->lipo1_valid && reading->lipo1_mv < BATTERY_UV_ADC_MV) {
+    return true;
+  }
+  if (reading->lipo2_valid && reading->lipo2_mv < BATTERY_UV_ADC_MV) {
+    return true;
+  }
+  return false;
+}
+
+bool battery_uv_reading_is_charged(const board_lipo_reading_t *reading) {
+  if (reading == NULL) {
+    return false;
+  }
+
+  bool any_valid = false;
+  if (reading->lipo1_valid) {
+    any_valid = true;
+    if (reading->lipo1_mv < BATTERY_CHARGE_ADC_MV) {
+      return false;
+    }
+  }
+  if (reading->lipo2_valid) {
+    any_valid = true;
+    if (reading->lipo2_mv < BATTERY_CHARGE_ADC_MV) {
+      return false;
+    }
+  }
+  return any_valid;
+}
+
+bool battery_uv_evaluate_boot(void) {
+  board_lipo_reading_t reading;
+  board_input_read_lipo(&reading);
+
+  if (pod_settings_is_uv_latched() && battery_uv_reading_is_charged(&reading)) {
+    ESP_LOGI(TAG, "charged — clearing UV latch");
+    pod_settings_clear_uv_latched();
+    return false;
+  }
+
+  if (pod_settings_is_uv_latched() || battery_uv_reading_is_under(&reading)) {
+    if (!pod_settings_is_uv_latched()) {
+      ESP_LOGW(TAG, "under-voltage at boot — latching UV");
+    } else {
+      ESP_LOGW(TAG, "UV latched — energy-save boot");
+    }
+    pod_settings_set_uv_latched(true);
+    return true;
+  }
+
+  return false;
+}
+
+void battery_uv_poll(const board_lipo_reading_t *reading) {
+  if (reading == NULL || pod_settings_is_uv_latched()) {
+    return;
+  }
+
+  if (battery_uv_reading_is_under(reading)) {
+    s_uv_streak++;
+    ESP_LOGW(TAG, "under-voltage sample %u/%u", (unsigned)s_uv_streak,
+             (unsigned)UV_DEBOUNCE_SAMPLES);
+    if (s_uv_streak >= UV_DEBOUNCE_SAMPLES) {
+      ESP_LOGW(TAG, "UV confirmed — latching and restarting");
+      pod_settings_set_uv_latched(true);
+      pod_schedule_restart();
+    }
+    return;
+  }
+
+  s_uv_streak = 0;
+}
+
+void battery_uv_run_mode(void) {
+  s_charge_streak = 0;
+  s_uv_streak = 0;
+
+  led_ring_init();
+  led_ring_show_battery_low();
+
+  ESP_LOGW(TAG, "energy-save mode — ADC poll every %u ms", UV_POLL_INTERVAL_MS);
+
+  while (1) {
+    board_lipo_reading_t reading;
+    board_input_read_lipo(&reading);
+
+    if (battery_uv_reading_is_charged(&reading)) {
+      s_charge_streak++;
+      ESP_LOGI(TAG, "charge sample %u/%u", (unsigned)s_charge_streak,
+               (unsigned)UV_DEBOUNCE_SAMPLES);
+      if (s_charge_streak >= UV_DEBOUNCE_SAMPLES) {
+        ESP_LOGI(TAG, "charged — clearing UV latch and restarting");
+        pod_settings_clear_uv_latched();
+        pod_schedule_restart();
+      }
+    } else {
+      s_charge_streak = 0;
+    }
+
+    vTaskDelay(pdMS_TO_TICKS(UV_POLL_INTERVAL_MS));
+  }
+}
+
+#endif

main/battery_uv.h

@@ -0,0 +1,51 @@
+#ifndef BATTERY_UV_H
+#define BATTERY_UV_H
+
+#include "board_input.h"
+#include "powerpod.h"
+#include <stdbool.h>
+
+#if POWERPOD_BATTERY_UV_ENABLE
+
+/** ADC pin voltage (mV) below which UV is triggered (3.0 V pack via 33k/10k divider). */
+#define BATTERY_UV_ADC_MV 2300u
+/** ADC pin voltage (mV) at which charging is detected (4.0 V pack, rounded). */
+#define BATTERY_CHARGE_ADC_MV 3000u
+
+bool battery_uv_is_latched(void);
+bool battery_uv_reading_is_under(const board_lipo_reading_t *reading);
+bool battery_uv_reading_is_charged(const board_lipo_reading_t *reading);
+
+/** true → enter UV energy-save path (does not return). */
+bool battery_uv_evaluate_boot(void);
+
+void battery_uv_poll(const board_lipo_reading_t *reading);
+
+/** Blocks: LED indicator, then minimal ADC polling until charged. */
+void battery_uv_run_mode(void);
+
+#else
+
+static inline bool battery_uv_is_latched(void) { return false; }
+
+static inline bool battery_uv_reading_is_under(const board_lipo_reading_t *reading) {
+  (void)reading;
+  return false;
+}
+
+static inline bool battery_uv_reading_is_charged(const board_lipo_reading_t *reading) {
+  (void)reading;
+  return false;
+}
+
+static inline bool battery_uv_evaluate_boot(void) { return false; }
+
+static inline void battery_uv_poll(const board_lipo_reading_t *reading) {
+  (void)reading;
+}
+
+static inline void battery_uv_run_mode(void) {}
+
+#endif
+
+#endif

main/board_input.c

@@ -1,12 +1,16 @@
 #include "board_input.h"
 #include "powerpod.h"
+#include "client_registry.h"
 #include "driver/gpio.h"
+#if POWERPOD_BATTERY_UV_ENABLE
+#include "battery_uv.h"
+#endif
 #include "esp_adc/adc_oneshot.h"
 #include "esp_log.h"
 #include "freertos/FreeRTOS.h"
 #include "freertos/idf_additions.h"
 #include "freertos/queue.h"
-#include <stdint.h>
+#include <string.h>
 
 static const char *TAG_BTN = "[BTN]";
 static const char *TAG_LIPO = "[LIPO]";
@@ -14,66 +18,108 @@ static const char *TAG_LIPO = "[LIPO]";
 #define LIPO_SAMPLE_INTERVAL_MS 10000
 #define BUTTON_QUEUE_LEN 4
 #define BUTTON_DEBOUNCE_MS 80
+#define LIPO_ADC_FULL_SCALE_MV 3300
+#define LIPO_ADC_MAX_RAW 4095
 
 static QueueHandle_t s_button_queue;
-static adc_oneshot_unit_handle_t s_adc;
-static bool s_lipo1_ok;
-static bool s_lipo2_ok;
-static adc_channel_t s_lipo1_ch;
-static adc_channel_t s_lipo2_ch;
 
-static esp_err_t adc_init_channel(int gpio, adc_channel_t *out_ch, bool *out_ok) {
-  adc_unit_t unit;
-  esp_err_t err = adc_oneshot_io_to_channel(gpio, &unit, out_ch);
+typedef struct {
+  adc_oneshot_unit_handle_t unit;
+  adc_channel_t ch;
+  bool ok;
+} lipo_adc_t;
+
+static lipo_adc_t s_lipo1;
+static lipo_adc_t s_lipo2;
+
+static esp_err_t adc_init_gpio(int gpio, lipo_adc_t *out) {
+  out->unit = NULL;
+  out->ok = false;
+
+  adc_unit_t unit_id;
+  esp_err_t err = adc_oneshot_io_to_channel(gpio, &unit_id, &out->ch);
   if (err != ESP_OK) {
     ESP_LOGW(TAG_LIPO, "GPIO%d not an ADC channel: %s", gpio, esp_err_to_name(err));
-    *out_ok = false;
     return err;
   }
-  if (unit != ADC_UNIT_1) {
-    ESP_LOGW(TAG_LIPO, "GPIO%d on ADC unit %d (expected ADC1)", gpio, (int)unit);
+
+  adc_oneshot_unit_init_cfg_t init_cfg = {
+      .unit_id = unit_id,
+  };
+  err = adc_oneshot_new_unit(&init_cfg, &out->unit);
+  if (err != ESP_OK) {
+    ESP_LOGW(TAG_LIPO, "ADC unit %d init GPIO%d failed: %s", (int)unit_id, gpio,
+             esp_err_to_name(err));
+    return err;
   }
+
   adc_oneshot_chan_cfg_t chan_cfg = {
       .atten = ADC_ATTEN_DB_12,
       .bitwidth = ADC_BITWIDTH_DEFAULT,
   };
-  err = adc_oneshot_config_channel(s_adc, *out_ch, &chan_cfg);
+  err = adc_oneshot_config_channel(out->unit, out->ch, &chan_cfg);
   if (err != ESP_OK) {
     ESP_LOGW(TAG_LIPO, "ADC config GPIO%d failed: %s", gpio, esp_err_to_name(err));
-    *out_ok = false;
+    adc_oneshot_del_unit(out->unit);
+    out->unit = NULL;
     return err;
   }
-  *out_ok = true;
+
+  out->ok = true;
+  ESP_LOGI(TAG_LIPO, "GPIO%d ready (ADC unit %d)", gpio, (int)unit_id);
   return ESP_OK;
 }
 
+static uint32_t raw_to_mv(int raw) {
+  if (raw < 0) {
+    return 0;
+  }
+  return (uint32_t)((raw * LIPO_ADC_FULL_SCALE_MV) / LIPO_ADC_MAX_RAW);
+}
+
+static void sample_one_channel(const lipo_adc_t *adc, uint32_t *mv_out,
+                               bool *valid_out) {
+  *valid_out = false;
+  *mv_out = 0;
+  if (adc == NULL || !adc->ok || adc->unit == NULL) {
+    return;
+  }
+  int raw = 0;
+  if (adc_oneshot_read(adc->unit, adc->ch, &raw) == ESP_OK) {
+    *valid_out = true;
+    *mv_out = raw_to_mv(raw);
+  }
+}
+
+void board_input_read_lipo(board_lipo_reading_t *out) {
+  if (out == NULL) {
+    return;
+  }
+  memset(out, 0, sizeof(*out));
+  sample_one_channel(&s_lipo1, &out->lipo1_mv, &out->lipo1_valid);
+  sample_one_channel(&s_lipo2, &out->lipo2_mv, &out->lipo2_valid);
+}
+
 static void lipo_monitor_task(void *param) {
   (void)param;
 
   ESP_LOGI(TAG_LIPO, "monitor task (interval %d ms)", LIPO_SAMPLE_INTERVAL_MS);
 
   while (1) {
-    int raw1 = -1;
-    int raw2 = -1;
-    int mv1 = -1;
-    int mv2 = -1;
-
-    if (s_lipo1_ok) {
-      raw1 = 0;
-      if (adc_oneshot_read(s_adc, s_lipo1_ch, &raw1) == ESP_OK) {
-        mv1 = (raw1 * 3300) / 4095;
-      }
-    }
-    if (s_lipo2_ok) {
-      raw2 = 0;
-      if (adc_oneshot_read(s_adc, s_lipo2_ch, &raw2) == ESP_OK) {
-        mv2 = (raw2 * 3300) / 4095;
-      }
-    }
+    board_lipo_reading_t reading;
+    board_input_read_lipo(&reading);
+    client_registry_set_master_battery(&reading);
 
     ESP_LOGI(TAG_LIPO,
-             "LIPO1 GPIO%d raw=%d (~%d mV)  LIPO2 GPIO%d raw=%d (~%d mV)",
-             V_LIPO_1_GPIO, raw1, mv1, V_LIPO_2_GPIO, raw2, mv2);
+             "LIPO1 GPIO%d %s %lu mV  LIPO2 GPIO%d %s %lu mV",
+             V_LIPO_1_GPIO, reading.lipo1_valid ? "ok" : "n/a",
+             (unsigned long)reading.lipo1_mv, V_LIPO_2_GPIO,
+             reading.lipo2_valid ? "ok" : "n/a",
+             (unsigned long)reading.lipo2_mv);
+
+#if POWERPOD_BATTERY_UV_ENABLE
+    battery_uv_poll(&reading);
+#endif
 
     vTaskDelay(pdMS_TO_TICKS(LIPO_SAMPLE_INTERVAL_MS));
   }
@@ -145,29 +191,30 @@ static esp_err_t init_button(void) {
   return ESP_OK;
 }
 
-static esp_err_t init_lipo_adc(void) {
-  adc_oneshot_unit_init_cfg_t init_cfg = {
-      .unit_id = ADC_UNIT_1,
-  };
-  esp_err_t err = adc_oneshot_new_unit(&init_cfg, &s_adc);
-  if (err != ESP_OK) {
-    ESP_LOGW(TAG_LIPO, "ADC init failed: %s", esp_err_to_name(err));
-    return err;
-  }
+static esp_err_t init_lipo_adc_hw(void) {
+  memset(&s_lipo1, 0, sizeof(s_lipo1));
+  memset(&s_lipo2, 0, sizeof(s_lipo2));
 
-  adc_init_channel(V_LIPO_1_GPIO, &s_lipo1_ch, &s_lipo1_ok);
+  adc_init_gpio(V_LIPO_1_GPIO, &s_lipo1);
 
   if (V_LIPO_2_GPIO == TASTER_GPIO) {
     ESP_LOGW(TAG_LIPO, "LIPO2 on GPIO%d skipped (button uses same pin)",
              V_LIPO_2_GPIO);
-    s_lipo2_ok = false;
   } else {
-    adc_init_channel(V_LIPO_2_GPIO, &s_lipo2_ch, &s_lipo2_ok);
+    adc_init_gpio(V_LIPO_2_GPIO, &s_lipo2);
   }
 
-  if (!s_lipo1_ok && !s_lipo2_ok) {
-    adc_oneshot_del_unit(s_adc);
-    s_adc = NULL;
+  if (!s_lipo1.ok && !s_lipo2.ok) {
+    return ESP_FAIL;
+  }
+
+  return ESP_OK;
+}
+
+esp_err_t board_input_init_adc_only(void) { return init_lipo_adc_hw(); }
+
+esp_err_t board_input_start_lipo_monitor(void) {
+  if (!s_lipo1.ok && !s_lipo2.ok) {
     return ESP_FAIL;
   }
 
@@ -178,16 +225,23 @@ static esp_err_t init_lipo_adc(void) {
   return ESP_OK;
 }
 
+esp_err_t board_input_init_button(void) { return init_button(); }
+
 esp_err_t board_input_init(void) {
-  esp_err_t err = init_button();
+  esp_err_t err = board_input_init_adc_only();
+  if (err != ESP_OK) {
+    ESP_LOGW(TAG_LIPO, "ADC init failed: %s", esp_err_to_name(err));
+  } else {
+    err = board_input_start_lipo_monitor();
+    if (err != ESP_OK) {
+      ESP_LOGW(TAG_LIPO, "monitor task failed: %s", esp_err_to_name(err));
+    }
+  }
+
+  err = board_input_init_button();
   if (err != ESP_OK) {
     ESP_LOGW(TAG_BTN, "init failed: %s", esp_err_to_name(err));
   }
 
-  err = init_lipo_adc();
-  if (err != ESP_OK) {
-    ESP_LOGW(TAG_LIPO, "init failed: %s", esp_err_to_name(err));
-  }
-
   return ESP_OK;
 }

main/board_input.h

@@ -1,12 +1,34 @@
 #ifndef BOARD_INPUT_H
 #define BOARD_INPUT_H
 
+#include <stdbool.h>
+#include <stdint.h>
+
 #include "esp_err.h"
 
+typedef struct {
+  bool lipo1_valid;
+  bool lipo2_valid;
+  uint32_t lipo1_mv;
+  uint32_t lipo2_mv;
+} board_lipo_reading_t;
+
 /**
- * Button (log on press) and LiPo ADC sampling (log every 10 s).
+ * Button (log on press) and LiPo ADC sampling (background log every 10 s).
  * TODO: Pin assignments come from powerpod.h and may not match final hardware yet.
  */
 esp_err_t board_input_init(void);
 
+/** LiPo ADC channels only (no button, no background task). */
+esp_err_t board_input_init_adc_only(void);
+
+/** Start 10 s LiPo monitor task (normal boot only). */
+esp_err_t board_input_start_lipo_monitor(void);
+
+/** Front-panel button debounce task. */
+esp_err_t board_input_init_button(void);
+
+/** On-demand ADC read of both LiPo sense inputs (if configured). */
+void board_input_read_lipo(board_lipo_reading_t *out);
+
 #endif

main/bosch456.c

@@ -2,7 +2,7 @@
  * BMA456H integration for Powerpod (ESP-IDF I2C master + Bosch SensorAPI).
  *
  * Polls accelerometer at 10 Hz; tap events arrive on BMA456_INT_GPIO.
- * Accel logging is filtered in software (deadzone); see ACCEL_DEADZONE UART command.
+ * Accel logging is filtered in software (deadzone); slaves stream samples via ESP-NOW.
  */
 
 #include "bosch456.h"
@@ -14,6 +14,7 @@
 #include "esp_err.h"
 #include "esp_log.h"
 #include "freertos/idf_additions.h"
+#include "freertos/semphr.h"
 #include <rom/ets_sys.h>
 #include <string.h>
 
@@ -34,6 +35,10 @@ static int16_t s_last_z;
 static bool s_have_last_sample;
 
 static volatile bool s_int_pending;
+static SemaphoreHandle_t s_accel_mutex;
+static bma456_tap_handler_t s_tap_handler;
+static void *s_tap_handler_ctx;
+static const bma456_tap_config_t s_tap_config = BMA456_TAP_CONFIG_DEFAULT;
 
 static esp_err_t check_bma4(const char *api_name, int8_t rslt);
 
@@ -121,6 +126,35 @@ void bma456_set_accel_deadzone(uint32_t deadzone_lsb) {
 
 uint32_t bma456_get_accel_deadzone(void) { return s_accel_deadzone; }
 
+void bma456_set_tap_handler(bma456_tap_handler_t handler, void *ctx) {
+  s_tap_handler = handler;
+  s_tap_handler_ctx = ctx;
+}
+
+esp_err_t bma456_read_accel(int16_t *x, int16_t *y, int16_t *z) {
+  if (!s_bma456_ready || x == NULL || y == NULL || z == NULL) {
+    return ESP_ERR_INVALID_STATE;
+  }
+  if (s_accel_mutex == NULL ||
+      xSemaphoreTake(s_accel_mutex, pdMS_TO_TICKS(500)) != pdTRUE) {
+    return ESP_ERR_TIMEOUT;
+  }
+
+  struct bma4_accel sens_data = {0};
+  int8_t ret = bma4_read_accel_xyz(&sens_data, &s_bma456);
+  xSemaphoreGive(s_accel_mutex);
+
+  if (ret != BMA4_OK) {
+    bma4_error_codes_print_result("bma4_read_accel_xyz", ret);
+    return ESP_FAIL;
+  }
+
+  *x = sens_data.x;
+  *y = sens_data.y;
+  *z = sens_data.z;
+  return ESP_OK;
+}
+
 void bma456_report_accel_if_changed(int16_t x, int16_t y, int16_t z) {
   if (!s_bma456_ready || !sample_exceeds_deadzone(x, y, z)) {
     return;
@@ -157,10 +191,19 @@ static void handle_tap_interrupt(void) {
 
   if (tap_out.single_tap) {
     ESP_LOGI(TAG, "tap: single");
+    if (s_tap_handler != NULL) {
+      s_tap_handler(BMA456_TAP_SINGLE, s_tap_handler_ctx);
+    }
   } else if (tap_out.double_tap) {
     ESP_LOGI(TAG, "tap: double");
+    if (s_tap_handler != NULL) {
+      s_tap_handler(BMA456_TAP_DOUBLE, s_tap_handler_ctx);
+    }
   } else if (tap_out.triple_tap) {
     ESP_LOGI(TAG, "tap: triple");
+    if (s_tap_handler != NULL) {
+      s_tap_handler(BMA456_TAP_TRIPLE, s_tap_handler_ctx);
+    }
   }
 }
 
@@ -187,11 +230,19 @@ static void read_sensor_task(void *param) {
   struct bma4_accel sens_data = {0};
 
   while (1) {
-    int8_t ret = bma4_read_accel_xyz(&sens_data, &s_bma456);
-    if (ret == BMA4_OK) {
+    bool got_sample = false;
+    if (s_accel_mutex != NULL &&
+        xSemaphoreTake(s_accel_mutex, pdMS_TO_TICKS(500)) == pdTRUE) {
+      int8_t ret = bma4_read_accel_xyz(&sens_data, &s_bma456);
+      xSemaphoreGive(s_accel_mutex);
+      if (ret == BMA4_OK) {
+        got_sample = true;
+      } else {
+        bma4_error_codes_print_result("bma4_read_accel_xyz", ret);
+      }
+    }
+    if (got_sample) {
       bma456_report_accel_if_changed(sens_data.x, sens_data.y, sens_data.z);
-    } else {
-      bma4_error_codes_print_result("bma4_read_accel_xyz", ret);
     }
 
     if (s_int_pending) {
@@ -213,19 +264,48 @@ static esp_err_t configure_tap_interrupt(void) {
   if (check_bma4("bma456h_tap_get_parameter", ret) != ESP_OK) {
     return ESP_FAIL;
   }
-  tap_settings.tap_sens_thres = 0;
+  tap_settings.tap_sens_thres = s_tap_config.tap_sens_thres;
+  tap_settings.max_gest_dur = s_tap_config.max_gest_dur;
+  tap_settings.tap_shock_dur = s_tap_config.tap_shock_dur;
+  tap_settings.quite_time_after_gest = s_tap_config.quite_time_after_gest;
+  tap_settings.wait_for_timeout = s_tap_config.wait_for_timeout;
+  tap_settings.axis_sel = s_tap_config.axis_sel;
   ret = bma456h_tap_set_parameter(&tap_settings, &s_bma456);
   if (check_bma4("bma456h_tap_set_parameter", ret) != ESP_OK) {
     return ESP_FAIL;
   }
 
-  ret = bma456h_feature_enable(
-      (BMA456H_SINGLE_TAP_EN | BMA456H_DOUBLE_TAP_EN | BMA456H_TRIPLE_TAP_EN),
-      BMA4_ENABLE, &s_bma456);
+  uint16_t tap_features = 0;
+  if (s_tap_config.enable_single) {
+    tap_features |= BMA456H_SINGLE_TAP_EN;
+  }
+  if (s_tap_config.enable_double) {
+    tap_features |= BMA456H_DOUBLE_TAP_EN;
+  }
+  if (s_tap_config.enable_triple) {
+    tap_features |= BMA456H_TRIPLE_TAP_EN;
+  }
+  if (tap_features == 0) {
+    ESP_LOGW(TAG, "tap config: no tap kinds enabled");
+    return ESP_ERR_INVALID_ARG;
+  }
+
+  ret = bma456h_feature_enable(tap_features, BMA4_ENABLE, &s_bma456);
   if (check_bma4("bma456h_feature_enable", ret) != ESP_OK) {
     return ESP_FAIL;
   }
 
+  ESP_LOGI(TAG,
+           "tap config sens=%u max_gest=%u shock=%u quiet=%u wait=%u axis=%u "
+           "(single=%d double=%d triple=%d)",
+           (unsigned)s_tap_config.tap_sens_thres,
+           (unsigned)s_tap_config.max_gest_dur,
+           (unsigned)s_tap_config.tap_shock_dur,
+           (unsigned)s_tap_config.quite_time_after_gest,
+           (unsigned)s_tap_config.wait_for_timeout,
+           (unsigned)s_tap_config.axis_sel, s_tap_config.enable_single,
+           s_tap_config.enable_double, s_tap_config.enable_triple);
+
   ret = bma456h_map_interrupt(int_line, BMA456H_TAP_OUT_INT, BMA4_ENABLE,
                               &s_bma456);
   if (check_bma4("bma456h_map_interrupt", ret) != ESP_OK) {
@@ -343,6 +423,13 @@ esp_err_t init_bma456(i2c_master_bus_handle_t bus_handle) {
     goto fail;
   }
 
+  if (s_accel_mutex == NULL) {
+    s_accel_mutex = xSemaphoreCreateMutex();
+    if (s_accel_mutex == NULL) {
+      goto fail;
+    }
+  }
+
   if (xTaskCreate(read_sensor_task, "bma456_poll", 4096, NULL, 1, NULL) !=
       pdPASS) {
     goto fail;

main/bosch456.h

@@ -10,6 +10,8 @@
 
 #include "driver/i2c_types.h"
 #include "esp_err.h"
+#include <stdbool.h>
+#include <stdint.h>
 
 /** 7-bit I2C address (SDO low). */
 #define BMA456_I2C_ADDR 0x18
@@ -20,6 +22,40 @@
 /** Software filter: log accel only when |axis - last| > deadzone (raw LSB). */
 #define BMA456_DEFAULT_ACCEL_DEADZONE 100u
 
+/**
+ * BMA456H multitap tuning (see BST-BMA456-AN000).
+ *
+ * Time fields use register units: value × 5 ms (e.g. 100 → 500 ms).
+ * tap_sens_thres: 0 = most sensitive … 15 = least (~78 mg per LSB).
+ * axis_sel: 0 = X, 1 = Y, 2 = Z.
+ * wait_for_timeout: 0 = report immediately, 1 = wait max_gest_dur for classification.
+ */
+typedef struct {
+  uint16_t tap_sens_thres;
+  uint16_t max_gest_dur;
+  uint16_t tap_shock_dur;
+  uint16_t quite_time_after_gest;
+  uint16_t wait_for_timeout;
+  uint16_t axis_sel;
+  bool enable_single;
+  bool enable_double;
+  bool enable_triple;
+} bma456_tap_config_t;
+
+/** Edit these values to tune tap detection, then rebuild. */
+#define BMA456_TAP_CONFIG_DEFAULT                                              \
+  {                                                                            \
+      .tap_sens_thres = 5,           /* sensitive; 0=max, Bosch default=9 */   \
+      .max_gest_dur = 100,             /* 500 ms window for double/triple */   \
+      .tap_shock_dur = 6,              /* 30 ms debounce after each impulse */ \
+      .quite_time_after_gest = 60,     /* 300 ms min gap between gestures */   \
+      .wait_for_timeout = 0,           /* 0 = faster single-tap response */    \
+      .axis_sel = 2,                   /* Z axis */                            \
+      .enable_single = true,                                                   \
+      .enable_double = true,                                                   \
+      .enable_triple = true,                                                   \
+  }
+
 /**
  * Probe and configure the sensor on bus_handle (100 kHz device).
  * On failure the device is removed and ESP_ERR_NOT_FOUND / ESP_FAIL is returned;
@@ -35,4 +71,19 @@ uint32_t bma456_get_accel_deadzone(void);
 /** Log accel when any axis moved more than deadzone since last reported sample. */
 void bma456_report_accel_if_changed(int16_t x, int16_t y, int16_t z);
 
+/** Tap kinds from BMA456H multitap output. */
+typedef enum {
+  BMA456_TAP_SINGLE = 1,
+  BMA456_TAP_DOUBLE = 2,
+  BMA456_TAP_TRIPLE = 3,
+} bma456_tap_kind_t;
+
+typedef void (*bma456_tap_handler_t)(bma456_tap_kind_t kind, void *ctx);
+
+/** Optional callback invoked from sensor task on tap interrupt (may be NULL). */
+void bma456_set_tap_handler(bma456_tap_handler_t handler, void *ctx);
+
+/** On-demand read of current accel XYZ (raw LSB). Returns ESP_ERR_INVALID_STATE if sensor not ready. */
+esp_err_t bma456_read_accel(int16_t *x, int16_t *y, int16_t *z);
+
 #endif

main/client_registry.c

@@ -14,6 +14,11 @@ typedef struct {
 
 static client_slot_t s_clients[CLIENT_REGISTRY_MAX];
 
+static struct {
+  board_lipo_reading_t reading;
+  uint32_t updated_at;
+} s_master_battery;
+
 uint32_t client_registry_now_ms(void) {
   return (uint32_t)(xTaskGetTickCount() * portTICK_PERIOD_MS);
 }
@@ -241,6 +246,286 @@ size_t client_registry_set_accel_deadzone_all(uint32_t deadzone) {
   return n;
 }
 
+static void clear_client_accel(client_slot_t *slot) {
+  if (slot == NULL) {
+    return;
+  }
+  slot->info.accel_valid = false;
+  slot->info.accel_x = 0;
+  slot->info.accel_y = 0;
+  slot->info.accel_z = 0;
+  slot->info.accel_updated_at = 0;
+}
+
+static void clear_client_tap(client_slot_t *slot) {
+  if (slot == NULL) {
+    return;
+  }
+  slot->info.tap_valid = false;
+  slot->info.tap_kind = 0;
+  slot->info.tap_updated_at = 0;
+}
+
+static bool tap_kind_enabled(const client_info_t *info, uint32_t kind) {
+  if (info == NULL) {
+    return false;
+  }
+  switch (kind) {
+  case 1:
+    return info->tap_notify_single;
+  case 2:
+    return info->tap_notify_double;
+  case 3:
+    return info->tap_notify_triple;
+  default:
+    return false;
+  }
+}
+
+esp_err_t client_registry_set_accel_stream(uint32_t client_id, bool enabled) {
+  for (size_t i = 0; i < CLIENT_REGISTRY_MAX; i++) {
+    if (!s_clients[i].active || s_clients[i].info.id != client_id) {
+      continue;
+    }
+    s_clients[i].info.accel_stream_enabled = enabled;
+    if (!enabled) {
+      clear_client_accel(&s_clients[i]);
+    }
+    return ESP_OK;
+  }
+  return ESP_ERR_NOT_FOUND;
+}
+
+esp_err_t client_registry_get_accel_stream(uint32_t client_id,
+                                           bool *enabled_out) {
+  if (enabled_out == NULL) {
+    return ESP_ERR_INVALID_ARG;
+  }
+  const client_info_t *info = client_registry_find_by_id(client_id);
+  if (info == NULL) {
+    return ESP_ERR_NOT_FOUND;
+  }
+  *enabled_out = info->accel_stream_enabled;
+  return ESP_OK;
+}
+
+size_t client_registry_set_accel_stream_all(bool enabled) {
+  size_t n = 0;
+  for (size_t i = 0; i < CLIENT_REGISTRY_MAX; i++) {
+    if (!s_clients[i].active) {
+      continue;
+    }
+    s_clients[i].info.accel_stream_enabled = enabled;
+    if (!enabled) {
+      clear_client_accel(&s_clients[i]);
+    }
+    n++;
+  }
+  return n;
+}
+
+esp_err_t client_registry_update_accel(const uint8_t mac[CLIENT_MAC_LEN],
+                                       uint32_t slave_id, int16_t x, int16_t y,
+                                       int16_t z) {
+  if (mac == NULL) {
+    return ESP_ERR_INVALID_ARG;
+  }
+
+  client_slot_t *slot = find_slot(mac);
+  if (slot == NULL) {
+    return ESP_ERR_NOT_FOUND;
+  }
+  if (slot->info.id != slave_id) {
+    return ESP_ERR_INVALID_ARG;
+  }
+  if (!slot->info.accel_stream_enabled) {
+    return ESP_ERR_INVALID_STATE;
+  }
+
+  slot->info.accel_x = x;
+  slot->info.accel_y = y;
+  slot->info.accel_z = z;
+  slot->info.accel_valid = true;
+  slot->info.accel_updated_at = now_ms();
+  return ESP_OK;
+}
+
+esp_err_t client_registry_set_tap_notify(uint32_t client_id, bool single,
+                                         bool double_tap, bool triple) {
+  for (size_t i = 0; i < CLIENT_REGISTRY_MAX; i++) {
+    if (!s_clients[i].active || s_clients[i].info.id != client_id) {
+      continue;
+    }
+    s_clients[i].info.tap_notify_single = single;
+    s_clients[i].info.tap_notify_double = double_tap;
+    s_clients[i].info.tap_notify_triple = triple;
+    if (!single && !double_tap && !triple) {
+      clear_client_tap(&s_clients[i]);
+    }
+    return ESP_OK;
+  }
+  return ESP_ERR_NOT_FOUND;
+}
+
+esp_err_t client_registry_get_tap_notify(uint32_t client_id, bool *single_out,
+                                         bool *double_tap_out,
+                                         bool *triple_out) {
+  if (single_out == NULL || double_tap_out == NULL || triple_out == NULL) {
+    return ESP_ERR_INVALID_ARG;
+  }
+  const client_info_t *info = client_registry_find_by_id(client_id);
+  if (info == NULL) {
+    return ESP_ERR_NOT_FOUND;
+  }
+  *single_out = info->tap_notify_single;
+  *double_tap_out = info->tap_notify_double;
+  *triple_out = info->tap_notify_triple;
+  return ESP_OK;
+}
+
+size_t client_registry_set_tap_notify_all(bool single, bool double_tap,
+                                          bool triple) {
+  size_t n = 0;
+  for (size_t i = 0; i < CLIENT_REGISTRY_MAX; i++) {
+    if (!s_clients[i].active) {
+      continue;
+    }
+    s_clients[i].info.tap_notify_single = single;
+    s_clients[i].info.tap_notify_double = double_tap;
+    s_clients[i].info.tap_notify_triple = triple;
+    if (!single && !double_tap && !triple) {
+      clear_client_tap(&s_clients[i]);
+    }
+    n++;
+  }
+  return n;
+}
+
+esp_err_t client_registry_update_tap(const uint8_t mac[CLIENT_MAC_LEN],
+                                     uint32_t slave_id, uint32_t kind) {
+  if (mac == NULL || kind < 1 || kind > 3) {
+    return ESP_ERR_INVALID_ARG;
+  }
+
+  client_slot_t *slot = find_slot(mac);
+  if (slot == NULL) {
+    return ESP_ERR_NOT_FOUND;
+  }
+  if (slot->info.id != slave_id) {
+    return ESP_ERR_INVALID_ARG;
+  }
+  if (!tap_kind_enabled(&slot->info, kind)) {
+    return ESP_ERR_INVALID_STATE;
+  }
+
+  slot->info.tap_kind = kind;
+  slot->info.tap_valid = true;
+  slot->info.tap_updated_at = now_ms();
+  return ESP_OK;
+}
+
+void client_registry_expire_tap(client_info_t *info) {
+  if (info == NULL || !info->tap_valid) {
+    return;
+  }
+  if (client_registry_ms_since(info->tap_updated_at) >
+      CLIENT_REGISTRY_TAP_MAX_AGE_MS) {
+    info->tap_valid = false;
+    info->tap_kind = 0;
+    info->tap_updated_at = 0;
+  }
+}
+
+void client_registry_clear_tap(client_info_t *info) {
+  if (info == NULL) {
+    return;
+  }
+  info->tap_valid = false;
+  info->tap_kind = 0;
+  info->tap_updated_at = 0;
+}
+
+bool client_registry_take_tap(uint32_t client_id, uint32_t *kind_out,
+                              uint32_t *age_ms_out) {
+  for (size_t i = 0; i < CLIENT_REGISTRY_MAX; i++) {
+    if (!s_clients[i].active || s_clients[i].info.id != client_id) {
+      continue;
+    }
+    client_info_t *info = &s_clients[i].info;
+    client_registry_expire_tap(info);
+    if (!info->tap_valid) {
+      return false;
+    }
+    if (kind_out != NULL) {
+      *kind_out = info->tap_kind;
+    }
+    if (age_ms_out != NULL) {
+      *age_ms_out = client_registry_ms_since(info->tap_updated_at);
+    }
+    client_registry_clear_tap(info);
+    return true;
+  }
+  return false;
+}
+
+void client_registry_set_master_battery(const board_lipo_reading_t *reading) {
+  if (reading == NULL) {
+    return;
+  }
+  s_master_battery.reading = *reading;
+  s_master_battery.updated_at = now_ms();
+}
+
+bool client_registry_get_master_battery(board_lipo_reading_t *reading_out,
+                                        uint32_t *age_ms_out) {
+  if (reading_out == NULL) {
+    return false;
+  }
+  *reading_out = s_master_battery.reading;
+  if (age_ms_out != NULL) {
+    *age_ms_out = client_registry_ms_since(s_master_battery.updated_at);
+  }
+  return s_master_battery.updated_at != 0;
+}
+
+esp_err_t client_registry_update_battery(const uint8_t mac[CLIENT_MAC_LEN],
+                                         uint32_t slave_id, bool lipo1_valid,
+                                         uint32_t lipo1_mv, bool lipo2_valid,
+                                         uint32_t lipo2_mv) {
+  if (mac == NULL) {
+    return ESP_ERR_INVALID_ARG;
+  }
+
+  client_slot_t *slot = find_slot(mac);
+  if (slot == NULL) {
+    bool is_new = false;
+    esp_err_t err = client_registry_upsert(mac, slave_id, 0, true, false, &is_new);
+    if (err != ESP_OK) {
+      return err;
+    }
+    slot = find_slot(mac);
+    if (slot == NULL) {
+      return ESP_ERR_NOT_FOUND;
+    }
+    ESP_LOGI(TAG, "battery auto-registered id=%lu (report before heartbeat)",
+             (unsigned long)slave_id);
+  }
+
+  if (slot->info.id != slave_id) {
+    ESP_LOGW(TAG, "battery id %lu → %lu for mac %02x:…:%02x",
+             (unsigned long)slot->info.id, (unsigned long)slave_id, mac[0],
+             mac[5]);
+    slot->info.id = slave_id;
+  }
+
+  slot->info.lipo1_valid = lipo1_valid;
+  slot->info.lipo2_valid = lipo2_valid;
+  slot->info.lipo1_mv = lipo1_mv;
+  slot->info.lipo2_mv = lipo2_mv;
+  slot->info.battery_updated_at = now_ms();
+  return ESP_OK;
+}
+
 const client_info_t *client_registry_at(size_t index) {
   size_t n = 0;
   for (size_t i = 0; i < CLIENT_REGISTRY_MAX; i++) {

main/client_registry.h

@@ -1,6 +1,7 @@
 #ifndef CLIENT_REGISTRY_H
 #define CLIENT_REGISTRY_H
 
+#include "board_input.h"
 #include "esp_err.h"
 #include <stdbool.h>
 #include <stddef.h>
@@ -21,9 +22,33 @@ typedef struct {
   uint32_t version;
   /** Accel deadzone in raw LSB per axis (master copy for ESP-NOW config). */
   uint32_t accel_deadzone;
+  /** Latest accel from slave ESP-NOW stream (master only). */
+  bool accel_valid;
+  int16_t accel_x;
+  int16_t accel_y;
+  int16_t accel_z;
+  uint32_t accel_updated_at;
+  /** Host-enabled ESP-NOW accel stream to master. */
+  bool accel_stream_enabled;
+  /** Host-enabled ESP-NOW tap notify flags. */
+  bool tap_notify_single;
+  bool tap_notify_double;
+  bool tap_notify_triple;
+  /** Latest tap from slave ESP-NOW (master only, short-lived cache). */
+  bool tap_valid;
+  uint32_t tap_kind;
+  uint32_t tap_updated_at;
+  /** Latest LiPo ADC from slave ESP-NOW battery report (~30 s). */
+  bool lipo1_valid;
+  bool lipo2_valid;
+  uint32_t lipo1_mv;
+  uint32_t lipo2_mv;
+  uint32_t battery_updated_at;
 } client_info_t;
 
 #define CLIENT_REGISTRY_DEFAULT_ACCEL_DEADZONE 100u
+/** Tap events older than this are discarded (matches accel stream interval). */
+#define CLIENT_REGISTRY_TAP_MAX_AGE_MS 16u
 
 void client_registry_init(void);
 
@@ -63,4 +88,49 @@ esp_err_t client_registry_get_accel_deadzone(uint32_t client_id,
 /** Push deadzone to all active registry entries; returns count updated. */
 size_t client_registry_set_accel_deadzone_all(uint32_t deadzone);
 
+/** Store latest accel sample from a slave (matched by sender MAC). */
+esp_err_t client_registry_update_accel(const uint8_t mac[CLIENT_MAC_LEN],
+                                       uint32_t slave_id, int16_t x, int16_t y,
+                                       int16_t z);
+
+esp_err_t client_registry_set_accel_stream(uint32_t client_id, bool enabled);
+esp_err_t client_registry_get_accel_stream(uint32_t client_id, bool *enabled_out);
+size_t client_registry_set_accel_stream_all(bool enabled);
+
+esp_err_t client_registry_set_tap_notify(uint32_t client_id, bool single,
+                                         bool double_tap, bool triple);
+esp_err_t client_registry_get_tap_notify(uint32_t client_id, bool *single_out,
+                                         bool *double_tap_out,
+                                         bool *triple_out);
+size_t client_registry_set_tap_notify_all(bool single, bool double_tap,
+                                          bool triple);
+
+/** Store tap event from slave (matched by sender MAC). kind: 1=single, 2=double, 3=triple. */
+esp_err_t client_registry_update_tap(const uint8_t mac[CLIENT_MAC_LEN],
+                                     uint32_t slave_id, uint32_t kind);
+
+/** Drop cached tap if older than CLIENT_REGISTRY_TAP_MAX_AGE_MS. */
+void client_registry_expire_tap(client_info_t *info);
+
+/** Clear cached tap after UART snapshot or expiry. */
+void client_registry_clear_tap(client_info_t *info);
+
+/**
+ * If client has a fresh tap (age <= CLIENT_REGISTRY_TAP_MAX_AGE_MS), copy it out
+ * and clear the cache. Returns true when an event was returned.
+ */
+bool client_registry_take_tap(uint32_t client_id, uint32_t *kind_out,
+                              uint32_t *age_ms_out);
+
+/** Master local LiPo (client_id 0 in UART battery responses). */
+void client_registry_set_master_battery(const board_lipo_reading_t *reading);
+bool client_registry_get_master_battery(board_lipo_reading_t *reading_out,
+                                        uint32_t *age_ms_out);
+
+/** Store latest battery report from a slave (matched by sender MAC). */
+esp_err_t client_registry_update_battery(const uint8_t mac[CLIENT_MAC_LEN],
+                                         uint32_t slave_id, bool lipo1_valid,
+                                         uint32_t lipo1_mv, bool lipo2_valid,
+                                         uint32_t lipo2_mv);
+
 #endif

main/cmd/cmd_accel_stream.c

@@ -0,0 +1,104 @@
+#include "client_registry.h"
+#include "cmd_accel_stream.h"
+#include "esp_log.h"
+#include "esp_now_comm.h"
+#include "uart_cmd.h"
+
+static const char *TAG = "[ACCEL_STREAM]";
+
+static void reply(bool enabled, uint32_t client_id, bool success,
+                  uint32_t slaves_updated) {
+  alox_UartMessage response;
+  uart_cmd_init_response(&response, alox_MessageType_ACCEL_STREAM,
+                         alox_UartMessage_accel_stream_response_tag);
+  response.payload.accel_stream_response.enabled = enabled;
+  response.payload.accel_stream_response.client_id = client_id;
+  response.payload.accel_stream_response.success = success;
+  response.payload.accel_stream_response.slaves_updated = slaves_updated;
+  uart_cmd_send(&response, TAG);
+}
+
+static esp_err_t push_stream_to_slave(const client_info_t *client, bool enable) {
+  if (client == NULL) {
+    return ESP_ERR_INVALID_ARG;
+  }
+  esp_err_t err = client_registry_set_accel_stream(client->id, enable);
+  if (err != ESP_OK) {
+    return err;
+  }
+  return esp_now_comm_send_accel_stream(client->mac, client->id, enable);
+}
+
+static void handle_accel_stream(const uint8_t *data, size_t len) {
+  alox_UartMessage uart_msg;
+  alox_AccelStreamRequest req = alox_AccelStreamRequest_init_zero;
+
+  if (len > 0) {
+    if (uart_cmd_decode(data, len, &uart_msg) != ESP_OK) {
+      ESP_LOGW(TAG, "decode failed");
+      reply(false, 0, false, 0);
+      return;
+    }
+    const alox_AccelStreamRequest *req_ptr = UART_CMD_REQ(
+        &uart_msg, alox_UartMessage_accel_stream_request_tag, accel_stream_request);
+    if (req_ptr == NULL) {
+      ESP_LOGW(TAG, "missing accel_stream_request");
+      reply(false, 0, false, 0);
+      return;
+    }
+    req = *req_ptr;
+  }
+
+  if (req.write) {
+    if (req.all_clients) {
+      size_t n = client_registry_set_accel_stream_all(req.enable);
+      uint32_t sent = 0;
+
+      for (size_t i = 0; i < client_registry_count(); i++) {
+        const client_info_t *client = client_registry_at(i);
+        if (client == NULL) {
+          continue;
+        }
+        if (esp_now_comm_send_accel_stream(client->mac, client->id,
+                                           req.enable) == ESP_OK) {
+          sent++;
+        }
+      }
+
+      ESP_LOGI(TAG, "accel stream %s for %u/%u slaves",
+               req.enable ? "on" : "off", (unsigned)sent, (unsigned)n);
+      reply(req.enable, 0, sent > 0, sent);
+      return;
+    }
+
+    if (req.client_id == 0) {
+      ESP_LOGW(TAG, "client_id required (or all_clients)");
+      reply(req.enable, 0, false, 0);
+      return;
+    }
+
+    const client_info_t *client = client_registry_find_by_id(req.client_id);
+    if (client == NULL) {
+      ESP_LOGW(TAG, "client id %lu not found", (unsigned long)req.client_id);
+      reply(req.enable, req.client_id, false, 0);
+      return;
+    }
+
+    esp_err_t err = push_stream_to_slave(client, req.enable);
+    reply(req.enable, req.client_id, err == ESP_OK, err == ESP_OK ? 1u : 0u);
+    return;
+  }
+
+  if (req.all_clients || req.client_id == 0) {
+    reply(false, 0, false, 0);
+    return;
+  }
+
+  bool enabled = false;
+  esp_err_t err = client_registry_get_accel_stream(req.client_id, &enabled);
+  reply(enabled, req.client_id, err == ESP_OK, 0);
+}
+
+void cmd_accel_stream_register(void) {
+  uart_cmd_register(alox_MessageType_ACCEL_STREAM, handle_accel_stream);
+}

main/cmd/cmd_accel_stream.h

@@ -0,0 +1,6 @@
+#ifndef CMD_ACCEL_STREAM_H
+#define CMD_ACCEL_STREAM_H
+
+void cmd_accel_stream_register(void);
+
+#endif

main/cmd/cmd_battery.c

@@ -0,0 +1,129 @@
+#include "cmd_battery.h"
+#include "board_input.h"
+#include "client_registry.h"
+#include "esp_log.h"
+#include "uart_cmd.h"
+
+static const char *TAG = "[BATTERY]";
+
+static void fill_lipo(alox_LipoReading *dst, bool *has_dst, bool valid,
+                      uint32_t mv) {
+  if (dst == NULL || has_dst == NULL) {
+    return;
+  }
+  *has_dst = true;
+  dst->valid = valid;
+  dst->voltage_mv = valid ? mv : 0;
+}
+
+static bool append_battery_sample(alox_BatteryStatusResponse *resp,
+                                  uint32_t client_id, bool lipo1_valid,
+                                  uint32_t lipo1_mv, bool lipo2_valid,
+                                  uint32_t lipo2_mv, uint32_t age_ms) {
+  if (resp->samples_count >=
+      sizeof(resp->samples) / sizeof(resp->samples[0])) {
+    return false;
+  }
+
+  alox_BatterySample *sample = &resp->samples[resp->samples_count++];
+  sample->client_id = client_id;
+  fill_lipo(&sample->lipo1, &sample->has_lipo1, lipo1_valid, lipo1_mv);
+  fill_lipo(&sample->lipo2, &sample->has_lipo2, lipo2_valid, lipo2_mv);
+  sample->age_ms = age_ms;
+  return lipo1_valid || lipo2_valid;
+}
+
+static bool append_master_sample(alox_BatteryStatusResponse *resp) {
+  board_lipo_reading_t reading;
+
+  board_input_read_lipo(&reading);
+  client_registry_set_master_battery(&reading);
+
+  return append_battery_sample(resp, 0, reading.lipo1_valid, reading.lipo1_mv,
+                               reading.lipo2_valid, reading.lipo2_mv, 0);
+}
+
+static bool append_slave_cached(alox_BatteryStatusResponse *resp,
+                                const client_info_t *client) {
+  if (client == NULL) {
+    return false;
+  }
+  if (client->battery_updated_at == 0) {
+    return false;
+  }
+
+  return append_battery_sample(
+      resp, client->id, client->lipo1_valid, client->lipo1_mv,
+      client->lipo2_valid, client->lipo2_mv,
+      client_registry_ms_since(client->battery_updated_at));
+}
+
+static void handle_battery_status(const uint8_t *data, size_t len) {
+  alox_BatteryStatusRequest req = alox_BatteryStatusRequest_init_zero;
+
+  if (len > 0) {
+    alox_UartMessage uart_msg;
+    if (uart_cmd_decode(data, len, &uart_msg) != ESP_OK) {
+      ESP_LOGW(TAG, "decode failed");
+      alox_UartMessage response;
+      uart_cmd_init_response(&response, alox_MessageType_BATTERY_STATUS,
+                             alox_UartMessage_battery_status_response_tag);
+      response.payload.battery_status_response.success = false;
+      uart_cmd_send(&response, TAG);
+      return;
+    }
+    const alox_BatteryStatusRequest *req_ptr = UART_CMD_REQ(
+        &uart_msg, alox_UartMessage_battery_status_request_tag,
+        battery_status_request);
+    if (req_ptr == NULL) {
+      ESP_LOGW(TAG, "missing battery_status_request");
+      alox_UartMessage response;
+      uart_cmd_init_response(&response, alox_MessageType_BATTERY_STATUS,
+                             alox_UartMessage_battery_status_response_tag);
+      response.payload.battery_status_response.success = false;
+      uart_cmd_send(&response, TAG);
+      return;
+    }
+    req = *req_ptr;
+  }
+
+  alox_UartMessage response;
+  uart_cmd_init_response(&response, alox_MessageType_BATTERY_STATUS,
+                         alox_UartMessage_battery_status_response_tag);
+  alox_BatteryStatusResponse *resp =
+      &response.payload.battery_status_response;
+  resp->success = false;
+  resp->samples_count = 0;
+
+  bool any = false;
+
+  if (req.all_clients) {
+    any |= append_master_sample(resp);
+    for (size_t i = 0; i < client_registry_count(); i++) {
+      const client_info_t *client = client_registry_at(i);
+      if (client == NULL) {
+        continue;
+      }
+      any |= append_slave_cached(resp, client);
+    }
+    ESP_LOGI(TAG, "battery cache all_clients → %u samples",
+             (unsigned)resp->samples_count);
+  } else if (req.client_id == 0) {
+    any = append_master_sample(resp);
+    ESP_LOGI(TAG, "battery cache master");
+  } else {
+    const client_info_t *client = client_registry_find_by_id(req.client_id);
+    if (client != NULL) {
+      any = append_slave_cached(resp, client);
+    } else {
+      ESP_LOGW(TAG, "client %lu not in registry", (unsigned long)req.client_id);
+    }
+  }
+
+  resp->success = any;
+  uart_cmd_send(&response, TAG);
+}
+
+void cmd_battery_register(void) {
+  uart_cmd_register(alox_MessageType_BATTERY_STATUS, handle_battery_status);
+}

main/cmd/cmd_battery.h

@@ -0,0 +1,6 @@
+#ifndef CMD_BATTERY_H
+#define CMD_BATTERY_H
+
+void cmd_battery_register(void);
+
+#endif

main/cmd/cmd_cache_status.c

@@ -0,0 +1,92 @@
+#include "client_registry.h"
+#include "cmd_cache_status.h"
+#include "uart_cmd.h"
+
+static const char *TAG = "[CACHE_STAT]";
+
+static bool tap_notify_any(const client_info_t *client) {
+  return client != NULL &&
+         (client->tap_notify_single || client->tap_notify_double ||
+          client->tap_notify_triple);
+}
+
+static alox_TapKind tap_kind_from_registry(uint32_t kind) {
+  switch (kind) {
+  case 1:
+    return alox_TapKind_TAP_SINGLE;
+  case 2:
+    return alox_TapKind_TAP_DOUBLE;
+  case 3:
+    return alox_TapKind_TAP_TRIPLE;
+  default:
+    return alox_TapKind_TAP_NONE;
+  }
+}
+
+static void fill_cache_status(alox_CacheStatusResponse *out) {
+  if (out == NULL) {
+    return;
+  }
+
+  out->clients_count = 0;
+
+  size_t count = client_registry_count();
+  for (size_t i = 0; i < count; i++) {
+    const client_info_t *client = client_registry_at(i);
+    if (client == NULL) {
+      continue;
+    }
+
+    const bool want_accel = client->accel_stream_enabled;
+    const bool want_tap = tap_notify_any(client);
+    if (!want_accel && !want_tap) {
+      continue;
+    }
+    if (out->clients_count >=
+        sizeof(out->clients) / sizeof(out->clients[0])) {
+      break;
+    }
+
+    alox_CacheClientStatus *entry = &out->clients[out->clients_count++];
+    entry->client_id = client->id;
+    entry->has_accel = false;
+    entry->has_tap = false;
+
+    if (want_accel) {
+      entry->has_accel = true;
+      entry->accel.valid = client->accel_valid;
+      if (client->accel_valid) {
+        entry->accel.x = client->accel_x;
+        entry->accel.y = client->accel_y;
+        entry->accel.z = client->accel_z;
+        entry->accel.age_ms =
+            client_registry_ms_since(client->accel_updated_at);
+      }
+    }
+
+    if (want_tap) {
+      uint32_t kind = 0;
+      uint32_t age_ms = 0;
+      if (client_registry_take_tap(client->id, &kind, &age_ms)) {
+        entry->has_tap = true;
+        entry->tap.kind = tap_kind_from_registry(kind);
+        entry->tap.age_ms = age_ms;
+      }
+    }
+  }
+}
+
+static void handle_cache_status(const uint8_t *data, size_t len) {
+  (void)data;
+  (void)len;
+
+  alox_UartMessage response;
+  uart_cmd_init_response(&response, alox_MessageType_CACHE_STATUS,
+                         alox_UartMessage_cache_status_response_tag);
+  fill_cache_status(&response.payload.cache_status_response);
+  uart_cmd_send(&response, TAG);
+}
+
+void cmd_cache_status_register(void) {
+  uart_cmd_register(alox_MessageType_CACHE_STATUS, handle_cache_status);
+}

main/cmd/cmd_cache_status.h

@@ -0,0 +1,3 @@
+#pragma once
+
+void cmd_cache_status_register(void);

main/cmd/cmd_client_info.c

@@ -27,6 +27,10 @@ static bool encode_clients_list(pb_ostream_t *stream, const pb_field_t *field,
     proto.last_success_ping =
         client_registry_ms_since(client->last_success_ping_at);
     proto.version = client->version;
+    proto.accel_stream_enabled = client->accel_stream_enabled;
+    proto.tap_notify_single = client->tap_notify_single;
+    proto.tap_notify_double = client->tap_notify_double;
+    proto.tap_notify_triple = client->tap_notify_triple;
     proto.mac.funcs.encode = uart_cmd_encode_bytes;
     proto.mac.arg = &mac;
 

main/cmd/cmd_espnow_echo_ping.c

@@ -0,0 +1,70 @@
+#include "client_registry.h"
+#include "cmd_espnow_echo_ping.h"
+#include "esp_log.h"
+#include "esp_now_comm.h"
+#include "uart_cmd.h"
+
+static const char *TAG = "[ECHO_PING]";
+
+static void reply(bool success, uint32_t client_id, uint64_t timestamp_us,
+                  uint32_t esp_rtt_us) {
+  alox_UartMessage response;
+  uart_cmd_init_response(&response, alox_MessageType_ESPNOW_ECHO_PING,
+                         alox_UartMessage_espnow_echo_ping_response_tag);
+  response.payload.espnow_echo_ping_response.success = success;
+  response.payload.espnow_echo_ping_response.client_id = client_id;
+  response.payload.espnow_echo_ping_response.timestamp_us = timestamp_us;
+  response.payload.espnow_echo_ping_response.esp_rtt_us = esp_rtt_us;
+  uart_cmd_send(&response, TAG);
+}
+
+static void handle_espnow_echo_ping(const uint8_t *data, size_t len) {
+  alox_UartMessage uart_msg;
+
+  if (uart_cmd_decode(data, len, &uart_msg) != ESP_OK) {
+    ESP_LOGW(TAG, "decode failed");
+    reply(false, 0, 0, 0);
+    return;
+  }
+
+  const alox_EspNowEchoPingRequest *req = UART_CMD_REQ(
+      &uart_msg, alox_UartMessage_espnow_echo_ping_request_tag,
+      espnow_echo_ping_request);
+  if (req == NULL || req->client_id == 0) {
+    ESP_LOGW(TAG, "need client_id in request");
+    reply(false, 0, 0, 0);
+    return;
+  }
+
+  const client_info_t *client = client_registry_find_by_id(req->client_id);
+  if (client == NULL) {
+    ESP_LOGW(TAG, "client id %lu not in registry",
+             (unsigned long)req->client_id);
+    reply(false, req->client_id, 0, 0);
+    return;
+  }
+
+  ESP_LOGI(TAG, "UART request client_id=%lu host_ts=%llu",
+           (unsigned long)req->client_id,
+           (unsigned long long)req->timestamp_us);
+
+  esp_now_echo_ping_result_t ping_result = {0};
+  esp_err_t err =
+      esp_now_comm_echo_ping(client->mac, req->timestamp_us, &ping_result);
+  if (err != ESP_OK) {
+    ESP_LOGW(TAG, "echo ping to id=%lu failed: %s", (unsigned long)req->client_id,
+             esp_err_to_name(err));
+    reply(false, req->client_id, 0, 0);
+    return;
+  }
+
+  ESP_LOGI(TAG, "UART reply client_id=%lu host_ts=%llu esp_rtt_us=%lu",
+           (unsigned long)req->client_id,
+           (unsigned long long)ping_result.echoed_us,
+           (unsigned long)ping_result.esp_rtt_us);
+  reply(true, req->client_id, ping_result.echoed_us, ping_result.esp_rtt_us);
+}
+
+void cmd_espnow_echo_ping_register(void) {
+  uart_cmd_register(alox_MessageType_ESPNOW_ECHO_PING, handle_espnow_echo_ping);
+}

main/cmd/cmd_espnow_echo_ping.h

@@ -0,0 +1,6 @@
+#ifndef CMD_ESPNOW_ECHO_PING_H
+#define CMD_ESPNOW_ECHO_PING_H
+
+void cmd_espnow_echo_ping_register(void);
+
+#endif

main/cmd/cmd_handler.c

@@ -1,4 +1,5 @@
 #include "cmd_handler.h"
+#include "ota_session.h"
 #include "esp_err.h"
 #include "esp_log.h"
 #include "freertos/FreeRTOS.h"
@@ -48,6 +49,18 @@ static const char *message_type_name(uint16_t id) {
     return "FIND_ME";
   case alox_MessageType_RESTART:
     return "RESTART";
+  case alox_MessageType_ACCEL_STREAM:
+    return "ACCEL_STREAM";
+  case alox_MessageType_BATTERY_STATUS:
+    return "BATTERY_STATUS";
+  case alox_MessageType_TAP_NOTIFY:
+    return "TAP_NOTIFY";
+  case alox_MessageType_CACHE_STATUS:
+    return "CACHE_STATUS";
+  case alox_MessageType_ESPNOW_ECHO_PING:
+    return "ESPNOW_ECHO_PING";
+  case alox_MessageType_SET_LOG_LEVEL:
+    return "SET_LOG_LEVEL";
   default:
     return "UNKNOWN";
   }
@@ -80,33 +93,19 @@ esp_err_t msg_register_handler(uint16_t id, msg_callback_t cb) {
   return ESP_OK;
 }
 
-esp_err_t msg_post(uint16_t id, const uint8_t *data, size_t len) {
-  if (cmd_queue == NULL) {
-    return ESP_ERR_INVALID_STATE;
-  }
-
-  generic_msg_t msg = {.msg_id = id, .len = len, .payload = NULL};
-  if (len > 0) {
-    msg.payload = malloc(len);
-    if (msg.payload == NULL) {
-      return ESP_ERR_NO_MEM;
-    }
-    memcpy(msg.payload, data, len);
-  }
-
-  if (xQueueSend(cmd_queue, &msg, pdMS_TO_TICKS(100)) != pdPASS) {
-    free(msg.payload);
-    return ESP_ERR_TIMEOUT;
-  }
-  return ESP_OK;
-}
-
 void vCmdDispatcherTask(void *param) {
   (void)param;
   generic_msg_t msg;
 
   while (1) {
     if (xQueueReceive(cmd_queue, &msg, portMAX_DELAY) == pdPASS) {
+      if (!ota_session_uart_cmd_allowed(msg.msg_id)) {
+        ESP_LOGW(TAG, "reject %s (0x%02x) during OTA session",
+                 message_type_name(msg.msg_id), (unsigned)msg.msg_id);
+        free(msg.payload);
+        continue;
+      }
+
       bool handled = false;
       for (int i = 0; i < handler_count; i++) {
         if (handlers[i].msg_id == msg.msg_id) {

main/cmd/cmd_handler.h

@@ -21,6 +21,5 @@ void init_cmdHandler(QueueHandle_t queue);
 void vCmdDispatcherTask(void *param);
 
 esp_err_t msg_register_handler(uint16_t id, msg_callback_t cb);
-esp_err_t msg_post(uint16_t id, const uint8_t *data, size_t len);
 
 #endif

main/cmd/cmd_led_ring.c

@@ -0,0 +1,208 @@
+#include "cmd_led_ring.h"
+#include "client_registry.h"
+#include "esp_log.h"
+#include "esp_now_comm.h"
+#include "led_ring.h"
+#include "uart_cmd.h"
+
+static const char *TAG = "[LED_RING_CMD]";
+
+#define LED_RING_MODE_CLEAR    0
+#define LED_RING_MODE_PROGRESS 1
+#define LED_RING_MODE_DIGIT    2
+#define LED_RING_MODE_BLINK    3
+#define LED_RING_MODE_FIND_ME  4
+#define LED_RING_MODE_COLOR    5
+#define LED_RING_MODE_BATTERY_LOW 6
+
+static uint8_t clamp_u8(uint32_t v) {
+  if (v > 255) {
+    return 255;
+  }
+  return (uint8_t)v;
+}
+
+static uint8_t clamp_progress(uint32_t v) {
+  if (v > 100) {
+    return 100;
+  }
+  return (uint8_t)v;
+}
+
+static uint8_t resolve_intensity(uint32_t intensity) {
+  if (intensity == 0) {
+    return LED_RING_DEFAULT_INTENSITY;
+  }
+  return clamp_u8(intensity);
+}
+
+bool cmd_led_ring_apply(const alox_LedRingProgressRequest *req) {
+  if (req == NULL) {
+    return false;
+  }
+
+  uint32_t mode = req->mode;
+  uint8_t r = clamp_u8(req->r);
+  uint8_t g = clamp_u8(req->g);
+  uint8_t b = clamp_u8(req->b);
+  uint8_t intensity = resolve_intensity(req->intensity);
+  led_command_t cmd = {0};
+
+  switch (mode) {
+  case LED_RING_MODE_CLEAR:
+    cmd.mode = LED_CMD_CLEAR;
+    led_ring_send_command(&cmd);
+    return true;
+
+  case LED_RING_MODE_COLOR:
+    cmd.mode = LED_CMD_SET_COLOR;
+    cmd.r = r;
+    cmd.g = g;
+    cmd.b = b;
+    cmd.intensity = intensity;
+    led_ring_send_command(&cmd);
+    return true;
+
+  case LED_RING_MODE_PROGRESS: {
+    cmd.mode = LED_CMD_PROGRESS;
+    cmd.progress = clamp_progress(req->progress);
+    cmd.r = r;
+    cmd.g = g;
+    cmd.b = b;
+    cmd.intensity = intensity;
+    led_ring_send_command(&cmd);
+    return true;
+  }
+
+  case LED_RING_MODE_DIGIT:
+    if (req->digit > 10) {
+      return false;
+    }
+    cmd.mode = LED_CMD_SET_DIGIT;
+    cmd.value = (uint8_t)req->digit;
+    cmd.r = r;
+    cmd.g = g;
+    cmd.b = b;
+    cmd.intensity = intensity;
+    led_ring_send_command(&cmd);
+    return true;
+
+  case LED_RING_MODE_FIND_ME:
+    led_ring_find_me();
+    return true;
+
+  case LED_RING_MODE_BATTERY_LOW:
+    led_ring_show_battery_low();
+    return true;
+
+  case LED_RING_MODE_BLINK:
+    cmd.mode = LED_CMD_BLINK;
+    cmd.r = r;
+    cmd.g = g;
+    cmd.b = b;
+    cmd.intensity = intensity;
+    cmd.blink_ms = (uint16_t)(req->blink_ms > 0 ? req->blink_ms : 350);
+    cmd.blink_count = req->blink_count > 0 ? (uint8_t)req->blink_count : 1;
+    if (cmd.blink_count == 0) {
+      cmd.blink_count = 1;
+    }
+    led_ring_send_command(&cmd);
+    return true;
+
+  default:
+    return false;
+  }
+}
+
+static void reply(bool success, uint32_t mode, uint32_t progress, uint32_t digit,
+                  uint32_t client_id, uint32_t slaves_updated) {
+  alox_UartMessage response;
+  uart_cmd_init_response(&response, alox_MessageType_LED_RING,
+                         alox_UartMessage_led_ring_progress_response_tag);
+  response.payload.led_ring_progress_response.success = success;
+  response.payload.led_ring_progress_response.mode = mode;
+  response.payload.led_ring_progress_response.progress = progress;
+  response.payload.led_ring_progress_response.digit = digit;
+  response.payload.led_ring_progress_response.client_id = client_id;
+  response.payload.led_ring_progress_response.slaves_updated = slaves_updated;
+  uart_cmd_send(&response, TAG);
+}
+
+static esp_err_t push_led_ring_to_slave(const client_info_t *client,
+                                        const alox_LedRingProgressRequest *req) {
+  if (client == NULL || req == NULL) {
+    return ESP_ERR_INVALID_ARG;
+  }
+  return esp_now_comm_send_led_ring(client->mac, client->id, req);
+}
+
+static void handle_led_ring(const uint8_t *data, size_t len) {
+  alox_UartMessage uart_msg;
+  alox_LedRingProgressRequest req = alox_LedRingProgressRequest_init_zero;
+
+  if (uart_cmd_decode(data, len, &uart_msg) != ESP_OK) {
+    ESP_LOGW(TAG, "decode failed");
+    reply(false, 0, 0, 0, 0, 0);
+    return;
+  }
+
+  const alox_LedRingProgressRequest *req_ptr = UART_CMD_REQ(
+      &uart_msg, alox_UartMessage_led_ring_progress_request_tag,
+      led_ring_progress_request);
+  if (req_ptr != NULL) {
+    req = *req_ptr;
+  }
+
+  uint32_t mode = req.mode;
+
+  if (req.all_clients) {
+    size_t n = client_registry_count();
+    uint32_t sent = 0;
+    for (size_t i = 0; i < n; i++) {
+      const client_info_t *client = client_registry_at(i);
+      if (client == NULL) {
+        continue;
+      }
+      if (push_led_ring_to_slave(client, &req) == ESP_OK) {
+        sent++;
+      }
+    }
+    bool local_ok = true;
+    if (!req.slaves_only) {
+      local_ok = cmd_led_ring_apply(&req);
+    }
+    ESP_LOGI(TAG, "LED ring mode %lu → %u/%u slaves%s", (unsigned long)mode,
+             (unsigned)sent, (unsigned)n, req.slaves_only ? "" : " + master");
+    reply(local_ok || sent > 0, mode, req.progress, req.digit, 0, sent);
+    return;
+  }
+
+  if (req.client_id == 0) {
+    bool ok = cmd_led_ring_apply(&req);
+    ESP_LOGI(TAG, "LED ring mode %lu on master", (unsigned long)mode);
+    reply(ok, mode, req.progress, req.digit, 0, 0);
+    return;
+  }
+
+  const client_info_t *client = client_registry_find_by_id(req.client_id);
+  if (client == NULL) {
+    ESP_LOGW(TAG, "client id %lu not in registry", (unsigned long)req.client_id);
+    reply(false, mode, req.progress, req.digit, req.client_id, 0);
+    return;
+  }
+
+  esp_err_t err = push_led_ring_to_slave(client, &req);
+  if (err == ESP_OK) {
+    ESP_LOGI(TAG, "LED ring mode %lu → slave %lu", (unsigned long)mode,
+             (unsigned long)req.client_id);
+  } else {
+    ESP_LOGW(TAG, "LED ring to slave %lu failed: %s",
+             (unsigned long)req.client_id, esp_err_to_name(err));
+  }
+  reply(err == ESP_OK, mode, req.progress, req.digit, req.client_id,
+        err == ESP_OK ? 1 : 0);
+}
+
+void cmd_led_ring_register(void) {
+  uart_cmd_register(alox_MessageType_LED_RING, handle_led_ring);
+}

main/cmd/cmd_led_ring.h

@@ -0,0 +1,12 @@
+#ifndef CMD_LED_RING_H
+#define CMD_LED_RING_H
+
+#include <stdbool.h>
+#include "uart_messages.pb.h"
+
+/** Apply LED ring command locally (master or slave). */
+bool cmd_led_ring_apply(const alox_LedRingProgressRequest *req);
+
+void cmd_led_ring_register(void);
+
+#endif

main/cmd/cmd_ota.c

@@ -81,8 +81,6 @@ static const ota_espnow_progress_cbs_t s_dist_progress = {
 static void ota_prepare_task(void *param) {
   uint32_t total_size = (uint32_t)(uintptr_t)param;
 
-  send_ota_status(OTA_UART_ST_PREPARING, 0);
-
   int slot = ota_uart_prepare(total_size);
   if (slot < 0) {
     send_ota_failed(1);
@@ -116,27 +114,32 @@ static void handle_ota_start(const uint8_t *data, size_t len) {
 
   const alox_OtaStartPayload *req_ptr =
       UART_CMD_REQ(&uart_msg, alox_UartMessage_ota_start_tag, ota_start);
-  if (req_ptr != NULL) {
-    req = *req_ptr;
+  if (req_ptr == NULL) {
+    ESP_LOGW(TAG, "OTA_START: missing ota_start payload");
+    send_ota_failed(3);
+    return;
   }
+  req = *req_ptr;
 
   if (req.total_size == 0) {
     ESP_LOGW(TAG, "OTA_START: total_size required");
-    send_ota_failed( 3);
+    send_ota_failed(3);
     return;
   }
 
   if (ota_uart_is_active()) {
     ESP_LOGW(TAG, "OTA_START while session active");
-    send_ota_failed( 4);
+    send_ota_failed(4);
     return;
   }
 
+  send_ota_status(OTA_UART_ST_PREPARING, 0);
+
   if (xTaskCreate(ota_prepare_task, "ota_prepare", OTA_PREPARE_STACK,
                   (void *)(uintptr_t)req.total_size, OTA_PREPARE_PRIO,
                   NULL) != pdPASS) {
     ESP_LOGE(TAG, "failed to create ota_prepare task");
-    send_ota_failed( 5);
+    send_ota_failed(5);
   }
 }
 
@@ -172,8 +175,18 @@ static void handle_ota_payload(const uint8_t *data, size_t len) {
     return;
   }
 
-  ota_feed_result_t r =
-      ota_uart_feed(req_ptr->data.bytes, req_ptr->data.size);
+  ota_feed_result_t r = ota_uart_feed_chunk(req_ptr->seq, req_ptr->data.bytes,
+                                            req_ptr->data.size);
+  if (r == OTA_FEED_SEQ_GAP) {
+    send_ota_failed(16);
+    return;
+  }
+  if (r == OTA_FEED_SEQ_DUP) {
+    if (ota_uart_block_ready_for_reack()) {
+      send_ota_status(OTA_UART_ST_BLOCK_ACK, 0);
+    }
+    return;
+  }
   if (r == OTA_FEED_ERROR) {
     send_ota_failed( 13);
     return;
@@ -186,15 +199,6 @@ static void handle_ota_payload(const uint8_t *data, size_t len) {
     led_ring_show_ota_progress(done, total, OTA_LED_UART_R, OTA_LED_UART_G,
                                OTA_LED_UART_B);
     send_ota_status(OTA_UART_ST_BLOCK_ACK, 0);
-    return;
-  }
-
-  if (r == OTA_FEED_OK) {
-    uint32_t total = ota_uart_total_size();
-    if (total > 0) {
-      led_ring_show_ota_progress(ota_uart_bytes_received(), total,
-                                 OTA_LED_UART_R, OTA_LED_UART_G, OTA_LED_UART_B);
-    }
   }
 }
 
@@ -293,31 +297,28 @@ static void handle_ota_end(const uint8_t *data, size_t len) {
   }
 }
 
-static void handle_ota_start_espnow(const uint8_t *data, size_t len) {
-  (void)data;
-  (void)len;
-
-  if (ota_uart_is_active()) {
-    send_ota_failed( 40);
-    return;
-  }
+static void ota_start_espnow_task(void *param) {
+  (void)param;
 
   const esp_partition_t *part = NULL;
   uint32_t image_size = 0;
   if (!ota_uart_get_staged_image(&part, &image_size)) {
-    send_ota_failed( 41);
+    send_ota_failed(41);
+    vTaskDelete(NULL);
     return;
   }
 
-  esp_err_t   err = ota_espnow_distribute(part, image_size, &s_dist_progress);
+  esp_err_t err = ota_espnow_distribute(part, image_size, &s_dist_progress);
   if (err != ESP_OK) {
-    send_ota_failed( 42);
+    send_ota_failed(42);
+    vTaskDelete(NULL);
     return;
   }
 
   err = ota_uart_apply_boot();
   if (err != ESP_OK) {
-    send_ota_failed( (uint32_t)err);
+    send_ota_failed((uint32_t)err);
+    vTaskDelete(NULL);
     return;
   }
 
@@ -329,6 +330,30 @@ static void handle_ota_start_espnow(const uint8_t *data, size_t len) {
   response.payload.ota_status.error = 0;
   uart_cmd_send(&response, TAG);
   led_ring_ota_success();
+  vTaskDelete(NULL);
+}
+
+static void handle_ota_start_espnow(const uint8_t *data, size_t len) {
+  (void)data;
+  (void)len;
+
+  if (ota_uart_is_active()) {
+    send_ota_failed(40);
+    return;
+  }
+
+  const esp_partition_t *part = NULL;
+  uint32_t image_size = 0;
+  if (!ota_uart_get_staged_image(&part, &image_size)) {
+    send_ota_failed(41);
+    return;
+  }
+
+  if (xTaskCreate(ota_start_espnow_task, "ota_espnow", OTA_DIST_STACK, NULL,
+                  OTA_DIST_PRIO, NULL) != pdPASS) {
+    ESP_LOGE(TAG, "failed to create ota_start_espnow task");
+    send_ota_failed(43);
+  }
 }
 
 void cmd_ota_register(void) {

main/cmd/cmd_ota_slave_progress.c

@@ -9,13 +9,29 @@ static void handle_ota_slave_progress(const uint8_t *data, size_t len) {
   alox_UartMessage uart_msg;
   uint32_t filter = 0;
 
-  if (uart_cmd_decode(data, len, &uart_msg) == ESP_OK) {
+  if (len > 0) {
+    if (uart_cmd_decode(data, len, &uart_msg) != ESP_OK) {
+      ESP_LOGW(TAG, "decode failed");
+      alox_UartMessage response;
+      uart_cmd_init_response(
+          &response, alox_MessageType_OTA_SLAVE_PROGRESS,
+          alox_UartMessage_ota_slave_progress_response_tag);
+      uart_cmd_send(&response, TAG);
+      return;
+    }
     const alox_OtaSlaveProgressRequest *req =
         UART_CMD_REQ(&uart_msg, alox_UartMessage_ota_slave_progress_request_tag,
                      ota_slave_progress_request);
-    if (req != NULL) {
-      filter = req->client_id;
+    if (req == NULL) {
+      ESP_LOGW(TAG, "missing ota_slave_progress_request");
+      alox_UartMessage response;
+      uart_cmd_init_response(
+          &response, alox_MessageType_OTA_SLAVE_PROGRESS,
+          alox_UartMessage_ota_slave_progress_response_tag);
+      uart_cmd_send(&response, TAG);
+      return;
     }
+    filter = req->client_id;
   }
 
   alox_UartMessage response;

main/cmd/cmd_set_log_level.c

@@ -0,0 +1,51 @@
+#include "cmd_set_log_level.h"
+#include "esp_log.h"
+#include "uart_cmd.h"
+
+static const char *TAG = "[LOG_LVL]";
+
+static bool valid_level(uint32_t level) { return level <= ESP_LOG_VERBOSE; }
+
+static void reply(uint32_t level, bool success) {
+  alox_UartMessage response;
+  uart_cmd_init_response(&response, alox_MessageType_SET_LOG_LEVEL,
+                         alox_UartMessage_set_log_level_response_tag);
+  response.payload.set_log_level_response.success = success;
+  response.payload.set_log_level_response.level = level;
+  uart_cmd_send(&response, TAG);
+}
+
+static void handle_set_log_level(const uint8_t *data, size_t len) {
+  alox_UartMessage uart_msg;
+  alox_SetLogLevelRequest req = alox_SetLogLevelRequest_init_zero;
+
+  if (uart_cmd_decode(data, len, &uart_msg) != ESP_OK) {
+    ESP_LOGW(TAG, "decode failed");
+    reply((uint32_t)esp_log_level_get("*"), false);
+    return;
+  }
+
+  const alox_SetLogLevelRequest *req_ptr = UART_CMD_REQ(
+      &uart_msg, alox_UartMessage_set_log_level_request_tag, set_log_level_request);
+  if (req_ptr != NULL) {
+    req = *req_ptr;
+  }
+
+  if (req.write) {
+    if (!valid_level(req.level)) {
+      ESP_LOGW(TAG, "invalid level %lu", (unsigned long)req.level);
+      reply((uint32_t)esp_log_level_get("*"), false);
+      return;
+    }
+    esp_log_level_set("*", (esp_log_level_t)req.level);
+    ESP_LOGI(TAG, "global log level set to %lu", (unsigned long)req.level);
+    reply(req.level, true);
+    return;
+  }
+
+  reply((uint32_t)esp_log_level_get("*"), true);
+}
+
+void cmd_set_log_level_register(void) {
+  uart_cmd_register(alox_MessageType_SET_LOG_LEVEL, handle_set_log_level);
+}

main/cmd/cmd_set_log_level.h

@@ -0,0 +1,6 @@
+#ifndef CMD_SET_LOG_LEVEL_H
+#define CMD_SET_LOG_LEVEL_H
+
+void cmd_set_log_level_register(void);
+
+#endif

main/cmd/cmd_tap_notify.c

@@ -0,0 +1,118 @@
+#include "client_registry.h"
+#include "cmd_tap_notify.h"
+#include "esp_log.h"
+#include "esp_now_comm.h"
+#include "uart_cmd.h"
+
+static const char *TAG = "[TAP_NOTIFY]";
+
+static void reply(uint32_t client_id, bool success, uint32_t slaves_updated,
+                  bool single, bool double_tap, bool triple) {
+  alox_UartMessage response;
+  uart_cmd_init_response(&response, alox_MessageType_TAP_NOTIFY,
+                         alox_UartMessage_tap_notify_response_tag);
+  response.payload.tap_notify_response.client_id = client_id;
+  response.payload.tap_notify_response.success = success;
+  response.payload.tap_notify_response.slaves_updated = slaves_updated;
+  response.payload.tap_notify_response.single = single;
+  response.payload.tap_notify_response.double_tap = double_tap;
+  response.payload.tap_notify_response.triple = triple;
+  uart_cmd_send(&response, TAG);
+}
+
+static esp_err_t push_tap_notify_to_slave(const client_info_t *client,
+                                          bool single, bool double_tap,
+                                          bool triple) {
+  if (client == NULL) {
+    return ESP_ERR_INVALID_ARG;
+  }
+  esp_err_t err =
+      client_registry_set_tap_notify(client->id, single, double_tap, triple);
+  if (err != ESP_OK) {
+    return err;
+  }
+  return esp_now_comm_send_tap_notify(client->mac, client->id, single,
+                                      double_tap, triple);
+}
+
+static void handle_tap_notify(const uint8_t *data, size_t len) {
+  alox_UartMessage uart_msg;
+  alox_TapNotifyRequest req = alox_TapNotifyRequest_init_zero;
+
+  if (len > 0) {
+    if (uart_cmd_decode(data, len, &uart_msg) != ESP_OK) {
+      ESP_LOGW(TAG, "decode failed");
+      reply(0, false, 0, false, false, false);
+      return;
+    }
+    const alox_TapNotifyRequest *req_ptr = UART_CMD_REQ(
+        &uart_msg, alox_UartMessage_tap_notify_request_tag, tap_notify_request);
+    if (req_ptr == NULL) {
+      ESP_LOGW(TAG, "missing tap_notify_request");
+      reply(0, false, 0, false, false, false);
+      return;
+    }
+    req = *req_ptr;
+  }
+
+  if (req.write) {
+    if (req.all_clients) {
+      size_t n = client_registry_set_tap_notify_all(req.single, req.double_tap,
+                                                    req.triple);
+      uint32_t sent = 0;
+
+      for (size_t i = 0; i < client_registry_count(); i++) {
+        const client_info_t *client = client_registry_at(i);
+        if (client == NULL) {
+          continue;
+        }
+        if (esp_now_comm_send_tap_notify(client->mac, client->id, req.single,
+                                         req.double_tap,
+                                         req.triple) == ESP_OK) {
+          sent++;
+        }
+      }
+
+      ESP_LOGI(TAG, "tap notify single=%d double=%d triple=%d for %u/%u slaves",
+               req.single, req.double_tap, req.triple, (unsigned)sent,
+               (unsigned)n);
+      reply(0, sent > 0, sent, req.single, req.double_tap, req.triple);
+      return;
+    }
+
+    if (req.client_id == 0) {
+      ESP_LOGW(TAG, "client_id required (or all_clients)");
+      reply(0, false, 0, req.single, req.double_tap, req.triple);
+      return;
+    }
+
+    const client_info_t *client = client_registry_find_by_id(req.client_id);
+    if (client == NULL) {
+      ESP_LOGW(TAG, "client id %lu not found", (unsigned long)req.client_id);
+      reply(req.client_id, false, 0, req.single, req.double_tap, req.triple);
+      return;
+    }
+
+    esp_err_t err =
+        push_tap_notify_to_slave(client, req.single, req.double_tap, req.triple);
+    reply(req.client_id, err == ESP_OK, err == ESP_OK ? 1u : 0u, req.single,
+          req.double_tap, req.triple);
+    return;
+  }
+
+  if (req.all_clients || req.client_id == 0) {
+    reply(0, false, 0, false, false, false);
+    return;
+  }
+
+  bool single = false;
+  bool double_tap = false;
+  bool triple = false;
+  esp_err_t err = client_registry_get_tap_notify(req.client_id, &single,
+                                                 &double_tap, &triple);
+  reply(req.client_id, err == ESP_OK, 0, single, double_tap, triple);
+}
+
+void cmd_tap_notify_register(void) {
+  uart_cmd_register(alox_MessageType_TAP_NOTIFY, handle_tap_notify);
+}

main/cmd/cmd_tap_notify.h

@@ -0,0 +1,6 @@
+#ifndef CMD_TAP_NOTIFY_H
+#define CMD_TAP_NOTIFY_H
+
+void cmd_tap_notify_register(void);
+
+#endif

main/cmd_led_ring.c

@@ -1,146 +0,0 @@
-#include "cmd_led_ring.h"
-#include "esp_log.h"
-#include "led_ring.h"
-#include "uart_cmd.h"
-
-static const char *TAG = "[LED_RING_CMD]";
-
-#define LED_RING_MODE_CLEAR    0
-#define LED_RING_MODE_PROGRESS 1
-#define LED_RING_MODE_DIGIT    2
-#define LED_RING_MODE_BLINK    3
-#define LED_RING_MODE_FIND_ME  4
-
-static uint8_t clamp_u8(uint32_t v) {
-  if (v > 255) {
-    return 255;
-  }
-  return (uint8_t)v;
-}
-
-static uint8_t clamp_progress(uint32_t v) {
-  if (v > 100) {
-    return 100;
-  }
-  return (uint8_t)v;
-}
-
-static uint8_t resolve_intensity(uint32_t intensity) {
-  if (intensity == 0) {
-    return LED_RING_DEFAULT_INTENSITY;
-  }
-  return clamp_u8(intensity);
-}
-
-static void reply(bool success, uint32_t mode, uint32_t progress, uint32_t digit) {
-  alox_UartMessage response;
-  uart_cmd_init_response(&response, alox_MessageType_LED_RING,
-                         alox_UartMessage_led_ring_progress_response_tag);
-  response.payload.led_ring_progress_response.success = success;
-  response.payload.led_ring_progress_response.mode = mode;
-  response.payload.led_ring_progress_response.progress = progress;
-  response.payload.led_ring_progress_response.digit = digit;
-  uart_cmd_send(&response, TAG);
-}
-
-static void handle_led_ring(const uint8_t *data, size_t len) {
-  alox_UartMessage uart_msg;
-  alox_LedRingProgressRequest req = alox_LedRingProgressRequest_init_zero;
-
-  if (uart_cmd_decode(data, len, &uart_msg) != ESP_OK) {
-    ESP_LOGW(TAG, "decode failed");
-    reply(false, 0, 0, 0);
-    return;
-  }
-
-  const alox_LedRingProgressRequest *req_ptr = UART_CMD_REQ(
-      &uart_msg, alox_UartMessage_led_ring_progress_request_tag,
-      led_ring_progress_request);
-  if (req_ptr != NULL) {
-    req = *req_ptr;
-  }
-
-  uint32_t mode = req.mode;
-  uint8_t r = clamp_u8(req.r);
-  uint8_t g = clamp_u8(req.g);
-  uint8_t b = clamp_u8(req.b);
-  uint8_t intensity = resolve_intensity(req.intensity);
-
-  led_command_t cmd = {0};
-
-  switch (mode) {
-  case LED_RING_MODE_CLEAR:
-    cmd.mode = LED_CMD_CLEAR;
-    led_ring_send_command(&cmd);
-    ESP_LOGI(TAG, "clear");
-    reply(true, mode, 0, 0);
-    return;
-
-  case LED_RING_MODE_PROGRESS: {
-    uint8_t progress = clamp_progress(req.progress);
-    cmd.mode = LED_CMD_PROGRESS;
-    cmd.progress = progress;
-    cmd.r = r;
-    cmd.g = g;
-    cmd.b = b;
-    cmd.intensity = intensity;
-    led_ring_send_command(&cmd);
-    ESP_LOGI(TAG, "progress %u%% rgb=%u,%u,%u", (unsigned)progress,
-             (unsigned)r, (unsigned)g, (unsigned)b);
-    reply(true, mode, progress, 0);
-    return;
-  }
-
-  case LED_RING_MODE_DIGIT: {
-    if (req.digit > 10) {
-      ESP_LOGW(TAG, "digit %lu out of range", (unsigned long)req.digit);
-      reply(false, mode, 0, req.digit);
-      return;
-    }
-    cmd.mode = LED_CMD_SET_DIGIT;
-    cmd.value = (uint8_t)req.digit;
-    cmd.r = r;
-    cmd.g = g;
-    cmd.b = b;
-    cmd.intensity = intensity;
-    led_ring_send_command(&cmd);
-    ESP_LOGI(TAG, "digit %u rgb=%u,%u,%u", (unsigned)cmd.value, (unsigned)r,
-             (unsigned)g, (unsigned)b);
-    reply(true, mode, 0, req.digit);
-    return;
-  }
-
-  case LED_RING_MODE_FIND_ME:
-    led_ring_find_me();
-    ESP_LOGI(TAG, "find-me");
-    reply(true, mode, 0, 0);
-    return;
-
-  case LED_RING_MODE_BLINK: {
-    cmd.mode = LED_CMD_BLINK;
-    cmd.r = r;
-    cmd.g = g;
-    cmd.b = b;
-    cmd.intensity = intensity;
-    cmd.blink_ms = (uint16_t)(req.blink_ms > 0 ? req.blink_ms : 350);
-    cmd.blink_count = req.blink_count > 0 ? (uint8_t)req.blink_count : 1;
-    if (cmd.blink_count == 0) {
-      cmd.blink_count = 1;
-    }
-    led_ring_send_command(&cmd);
-    ESP_LOGI(TAG, "blink x%u %u ms rgb=%u,%u,%u", (unsigned)cmd.blink_count,
-             (unsigned)cmd.blink_ms, (unsigned)r, (unsigned)g, (unsigned)b);
-    reply(true, mode, 0, 0);
-    return;
-  }
-
-  default:
-    ESP_LOGW(TAG, "unknown mode %lu", (unsigned long)mode);
-    reply(false, mode, 0, 0);
-    return;
-  }
-}
-
-void cmd_led_ring_register(void) {
-  uart_cmd_register(alox_MessageType_LED_RING, handle_led_ring);
-}

main/cmd_led_ring.h

@@ -1,6 +0,0 @@
-#ifndef CMD_LED_RING_H
-#define CMD_LED_RING_H
-
-void cmd_led_ring_register(void);
-
-#endif

main/esp_now_comm.c

@@ -1,688 +1,23 @@
-#include "bosch456.h"
-#include "client_registry.h"
 #include "esp_now_comm.h"
-#include "led_ring.h"
-#include "ota_espnow.h"
-#include "pod_reboot.h"
-#include "pod_settings.h"
-#include "esp_now_proto.h"
+#include "client_registry.h"
+#include "esp_now_core.h"
+#include "esp_now_master.h"
+#include "esp_now_slave.h"
 #include "esp_err.h"
-#include "esp_event.h"
 #include "esp_log.h"
-#include "esp_mac.h"
-#include "esp_netif.h"
 #include "esp_now.h"
-#include "esp_wifi.h"
-#include "freertos/FreeRTOS.h"
-#include "freertos/idf_additions.h"
-#include "ota_uart.h"
 #include <stdio.h>
 #include <string.h>
 
-#ifndef POWERPOD_FW_VERSION
-#define POWERPOD_FW_VERSION 1u
-#endif
-
-#define ESPNOW_DISCOVER_INTERVAL_MS 500
-#define ESPNOW_HEARTBEAT_INTERVAL_MS 1000
-#define ESPNOW_HEARTBEAT_MISS_COUNT 3
-#define ESPNOW_CLIENT_TIMEOUT_MS                                               \
-  (ESPNOW_HEARTBEAT_INTERVAL_MS * ESPNOW_HEARTBEAT_MISS_COUNT)
-#define SLAVE_MASTER_LOST_MS (ESPNOW_HEARTBEAT_INTERVAL_MS * 5)
-
-static const uint8_t ESPNOW_BCAST[ESP_NOW_ETH_ALEN] = {0xff, 0xff, 0xff,
-                                                       0xff, 0xff, 0xff};
-
 static const char *TAG = "[ESPNOW]";
 
-static app_config_t s_config;
-static uint8_t s_wifi_channel;
-static uint8_t s_own_mac[ESP_NOW_ETH_ALEN];
-static bool s_slave_joined;
-static uint8_t s_master_mac[ESP_NOW_ETH_ALEN];
-static uint32_t s_last_discover_ms;
-
-static SemaphoreHandle_t s_send_done;
-static bool s_send_cb_ready;
-
-static uint32_t now_ms(void) {
-  return (uint32_t)(xTaskGetTickCount() * portTICK_PERIOD_MS);
-}
-
-static uint8_t network_to_channel(uint8_t network) {
-  if (network < 1 || network > 13) {
-    return 1;
-  }
-  return network;
-}
-
-static bool mac_equal(const uint8_t *a, const uint8_t *b) {
-  return memcmp(a, b, ESP_NOW_ETH_ALEN) == 0;
-}
-
-static void mac_to_str(const uint8_t *mac, char *out, size_t out_len) {
-  snprintf(out, out_len, "%02x:%02x:%02x:%02x:%02x:%02x", mac[0], mac[1],
-           mac[2], mac[3], mac[4], mac[5]);
-}
-
-static esp_err_t ensure_peer(const uint8_t *mac) {
-  if (esp_now_is_peer_exist(mac)) {
-    return ESP_OK;
-  }
-
-  esp_now_peer_info_t peer = {0};
-  memcpy(peer.peer_addr, mac, ESP_NOW_ETH_ALEN);
-  peer.channel = s_wifi_channel;
-  peer.ifidx = WIFI_IF_STA;
-  peer.encrypt = false;
-
-  esp_err_t err = esp_now_add_peer(&peer);
-  if (err != ESP_OK) {
-    ESP_LOGW(TAG, "add peer failed: %s", esp_err_to_name(err));
-  }
-  return err;
-}
-
-static esp_err_t ensure_broadcast_peer(void) { return ensure_peer(ESPNOW_BCAST); }
-
-static esp_err_t send_message_ex(const uint8_t *dest_mac,
-                                 const alox_EspNowMessage *msg, bool wait_done);
-
-static void fill_presence(alox_EspNowSlavePresence *presence) {
-  presence->network = s_config.network;
-  presence->version = POWERPOD_FW_VERSION;
-  presence->slave_id = s_own_mac[5];
-  presence->available = true;
-  presence->used = false;
-  esp_now_proto_setup_presence_encode(presence, s_own_mac);
-}
-
-static void espnow_send_done_cb(const esp_now_send_info_t *tx_info,
-                                esp_now_send_status_t status) {
-  (void)tx_info;
-  (void)status;
-  if (s_send_done != NULL) {
-    xSemaphoreGive(s_send_done);
-  }
-}
-
-static esp_err_t send_message(const uint8_t *dest_mac,
-                              const alox_EspNowMessage *msg) {
-  return send_message_ex(dest_mac, msg, false);
-}
-
-static esp_err_t send_message_ex(const uint8_t *dest_mac,
-                                 const alox_EspNowMessage *msg, bool wait_done) {
-  uint8_t buf[ESPNOW_PB_MAX_SIZE];
-  size_t len = 0;
-
-  esp_err_t err = esp_now_proto_encode(msg, buf, sizeof(buf), &len);
-  if (err != ESP_OK) {
-    ESP_LOGW(TAG, "encode failed");
-    return err;
-  }
-
-  if (len > ESP_NOW_MAX_DATA_LEN) {
-    ESP_LOGW(TAG, "encoded len %u > ESP-NOW max %u", (unsigned)len,
-             (unsigned)ESP_NOW_MAX_DATA_LEN);
-    return ESP_ERR_INVALID_SIZE;
-  }
-
-  if (ensure_peer(dest_mac) != ESP_OK) {
-    return ESP_FAIL;
-  }
-
-  if (wait_done && s_send_cb_ready && s_send_done != NULL) {
-    xSemaphoreTake(s_send_done, 0);
-  }
-
-  err = esp_now_send(dest_mac, buf, len);
-  if (err != ESP_OK) {
-    ESP_LOGW(TAG, "send type=%u failed: %s", (unsigned)msg->type,
-             esp_err_to_name(err));
-    return err;
-  }
-
-  if (wait_done && s_send_cb_ready && s_send_done != NULL) {
-    if (xSemaphoreTake(s_send_done, pdMS_TO_TICKS(50)) != pdTRUE) {
-      ESP_LOGW(TAG, "send type=%u done timeout", (unsigned)msg->type);
-    }
-  }
-  return err;
-}
-
-static esp_err_t send_accel_deadzone(const uint8_t *dest_mac, uint32_t client_id,
-                                     uint32_t deadzone) {
-  alox_EspNowMessage msg = alox_EspNowMessage_init_zero;
-
-  msg.type = alox_EspNowMessageType_ESPNOW_SET_ACCEL_DEADZONE;
-  msg.which_payload = alox_EspNowMessage_accel_deadzone_tag;
-  msg.payload.accel_deadzone.deadzone = deadzone;
-  msg.payload.accel_deadzone.client_id = client_id;
-
-  return send_message(dest_mac, &msg);
-}
-
-static esp_err_t send_unicast_test(const uint8_t *dest_mac, uint32_t seq) {
-  alox_EspNowMessage msg = alox_EspNowMessage_init_zero;
-
-  msg.type = alox_EspNowMessageType_ESPNOW_UNICAST_TEST;
-  msg.which_payload = alox_EspNowMessage_unicast_test_tag;
-  msg.payload.unicast_test.seq = seq;
-
-  return send_message(dest_mac, &msg);
-}
-
-static esp_err_t send_find_me(const uint8_t *dest_mac, uint32_t client_id) {
-  alox_EspNowMessage msg = alox_EspNowMessage_init_zero;
-
-  msg.type = alox_EspNowMessageType_ESPNOW_FIND_ME;
-  msg.which_payload = alox_EspNowMessage_find_me_tag;
-  msg.payload.find_me.client_id = client_id;
-
-  return send_message(dest_mac, &msg);
-}
-
-static esp_err_t send_restart(const uint8_t *dest_mac, uint32_t client_id) {
-  alox_EspNowMessage msg = alox_EspNowMessage_init_zero;
-
-  msg.type = alox_EspNowMessageType_ESPNOW_RESTART;
-  msg.which_payload = alox_EspNowMessage_restart_tag;
-  msg.payload.restart.client_id = client_id;
-
-  return send_message(dest_mac, &msg);
-}
-
-static esp_err_t send_ota_start(const uint8_t *dest_mac, uint32_t total_size) {
-  alox_EspNowMessage msg = alox_EspNowMessage_init_zero;
-
-  msg.type = alox_EspNowMessageType_ESPNOW_OTA_START;
-  msg.which_payload = alox_EspNowMessage_ota_start_tag;
-  msg.payload.ota_start.total_size = total_size;
-
-  return send_message_ex(dest_mac, &msg, true);
-}
-
-static esp_err_t send_ota_payload(const uint8_t *dest_mac, uint32_t seq,
-                                  const uint8_t *data, size_t len) {
-  if (data == NULL || len == 0 || len > OTA_UART_HOST_CHUNK_SIZE) {
-    return ESP_ERR_INVALID_ARG;
-  }
-
-  alox_EspNowMessage msg = alox_EspNowMessage_init_zero;
-
-  msg.type = alox_EspNowMessageType_ESPNOW_OTA_PAYLOAD;
-  msg.which_payload = alox_EspNowMessage_ota_payload_tag;
-  msg.payload.ota_payload.seq = seq;
-  msg.payload.ota_payload.data.size = len;
-  memcpy(msg.payload.ota_payload.data.bytes, data, len);
-
-  return send_message_ex(dest_mac, &msg, true);
-}
-
-static esp_err_t send_ota_end(const uint8_t *dest_mac) {
-  alox_EspNowMessage msg = alox_EspNowMessage_init_zero;
-
-  msg.type = alox_EspNowMessageType_ESPNOW_OTA_END;
-  msg.which_payload = alox_EspNowMessage_ota_end_tag;
-
-  return send_message_ex(dest_mac, &msg, true);
-}
-
-static esp_err_t send_ota_status(const uint8_t *dest_mac, uint32_t status,
-                                 uint32_t bytes_written, uint32_t error) {
-  alox_EspNowMessage msg = alox_EspNowMessage_init_zero;
-
-  msg.type = alox_EspNowMessageType_ESPNOW_OTA_STATUS;
-  msg.which_payload = alox_EspNowMessage_ota_status_tag;
-  msg.payload.ota_status.status = status;
-  msg.payload.ota_status.bytes_written = bytes_written;
-  msg.payload.ota_status.error = error;
-
-  return send_message_ex(dest_mac, &msg, true);
-}
-
-esp_err_t esp_now_comm_send_ota_start(const uint8_t mac[CLIENT_MAC_LEN],
-                                      uint32_t total_size) {
-  if (mac == NULL || !s_config.master) {
-    return ESP_ERR_INVALID_STATE;
-  }
-  return send_ota_start(mac, total_size);
-}
-
-esp_err_t esp_now_comm_send_ota_payload(const uint8_t mac[CLIENT_MAC_LEN],
-                                        uint32_t seq, const uint8_t *data,
-                                        size_t len) {
-  if (mac == NULL || !s_config.master) {
-    return ESP_ERR_INVALID_STATE;
-  }
-  return send_ota_payload(mac, seq, data, len);
-}
-
-esp_err_t esp_now_comm_send_ota_end(const uint8_t mac[CLIENT_MAC_LEN]) {
-  if (mac == NULL || !s_config.master) {
-    return ESP_ERR_INVALID_STATE;
-  }
-  return send_ota_end(mac);
-}
-
-esp_err_t esp_now_comm_send_ota_status(const uint8_t master_mac[CLIENT_MAC_LEN],
-                                       uint32_t status, uint32_t bytes_written,
-                                       uint32_t error) {
-  if (master_mac == NULL || s_config.master) {
-    return ESP_ERR_INVALID_STATE;
-  }
-  return send_ota_status(master_mac, status, bytes_written, error);
-}
-
-bool esp_now_comm_get_master_mac(uint8_t mac_out[CLIENT_MAC_LEN]) {
-  if (mac_out == NULL || s_config.master || !s_slave_joined) {
-    return false;
-  }
-  memcpy(mac_out, s_master_mac, CLIENT_MAC_LEN);
-  return true;
-}
-
-esp_err_t esp_now_comm_send_restart(const uint8_t mac[CLIENT_MAC_LEN],
-                                    uint32_t client_id) {
-  if (mac == NULL || !s_config.master) {
-    return ESP_ERR_INVALID_STATE;
-  }
-
-  char mac_str[18];
-  mac_to_str(mac, mac_str, sizeof(mac_str));
-  esp_err_t err = send_restart(mac, client_id);
-  if (err == ESP_OK) {
-    ESP_LOGI(TAG, "unicast RESTART to %s client_id=%lu", mac_str,
-             (unsigned long)client_id);
-  } else {
-    ESP_LOGW(TAG, "unicast RESTART to %s failed: %s", mac_str,
-             esp_err_to_name(err));
-  }
-  return err;
-}
-
-esp_err_t esp_now_comm_send_find_me(const uint8_t mac[CLIENT_MAC_LEN],
-                                    uint32_t client_id) {
-  if (mac == NULL || !s_config.master) {
-    return ESP_ERR_INVALID_STATE;
-  }
-
-  char mac_str[18];
-  mac_to_str(mac, mac_str, sizeof(mac_str));
-  esp_err_t err = send_find_me(mac, client_id);
-  if (err == ESP_OK) {
-    ESP_LOGI(TAG, "unicast FIND_ME to %s client_id=%lu", mac_str,
-             (unsigned long)client_id);
-  } else {
-    ESP_LOGW(TAG, "unicast FIND_ME to %s failed: %s", mac_str,
-             esp_err_to_name(err));
-  }
-  return err;
-}
-
-esp_err_t esp_now_comm_send_unicast_test(const uint8_t mac[CLIENT_MAC_LEN],
-                                         uint32_t seq) {
-  if (mac == NULL || !s_config.master) {
-    return ESP_ERR_INVALID_STATE;
-  }
-
-  char mac_str[18];
-  mac_to_str(mac, mac_str, sizeof(mac_str));
-  esp_err_t err = send_unicast_test(mac, seq);
-  if (err == ESP_OK) {
-    ESP_LOGI(TAG, "unicast TEST to %s seq=%lu", mac_str, (unsigned long)seq);
-  } else {
-    ESP_LOGW(TAG, "unicast TEST to %s failed: %s", mac_str, esp_err_to_name(err));
-  }
-  return err;
-}
-
-esp_err_t esp_now_comm_send_accel_deadzone(const uint8_t mac[CLIENT_MAC_LEN],
-                                           uint32_t client_id, uint32_t deadzone) {
-  if (mac == NULL || !s_config.master) {
-    return ESP_ERR_INVALID_STATE;
-  }
-
-  char mac_str[18];
-  mac_to_str(mac, mac_str, sizeof(mac_str));
-  esp_err_t err = send_accel_deadzone(mac, client_id, deadzone);
-  if (err == ESP_OK) {
-    ESP_LOGI(TAG, "unicast SET_ACCEL_DEADZONE to %s: deadzone=%lu client_id=%lu",
-             mac_str, (unsigned long)deadzone, (unsigned long)client_id);
-  } else {
-    ESP_LOGW(TAG, "unicast SET_ACCEL_DEADZONE to %s failed: %s", mac_str,
-             esp_err_to_name(err));
-  }
-  return err;
-}
-
-static void send_presence(const uint8_t *dest_mac,
-                          alox_EspNowMessageType type) {
-  alox_EspNowMessage msg = alox_EspNowMessage_init_zero;
-  alox_EspNowSlavePresence *presence = NULL;
-
-  msg.type = type;
-  if (type == alox_EspNowMessageType_ESPNOW_SLAVE_INFO) {
-    msg.which_payload = alox_EspNowMessage_slave_info_tag;
-    presence = &msg.payload.slave_info;
-  } else {
-    msg.which_payload = alox_EspNowMessage_heartbeat_tag;
-    presence = &msg.payload.heartbeat;
-  }
-
-  fill_presence(presence);
-  send_message(dest_mac, &msg);
-}
-
-static void slave_reset_join(void) {
-  s_slave_joined = false;
-  memset(s_master_mac, 0, sizeof(s_master_mac));
-  s_last_discover_ms = 0;
-}
-
-static void handle_slave_unicast_test(const uint8_t *master_mac,
-                                      const alox_EspNowUnicastTest *test) {
-  char mac_str[18];
-  mac_to_str(master_mac, mac_str, sizeof(mac_str));
-
-  ESP_LOGI(TAG, "UNICAST TEST OK from master %s seq=%lu (joined=%d)",
-           mac_str, (unsigned long)test->seq, (int)s_slave_joined);
-}
-
-static void handle_slave_restart(const uint8_t *master_mac,
-                                 const alox_EspNowRestart *req) {
-  uint32_t my_id = s_own_mac[5];
-
-  if (req->client_id != 0 && req->client_id != my_id) {
-    return;
-  }
-
-  if (s_slave_joined && !mac_equal(master_mac, s_master_mac)) {
-    return;
-  }
-
-  char mac_str[18];
-  mac_to_str(master_mac, mac_str, sizeof(mac_str));
-  ESP_LOGI(TAG, "RESTART from master %s (id=%lu)", mac_str, (unsigned long)my_id);
-  pod_schedule_restart();
-}
-
-static void handle_slave_find_me(const uint8_t *master_mac,
-                                 const alox_EspNowFindMe *req) {
-  uint32_t my_id = s_own_mac[5];
-
-  if (req->client_id != 0 && req->client_id != my_id) {
-    return;
-  }
-
-  if (s_slave_joined && !mac_equal(master_mac, s_master_mac)) {
-    return;
-  }
-
-  char mac_str[18];
-  mac_to_str(master_mac, mac_str, sizeof(mac_str));
-  ESP_LOGI(TAG, "FIND_ME from master %s (id=%lu)", mac_str, (unsigned long)my_id);
-  led_ring_find_me();
-}
-
-static void handle_slave_accel_deadzone(const uint8_t *master_mac,
-                                        const alox_EspNowAccelDeadzone *cfg) {
-  uint32_t my_id = s_own_mac[5];
-
-  if (cfg->client_id != 0 && cfg->client_id != my_id) {
-    return;
-  }
-
-  if (s_slave_joined && !mac_equal(master_mac, s_master_mac)) {
-    return;
-  }
-
-  char mac_str[18];
-  mac_to_str(master_mac, mac_str, sizeof(mac_str));
-
-  ESP_LOGI(TAG,
-           "accel deadzone from master %s: %lu LSB id=%lu (sensor %s)",
-           mac_str, (unsigned long)cfg->deadzone, (unsigned long)my_id,
-           bma456_is_ready() ? "ok" : "not installed");
-
-  bma456_set_accel_deadzone(cfg->deadzone);
-  if (pod_settings_save_accel_deadzone(cfg->deadzone) != ESP_OK) {
-    ESP_LOGW(TAG, "slave deadzone %lu applied but not saved to NVS",
-             (unsigned long)cfg->deadzone);
-  }
-}
-
-static void handle_client_presence(const alox_EspNowSlavePresence *presence,
-                                   const uint8_t mac[CLIENT_MAC_LEN]) {
-  if (presence->network != s_config.network) {
-    return;
-  }
-
-  ensure_peer(mac);
-
-  bool is_new = false;
-  bool reactivated = false;
-  esp_err_t err = client_registry_heartbeat(
-      mac, presence->slave_id, presence->version, presence->used, &is_new,
-      &reactivated);
-  if (err != ESP_OK) {
-    ESP_LOGW(TAG, "client registry full");
-    return;
-  }
-
-  char mac_str[18];
-  mac_to_str(mac, mac_str, sizeof(mac_str));
-  if (is_new) {
-    ESP_LOGI(TAG, "client registered id=%lu mac=%s ver=%lu",
-             (unsigned long)presence->slave_id, mac_str,
-             (unsigned long)presence->version);
-  } else if (reactivated) {
-    ESP_LOGI(TAG, "client reconnected id=%lu mac=%s",
-             (unsigned long)presence->slave_id, mac_str);
-  }
-}
-
-static void handle_discover(const uint8_t *sender_mac,
-                            const alox_EspNowDiscover *discover) {
-  if (discover->network != s_config.network) {
-    return;
-  }
-
-  uint32_t now = now_ms();
-
-  if (s_slave_joined) {
-    if (!mac_equal(sender_mac, s_master_mac)) {
-      return;
-    }
-    if ((now - s_last_discover_ms) <= SLAVE_MASTER_LOST_MS) {
-      s_last_discover_ms = now;
-      return;
-    }
-    ESP_LOGW(TAG, "master lost, rejoining");
-    slave_reset_join();
-  }
-
-  memcpy(s_master_mac, sender_mac, ESP_NOW_ETH_ALEN);
-  s_slave_joined = true;
-  s_last_discover_ms = now;
-  ensure_peer(sender_mac);
-
-  char mac_str[18];
-  mac_to_str(sender_mac, mac_str, sizeof(mac_str));
-  ESP_LOGI(TAG, "joined network %u, master %s", (unsigned)discover->network,
-           mac_str);
-
-  send_presence(sender_mac, alox_EspNowMessageType_ESPNOW_SLAVE_INFO);
-}
-
-static void slave_check_master_timeout(void) {
-  if (!s_slave_joined) {
-    return;
-  }
-
-  uint32_t now = now_ms();
-  if (s_last_discover_ms == 0) {
-    return;
-  }
-
-  if ((now - s_last_discover_ms) > SLAVE_MASTER_LOST_MS) {
-    ESP_LOGW(TAG, "no master discover for %u ms, reconnecting",
-             (unsigned)(now - s_last_discover_ms));
-    slave_reset_join();
-  }
-}
-
-static void slave_heartbeat_task(void *param) {
-  (void)param;
-
-  ESP_LOGI(TAG, "slave heartbeat task (interval %u ms)",
-           (unsigned)ESPNOW_HEARTBEAT_INTERVAL_MS);
-
-  while (1) {
-    vTaskDelay(pdMS_TO_TICKS(ESPNOW_HEARTBEAT_INTERVAL_MS));
-
-    slave_check_master_timeout();
-
-    if (!s_slave_joined) {
-      continue;
-    }
-
-    send_presence(s_master_mac, alox_EspNowMessageType_ESPNOW_HEARTBEAT);
-  }
-}
-
-static void master_monitor_task(void *param) {
-  (void)param;
-
-  ESP_LOGI(TAG, "master monitor task (timeout %u ms)",
-           (unsigned)ESPNOW_CLIENT_TIMEOUT_MS);
-
-  while (1) {
-    vTaskDelay(pdMS_TO_TICKS(ESPNOW_HEARTBEAT_INTERVAL_MS));
-    client_registry_check_timeouts(ESPNOW_CLIENT_TIMEOUT_MS);
-  }
-}
-
 static void espnow_recv_cb(const esp_now_recv_info_t *info, const uint8_t *data,
                            int len) {
-  if (info == NULL || data == NULL || len <= 0) {
-    return;
+  if (esp_now_core_is_master()) {
+    esp_now_master_on_recv(info, data, len);
+  } else {
+    esp_now_slave_on_recv(info, data, len);
   }
-
-  if (!s_config.master) {
-    alox_EspNowMessage msg = alox_EspNowMessage_init_zero;
-
-    if (esp_now_proto_decode(data, (size_t)len, &msg) != ESP_OK) {
-      ESP_LOGW(TAG, "slave: ESP-NOW decode failed (%d bytes)", len);
-      return;
-    }
-
-    if (s_slave_joined && mac_equal(info->src_addr, s_master_mac)) {
-      ensure_peer(info->src_addr);
-    }
-
-    switch (msg.which_payload) {
-    case alox_EspNowMessage_discover_tag:
-      handle_discover(info->src_addr, &msg.payload.discover);
-      break;
-    case alox_EspNowMessage_unicast_test_tag:
-      handle_slave_unicast_test(info->src_addr, &msg.payload.unicast_test);
-      break;
-    case alox_EspNowMessage_accel_deadzone_tag:
-      handle_slave_accel_deadzone(info->src_addr, &msg.payload.accel_deadzone);
-      break;
-    case alox_EspNowMessage_find_me_tag:
-      if (!s_slave_joined || !mac_equal(info->src_addr, s_master_mac)) {
-        break;
-      }
-      handle_slave_find_me(info->src_addr, &msg.payload.find_me);
-      break;
-    case alox_EspNowMessage_restart_tag:
-      if (!s_slave_joined || !mac_equal(info->src_addr, s_master_mac)) {
-        break;
-      }
-      handle_slave_restart(info->src_addr, &msg.payload.restart);
-      break;
-    case alox_EspNowMessage_ota_start_tag:
-    case alox_EspNowMessage_ota_payload_tag:
-    case alox_EspNowMessage_ota_end_tag:
-      if (!s_slave_joined || !mac_equal(info->src_addr, s_master_mac)) {
-        break;
-      }
-      if (msg.which_payload == alox_EspNowMessage_ota_start_tag) {
-        ota_espnow_slave_on_start(info->src_addr, &msg.payload.ota_start);
-      } else if (msg.which_payload == alox_EspNowMessage_ota_payload_tag) {
-        ota_espnow_slave_on_payload(info->src_addr, &msg.payload.ota_payload);
-      } else {
-        ota_espnow_slave_on_end(info->src_addr);
-      }
-      break;
-    default:
-      ESP_LOGW(TAG, "slave: unhandled ESP-NOW which=%u type=%u", msg.which_payload,
-               (unsigned)msg.type);
-      break;
-    }
-    return;
-  }
-
-  alox_EspNowMessage msg = alox_EspNowMessage_init_zero;
-
-  if (esp_now_proto_decode(data, (size_t)len, &msg) != ESP_OK) {
-    ESP_LOGW(TAG, "master: ESP-NOW decode failed (%d bytes)", len);
-    return;
-  }
-
-  if (msg.which_payload == alox_EspNowMessage_ota_status_tag) {
-    ensure_peer(info->src_addr);
-    ota_espnow_master_on_status(info->src_addr, &msg.payload.ota_status);
-    return;
-  }
-
-  const alox_EspNowSlavePresence *presence = esp_now_proto_get_presence(&msg);
-  if (presence != NULL) {
-    /* Registry key is the ESP-NOW sender MAC, not the optional protobuf mac field. */
-    ensure_peer(info->src_addr);
-    handle_client_presence(presence, info->src_addr);
-  }
-}
-
-static void master_discover_task(void *param) {
-  (void)param;
-
-  alox_EspNowMessage msg = alox_EspNowMessage_init_zero;
-  msg.type = alox_EspNowMessageType_ESPNOW_DISCOVER;
-  msg.which_payload = alox_EspNowMessage_discover_tag;
-  msg.payload.discover.network = s_config.network;
-
-  ESP_LOGI(TAG, "master discover task on network %u ch %u",
-           (unsigned)s_config.network, (unsigned)s_wifi_channel);
-
-  while (1) {
-    send_message(ESPNOW_BCAST, &msg);
-    vTaskDelay(pdMS_TO_TICKS(ESPNOW_DISCOVER_INTERVAL_MS));
-  }
-}
-
-static esp_err_t init_wifi_stack(uint8_t channel) {
-  ESP_ERROR_CHECK(esp_netif_init());
-  ESP_ERROR_CHECK(esp_event_loop_create_default());
-
-  wifi_init_config_t cfg = WIFI_INIT_CONFIG_DEFAULT();
-  ESP_ERROR_CHECK(esp_wifi_init(&cfg));
-
-  wifi_config_t wifi_config = {0};
-  wifi_config.sta.channel = channel;
-  wifi_config.sta.scan_method = WIFI_ALL_CHANNEL_SCAN;
-  wifi_config.sta.sort_method = WIFI_CONNECT_AP_BY_SIGNAL;
-
-  ESP_ERROR_CHECK(esp_wifi_set_mode(WIFI_MODE_STA));
-  ESP_ERROR_CHECK(esp_wifi_set_config(WIFI_IF_STA, &wifi_config));
-  ESP_ERROR_CHECK(esp_wifi_start());
-  ESP_ERROR_CHECK(esp_wifi_set_ps(WIFI_PS_NONE));
-  ESP_ERROR_CHECK(esp_wifi_set_channel(channel, WIFI_SECOND_CHAN_NONE));
-
-  return ESP_OK;
 }
 
 esp_err_t esp_now_comm_init(const app_config_t *config) {
@@ -690,56 +25,27 @@ esp_err_t esp_now_comm_init(const app_config_t *config) {
     return ESP_ERR_INVALID_ARG;
   }
 
-  memset(&s_config, 0, sizeof(s_config));
-  memcpy(&s_config, config, sizeof(s_config));
+  esp_now_core_store_config(config);
   client_registry_init();
-  slave_reset_join();
 
-  s_wifi_channel = network_to_channel(config->network);
-  ESP_ERROR_CHECK(esp_read_mac(s_own_mac, ESP_MAC_WIFI_STA));
-
-  char mac_str[18];
-  mac_to_str(s_own_mac, mac_str, sizeof(mac_str));
-  ESP_LOGI(TAG, "role=%s network=%u channel=%u mac=%s",
-           config->master ? "master" : "slave", (unsigned)config->network,
-           (unsigned)s_wifi_channel, mac_str);
-
-  esp_err_t err = init_wifi_stack(s_wifi_channel);
+  esp_err_t err = esp_now_core_init_radio(esp_now_core_wifi_channel());
   if (err != ESP_OK) {
     ESP_LOGE(TAG, "wifi init failed: %s", esp_err_to_name(err));
     return err;
   }
 
+  char mac_str[18];
+  esp_now_core_mac_to_str(esp_now_core_own_mac(), mac_str, sizeof(mac_str));
+  ESP_LOGI(TAG, "role=%s network=%u channel=%u mac=%s",
+           config->master ? "master" : "slave", (unsigned)config->network,
+           (unsigned)esp_now_core_wifi_channel(), mac_str);
+
   ESP_ERROR_CHECK(esp_now_init());
   ESP_ERROR_CHECK(esp_now_register_recv_cb(espnow_recv_cb));
-
-  s_send_done = xSemaphoreCreateBinary();
-  if (s_send_done != NULL &&
-      esp_now_register_send_cb(espnow_send_done_cb) == ESP_OK) {
-    s_send_cb_ready = true;
-  } else {
-    ESP_LOGW(TAG, "ESP-NOW send-done callback unavailable (OTA may drop packets)");
-  }
+  esp_now_core_init_send_done();
 
   if (config->master) {
-    ESP_ERROR_CHECK(ensure_broadcast_peer());
-    if (xTaskCreate(master_discover_task, "espnow_disc", 4096, NULL, 4,
-                    NULL) != pdPASS) {
-      ESP_LOGE(TAG, "failed to create discover task");
-      return ESP_FAIL;
-    }
-    if (xTaskCreate(master_monitor_task, "espnow_mon", 4096, NULL, 4, NULL) !=
-        pdPASS) {
-      ESP_LOGE(TAG, "failed to create monitor task");
-      return ESP_FAIL;
-    }
-  } else {
-    if (xTaskCreate(slave_heartbeat_task, "espnow_hb", 4096, NULL, 4, NULL) !=
-        pdPASS) {
-      ESP_LOGE(TAG, "failed to create heartbeat task");
-      return ESP_FAIL;
-    }
+    return esp_now_master_start();
   }
-
-  return ESP_OK;
+  return esp_now_slave_start();
 }

main/esp_now_comm.h

@@ -4,9 +4,20 @@
 #include "app_config.h"
 #include "client_registry.h"
 #include "esp_err.h"
+#include "esp_now_messages.pb.h"
+#include "uart_messages.pb.h"
 
 esp_err_t esp_now_comm_init(const app_config_t *config);
 
+/** Master: enable/disable accel ESP-NOW stream on one slave. */
+esp_err_t esp_now_comm_send_accel_stream(const uint8_t mac[CLIENT_MAC_LEN],
+                                         uint32_t client_id, bool enable);
+
+/** Master: configure tap notify flags on one slave. */
+esp_err_t esp_now_comm_send_tap_notify(const uint8_t mac[CLIENT_MAC_LEN],
+                                       uint32_t client_id, bool single,
+                                       bool double_tap, bool triple);
+
 /** Master: unicast accel deadzone to one slave (client_id is echoed for filtering). */
 esp_err_t esp_now_comm_send_accel_deadzone(const uint8_t mac[CLIENT_MAC_LEN],
                                            uint32_t client_id, uint32_t deadzone);
@@ -15,10 +26,26 @@ esp_err_t esp_now_comm_send_accel_deadzone(const uint8_t mac[CLIENT_MAC_LEN],
 esp_err_t esp_now_comm_send_unicast_test(const uint8_t mac[CLIENT_MAC_LEN],
                                          uint32_t seq);
 
+/** Result of a master-side ESP-NOW echo ping round-trip. */
+typedef struct {
+  uint64_t echoed_us;
+  uint32_t esp_rtt_us;
+} esp_now_echo_ping_result_t;
+
+/** Master: ESP-NOW echo ping round-trip; fills result on success. */
+esp_err_t esp_now_comm_echo_ping(const uint8_t mac[CLIENT_MAC_LEN],
+                                 uint64_t timestamp_us,
+                                 esp_now_echo_ping_result_t *result);
+
 /** Master: trigger find-me LED sequence on one slave. */
 esp_err_t esp_now_comm_send_find_me(const uint8_t mac[CLIENT_MAC_LEN],
                                     uint32_t client_id);
 
+/** Master: LED ring command on one slave. */
+esp_err_t esp_now_comm_send_led_ring(const uint8_t mac[CLIENT_MAC_LEN],
+                                     uint32_t client_id,
+                                     const alox_LedRingProgressRequest *req);
+
 /** Master: request reboot on one slave. */
 esp_err_t esp_now_comm_send_restart(const uint8_t mac[CLIENT_MAC_LEN],
                                     uint32_t client_id);

main/esp_now_core.c

@@ -0,0 +1,282 @@
+#include "esp_now_core.h"
+#include "esp_now_proto.h"
+#include "esp_err.h"
+#include "esp_event.h"
+#include "esp_log.h"
+#include "esp_mac.h"
+#include "esp_netif.h"
+#include "esp_now.h"
+#include "esp_wifi.h"
+#include "freertos/FreeRTOS.h"
+#include "freertos/idf_additions.h"
+#include <stdio.h>
+#include <string.h>
+
+static const char *TAG = "[ESPNOW_CORE]";
+
+static const uint8_t ESPNOW_BCAST[ESP_NOW_ETH_ALEN] = {0xff, 0xff, 0xff,
+                                                       0xff, 0xff, 0xff};
+
+static app_config_t s_config;
+static uint8_t s_wifi_channel;
+static uint8_t s_own_mac[ESP_NOW_ETH_ALEN];
+static SemaphoreHandle_t s_send_done;
+static SemaphoreHandle_t s_send_lock;
+static bool s_send_cb_ready;
+static volatile esp_now_send_status_t s_last_send_status;
+static volatile bool s_last_send_ok;
+
+#define ESPNOW_SEND_DONE_TIMEOUT_MS 500u
+#define ESPNOW_SEND_MAX_ATTEMPTS 8u
+#define ESPNOW_SEND_RETRY_DELAY_MS 10u
+#define ESPNOW_NOMEM_RETRY_DELAY_MS 50u
+
+#define ESPNOW_RELIABLE_MAX_ATTEMPTS 24u
+#define ESPNOW_RELIABLE_NOMEM_DELAY_MS 50u
+
+static uint8_t network_to_channel(uint8_t network) {
+  if (network < 1 || network > 13) {
+    return 1;
+  }
+  return network;
+}
+
+static void espnow_send_done_cb(const esp_now_send_info_t *tx_info,
+                                esp_now_send_status_t status) {
+  (void)tx_info;
+  s_last_send_status = status;
+  s_last_send_ok = (status == ESP_NOW_SEND_SUCCESS);
+  if (s_send_done != NULL) {
+    xSemaphoreGive(s_send_done);
+  }
+}
+
+void esp_now_core_store_config(const app_config_t *config) {
+  if (config == NULL) {
+    return;
+  }
+  memset(&s_config, 0, sizeof(s_config));
+  memcpy(&s_config, config, sizeof(s_config));
+  s_wifi_channel = network_to_channel(config->network);
+}
+
+const app_config_t *esp_now_core_get_config(void) { return &s_config; }
+
+bool esp_now_core_is_master(void) { return s_config.master; }
+
+uint8_t esp_now_core_network(void) { return s_config.network; }
+
+uint8_t esp_now_core_wifi_channel(void) { return s_wifi_channel; }
+
+const uint8_t *esp_now_core_own_mac(void) { return s_own_mac; }
+
+uint32_t esp_now_core_now_ms(void) {
+  return (uint32_t)(xTaskGetTickCount() * portTICK_PERIOD_MS);
+}
+
+bool esp_now_core_mac_equal(const uint8_t *a, const uint8_t *b) {
+  return memcmp(a, b, ESP_NOW_ETH_ALEN) == 0;
+}
+
+void esp_now_core_mac_to_str(const uint8_t *mac, char *out, size_t out_len) {
+  snprintf(out, out_len, "%02x:%02x:%02x:%02x:%02x:%02x", mac[0], mac[1],
+           mac[2], mac[3], mac[4], mac[5]);
+}
+
+esp_err_t esp_now_core_ensure_peer(const uint8_t *mac) {
+  if (esp_now_is_peer_exist(mac)) {
+    return ESP_OK;
+  }
+
+  esp_now_peer_info_t peer = {0};
+  memcpy(peer.peer_addr, mac, ESP_NOW_ETH_ALEN);
+  peer.channel = s_wifi_channel;
+  peer.ifidx = WIFI_IF_STA;
+  peer.encrypt = false;
+
+  esp_err_t err = esp_now_add_peer(&peer);
+  if (err != ESP_OK) {
+    ESP_LOGW(TAG, "add peer failed: %s", esp_err_to_name(err));
+  }
+  return err;
+}
+
+esp_err_t esp_now_core_ensure_broadcast_peer(void) {
+  return esp_now_core_ensure_peer(ESPNOW_BCAST);
+}
+
+static esp_err_t send_with_backpressure(const uint8_t *dest_mac,
+                                        const alox_EspNowMessage *msg,
+                                        uint32_t max_attempts,
+                                        uint32_t nomem_delay_ms,
+                                        uint32_t retry_delay_ms,
+                                        bool quiet_retries) {
+  if (s_send_lock == NULL ||
+      xSemaphoreTake(s_send_lock, pdMS_TO_TICKS(5000)) != pdTRUE) {
+    return ESP_ERR_TIMEOUT;
+  }
+
+  uint8_t buf[ESPNOW_PB_MAX_SIZE];
+  size_t len = 0;
+  esp_err_t result = ESP_FAIL;
+
+  esp_err_t err = esp_now_proto_encode(msg, buf, sizeof(buf), &len);
+  if (err != ESP_OK) {
+    ESP_LOGW(TAG, "encode failed");
+    result = err;
+    goto out;
+  }
+
+  if (len > ESP_NOW_MAX_DATA_LEN) {
+    ESP_LOGW(TAG, "encoded len %u > ESP-NOW max %u", (unsigned)len,
+             (unsigned)ESP_NOW_MAX_DATA_LEN);
+    result = ESP_ERR_INVALID_SIZE;
+    goto out;
+  }
+
+  if (esp_now_core_ensure_peer(dest_mac) != ESP_OK) {
+    result = ESP_FAIL;
+    goto out;
+  }
+
+  for (uint32_t attempt = 0; attempt < max_attempts; attempt++) {
+    if (s_send_cb_ready && s_send_done != NULL) {
+      xSemaphoreTake(s_send_done, 0);
+    }
+    s_last_send_ok = false;
+
+    err = esp_now_send(dest_mac, buf, len);
+    if (err != ESP_OK) {
+      const bool last = (attempt + 1 >= max_attempts);
+      if (!quiet_retries || last) {
+        ESP_LOGW(TAG, "send type=%u failed (attempt %lu/%lu): %s",
+                 (unsigned)msg->type, (unsigned long)(attempt + 1),
+                 (unsigned long)max_attempts, esp_err_to_name(err));
+      }
+      vTaskDelay(pdMS_TO_TICKS(err == ESP_ERR_ESPNOW_NO_MEM ? nomem_delay_ms
+                                                             : retry_delay_ms));
+      continue;
+    }
+
+    if (s_send_cb_ready && s_send_done != NULL) {
+      if (xSemaphoreTake(s_send_done, pdMS_TO_TICKS(ESPNOW_SEND_DONE_TIMEOUT_MS)) !=
+          pdTRUE) {
+        const bool last = (attempt + 1 >= max_attempts);
+        if (!quiet_retries || last) {
+          ESP_LOGW(TAG, "send type=%u done timeout (attempt %lu/%lu)",
+                   (unsigned)msg->type, (unsigned long)(attempt + 1),
+                   (unsigned long)max_attempts);
+        }
+        vTaskDelay(pdMS_TO_TICKS(retry_delay_ms));
+        continue;
+      }
+      if (!s_last_send_ok) {
+        const bool last = (attempt + 1 >= max_attempts);
+        if (!quiet_retries || last) {
+          ESP_LOGW(TAG, "send type=%u peer status=%d (attempt %lu/%lu)",
+                   (unsigned)msg->type, (int)s_last_send_status,
+                   (unsigned long)(attempt + 1), (unsigned long)max_attempts);
+        }
+        vTaskDelay(pdMS_TO_TICKS(retry_delay_ms));
+        continue;
+      }
+    }
+    result = ESP_OK;
+    goto out;
+  }
+
+out:
+  xSemaphoreGive(s_send_lock);
+  return result;
+}
+
+esp_err_t esp_now_core_send_wait(const uint8_t *dest_mac,
+                                 const alox_EspNowMessage *msg) {
+  return send_with_backpressure(dest_mac, msg, ESPNOW_SEND_MAX_ATTEMPTS,
+                                ESPNOW_NOMEM_RETRY_DELAY_MS,
+                                ESPNOW_SEND_RETRY_DELAY_MS, false);
+}
+
+esp_err_t esp_now_core_send_reliable(const uint8_t *dest_mac,
+                                     const alox_EspNowMessage *msg) {
+  return send_with_backpressure(dest_mac, msg, ESPNOW_RELIABLE_MAX_ATTEMPTS,
+                                ESPNOW_RELIABLE_NOMEM_DELAY_MS,
+                                ESPNOW_SEND_RETRY_DELAY_MS, true);
+}
+
+esp_err_t esp_now_core_send_fast(const uint8_t *dest_mac,
+                                 const alox_EspNowMessage *msg) {
+  if (s_send_lock == NULL ||
+      xSemaphoreTake(s_send_lock, pdMS_TO_TICKS(5000)) != pdTRUE) {
+    return ESP_ERR_TIMEOUT;
+  }
+
+  uint8_t buf[ESPNOW_PB_MAX_SIZE];
+  size_t len = 0;
+
+  esp_err_t err = esp_now_proto_encode(msg, buf, sizeof(buf), &len);
+  if (err != ESP_OK) {
+    ESP_LOGW(TAG, "encode failed");
+    xSemaphoreGive(s_send_lock);
+    return err;
+  }
+
+  if (len > ESP_NOW_MAX_DATA_LEN) {
+    ESP_LOGW(TAG, "encoded len %u > ESP-NOW max %u", (unsigned)len,
+             (unsigned)ESP_NOW_MAX_DATA_LEN);
+    xSemaphoreGive(s_send_lock);
+    return ESP_ERR_INVALID_SIZE;
+  }
+
+  if (esp_now_core_ensure_peer(dest_mac) != ESP_OK) {
+    xSemaphoreGive(s_send_lock);
+    return ESP_FAIL;
+  }
+
+  err = esp_now_send(dest_mac, buf, len);
+  if (err != ESP_OK) {
+    ESP_LOGW(TAG, "send type=%u failed: %s", (unsigned)msg->type,
+             esp_err_to_name(err));
+  }
+  xSemaphoreGive(s_send_lock);
+  return err;
+}
+
+esp_err_t esp_now_core_send(const uint8_t *dest_mac,
+                            const alox_EspNowMessage *msg) {
+  return esp_now_core_send_wait(dest_mac, msg);
+}
+
+esp_err_t esp_now_core_init_radio(uint8_t channel) {
+  ESP_ERROR_CHECK(esp_netif_init());
+  ESP_ERROR_CHECK(esp_event_loop_create_default());
+
+  wifi_init_config_t cfg = WIFI_INIT_CONFIG_DEFAULT();
+  ESP_ERROR_CHECK(esp_wifi_init(&cfg));
+
+  wifi_config_t wifi_config = {0};
+  wifi_config.sta.channel = channel;
+  wifi_config.sta.scan_method = WIFI_ALL_CHANNEL_SCAN;
+  wifi_config.sta.sort_method = WIFI_CONNECT_AP_BY_SIGNAL;
+
+  ESP_ERROR_CHECK(esp_wifi_set_mode(WIFI_MODE_STA));
+  ESP_ERROR_CHECK(esp_wifi_set_config(WIFI_IF_STA, &wifi_config));
+  ESP_ERROR_CHECK(esp_wifi_start());
+  ESP_ERROR_CHECK(esp_wifi_set_ps(WIFI_PS_NONE));
+  ESP_ERROR_CHECK(esp_wifi_set_channel(channel, WIFI_SECOND_CHAN_NONE));
+
+  ESP_ERROR_CHECK(esp_read_mac(s_own_mac, ESP_MAC_WIFI_STA));
+  s_wifi_channel = channel;
+  return ESP_OK;
+}
+
+void esp_now_core_init_send_done(void) {
+  s_send_done = xSemaphoreCreateBinary();
+  s_send_lock = xSemaphoreCreateMutex();
+  if (s_send_done != NULL && s_send_lock != NULL &&
+      esp_now_register_send_cb(espnow_send_done_cb) == ESP_OK) {
+    s_send_cb_ready = true;
+  } else {
+    ESP_LOGW(TAG, "send-done callback unavailable (OTA may drop packets)");
+  }
+}

main/esp_now_core.h

@@ -0,0 +1,38 @@
+#ifndef ESP_NOW_CORE_H
+#define ESP_NOW_CORE_H
+
+#include "app_config.h"
+#include "esp_err.h"
+#include "esp_now_messages.pb.h"
+#include <stdbool.h>
+#include <stdint.h>
+
+void esp_now_core_store_config(const app_config_t *config);
+const app_config_t *esp_now_core_get_config(void);
+bool esp_now_core_is_master(void);
+uint8_t esp_now_core_network(void);
+uint8_t esp_now_core_wifi_channel(void);
+const uint8_t *esp_now_core_own_mac(void);
+
+uint32_t esp_now_core_now_ms(void);
+bool esp_now_core_mac_equal(const uint8_t *a, const uint8_t *b);
+void esp_now_core_mac_to_str(const uint8_t *mac, char *out, size_t out_len);
+
+esp_err_t esp_now_core_ensure_peer(const uint8_t *mac);
+esp_err_t esp_now_core_ensure_broadcast_peer(void);
+
+esp_err_t esp_now_core_send(const uint8_t *dest_mac,
+                            const alox_EspNowMessage *msg);
+/** Like send but does not wait for esp_now send-done (lower latency). */
+esp_err_t esp_now_core_send_fast(const uint8_t *dest_mac,
+                                 const alox_EspNowMessage *msg);
+esp_err_t esp_now_core_send_wait(const uint8_t *dest_mac,
+                                 const alox_EspNowMessage *msg);
+/** OTA payloads: wait for send-done with extra NO_MEM backoff (queue drain). */
+esp_err_t esp_now_core_send_reliable(const uint8_t *dest_mac,
+                                     const alox_EspNowMessage *msg);
+
+esp_err_t esp_now_core_init_radio(uint8_t channel);
+void esp_now_core_init_send_done(void);
+
+#endif

main/esp_now_master.c

@@ -0,0 +1,597 @@
+#include "esp_now_master.h"
+#include "client_registry.h"
+#include "esp_now_comm.h"
+#include "esp_now_core.h"
+#include "esp_now_proto.h"
+#include "board_input.h"
+#include "ota_espnow.h"
+#include "ota_session.h"
+#include "ota_uart.h"
+#include "esp_log.h"
+#include "esp_timer.h"
+#include "freertos/FreeRTOS.h"
+#include "freertos/idf_additions.h"
+#include <string.h>
+
+static const uint8_t ESPNOW_BCAST[ESP_NOW_ETH_ALEN] = {0xff, 0xff, 0xff,
+                                                       0xff, 0xff, 0xff};
+
+#define ESPNOW_DISCOVER_INTERVAL_MS 500
+#define ESPNOW_HEARTBEAT_INTERVAL_MS 1000
+#define ESPNOW_HEARTBEAT_MISS_COUNT 3
+#define ESPNOW_CLIENT_TIMEOUT_MS                                               \
+  (ESPNOW_HEARTBEAT_INTERVAL_MS * ESPNOW_HEARTBEAT_MISS_COUNT)
+#define ESPNOW_BATTERY_INTERVAL_MS 30000
+
+static const char *TAG = "[ESPNOW_M]";
+
+static esp_err_t send_accel_stream(const uint8_t *dest_mac, uint32_t client_id,
+                                   bool enable) {
+  alox_EspNowMessage msg = alox_EspNowMessage_init_zero;
+  msg.type = alox_EspNowMessageType_ESPNOW_SET_ACCEL_STREAM;
+  msg.which_payload = alox_EspNowMessage_accel_stream_tag;
+  msg.payload.accel_stream.enable = enable;
+  msg.payload.accel_stream.client_id = client_id;
+  return esp_now_core_send(dest_mac, &msg);
+}
+
+static esp_err_t send_accel_deadzone(const uint8_t *dest_mac, uint32_t client_id,
+                                     uint32_t deadzone) {
+  alox_EspNowMessage msg = alox_EspNowMessage_init_zero;
+  msg.type = alox_EspNowMessageType_ESPNOW_SET_ACCEL_DEADZONE;
+  msg.which_payload = alox_EspNowMessage_accel_deadzone_tag;
+  msg.payload.accel_deadzone.deadzone = deadzone;
+  msg.payload.accel_deadzone.client_id = client_id;
+  return esp_now_core_send(dest_mac, &msg);
+}
+
+static esp_err_t send_unicast_test(const uint8_t *dest_mac, uint32_t seq) {
+  alox_EspNowMessage msg = alox_EspNowMessage_init_zero;
+  msg.type = alox_EspNowMessageType_ESPNOW_UNICAST_TEST;
+  msg.which_payload = alox_EspNowMessage_unicast_test_tag;
+  msg.payload.unicast_test.seq = seq;
+  return esp_now_core_send(dest_mac, &msg);
+}
+
+#define ESPNOW_ECHO_PING_TIMEOUT_MS 500
+#define ECHO_PING_TAG "[ECHO_PING]"
+
+static SemaphoreHandle_t s_echo_pong_sem;
+static bool s_echo_waiting;
+static uint64_t s_echo_expect_ts;
+static uint32_t s_echo_esp_rtt_us;
+static uint8_t s_echo_expect_mac[ESP_NOW_ETH_ALEN];
+
+static esp_err_t echo_ping_init(void) {
+  if (s_echo_pong_sem != NULL) {
+    return ESP_OK;
+  }
+  s_echo_pong_sem = xSemaphoreCreateBinary();
+  if (s_echo_pong_sem == NULL) {
+    return ESP_ERR_NO_MEM;
+  }
+  return ESP_OK;
+}
+
+static esp_err_t send_echo_ping(const uint8_t *dest_mac, uint64_t host_timestamp_us,
+                                uint64_t master_time_us) {
+  alox_EspNowMessage msg = alox_EspNowMessage_init_zero;
+  msg.type = alox_EspNowMessageType_ESPNOW_ECHO_PING;
+  msg.which_payload = alox_EspNowMessage_echo_ping_tag;
+  msg.payload.echo_ping.host_timestamp_us = host_timestamp_us;
+  msg.payload.echo_ping.master_time_us = master_time_us;
+  char mac_str[18];
+  esp_now_core_mac_to_str(dest_mac, mac_str, sizeof(mac_str));
+  ESP_LOGI(ECHO_PING_TAG, "ESP-NOW PING send to %s host_ts=%llu master_time_us=%llu",
+           mac_str, (unsigned long long)host_timestamp_us,
+           (unsigned long long)master_time_us);
+  return esp_now_core_send_fast(dest_mac, &msg);
+}
+
+static void echo_ping_on_pong(const uint8_t mac[ESP_NOW_ETH_ALEN],
+                              const alox_EspNowEchoPong *pong) {
+  if (pong == NULL || !s_echo_waiting) {
+    return;
+  }
+  if (!esp_now_core_mac_equal(mac, s_echo_expect_mac)) {
+    return;
+  }
+  if (pong->host_timestamp_us != s_echo_expect_ts) {
+    return;
+  }
+  int64_t now_us = esp_timer_get_time();
+  s_echo_esp_rtt_us =
+      (uint32_t)(now_us - (int64_t)pong->master_time_us);
+  char mac_str[18];
+  esp_now_core_mac_to_str(mac, mac_str, sizeof(mac_str));
+  ESP_LOGI(ECHO_PING_TAG,
+           "ESP-NOW PONG recv from %s host_ts=%llu master_time_us=%llu "
+           "recv_time_us=%lld esp_rtt_us=%lu",
+           mac_str, (unsigned long long)pong->host_timestamp_us,
+           (unsigned long long)pong->master_time_us, (long long)now_us,
+           (unsigned long)s_echo_esp_rtt_us);
+  xSemaphoreGive(s_echo_pong_sem);
+}
+
+static esp_err_t send_find_me(const uint8_t *dest_mac, uint32_t client_id) {
+  alox_EspNowMessage msg = alox_EspNowMessage_init_zero;
+  msg.type = alox_EspNowMessageType_ESPNOW_FIND_ME;
+  msg.which_payload = alox_EspNowMessage_find_me_tag;
+  msg.payload.find_me.client_id = client_id;
+  return esp_now_core_send(dest_mac, &msg);
+}
+
+static esp_err_t send_led_ring(const uint8_t *dest_mac, uint32_t client_id,
+                               const alox_LedRingProgressRequest *req) {
+  if (req == NULL) {
+    return ESP_ERR_INVALID_ARG;
+  }
+  alox_EspNowMessage msg = alox_EspNowMessage_init_zero;
+  msg.type = alox_EspNowMessageType_ESPNOW_LED_RING;
+  msg.which_payload = alox_EspNowMessage_led_ring_tag;
+  msg.payload.led_ring.client_id = client_id;
+  msg.payload.led_ring.mode = req->mode;
+  msg.payload.led_ring.progress = req->progress;
+  msg.payload.led_ring.digit = req->digit;
+  msg.payload.led_ring.r = req->r;
+  msg.payload.led_ring.g = req->g;
+  msg.payload.led_ring.b = req->b;
+  msg.payload.led_ring.intensity = req->intensity;
+  msg.payload.led_ring.blink_ms = req->blink_ms;
+  msg.payload.led_ring.blink_count = req->blink_count;
+  return esp_now_core_send(dest_mac, &msg);
+}
+
+static esp_err_t send_restart(const uint8_t *dest_mac, uint32_t client_id) {
+  alox_EspNowMessage msg = alox_EspNowMessage_init_zero;
+  msg.type = alox_EspNowMessageType_ESPNOW_RESTART;
+  msg.which_payload = alox_EspNowMessage_restart_tag;
+  msg.payload.restart.client_id = client_id;
+  return esp_now_core_send(dest_mac, &msg);
+}
+
+static esp_err_t send_tap_notify(const uint8_t *dest_mac, uint32_t client_id,
+                                 bool single, bool double_tap, bool triple) {
+  alox_EspNowMessage msg = alox_EspNowMessage_init_zero;
+  msg.type = alox_EspNowMessageType_ESPNOW_SET_TAP_NOTIFY;
+  msg.which_payload = alox_EspNowMessage_tap_notify_tag;
+  msg.payload.tap_notify.client_id = client_id;
+  msg.payload.tap_notify.single = single;
+  msg.payload.tap_notify.double_tap = double_tap;
+  msg.payload.tap_notify.triple = triple;
+  return esp_now_core_send(dest_mac, &msg);
+}
+
+static esp_err_t send_ota_start(const uint8_t *dest_mac, uint32_t total_size) {
+  alox_EspNowMessage msg = alox_EspNowMessage_init_zero;
+  msg.type = alox_EspNowMessageType_ESPNOW_OTA_START;
+  msg.which_payload = alox_EspNowMessage_ota_start_tag;
+  msg.payload.ota_start.total_size = total_size;
+  return esp_now_core_send_wait(dest_mac, &msg);
+}
+
+static esp_err_t send_ota_payload(const uint8_t *dest_mac, uint32_t seq,
+                                  const uint8_t *data, size_t len) {
+  if (data == NULL || len == 0 || len > OTA_UART_HOST_CHUNK_SIZE) {
+    return ESP_ERR_INVALID_ARG;
+  }
+  alox_EspNowMessage msg = alox_EspNowMessage_init_zero;
+  msg.type = alox_EspNowMessageType_ESPNOW_OTA_PAYLOAD;
+  msg.which_payload = alox_EspNowMessage_ota_payload_tag;
+  msg.payload.ota_payload.seq = seq;
+  msg.payload.ota_payload.data.size = len;
+  memcpy(msg.payload.ota_payload.data.bytes, data, len);
+  return esp_now_core_send_reliable(dest_mac, &msg);
+}
+
+static esp_err_t send_ota_end(const uint8_t *dest_mac) {
+  alox_EspNowMessage msg = alox_EspNowMessage_init_zero;
+  msg.type = alox_EspNowMessageType_ESPNOW_OTA_END;
+  msg.which_payload = alox_EspNowMessage_ota_end_tag;
+  return esp_now_core_send_wait(dest_mac, &msg);
+}
+
+esp_err_t esp_now_comm_send_ota_start(const uint8_t mac[CLIENT_MAC_LEN],
+                                      uint32_t total_size) {
+  if (mac == NULL || !esp_now_core_is_master()) {
+    return ESP_ERR_INVALID_STATE;
+  }
+  return send_ota_start(mac, total_size);
+}
+
+esp_err_t esp_now_comm_send_ota_payload(const uint8_t mac[CLIENT_MAC_LEN],
+                                        uint32_t seq, const uint8_t *data,
+                                        size_t len) {
+  if (mac == NULL || !esp_now_core_is_master()) {
+    return ESP_ERR_INVALID_STATE;
+  }
+  return send_ota_payload(mac, seq, data, len);
+}
+
+esp_err_t esp_now_comm_send_ota_end(const uint8_t mac[CLIENT_MAC_LEN]) {
+  if (mac == NULL || !esp_now_core_is_master()) {
+    return ESP_ERR_INVALID_STATE;
+  }
+  return send_ota_end(mac);
+}
+
+esp_err_t esp_now_comm_send_restart(const uint8_t mac[CLIENT_MAC_LEN],
+                                    uint32_t client_id) {
+  if (mac == NULL || !esp_now_core_is_master()) {
+    return ESP_ERR_INVALID_STATE;
+  }
+  char mac_str[18];
+  esp_now_core_mac_to_str(mac, mac_str, sizeof(mac_str));
+  esp_err_t err = send_restart(mac, client_id);
+  if (err == ESP_OK) {
+    ESP_LOGI(TAG, "unicast RESTART to %s client_id=%lu", mac_str,
+             (unsigned long)client_id);
+  } else {
+    ESP_LOGW(TAG, "unicast RESTART to %s failed: %s", mac_str,
+             esp_err_to_name(err));
+  }
+  return err;
+}
+
+esp_err_t esp_now_comm_send_find_me(const uint8_t mac[CLIENT_MAC_LEN],
+                                    uint32_t client_id) {
+  if (mac == NULL || !esp_now_core_is_master()) {
+    return ESP_ERR_INVALID_STATE;
+  }
+  char mac_str[18];
+  esp_now_core_mac_to_str(mac, mac_str, sizeof(mac_str));
+  esp_err_t err = send_find_me(mac, client_id);
+  if (err == ESP_OK) {
+    ESP_LOGI(TAG, "unicast FIND_ME to %s client_id=%lu", mac_str,
+             (unsigned long)client_id);
+  } else {
+    ESP_LOGW(TAG, "unicast FIND_ME to %s failed: %s", mac_str,
+             esp_err_to_name(err));
+  }
+  return err;
+}
+
+esp_err_t esp_now_comm_send_led_ring(const uint8_t mac[CLIENT_MAC_LEN],
+                                     uint32_t client_id,
+                                     const alox_LedRingProgressRequest *req) {
+  if (mac == NULL || !esp_now_core_is_master() || req == NULL) {
+    return ESP_ERR_INVALID_STATE;
+  }
+  char mac_str[18];
+  esp_now_core_mac_to_str(mac, mac_str, sizeof(mac_str));
+  esp_err_t err = send_led_ring(mac, client_id, req);
+  if (err == ESP_OK) {
+    ESP_LOGI(TAG, "unicast LED_RING mode %lu to %s client_id=%lu",
+             (unsigned long)req->mode, mac_str, (unsigned long)client_id);
+  } else {
+    ESP_LOGW(TAG, "unicast LED_RING to %s failed: %s", mac_str,
+             esp_err_to_name(err));
+  }
+  return err;
+}
+
+esp_err_t esp_now_comm_send_unicast_test(const uint8_t mac[CLIENT_MAC_LEN],
+                                         uint32_t seq) {
+  if (mac == NULL || !esp_now_core_is_master()) {
+    return ESP_ERR_INVALID_STATE;
+  }
+  char mac_str[18];
+  esp_now_core_mac_to_str(mac, mac_str, sizeof(mac_str));
+  esp_err_t err = send_unicast_test(mac, seq);
+  if (err == ESP_OK) {
+    ESP_LOGI(TAG, "unicast TEST to %s seq=%lu", mac_str, (unsigned long)seq);
+  } else {
+    ESP_LOGW(TAG, "unicast TEST to %s failed: %s", mac_str, esp_err_to_name(err));
+  }
+  return err;
+}
+
+esp_err_t esp_now_comm_echo_ping(const uint8_t mac[CLIENT_MAC_LEN],
+                                 uint64_t timestamp_us,
+                                 esp_now_echo_ping_result_t *result) {
+  if (mac == NULL || !esp_now_core_is_master()) {
+    return ESP_ERR_INVALID_STATE;
+  }
+  if (echo_ping_init() != ESP_OK) {
+    return ESP_ERR_NO_MEM;
+  }
+
+  xSemaphoreTake(s_echo_pong_sem, 0);
+  s_echo_waiting = true;
+  s_echo_expect_ts = timestamp_us;
+  s_echo_esp_rtt_us = 0;
+  memcpy(s_echo_expect_mac, mac, ESP_NOW_ETH_ALEN);
+
+  uint64_t master_time_us = (uint64_t)esp_timer_get_time();
+  esp_err_t err = send_echo_ping(mac, timestamp_us, master_time_us);
+  if (err != ESP_OK) {
+    s_echo_waiting = false;
+    return err;
+  }
+
+  if (xSemaphoreTake(s_echo_pong_sem,
+                     pdMS_TO_TICKS(ESPNOW_ECHO_PING_TIMEOUT_MS)) != pdTRUE) {
+    s_echo_waiting = false;
+    char mac_str[18];
+    esp_now_core_mac_to_str(mac, mac_str, sizeof(mac_str));
+    ESP_LOGW(ECHO_PING_TAG,
+             "ESP-NOW PONG timeout to %s host_ts=%llu",
+             mac_str, (unsigned long long)timestamp_us);
+    return ESP_ERR_TIMEOUT;
+  }
+
+  s_echo_waiting = false;
+  if (result != NULL) {
+    result->echoed_us = timestamp_us;
+    result->esp_rtt_us = s_echo_esp_rtt_us;
+  }
+  return ESP_OK;
+}
+
+esp_err_t esp_now_comm_send_accel_stream(const uint8_t mac[CLIENT_MAC_LEN],
+                                         uint32_t client_id, bool enable) {
+  if (mac == NULL || !esp_now_core_is_master()) {
+    return ESP_ERR_INVALID_STATE;
+  }
+  char mac_str[18];
+  esp_now_core_mac_to_str(mac, mac_str, sizeof(mac_str));
+  esp_err_t err = send_accel_stream(mac, client_id, enable);
+  if (err == ESP_OK) {
+    ESP_LOGI(TAG, "unicast SET_ACCEL_STREAM to %s: %s client_id=%lu", mac_str,
+             enable ? "on" : "off", (unsigned long)client_id);
+  } else {
+    ESP_LOGW(TAG, "unicast SET_ACCEL_STREAM to %s failed: %s", mac_str,
+             esp_err_to_name(err));
+  }
+  return err;
+}
+
+esp_err_t esp_now_comm_send_tap_notify(const uint8_t mac[CLIENT_MAC_LEN],
+                                       uint32_t client_id, bool single,
+                                       bool double_tap, bool triple) {
+  if (mac == NULL || !esp_now_core_is_master()) {
+    return ESP_ERR_INVALID_STATE;
+  }
+  char mac_str[18];
+  esp_now_core_mac_to_str(mac, mac_str, sizeof(mac_str));
+  esp_err_t err =
+      send_tap_notify(mac, client_id, single, double_tap, triple);
+  if (err == ESP_OK) {
+    ESP_LOGI(TAG,
+             "unicast SET_TAP_NOTIFY to %s: single=%d double=%d triple=%d "
+             "client_id=%lu",
+             mac_str, single, double_tap, triple, (unsigned long)client_id);
+  } else {
+    ESP_LOGW(TAG, "unicast SET_TAP_NOTIFY to %s failed: %s", mac_str,
+             esp_err_to_name(err));
+  }
+  return err;
+}
+
+esp_err_t esp_now_comm_send_accel_deadzone(const uint8_t mac[CLIENT_MAC_LEN],
+                                           uint32_t client_id,
+                                           uint32_t deadzone) {
+  if (mac == NULL || !esp_now_core_is_master()) {
+    return ESP_ERR_INVALID_STATE;
+  }
+  char mac_str[18];
+  esp_now_core_mac_to_str(mac, mac_str, sizeof(mac_str));
+  esp_err_t err = send_accel_deadzone(mac, client_id, deadzone);
+  if (err == ESP_OK) {
+    ESP_LOGI(TAG, "unicast SET_ACCEL_DEADZONE to %s: deadzone=%lu client_id=%lu",
+             mac_str, (unsigned long)deadzone, (unsigned long)client_id);
+  } else {
+    ESP_LOGW(TAG, "unicast SET_ACCEL_DEADZONE to %s failed: %s", mac_str,
+             esp_err_to_name(err));
+  }
+  return err;
+}
+
+static void handle_accel_sample(const uint8_t mac[CLIENT_MAC_LEN],
+                                const alox_EspNowAccelSample *sample) {
+  if (sample == NULL) {
+    return;
+  }
+  esp_err_t err = client_registry_update_accel(
+      mac, sample->slave_id, (int16_t)sample->x, (int16_t)sample->y,
+      (int16_t)sample->z);
+  if (err == ESP_ERR_NOT_FOUND) {
+    return;
+  }
+  if (err != ESP_OK) {
+    ESP_LOGW(TAG, "accel sample id mismatch from %02x:…:%02x", mac[0], mac[5]);
+  }
+}
+
+static void handle_tap_event(const uint8_t mac[CLIENT_MAC_LEN],
+                             const alox_EspNowTapEvent *event) {
+  if (event == NULL) {
+    return;
+  }
+  esp_err_t err =
+      client_registry_update_tap(mac, event->slave_id, event->kind);
+  if (err == ESP_ERR_NOT_FOUND) {
+    return;
+  }
+  if (err != ESP_OK) {
+    ESP_LOGW(TAG, "tap event id=%lu kind=%lu rejected from %02x:…:%02x",
+             (unsigned long)event->slave_id, (unsigned long)event->kind, mac[0],
+             mac[5]);
+  }
+}
+
+static void handle_battery_report(const uint8_t mac[CLIENT_MAC_LEN],
+                                  const alox_EspNowBatteryReport *report) {
+  if (report == NULL) {
+    return;
+  }
+  esp_err_t err = client_registry_update_battery(
+      mac, report->client_id, report->lipo1_valid, report->lipo1_mv,
+      report->lipo2_valid, report->lipo2_mv);
+  if (err == ESP_ERR_NOT_FOUND) {
+    ESP_LOGW(TAG, "battery report from unregistered slave id=%lu",
+             (unsigned long)report->client_id);
+    return;
+  }
+  if (err != ESP_OK) {
+    ESP_LOGW(TAG, "battery report id=%lu rejected: %s",
+             (unsigned long)report->client_id, esp_err_to_name(err));
+    return;
+  }
+  ESP_LOGI(TAG, "battery cached id=%lu L1=%s %lu mV L2=%s %lu mV",
+           (unsigned long)report->client_id,
+           report->lipo1_valid ? "ok" : "n/a",
+           (unsigned long)report->lipo1_mv, report->lipo2_valid ? "ok" : "n/a",
+           (unsigned long)report->lipo2_mv);
+}
+
+static void handle_client_presence(const alox_EspNowSlavePresence *presence,
+                                   const uint8_t mac[CLIENT_MAC_LEN]) {
+  if (presence->network != esp_now_core_network()) {
+    return;
+  }
+
+  esp_now_core_ensure_peer(mac);
+
+  bool is_new = false;
+  bool reactivated = false;
+  esp_err_t err = client_registry_heartbeat(
+      mac, presence->slave_id, presence->version, presence->used, &is_new,
+      &reactivated);
+  if (err != ESP_OK) {
+    ESP_LOGW(TAG, "client registry full");
+    return;
+  }
+
+  char mac_str[18];
+  esp_now_core_mac_to_str(mac, mac_str, sizeof(mac_str));
+  if (is_new) {
+    ESP_LOGI(TAG, "client registered id=%lu mac=%s ver=%lu",
+             (unsigned long)presence->slave_id, mac_str,
+             (unsigned long)presence->version);
+  } else if (reactivated) {
+    ESP_LOGI(TAG, "client reconnected id=%lu mac=%s",
+             (unsigned long)presence->slave_id, mac_str);
+  }
+}
+
+void esp_now_master_on_recv(const esp_now_recv_info_t *info, const uint8_t *data,
+                            int len) {
+  if (info == NULL || data == NULL || len <= 0) {
+    return;
+  }
+
+  alox_EspNowMessage msg = alox_EspNowMessage_init_zero;
+  if (esp_now_proto_decode(data, (size_t)len, &msg) != ESP_OK) {
+    ESP_LOGW(TAG, "decode failed (%d bytes)", len);
+    return;
+  }
+
+  if (ota_espnow_distribution_active()) {
+    if (msg.which_payload == alox_EspNowMessage_ota_status_tag) {
+      esp_now_core_ensure_peer(info->src_addr);
+      ota_espnow_master_on_status(info->src_addr, &msg.payload.ota_status);
+    }
+    return;
+  }
+
+  if (msg.which_payload == alox_EspNowMessage_ota_status_tag) {
+    esp_now_core_ensure_peer(info->src_addr);
+    ota_espnow_master_on_status(info->src_addr, &msg.payload.ota_status);
+    return;
+  }
+
+  if (msg.which_payload == alox_EspNowMessage_accel_sample_tag) {
+    esp_now_core_ensure_peer(info->src_addr);
+    handle_accel_sample(info->src_addr, &msg.payload.accel_sample);
+    return;
+  }
+
+  if (msg.which_payload == alox_EspNowMessage_tap_event_tag) {
+    esp_now_core_ensure_peer(info->src_addr);
+    handle_tap_event(info->src_addr, &msg.payload.tap_event);
+    return;
+  }
+
+  if (msg.which_payload == alox_EspNowMessage_battery_report_tag) {
+    esp_now_core_ensure_peer(info->src_addr);
+    handle_battery_report(info->src_addr, &msg.payload.battery_report);
+    return;
+  }
+
+  if (msg.which_payload == alox_EspNowMessage_echo_pong_tag) {
+    esp_now_core_ensure_peer(info->src_addr);
+    echo_ping_on_pong(info->src_addr, &msg.payload.echo_pong);
+    return;
+  }
+
+  if (msg.type == alox_EspNowMessageType_ESPNOW_BATTERY_REPORT &&
+      msg.which_payload != alox_EspNowMessage_battery_report_tag) {
+    ESP_LOGW(TAG, "BATTERY_REPORT type but which=%u", msg.which_payload);
+  }
+
+  const alox_EspNowSlavePresence *presence = esp_now_proto_get_presence(&msg);
+  if (presence != NULL) {
+    esp_now_core_ensure_peer(info->src_addr);
+    handle_client_presence(presence, info->src_addr);
+  }
+}
+
+static void discover_task(void *param) {
+  (void)param;
+
+  alox_EspNowMessage msg = alox_EspNowMessage_init_zero;
+  msg.type = alox_EspNowMessageType_ESPNOW_DISCOVER;
+  msg.which_payload = alox_EspNowMessage_discover_tag;
+  msg.payload.discover.network = esp_now_core_network();
+
+  ESP_LOGI(TAG, "discover on network %u ch %u", (unsigned)esp_now_core_network(),
+           (unsigned)esp_now_core_wifi_channel());
+
+  while (1) {
+    msg.payload.discover.master_ota_pending = ota_session_busy();
+    if (!ota_espnow_distribution_active()) {
+      esp_now_core_send_fast(ESPNOW_BCAST, &msg);
+    }
+    vTaskDelay(pdMS_TO_TICKS(ESPNOW_DISCOVER_INTERVAL_MS));
+  }
+}
+
+static void monitor_task(void *param) {
+  (void)param;
+  uint32_t last_local_battery_ms = 0;
+
+  ESP_LOGI(TAG, "monitor (client timeout %u ms)",
+           (unsigned)ESPNOW_CLIENT_TIMEOUT_MS);
+
+  board_lipo_reading_t reading;
+  board_input_read_lipo(&reading);
+  client_registry_set_master_battery(&reading);
+  last_local_battery_ms = esp_now_core_now_ms();
+
+  while (1) {
+    vTaskDelay(pdMS_TO_TICKS(ESPNOW_HEARTBEAT_INTERVAL_MS));
+    client_registry_check_timeouts(ESPNOW_CLIENT_TIMEOUT_MS);
+
+    uint32_t t = esp_now_core_now_ms();
+    if (t - last_local_battery_ms >= ESPNOW_BATTERY_INTERVAL_MS) {
+      board_input_read_lipo(&reading);
+      client_registry_set_master_battery(&reading);
+      last_local_battery_ms = t;
+    }
+  }
+}
+
+esp_err_t esp_now_master_start(void) {
+  ESP_ERROR_CHECK(esp_now_core_ensure_broadcast_peer());
+
+  if (xTaskCreate(discover_task, "espnow_disc", 4096, NULL, 4, NULL) != pdPASS) {
+    ESP_LOGE(TAG, "failed to create discover task");
+    return ESP_FAIL;
+  }
+  if (xTaskCreate(monitor_task, "espnow_mon", 4096, NULL, 4, NULL) != pdPASS) {
+    ESP_LOGE(TAG, "failed to create monitor task");
+    return ESP_FAIL;
+  }
+  return ESP_OK;
+}

main/esp_now_master.h

@@ -0,0 +1,11 @@
+#ifndef ESP_NOW_MASTER_H
+#define ESP_NOW_MASTER_H
+
+#include "esp_err.h"
+#include "esp_now.h"
+
+esp_err_t esp_now_master_start(void);
+void esp_now_master_on_recv(const esp_now_recv_info_t *info, const uint8_t *data,
+                            int len);
+
+#endif

main/esp_now_slave.c

@@ -0,0 +1,646 @@
+#include "esp_now_slave.h"
+#include "bosch456.h"
+#include "cmd_led_ring.h"
+#include "esp_now_comm.h"
+#include "esp_now_core.h"
+#include "esp_now_proto.h"
+#include "board_input.h"
+#include "led_ring.h"
+#include "ota_espnow.h"
+#include "ota_uart.h"
+#include "pod_reboot.h"
+#include "pod_settings.h"
+#include "esp_log.h"
+#include "freertos/FreeRTOS.h"
+#include "freertos/idf_additions.h"
+#include <string.h>
+
+#ifndef POWERPOD_FW_VERSION
+#define POWERPOD_FW_VERSION 1u
+#endif
+
+#define ESPNOW_HEARTBEAT_INTERVAL_MS 1000
+#define SLAVE_MASTER_LOST_MS (ESPNOW_HEARTBEAT_INTERVAL_MS * 5)
+/** While master or slave OTA is in progress (discover may be sparse). */
+#define SLAVE_MASTER_OTA_GRACE_MS 300000u
+#define ESPNOW_ACCEL_INTERVAL_MS 16
+#define ESPNOW_BATTERY_INTERVAL_MS 30000
+#define SLAVE_BATTERY_AFTER_JOIN_MS 150
+
+static const char *TAG = "[ESPNOW_S]";
+
+static bool s_joined;
+static bool s_master_ota_grace;
+static bool s_accel_stream_enabled;
+static bool s_tap_notify_single;
+static bool s_tap_notify_double;
+static bool s_tap_notify_triple;
+static uint8_t s_master_mac[ESP_NOW_ETH_ALEN];
+static uint32_t s_last_discover_ms;
+
+typedef enum {
+  SLAVE_TX_SLAVE_INFO = 1,
+  SLAVE_TX_BATTERY,
+} slave_tx_op_t;
+
+static QueueHandle_t s_tx_queue;
+
+static bool from_joined_master(const uint8_t *master_mac) {
+  return s_joined && esp_now_core_mac_equal(master_mac, s_master_mac);
+}
+
+static void fill_presence(alox_EspNowSlavePresence *presence) {
+  const uint8_t *own = esp_now_core_own_mac();
+  presence->network = esp_now_core_network();
+  presence->version = POWERPOD_FW_VERSION;
+  presence->slave_id = own[5];
+  presence->available = true;
+  presence->used = false;
+  esp_now_proto_setup_presence_encode(presence, own);
+}
+
+static void send_presence(const uint8_t *dest_mac, alox_EspNowMessageType type) {
+  alox_EspNowMessage msg = alox_EspNowMessage_init_zero;
+  alox_EspNowSlavePresence *presence = NULL;
+
+  msg.type = type;
+  if (type == alox_EspNowMessageType_ESPNOW_SLAVE_INFO) {
+    msg.which_payload = alox_EspNowMessage_slave_info_tag;
+    presence = &msg.payload.slave_info;
+  } else {
+    msg.which_payload = alox_EspNowMessage_heartbeat_tag;
+    presence = &msg.payload.heartbeat;
+  }
+  fill_presence(presence);
+  esp_now_core_send(dest_mac, &msg);
+}
+
+static esp_err_t send_accel_sample(const uint8_t *dest_mac, uint32_t slave_id,
+                                   int16_t x, int16_t y, int16_t z) {
+  alox_EspNowMessage msg = alox_EspNowMessage_init_zero;
+  msg.type = alox_EspNowMessageType_ESPNOW_ACCEL_SAMPLE;
+  msg.which_payload = alox_EspNowMessage_accel_sample_tag;
+  msg.payload.accel_sample.slave_id = slave_id;
+  msg.payload.accel_sample.x = x;
+  msg.payload.accel_sample.y = y;
+  msg.payload.accel_sample.z = z;
+  return esp_now_core_send(dest_mac, &msg);
+}
+
+static esp_err_t send_tap_event(const uint8_t *dest_mac, uint32_t slave_id,
+                                uint32_t kind) {
+  alox_EspNowMessage msg = alox_EspNowMessage_init_zero;
+  msg.type = alox_EspNowMessageType_ESPNOW_TAP_EVENT;
+  msg.which_payload = alox_EspNowMessage_tap_event_tag;
+  msg.payload.tap_event.slave_id = slave_id;
+  msg.payload.tap_event.kind = kind;
+  return esp_now_core_send(dest_mac, &msg);
+}
+
+static esp_err_t send_battery_report(const uint8_t *dest_mac,
+                                     const alox_EspNowBatteryReport *report) {
+  if (report == NULL) {
+    return ESP_ERR_INVALID_ARG;
+  }
+  alox_EspNowMessage msg = alox_EspNowMessage_init_zero;
+  msg.type = alox_EspNowMessageType_ESPNOW_BATTERY_REPORT;
+  msg.which_payload = alox_EspNowMessage_battery_report_tag;
+  msg.payload.battery_report = *report;
+  return esp_now_core_send(dest_mac, &msg);
+}
+
+static uint32_t slave_master_lost_ms(void) {
+  if (ota_uart_is_active() || s_master_ota_grace) {
+    return SLAVE_MASTER_OTA_GRACE_MS;
+  }
+  return SLAVE_MASTER_LOST_MS;
+}
+
+static void touch_master_presence(uint32_t now) { s_last_discover_ms = now; }
+
+static void reset_join(void) {
+  s_joined = false;
+  s_master_ota_grace = false;
+  s_accel_stream_enabled = false;
+  memset(s_master_mac, 0, sizeof(s_master_mac));
+  s_last_discover_ms = 0;
+  if (s_tx_queue != NULL) {
+    xQueueReset(s_tx_queue);
+  }
+}
+
+static void queue_tx(slave_tx_op_t op) {
+  if (s_tx_queue == NULL) {
+    return;
+  }
+  if (xQueueSend(s_tx_queue, &op, 0) != pdTRUE) {
+    ESP_LOGW(TAG, "tx queue full (op=%d)", (int)op);
+  }
+}
+
+static void send_battery_to_master(void) {
+  if (!s_joined) {
+    return;
+  }
+
+  board_lipo_reading_t reading;
+  board_input_read_lipo(&reading);
+
+  alox_EspNowBatteryReport report = alox_EspNowBatteryReport_init_zero;
+  report.client_id = esp_now_core_own_mac()[5];
+  report.lipo1_valid = reading.lipo1_valid;
+  report.lipo2_valid = reading.lipo2_valid;
+  report.lipo1_mv = reading.lipo1_mv;
+  report.lipo2_mv = reading.lipo2_mv;
+
+  esp_err_t err = send_battery_report(s_master_mac, &report);
+  if (err != ESP_OK) {
+    ESP_LOGW(TAG, "battery report send failed id=%lu: %s",
+             (unsigned long)report.client_id, esp_err_to_name(err));
+  } else {
+    ESP_LOGI(TAG, "battery report sent id=%lu L1=%s %lu mV L2=%s %lu mV",
+             (unsigned long)report.client_id,
+             report.lipo1_valid ? "ok" : "n/a",
+             (unsigned long)report.lipo1_mv,
+             report.lipo2_valid ? "ok" : "n/a",
+             (unsigned long)report.lipo2_mv);
+  }
+}
+
+esp_err_t esp_now_comm_send_ota_status(const uint8_t master_mac[CLIENT_MAC_LEN],
+                                       uint32_t status, uint32_t bytes_written,
+                                       uint32_t error) {
+  if (master_mac == NULL || esp_now_core_is_master()) {
+    return ESP_ERR_INVALID_STATE;
+  }
+  alox_EspNowMessage msg = alox_EspNowMessage_init_zero;
+  msg.type = alox_EspNowMessageType_ESPNOW_OTA_STATUS;
+  msg.which_payload = alox_EspNowMessage_ota_status_tag;
+  msg.payload.ota_status.status = status;
+  msg.payload.ota_status.bytes_written = bytes_written;
+  msg.payload.ota_status.error = error;
+  return esp_now_core_send_wait(master_mac, &msg);
+}
+
+bool esp_now_comm_get_master_mac(uint8_t mac_out[CLIENT_MAC_LEN]) {
+  return esp_now_slave_get_master_mac(mac_out);
+}
+
+bool esp_now_slave_get_master_mac(uint8_t mac_out[CLIENT_MAC_LEN]) {
+  if (mac_out == NULL || !s_joined) {
+    return false;
+  }
+  memcpy(mac_out, s_master_mac, CLIENT_MAC_LEN);
+  return true;
+}
+
+static void tx_task(void *param) {
+  (void)param;
+  slave_tx_op_t op;
+
+  ESP_LOGI(TAG, "deferred tx task ready");
+
+  while (1) {
+    if (xQueueReceive(s_tx_queue, &op, portMAX_DELAY) != pdTRUE) {
+      continue;
+    }
+    if (!s_joined) {
+      continue;
+    }
+    switch (op) {
+    case SLAVE_TX_SLAVE_INFO:
+      send_presence(s_master_mac, alox_EspNowMessageType_ESPNOW_SLAVE_INFO);
+      break;
+    case SLAVE_TX_BATTERY:
+      vTaskDelay(pdMS_TO_TICKS(SLAVE_BATTERY_AFTER_JOIN_MS));
+      send_battery_to_master();
+      break;
+    default:
+      break;
+    }
+  }
+}
+
+static void handle_unicast_test(const uint8_t *master_mac,
+                                const alox_EspNowUnicastTest *test) {
+  char mac_str[18];
+  esp_now_core_mac_to_str(master_mac, mac_str, sizeof(mac_str));
+  ESP_LOGI(TAG, "UNICAST TEST OK from master %s seq=%lu (joined=%d)", mac_str,
+           (unsigned long)test->seq, (int)s_joined);
+}
+
+static void handle_echo_ping(const uint8_t *master_mac,
+                             const alox_EspNowEchoPing *ping) {
+  if (ping == NULL || !s_joined ||
+      !esp_now_core_mac_equal(master_mac, s_master_mac)) {
+    return;
+  }
+
+  char mac_str[18];
+  esp_now_core_mac_to_str(master_mac, mac_str, sizeof(mac_str));
+  ESP_LOGI(TAG, "ESP-NOW PING recv from %s host_ts=%llu master_time_us=%llu",
+           mac_str, (unsigned long long)ping->host_timestamp_us,
+           (unsigned long long)ping->master_time_us);
+
+  alox_EspNowMessage msg = alox_EspNowMessage_init_zero;
+  msg.type = alox_EspNowMessageType_ESPNOW_ECHO_PONG;
+  msg.which_payload = alox_EspNowMessage_echo_pong_tag;
+  msg.payload.echo_pong.host_timestamp_us = ping->host_timestamp_us;
+  msg.payload.echo_pong.master_time_us = ping->master_time_us;
+
+  esp_err_t err = esp_now_core_send_fast(s_master_mac, &msg);
+  if (err != ESP_OK) {
+    ESP_LOGW(TAG, "ECHO PONG send failed: %s", esp_err_to_name(err));
+    return;
+  }
+
+  ESP_LOGI(TAG, "ESP-NOW PONG send to %s host_ts=%llu master_time_us=%llu",
+           mac_str, (unsigned long long)ping->host_timestamp_us,
+           (unsigned long long)ping->master_time_us);
+}
+
+static void handle_restart(const uint8_t *master_mac,
+                           const alox_EspNowRestart *req) {
+  const uint8_t *own = esp_now_core_own_mac();
+  uint32_t my_id = own[5];
+
+  if (req->client_id != 0 && req->client_id != my_id) {
+    return;
+  }
+  if (s_joined && !esp_now_core_mac_equal(master_mac, s_master_mac)) {
+    return;
+  }
+
+  char mac_str[18];
+  esp_now_core_mac_to_str(master_mac, mac_str, sizeof(mac_str));
+  ESP_LOGI(TAG, "RESTART from master %s (id=%lu)", mac_str, (unsigned long)my_id);
+  pod_schedule_restart();
+}
+
+static void handle_battery_query(const uint8_t *master_mac,
+                                 const alox_EspNowBatteryQuery *query) {
+  uint32_t my_id = esp_now_core_own_mac()[5];
+  if (query->client_id != 0 && query->client_id != my_id) {
+    return;
+  }
+  if (s_joined && !esp_now_core_mac_equal(master_mac, s_master_mac)) {
+    return;
+  }
+  send_battery_to_master();
+}
+
+static void handle_led_ring(const uint8_t *master_mac,
+                            const alox_EspNowLedRing *msg) {
+  uint32_t my_id = esp_now_core_own_mac()[5];
+  if (msg->client_id != 0 && msg->client_id != my_id) {
+    return;
+  }
+  if (s_joined && !esp_now_core_mac_equal(master_mac, s_master_mac)) {
+    return;
+  }
+
+  alox_LedRingProgressRequest req = alox_LedRingProgressRequest_init_zero;
+  req.mode = msg->mode;
+  req.progress = msg->progress;
+  req.digit = msg->digit;
+  req.r = msg->r;
+  req.g = msg->g;
+  req.b = msg->b;
+  req.intensity = msg->intensity;
+  req.blink_ms = msg->blink_ms;
+  req.blink_count = msg->blink_count;
+
+  char mac_str[18];
+  esp_now_core_mac_to_str(master_mac, mac_str, sizeof(mac_str));
+  ESP_LOGI(TAG, "LED_RING mode %lu from master %s (id=%lu)",
+           (unsigned long)req.mode, mac_str, (unsigned long)my_id);
+  cmd_led_ring_apply(&req);
+}
+
+static void handle_find_me(const uint8_t *master_mac, const alox_EspNowFindMe *req) {
+  uint32_t my_id = esp_now_core_own_mac()[5];
+  if (req->client_id != 0 && req->client_id != my_id) {
+    return;
+  }
+  if (s_joined && !esp_now_core_mac_equal(master_mac, s_master_mac)) {
+    return;
+  }
+  char mac_str[18];
+  esp_now_core_mac_to_str(master_mac, mac_str, sizeof(mac_str));
+  ESP_LOGI(TAG, "FIND_ME from master %s (id=%lu)", mac_str, (unsigned long)my_id);
+  led_ring_find_me();
+}
+
+static void handle_accel_stream(const uint8_t *master_mac,
+                                const alox_EspNowAccelStream *cfg) {
+  uint32_t my_id = esp_now_core_own_mac()[5];
+  if (cfg->client_id != 0 && cfg->client_id != my_id) {
+    return;
+  }
+  if (s_joined && !esp_now_core_mac_equal(master_mac, s_master_mac)) {
+    return;
+  }
+  s_accel_stream_enabled = cfg->enable;
+  char mac_str[18];
+  esp_now_core_mac_to_str(master_mac, mac_str, sizeof(mac_str));
+  ESP_LOGI(TAG, "accel stream %s from master %s (id=%lu)",
+           cfg->enable ? "on" : "off", mac_str, (unsigned long)my_id);
+}
+
+static void handle_tap_notify(const uint8_t *master_mac,
+                              const alox_EspNowTapNotify *cfg) {
+  uint32_t my_id = esp_now_core_own_mac()[5];
+  if (cfg->client_id != 0 && cfg->client_id != my_id) {
+    return;
+  }
+  if (s_joined && !esp_now_core_mac_equal(master_mac, s_master_mac)) {
+    return;
+  }
+  s_tap_notify_single = cfg->single;
+  s_tap_notify_double = cfg->double_tap;
+  s_tap_notify_triple = cfg->triple;
+  char mac_str[18];
+  esp_now_core_mac_to_str(master_mac, mac_str, sizeof(mac_str));
+  ESP_LOGI(TAG,
+           "tap notify single=%d double=%d triple=%d from master %s (id=%lu)",
+           cfg->single, cfg->double_tap, cfg->triple, mac_str,
+           (unsigned long)my_id);
+}
+
+static void handle_accel_deadzone(const uint8_t *master_mac,
+                                  const alox_EspNowAccelDeadzone *cfg) {
+  uint32_t my_id = esp_now_core_own_mac()[5];
+  if (cfg->client_id != 0 && cfg->client_id != my_id) {
+    return;
+  }
+  if (s_joined && !esp_now_core_mac_equal(master_mac, s_master_mac)) {
+    return;
+  }
+  char mac_str[18];
+  esp_now_core_mac_to_str(master_mac, mac_str, sizeof(mac_str));
+  ESP_LOGI(TAG,
+           "accel deadzone from master %s: %lu LSB id=%lu (sensor %s)", mac_str,
+           (unsigned long)cfg->deadzone, (unsigned long)my_id,
+           bma456_is_ready() ? "ok" : "not installed");
+  bma456_set_accel_deadzone(cfg->deadzone);
+  if (pod_settings_save_accel_deadzone(cfg->deadzone) != ESP_OK) {
+    ESP_LOGW(TAG, "deadzone %lu applied but not saved to NVS",
+             (unsigned long)cfg->deadzone);
+  }
+}
+
+static void handle_discover(const uint8_t *sender_mac,
+                            const alox_EspNowDiscover *discover) {
+  if (discover->network != esp_now_core_network()) {
+    return;
+  }
+
+  uint32_t now = esp_now_core_now_ms();
+
+  if (s_joined) {
+    if (!esp_now_core_mac_equal(sender_mac, s_master_mac)) {
+      return;
+    }
+    s_master_ota_grace = discover->master_ota_pending;
+    if ((now - s_last_discover_ms) <= slave_master_lost_ms()) {
+      touch_master_presence(now);
+      return;
+    }
+    if (ota_uart_is_active()) {
+      touch_master_presence(now);
+      return;
+    }
+    ESP_LOGW(TAG, "master lost, rejoining");
+    reset_join();
+  }
+
+  memcpy(s_master_mac, sender_mac, ESP_NOW_ETH_ALEN);
+  s_joined = true;
+  s_master_ota_grace = discover->master_ota_pending;
+  touch_master_presence(now);
+  esp_now_core_ensure_peer(sender_mac);
+
+  char mac_str[18];
+  esp_now_core_mac_to_str(sender_mac, mac_str, sizeof(mac_str));
+  ESP_LOGI(TAG, "joined network %u, master %s", (unsigned)discover->network,
+           mac_str);
+
+  queue_tx(SLAVE_TX_SLAVE_INFO);
+  queue_tx(SLAVE_TX_BATTERY);
+}
+
+static void check_master_timeout(void) {
+  if (!s_joined || s_last_discover_ms == 0) {
+    return;
+  }
+  if (ota_uart_is_active()) {
+    return;
+  }
+  uint32_t now = esp_now_core_now_ms();
+  uint32_t limit = slave_master_lost_ms();
+  if ((now - s_last_discover_ms) > limit) {
+    ESP_LOGW(TAG, "no master discover for %u ms (limit %u), reconnecting",
+             (unsigned)(now - s_last_discover_ms), (unsigned)limit);
+    reset_join();
+  }
+}
+
+static void accel_stream_task(void *param) {
+  (void)param;
+  const uint8_t *own = esp_now_core_own_mac();
+
+  ESP_LOGI(TAG, "accel stream task (interval %u ms)",
+           (unsigned)ESPNOW_ACCEL_INTERVAL_MS);
+
+  while (1) {
+    vTaskDelay(pdMS_TO_TICKS(ESPNOW_ACCEL_INTERVAL_MS));
+    if (!s_joined || !s_accel_stream_enabled || !bma456_is_ready()) {
+      continue;
+    }
+    int16_t x = 0;
+    int16_t y = 0;
+    int16_t z = 0;
+    if (bma456_read_accel(&x, &y, &z) != ESP_OK) {
+      continue;
+    }
+    (void)send_accel_sample(s_master_mac, own[5], x, y, z);
+  }
+}
+
+static void on_bma456_tap(bma456_tap_kind_t kind, void *ctx) {
+  (void)ctx;
+  if (!s_joined) {
+    return;
+  }
+  bool enabled = false;
+  switch (kind) {
+  case BMA456_TAP_SINGLE:
+    enabled = s_tap_notify_single;
+    break;
+  case BMA456_TAP_DOUBLE:
+    enabled = s_tap_notify_double;
+    break;
+  case BMA456_TAP_TRIPLE:
+    enabled = s_tap_notify_triple;
+    break;
+  default:
+    return;
+  }
+  if (!enabled) {
+    return;
+  }
+  (void)send_tap_event(s_master_mac, esp_now_core_own_mac()[5], (uint32_t)kind);
+}
+
+static void heartbeat_task(void *param) {
+  (void)param;
+  uint32_t last_battery_ms = 0;
+
+  ESP_LOGI(TAG, "heartbeat task (interval %u ms)",
+           (unsigned)ESPNOW_HEARTBEAT_INTERVAL_MS);
+
+  while (1) {
+    vTaskDelay(pdMS_TO_TICKS(ESPNOW_HEARTBEAT_INTERVAL_MS));
+    check_master_timeout();
+    if (!s_joined) {
+      last_battery_ms = 0;
+      continue;
+    }
+    send_presence(s_master_mac, alox_EspNowMessageType_ESPNOW_HEARTBEAT);
+    uint32_t now = esp_now_core_now_ms();
+    if (last_battery_ms == 0 ||
+        (now - last_battery_ms) >= ESPNOW_BATTERY_INTERVAL_MS) {
+      send_battery_to_master();
+      last_battery_ms = now;
+    }
+  }
+}
+
+void esp_now_slave_on_recv(const esp_now_recv_info_t *info, const uint8_t *data,
+                           int len) {
+  if (info == NULL || data == NULL || len <= 0) {
+    return;
+  }
+
+  alox_EspNowMessage msg = alox_EspNowMessage_init_zero;
+  if (esp_now_proto_decode(data, (size_t)len, &msg) != ESP_OK) {
+    ESP_LOGW(TAG, "decode failed (%d bytes)", len);
+    return;
+  }
+
+  if (from_joined_master(info->src_addr)) {
+    esp_now_core_ensure_peer(info->src_addr);
+  }
+
+  if (ota_uart_is_active()) {
+    switch (msg.which_payload) {
+    case alox_EspNowMessage_discover_tag:
+      handle_discover(info->src_addr, &msg.payload.discover);
+      break;
+    case alox_EspNowMessage_ota_start_tag:
+    case alox_EspNowMessage_ota_payload_tag:
+    case alox_EspNowMessage_ota_end_tag:
+      if (!from_joined_master(info->src_addr)) {
+        break;
+      }
+      touch_master_presence(esp_now_core_now_ms());
+      if (msg.which_payload == alox_EspNowMessage_ota_start_tag) {
+        ota_espnow_slave_on_start(info->src_addr, &msg.payload.ota_start);
+      } else if (msg.which_payload == alox_EspNowMessage_ota_payload_tag) {
+        ota_espnow_slave_on_payload(info->src_addr, &msg.payload.ota_payload);
+      } else {
+        ota_espnow_slave_on_end(info->src_addr);
+      }
+      break;
+    default:
+      break;
+    }
+    return;
+  }
+
+  switch (msg.which_payload) {
+  case alox_EspNowMessage_discover_tag:
+    handle_discover(info->src_addr, &msg.payload.discover);
+    break;
+  case alox_EspNowMessage_unicast_test_tag:
+    if (from_joined_master(info->src_addr)) {
+      handle_unicast_test(info->src_addr, &msg.payload.unicast_test);
+    }
+    break;
+  case alox_EspNowMessage_echo_ping_tag:
+    if (from_joined_master(info->src_addr)) {
+      handle_echo_ping(info->src_addr, &msg.payload.echo_ping);
+    }
+    break;
+  case alox_EspNowMessage_accel_deadzone_tag:
+    if (from_joined_master(info->src_addr)) {
+      handle_accel_deadzone(info->src_addr, &msg.payload.accel_deadzone);
+    }
+    break;
+  case alox_EspNowMessage_accel_stream_tag:
+    if (from_joined_master(info->src_addr)) {
+      handle_accel_stream(info->src_addr, &msg.payload.accel_stream);
+    }
+    break;
+  case alox_EspNowMessage_tap_notify_tag:
+    if (from_joined_master(info->src_addr)) {
+      handle_tap_notify(info->src_addr, &msg.payload.tap_notify);
+    }
+    break;
+  case alox_EspNowMessage_battery_query_tag:
+    if (from_joined_master(info->src_addr)) {
+      handle_battery_query(info->src_addr, &msg.payload.battery_query);
+    }
+    break;
+  case alox_EspNowMessage_led_ring_tag:
+    if (from_joined_master(info->src_addr)) {
+      handle_led_ring(info->src_addr, &msg.payload.led_ring);
+    }
+    break;
+  case alox_EspNowMessage_find_me_tag:
+    if (from_joined_master(info->src_addr)) {
+      handle_find_me(info->src_addr, &msg.payload.find_me);
+    }
+    break;
+  case alox_EspNowMessage_restart_tag:
+    if (from_joined_master(info->src_addr)) {
+      handle_restart(info->src_addr, &msg.payload.restart);
+    }
+    break;
+  case alox_EspNowMessage_ota_start_tag:
+    if (from_joined_master(info->src_addr)) {
+      ota_espnow_slave_on_start(info->src_addr, &msg.payload.ota_start);
+    }
+    break;
+  default:
+    ESP_LOGW(TAG, "unhandled which=%u type=%u", msg.which_payload,
+             (unsigned)msg.type);
+    break;
+  }
+}
+
+esp_err_t esp_now_slave_start(void) {
+  reset_join();
+
+  s_tx_queue = xQueueCreate(4, sizeof(slave_tx_op_t));
+  if (s_tx_queue == NULL) {
+    ESP_LOGE(TAG, "failed to create tx queue");
+    return ESP_ERR_NO_MEM;
+  }
+  if (xTaskCreate(tx_task, "espnow_stx", 4096, NULL, 5, NULL) != pdPASS) {
+    ESP_LOGE(TAG, "failed to create tx task");
+    return ESP_FAIL;
+  }
+  if (xTaskCreate(heartbeat_task, "espnow_hb", 4096, NULL, 4, NULL) != pdPASS) {
+    ESP_LOGE(TAG, "failed to create heartbeat task");
+    return ESP_FAIL;
+  }
+  if (xTaskCreate(accel_stream_task, "espnow_accel", 4096, NULL, 5, NULL) !=
+      pdPASS) {
+    ESP_LOGE(TAG, "failed to create accel stream task");
+    return ESP_FAIL;
+  }
+  ota_espnow_slave_init();
+  bma456_set_tap_handler(on_bma456_tap, NULL);
+  return ESP_OK;
+}

main/esp_now_slave.h

@@ -0,0 +1,14 @@
+#ifndef ESP_NOW_SLAVE_H
+#define ESP_NOW_SLAVE_H
+
+#include "client_registry.h"
+#include "esp_err.h"
+#include "esp_now.h"
+
+esp_err_t esp_now_slave_start(void);
+void esp_now_slave_on_recv(const esp_now_recv_info_t *info, const uint8_t *data,
+                           int len);
+
+bool esp_now_slave_get_master_mac(uint8_t mac_out[CLIENT_MAC_LEN]);
+
+#endif

main/led_ring.c

@@ -5,6 +5,7 @@
 #include "esp_log.h"
 #include "freertos/FreeRTOS.h"
 #include "freertos/task.h"
+#include "freertos/semphr.h"
 #include "led_strip.h"
 #include <stdint.h>
 
@@ -23,8 +24,12 @@ static led_strip_handle_t led_ring;
 #define LED_RING_FIND_ME_ON_MS 300
 #define LED_RING_FIND_ME_OFF_MS 150
 #define LED_RING_FIND_ME_BLINKS_PER_COLOR 3
+#define LED_RING_BATTERY_LOW_R 255
+#define LED_RING_BATTERY_LOW_G 0
+#define LED_RING_BATTERY_LOW_B 0
 
 static QueueHandle_t led_queue;
+static SemaphoreHandle_t s_battery_low_done;
 
 // Led Matrix Maps
 const uint8_t d0[] = {46, 47, 60, 61, 62, 75, 78, 79,
@@ -116,6 +121,8 @@ void vTaskLedRing(void *pvParameters) {
         for (int i = 0; i < digit.count; i++) {
           led_strip_set_pixel(led_ring, RING_LEDS - digit.leds[i], r, g, b);
         }
+      } else if (cmd.mode == LED_CMD_SET_COLOR) {
+        ring_fill_color(r, g, b);
       } else if (cmd.mode == LED_CMD_PROGRESS) {
         uint32_t lit = ((uint32_t)cmd.progress * RING_LEDS + 50) / 100;
         if (lit > RING_LEDS) {
@@ -143,6 +150,22 @@ void vTaskLedRing(void *pvParameters) {
           }
         }
         continue;
+      } else if (cmd.mode == LED_CMD_BATTERY_LOW) {
+        uint8_t r = LED_RING_BATTERY_LOW_R;
+        uint8_t g = LED_RING_BATTERY_LOW_G;
+        uint8_t b = LED_RING_BATTERY_LOW_B;
+        led_ring_scale_rgb(&r, &g, &b, LED_RING_BATTERY_LOW_INTENSITY);
+        for (uint32_t i = 0; i < LED_RING_BATTERY_LOW_LEDS; i++) {
+          led_strip_set_pixel(led_ring, i, r, g, b);
+        }
+        led_strip_refresh(led_ring);
+        vTaskDelay(pdMS_TO_TICKS(LED_RING_BATTERY_LOW_HOLD_MS));
+        led_strip_clear(led_ring);
+        led_strip_refresh(led_ring);
+        if (s_battery_low_done != NULL) {
+          xSemaphoreGive(s_battery_low_done);
+        }
+        continue;
       }
       led_strip_refresh(led_ring);
     }
@@ -151,12 +174,13 @@ void vTaskLedRing(void *pvParameters) {
 
 void led_ring_init(void) {
   led_queue = xQueueCreate(10, sizeof(led_command_t));
+  s_battery_low_done = xSemaphoreCreateBinary();
   xTaskCreate(vTaskLedRing, "led_task", 4096, NULL, 5, NULL);
 }
 
 void led_ring_send_command(led_command_t *cmd) {
   if (led_queue != NULL) {
-    xQueueSend(led_queue, cmd, portMAX_DELAY);
+    (void)xQueueSend(led_queue, cmd, 0);
   }
 }
 
@@ -222,3 +246,13 @@ void led_ring_find_me(void) {
   led_command_t cmd = {.mode = LED_CMD_FIND_ME};
   led_ring_send_command(&cmd);
 }
+
+void led_ring_show_battery_low(void) {
+  if (led_queue == NULL || s_battery_low_done == NULL) {
+    return;
+  }
+  (void)xSemaphoreTake(s_battery_low_done, 0);
+  led_command_t cmd = {.mode = LED_CMD_BATTERY_LOW};
+  led_ring_send_command(&cmd);
+  (void)xSemaphoreTake(s_battery_low_done, portMAX_DELAY);
+}

main/led_ring.h

@@ -7,6 +7,10 @@
 #define LED_RING_DEFAULT_INTENSITY 13
 /** Full brightness for find-me and similar alerts. */
 #define LED_RING_FULL_INTENSITY 255
+/** ~10 % brightness for battery-low indicator. */
+#define LED_RING_BATTERY_LOW_INTENSITY 26
+#define LED_RING_BATTERY_LOW_LEDS 4
+#define LED_RING_BATTERY_LOW_HOLD_MS 5000
 
 typedef enum {
   LED_CMD_CLEAR,
@@ -14,7 +18,8 @@ typedef enum {
   LED_CMD_SET_COLOR,
   LED_CMD_PROGRESS,
   LED_CMD_BLINK,
-  LED_CMD_FIND_ME
+  LED_CMD_FIND_ME,
+  LED_CMD_BATTERY_LOW
 } led_mode_t;
 
 typedef struct {
@@ -45,4 +50,7 @@ void led_ring_ota_failed(void);
 /** Red / green / blue: 3 blinks each at full intensity. */
 void led_ring_find_me(void);
 
+/** First 4 LEDs red at ~10 % for 5 s, then off (blocking in LED task). */
+void led_ring_show_battery_low(void);
+
 #endif

main/ota_espnow.c

@@ -18,9 +18,9 @@ static const char *TAG = "[OTA_ESPNOW]";
 #define OTA_ESPNOW_PREPARE_PRIO 5
 
 #define OTA_PREPARE_TIMEOUT_MS 120000u
-#define OTA_BLOCK_TIMEOUT_MS 30000u
+#define OTA_BLOCK_TIMEOUT_PER_SLAVE_MS 2000u
+#define OTA_BLOCK_MAX_RETRIES 2u
 #define OTA_END_TIMEOUT_MS 60000u
-#define OTA_PAYLOAD_DELAY_MS 3
 
 #define OTA_ST_PREPARING 1u
 #define OTA_ST_READY 2u
@@ -35,7 +35,29 @@ static const char *TAG = "[OTA_ESPNOW]";
 
 #define OTA_MAX_TARGETS CLIENT_REGISTRY_MAX
 
+/** ~21 payloads per 4 KiB block; headroom for bursts + status/end. */
+#define OTA_SLAVE_WORK_QUEUE_LEN 32
+#define OTA_SLAVE_WORK_STACK 8192
+#define OTA_SLAVE_WORK_PRIO 5
+
+typedef enum {
+  OTA_SLAVE_WORK_STATUS = 1,
+  OTA_SLAVE_WORK_PAYLOAD,
+  OTA_SLAVE_WORK_END,
+} ota_slave_work_op_t;
+
+typedef struct {
+  ota_slave_work_op_t op;
+  uint8_t master_mac[6];
+  uint32_t status;
+  uint32_t bytes_written;
+  uint32_t error;
+  alox_EspNowOtaPayload payload;
+} ota_slave_work_t;
+
 static EventGroupHandle_t s_eg;
+static QueueHandle_t s_slave_work_queue;
+static bool s_distribution_active;
 
 typedef struct {
   uint8_t count;
@@ -152,11 +174,204 @@ static bool wait_target_bits(uint32_t want_bits, uint32_t timeout_ms) {
   return (got & want_bits) == want_bits;
 }
 
+static uint32_t block_ack_timeout_ms(void) {
+  if (s_dist.count == 0) {
+    return OTA_BLOCK_TIMEOUT_PER_SLAVE_MS;
+  }
+  return (uint32_t)s_dist.count * OTA_BLOCK_TIMEOUT_PER_SLAVE_MS;
+}
+
+static void log_missing_block_acks(uint32_t expected_bytes) {
+  if (s_eg == NULL || s_dist.count == 0) {
+    return;
+  }
+  EventBits_t bits = xEventGroupGetBits(s_eg);
+  for (uint8_t i = 0; i < s_dist.count; i++) {
+    uint32_t bit = (1u << (unsigned)i);
+    if (bits & bit) {
+      continue;
+    }
+    const ota_prog_entry_t *e = &s_prog.entries[i];
+    ESP_LOGE(TAG,
+             "slave %lu missing block ack @%lu (last status=%lu bytes=%lu err=%lu)",
+             (unsigned long)s_dist.id[i], (unsigned long)expected_bytes,
+             (unsigned long)e->status, (unsigned long)e->bytes_written,
+             (unsigned long)e->error);
+  }
+}
+
+static esp_err_t send_block_payloads(const uint8_t *block_buf, uint32_t block_len,
+                                     uint32_t *seq_io) {
+  uint32_t sent = 0;
+  while (sent < block_len) {
+    uint32_t chunk = block_len - sent;
+    if (chunk > OTA_UART_HOST_CHUNK_SIZE) {
+      chunk = OTA_UART_HOST_CHUNK_SIZE;
+    }
+
+    for (uint8_t i = 0; i < s_dist.count; i++) {
+      esp_err_t err = esp_now_comm_send_ota_payload(s_dist.mac[i], *seq_io,
+                                                    block_buf + sent, chunk);
+      if (err != ESP_OK) {
+        return err;
+      }
+    }
+    (*seq_io)++;
+    sent += chunk;
+  }
+  return ESP_OK;
+}
+
+bool ota_espnow_distribution_active(void) { return s_distribution_active; }
+
 static void send_slave_status(const uint8_t master_mac[6], uint32_t status,
                               uint32_t bytes_written, uint32_t error) {
   esp_now_comm_send_ota_status(master_mac, status, bytes_written, error);
 }
 
+static bool queue_slave_work(const ota_slave_work_t *work) {
+  if (work == NULL || s_slave_work_queue == NULL) {
+    return false;
+  }
+  if (xQueueSend(s_slave_work_queue, work, 0) != pdTRUE) {
+    ESP_LOGW(TAG, "slave OTA work queue full (op=%d)", (int)work->op);
+    return false;
+  }
+  return true;
+}
+
+static void queue_slave_status(const uint8_t master_mac[6], uint32_t status,
+                               uint32_t bytes_written, uint32_t error) {
+  ota_slave_work_t work = {
+      .op = OTA_SLAVE_WORK_STATUS,
+      .status = status,
+      .bytes_written = bytes_written,
+      .error = error,
+  };
+  memcpy(work.master_mac, master_mac, 6);
+  (void)queue_slave_work(&work);
+}
+
+static void process_slave_payload(const uint8_t master_mac[6],
+                                  const alox_EspNowOtaPayload *payload) {
+  if (payload == NULL || payload->data.size == 0) {
+    send_slave_status(master_mac, OTA_ST_FAILED, 0, 11);
+    return;
+  }
+
+  if (!ota_uart_is_active()) {
+    ESP_LOGW(TAG, "OTA_PAYLOAD seq=%lu but no active session",
+             (unsigned long)payload->seq);
+    send_slave_status(master_mac, OTA_ST_FAILED, 0, 12);
+    return;
+  }
+
+  if (payload->seq == 0) {
+    ESP_LOGI(TAG, "ESP-NOW OTA payloads started");
+  }
+
+  ota_feed_result_t r = ota_uart_feed_chunk(payload->seq, payload->data.bytes,
+                                            payload->data.size);
+  if (r == OTA_FEED_SEQ_GAP) {
+    led_ring_ota_failed();
+    send_slave_status(master_mac, OTA_ST_FAILED, ota_uart_bytes_written(), 16);
+    return;
+  }
+  if (r == OTA_FEED_SEQ_DUP) {
+    if (ota_uart_block_ready_for_reack()) {
+      send_slave_status(master_mac, OTA_ST_BLOCK_ACK, ota_uart_bytes_written(),
+                        0);
+    }
+    return;
+  }
+  if (r == OTA_FEED_ERROR) {
+    led_ring_ota_failed();
+    send_slave_status(master_mac, OTA_ST_FAILED, ota_uart_bytes_written(), 13);
+    return;
+  }
+  if (r == OTA_FEED_BLOCK_WRITTEN) {
+    uint32_t written = ota_uart_bytes_written();
+    uint32_t total = ota_uart_total_size();
+    ESP_LOGI(TAG, "block written %lu bytes -> ack master", (unsigned long)written);
+    led_ring_show_ota_progress(written, total, OTA_LED_ESPNOW_RX_R, OTA_LED_ESPNOW_RX_G,
+                               OTA_LED_ESPNOW_RX_B);
+    send_slave_status(master_mac, OTA_ST_BLOCK_ACK, written, 0);
+    return;
+  }
+
+  if (r == OTA_FEED_OK) {
+    uint32_t total = ota_uart_total_size();
+    if (total > 0) {
+      led_ring_show_ota_progress(ota_uart_bytes_received(), total,
+                                 OTA_LED_ESPNOW_RX_R, OTA_LED_ESPNOW_RX_G,
+                                 OTA_LED_ESPNOW_RX_B);
+    }
+  }
+}
+
+static void process_slave_end(const uint8_t master_mac[6]) {
+  ESP_LOGI(TAG, "ESP-NOW OTA_END");
+  if (!ota_uart_is_active()) {
+    send_slave_status(master_mac, OTA_ST_FAILED, 0, 20);
+    return;
+  }
+
+  uint32_t written = ota_uart_bytes_written();
+  bool success = false;
+  esp_err_t err = ota_uart_finish(true, &success);
+  if (err != ESP_OK || !success) {
+    led_ring_ota_failed();
+    send_slave_status(master_mac, OTA_ST_FAILED, written, (uint32_t)err);
+    return;
+  }
+
+  send_slave_status(master_mac, OTA_ST_SUCCESS, written, 0);
+  led_ring_ota_success();
+  ESP_LOGI(TAG, "slave OTA success (%lu bytes), reboot to run",
+           (unsigned long)written);
+}
+
+static void ota_slave_work_task(void *param) {
+  (void)param;
+  ota_slave_work_t work;
+
+  while (1) {
+    if (xQueueReceive(s_slave_work_queue, &work, portMAX_DELAY) != pdTRUE) {
+      continue;
+    }
+
+    switch (work.op) {
+    case OTA_SLAVE_WORK_STATUS:
+      send_slave_status(work.master_mac, work.status, work.bytes_written,
+                        work.error);
+      break;
+    case OTA_SLAVE_WORK_PAYLOAD:
+      process_slave_payload(work.master_mac, &work.payload);
+      break;
+    case OTA_SLAVE_WORK_END:
+      process_slave_end(work.master_mac);
+      break;
+    default:
+      break;
+    }
+  }
+}
+
+void ota_espnow_slave_init(void) {
+  if (s_slave_work_queue != NULL) {
+    return;
+  }
+  s_slave_work_queue = xQueueCreate(OTA_SLAVE_WORK_QUEUE_LEN, sizeof(ota_slave_work_t));
+  if (s_slave_work_queue == NULL) {
+    ESP_LOGE(TAG, "failed to create slave OTA work queue");
+    return;
+  }
+  if (xTaskCreate(ota_slave_work_task, "ota_slave_wrk", OTA_SLAVE_WORK_STACK, NULL,
+                  OTA_SLAVE_WORK_PRIO, NULL) != pdPASS) {
+    ESP_LOGE(TAG, "failed to create slave OTA work task");
+  }
+}
+
 static void ota_slave_prepare_task(void *param) {
   uint32_t total_size = (uint32_t)(uintptr_t)param;
   uint8_t master_mac[6];
@@ -190,82 +405,37 @@ void ota_espnow_slave_on_start(const uint8_t master_mac[6],
   ESP_LOGI(TAG, "ESP-NOW OTA_START (%lu bytes)", (unsigned long)start->total_size);
 
   if (ota_uart_is_active()) {
-    send_slave_status(master_mac, OTA_ST_FAILED, 0, 4);
+    queue_slave_status(master_mac, OTA_ST_FAILED, 0, 4);
     return;
   }
 
   if (xTaskCreate(ota_slave_prepare_task, "ota_esp_prep", OTA_ESPNOW_PREPARE_STACK,
                   (void *)(uintptr_t)start->total_size, OTA_ESPNOW_PREPARE_PRIO,
                   NULL) != pdPASS) {
-    send_slave_status(master_mac, OTA_ST_FAILED, 0, 5);
+    queue_slave_status(master_mac, OTA_ST_FAILED, 0, 5);
   }
 }
 
 void ota_espnow_slave_on_payload(const uint8_t master_mac[6],
                                  const alox_EspNowOtaPayload *payload) {
-  if (payload == NULL || payload->data.size == 0) {
-    send_slave_status(master_mac, OTA_ST_FAILED, 0, 11);
+  if (payload == NULL) {
+    queue_slave_status(master_mac, OTA_ST_FAILED, 0, 11);
     return;
   }
 
-  if (!ota_uart_is_active()) {
-    ESP_LOGW(TAG, "OTA_PAYLOAD seq=%lu but no active session",
-             (unsigned long)payload->seq);
-    send_slave_status(master_mac, OTA_ST_FAILED, 0, 12);
-    return;
-  }
-
-  if (payload->seq == 0) {
-    ESP_LOGI(TAG, "ESP-NOW OTA payloads started");
-  }
-
-  ota_feed_result_t r =
-      ota_uart_feed(payload->data.bytes, payload->data.size);
-  if (r == OTA_FEED_ERROR) {
-    led_ring_ota_failed();
-    send_slave_status(master_mac, OTA_ST_FAILED, ota_uart_bytes_written(), 13);
-    return;
-  }
-  if (r == OTA_FEED_BLOCK_WRITTEN) {
-    uint32_t written = ota_uart_bytes_written();
-    uint32_t total = ota_uart_total_size();
-    ESP_LOGI(TAG, "block written %lu bytes -> ack master", (unsigned long)written);
-    led_ring_show_ota_progress(written, total, OTA_LED_ESPNOW_RX_R, OTA_LED_ESPNOW_RX_G,
-                               OTA_LED_ESPNOW_RX_B);
-    send_slave_status(master_mac, OTA_ST_BLOCK_ACK, written, 0);
-    return;
-  }
-
-  if (r == OTA_FEED_OK) {
-    uint32_t total = ota_uart_total_size();
-    if (total > 0) {
-      led_ring_show_ota_progress(ota_uart_bytes_received(), total,
-                                 OTA_LED_ESPNOW_RX_R, OTA_LED_ESPNOW_RX_G,
-                                 OTA_LED_ESPNOW_RX_B);
-    }
+  ota_slave_work_t work = {.op = OTA_SLAVE_WORK_PAYLOAD, .payload = *payload};
+  memcpy(work.master_mac, master_mac, 6);
+  if (!queue_slave_work(&work)) {
+    queue_slave_status(master_mac, OTA_ST_FAILED, 0, 14);
   }
 }
 
 void ota_espnow_slave_on_end(const uint8_t master_mac[6]) {
-  ESP_LOGI(TAG, "ESP-NOW OTA_END");
-  if (!ota_uart_is_active()) {
-    send_slave_status(master_mac, OTA_ST_FAILED, 0, 20);
-    return;
+  ota_slave_work_t work = {.op = OTA_SLAVE_WORK_END};
+  memcpy(work.master_mac, master_mac, 6);
+  if (!queue_slave_work(&work)) {
+    queue_slave_status(master_mac, OTA_ST_FAILED, 0, 15);
   }
-
-  uint32_t written = ota_uart_bytes_written();
-  bool success = false;
-  esp_err_t err = ota_uart_finish(true, &success);
-  if (err != ESP_OK || !success) {
-    led_ring_ota_failed();
-    send_slave_status(master_mac, OTA_ST_FAILED, written, (uint32_t)err);
-    return;
-  }
-
-  send_slave_status(master_mac, OTA_ST_SUCCESS, written, 0);
-  led_ring_ota_success();
-  ESP_LOGI(TAG, "slave OTA success (%lu bytes), reboot to run",
-           (unsigned long)written);
 }
 
 void ota_espnow_master_on_status(const uint8_t slave_mac[6],
@@ -342,6 +512,8 @@ static esp_err_t distribute_image(const esp_partition_t *partition,
     }
   }
 
+  s_distribution_active = true;
+
   memset(&s_dist.progress, 0, sizeof(s_dist.progress));
   if (progress != NULL) {
     s_dist.progress = *progress;
@@ -362,6 +534,7 @@ static esp_err_t distribute_image(const esp_partition_t *partition,
       ESP_LOGW(TAG, "OTA_START to slave %lu failed",
                (unsigned long)s_dist.id[i]);
       prog_end();
+      s_distribution_active = false;
       return err;
     }
   }
@@ -369,6 +542,7 @@ static esp_err_t distribute_image(const esp_partition_t *partition,
   if (!wait_target_bits(target_mask, OTA_PREPARE_TIMEOUT_MS)) {
     ESP_LOGE(TAG, "timeout waiting for slave OTA ready");
     prog_end();
+    s_distribution_active = false;
     return ESP_ERR_TIMEOUT;
   }
 
@@ -392,38 +566,77 @@ static esp_err_t distribute_image(const esp_partition_t *partition,
       ESP_LOGE(TAG, "partition read @%lu failed: %s", (unsigned long)offset,
                esp_err_to_name(err));
       prog_end();
+      s_distribution_active = false;
       return err;
     }
 
-    uint32_t sent = 0;
-    while (sent < block_len) {
-      uint32_t chunk = block_len - sent;
-      if (chunk > OTA_UART_HOST_CHUNK_SIZE) {
-        chunk = OTA_UART_HOST_CHUNK_SIZE;
-      }
-
-      for (uint8_t i = 0; i < s_dist.count; i++) {
-        err = esp_now_comm_send_ota_payload(s_dist.mac[i], seq,
-                                            block_buf + sent, chunk);
-        if (err != ESP_OK) {
-          prog_end();
-          return err;
-        }
-      }
-      seq++;
-      sent += chunk;
-      vTaskDelay(pdMS_TO_TICKS(OTA_PAYLOAD_DELAY_MS));
-    }
-
     const bool full_block = (block_len >= OTA_UART_FLASH_BLOCK_SIZE);
     s_dist.expected_bytes = offset + block_len;
+    const uint32_t block_start_seq = seq;
 
     if (full_block) {
       xEventGroupClearBits(s_eg, target_mask);
-      if (!wait_target_bits(target_mask, OTA_BLOCK_TIMEOUT_MS)) {
-        ESP_LOGE(TAG, "timeout block ack @%lu bytes",
-                 (unsigned long)s_dist.expected_bytes);
+    }
+
+    bool block_sent = false;
+    for (uint32_t send_attempt = 0; send_attempt <= OTA_BLOCK_MAX_RETRIES;
+         send_attempt++) {
+      if (send_attempt > 0) {
+        seq = block_start_seq;
+        if (full_block) {
+          xEventGroupClearBits(s_eg, target_mask);
+        }
+        ESP_LOGW(TAG, "block send failed @%lu — resend %lu/%lu",
+                 (unsigned long)s_dist.expected_bytes,
+                 (unsigned long)send_attempt,
+                 (unsigned long)OTA_BLOCK_MAX_RETRIES);
+      }
+      err = send_block_payloads(block_buf, block_len, &seq);
+      if (err == ESP_OK) {
+        block_sent = true;
+        break;
+      }
+    }
+    if (!block_sent) {
+      ESP_LOGE(TAG, "block send failed @%lu after %lu retries",
+               (unsigned long)s_dist.expected_bytes,
+               (unsigned long)OTA_BLOCK_MAX_RETRIES);
+      prog_end();
+      s_distribution_active = false;
+      return err;
+    }
+
+    if (full_block) {
+      const uint32_t ack_timeout = block_ack_timeout_ms();
+      bool acked = false;
+      for (uint32_t attempt = 0; attempt <= OTA_BLOCK_MAX_RETRIES; attempt++) {
+        if (wait_target_bits(target_mask, ack_timeout)) {
+          acked = true;
+          break;
+        }
+        log_missing_block_acks(s_dist.expected_bytes);
+        if (attempt >= OTA_BLOCK_MAX_RETRIES) {
+          break;
+        }
+        ESP_LOGW(TAG, "block ack timeout @%lu — resend %lu/%lu",
+                 (unsigned long)s_dist.expected_bytes,
+                 (unsigned long)(attempt + 1),
+                 (unsigned long)OTA_BLOCK_MAX_RETRIES);
+        xEventGroupClearBits(s_eg, target_mask);
+        seq = block_start_seq;
+        err = send_block_payloads(block_buf, block_len, &seq);
+        if (err != ESP_OK) {
+          prog_end();
+          s_distribution_active = false;
+          return err;
+        }
+      }
+      if (!acked) {
+        ESP_LOGE(TAG, "timeout block ack @%lu bytes after %lu retries",
+                 (unsigned long)s_dist.expected_bytes,
+                 (unsigned long)OTA_BLOCK_MAX_RETRIES);
         prog_end();
+        s_distribution_active = false;
         return ESP_ERR_TIMEOUT;
       }
       ESP_LOGI(TAG, "block ack @%lu/%lu (%lu%%)",
@@ -445,6 +658,7 @@ static esp_err_t distribute_image(const esp_partition_t *partition,
     err = esp_now_comm_send_ota_end(s_dist.mac[i]);
     if (err != ESP_OK) {
       prog_end();
+      s_distribution_active = false;
       return err;
     }
   }
@@ -452,11 +666,13 @@ static esp_err_t distribute_image(const esp_partition_t *partition,
   if (!wait_target_bits(target_mask, OTA_END_TIMEOUT_MS)) {
     ESP_LOGE(TAG, "timeout waiting for slave OTA success");
     prog_end();
+    s_distribution_active = false;
     return ESP_ERR_TIMEOUT;
   }
 
   prog_set_aggregate(size);
   prog_end();
+  s_distribution_active = false;
   ESP_LOGI(TAG, "ESP-NOW OTA complete for %u slave(s)", (unsigned)s_dist.count);
   return ESP_OK;
 }

main/ota_espnow.h

@@ -37,4 +37,10 @@ void ota_espnow_slave_on_end(const uint8_t master_mac[6]);
 void ota_espnow_progress_query(uint32_t filter_client_id,
                                alox_OtaSlaveProgressResponse *out);
 
+/** True while master is pushing a staged image to slaves. */
+bool ota_espnow_distribution_active(void);
+
+/** Slave: work queue for OTA (no esp_now_send from recv callback). */
+void ota_espnow_slave_init(void);
+
 #endif

main/ota_session.c

@@ -0,0 +1,25 @@
+#include "ota_session.h"
+#include "ota_espnow.h"
+#include "ota_uart.h"
+#include "uart_messages.pb.h"
+
+bool ota_session_busy(void) {
+  return ota_uart_is_active() || ota_espnow_distribution_active();
+}
+
+bool ota_session_uart_cmd_allowed(uint16_t msg_id) {
+  if (!ota_session_busy()) {
+    return true;
+  }
+
+  switch ((alox_MessageType)msg_id) {
+  case alox_MessageType_OTA_START:
+  case alox_MessageType_OTA_PAYLOAD:
+  case alox_MessageType_OTA_END:
+  case alox_MessageType_OTA_START_ESPNOW:
+  case alox_MessageType_OTA_SLAVE_PROGRESS:
+    return true;
+  default:
+    return false;
+  }
+}

main/ota_session.h

@@ -0,0 +1,13 @@
+#ifndef OTA_SESSION_H
+#define OTA_SESSION_H
+
+#include <stdbool.h>
+#include <stdint.h>
+
+/** UART upload or ESP-NOW slave distribution in progress. */
+bool ota_session_busy(void);
+
+/** During OTA only UART OTA-related commands are accepted on the master. */
+bool ota_session_uart_cmd_allowed(uint16_t msg_id);
+
+#endif

main/ota_uart.c

@@ -12,6 +12,7 @@ typedef struct {
   uint32_t total_size;
   uint32_t received;
   uint32_t written;
+  uint32_t expected_seq;
   int target_slot;
   uint8_t block_buf[OTA_UART_FLASH_BLOCK_SIZE];
   size_t block_len;
@@ -112,10 +113,30 @@ int ota_uart_prepare(uint32_t total_size) {
   return s_ota.target_slot;
 }
 
-ota_feed_result_t ota_uart_feed(const uint8_t *data, size_t len) {
+bool ota_uart_block_ready_for_reack(void) {
+  if (!s_ota.active) {
+    return false;
+  }
+  return s_ota.written > 0 &&
+         (s_ota.written % OTA_UART_FLASH_BLOCK_SIZE) == 0 &&
+         s_ota.block_len == 0;
+}
+
+ota_feed_result_t ota_uart_feed_chunk(uint32_t seq, const uint8_t *data,
+                                      size_t len) {
   if (!s_ota.active || data == NULL || len == 0) {
     return OTA_FEED_ERROR;
   }
+  if (seq < s_ota.expected_seq) {
+    return OTA_FEED_SEQ_DUP;
+  }
+  if (seq > s_ota.expected_seq) {
+    ESP_LOGW(TAG, "seq gap: got %lu expected %lu", (unsigned long)seq,
+             (unsigned long)s_ota.expected_seq);
+    return OTA_FEED_SEQ_GAP;
+  }
+  s_ota.expected_seq++;
+
   if (len > OTA_UART_HOST_CHUNK_SIZE) {
     ESP_LOGW(TAG, "chunk %u > %u, truncating", (unsigned)len,
              OTA_UART_HOST_CHUNK_SIZE);
@@ -200,6 +221,13 @@ esp_err_t ota_uart_finish(bool set_boot, bool *success_out) {
     return err;
   }
 
+  if (s_ota.total_size > 0 && s_ota.received != s_ota.total_size) {
+    ESP_LOGE(TAG, "size mismatch: received=%lu expected=%lu",
+             (unsigned long)s_ota.received, (unsigned long)s_ota.total_size);
+    ota_uart_abort();
+    return ESP_ERR_INVALID_SIZE;
+  }
+
   err = esp_ota_end(s_ota.handle);
   if (err != ESP_OK) {
     ESP_LOGE(TAG, "esp_ota_end failed: %s", esp_err_to_name(err));