Harden BLE host link and expose latency tools in the dashboard.

Add BLE RTT/stream tests and live tick median in the UI, fix concurrent WebSocket writes and late BATTERY replies, and skip 2M PHY updates that assert under ESP-NOW coexistence.

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

goTool/ble_link.go

@@ -175,7 +175,17 @@ func (b *bleLink) onNotify(buf []byte) {
 		select {
 		case b.respCh <- payload:
 		default:
-			log.Printf("BLE: response channel full, dropping frame type=0x%02x", payload[0])
+			// Prefer dropping the oldest queued frame so a late/stale reply
+			// does not block the matching response for the in-flight command.
+			select {
+			case <-b.respCh:
+			default:
+			}
+			select {
+			case b.respCh <- payload:
+			default:
+				log.Printf("BLE: response channel full, dropping frame type=0x%02x", payload[0])
+			}
 		}
 	}
 }
@@ -189,9 +199,21 @@ func (b *bleLink) exchange(cmdID byte, cmdName string) ([]byte, error) {
 }
 
 func (b *bleLink) exchangePayload(payload []byte, cmdName string) ([]byte, error) {
+	return b.exchangePayloadTimeout(payload, cmdName, readTimeout)
+}
+
+func (b *bleLink) exchangePayloadTimeout(payload []byte, cmdName string, timeout time.Duration) ([]byte, error) {
 	b.mu.Lock()
 	defer b.mu.Unlock()
 
+	if len(payload) == 0 {
+		return nil, fmt.Errorf("empty payload")
+	}
+	expect := payload[0]
+	if timeout <= 0 {
+		timeout = readTimeout
+	}
+
 	frame, err := uartframe.EncodeFrame(payload)
 	if err != nil {
 		return nil, fmt.Errorf("encode frame: %w", err)
@@ -212,16 +234,33 @@ sent:
 		return nil, fmt.Errorf("BLE write: %w (check DIP8=BLE)", err)
 	}
 
-	timer := time.NewTimer(readTimeout)
-	defer timer.Stop()
-	select {
-	case resp := <-b.respCh:
-		if !b.quiet {
-			log.Printf("BLE response (%d bytes)", len(resp))
+	deadline := time.Now().Add(timeout)
+	for {
+		remain := time.Until(deadline)
+		if remain <= 0 {
+			return nil, fmt.Errorf("BLE read timeout for %s (check DIP8=BLE / -ble)", cmdName)
+		}
+		timer := time.NewTimer(remain)
+		select {
+		case resp := <-b.respCh:
+			timer.Stop()
+			if len(resp) == 0 {
+				continue
+			}
+			if resp[0] != expect {
+				// Stale reply (e.g. late BATTERY_STATUS after a short timeout).
+				if !b.quiet {
+					log.Printf("BLE: discard type=0x%02x while waiting for 0x%02x (%s)", resp[0], expect, cmdName)
+				}
+				continue
+			}
+			if !b.quiet {
+				log.Printf("BLE response (%d bytes)", len(resp))
+			}
+			return resp, nil
+		case <-timer.C:
+			return nil, fmt.Errorf("BLE read timeout for %s (check DIP8=BLE / -ble)", cmdName)
 		}
-		return resp, nil
-	case <-timer.C:
-		return nil, fmt.Errorf("BLE read timeout for %s (check DIP8=BLE / -ble)", cmdName)
 	}
 }