Add BMA456 tap detection with ESP-NOW notify and host snapshot API.

Slaves forward configured tap kinds to the master; goTool exposes CLI, dashboard, REST, and WebSocket with separate notify vs receive and 2s display cache.

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

goTool/client_api.go

@@ -171,6 +171,64 @@ func (m *managedSerial) GetAccelStream(clientID uint32) (bool, error) {
 	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) readTapSnapshotPoll(clientID uint32) (*pb.TapSnapshotResponse, error) {
+	msg := &pb.UartMessage{
+		Type: pb.MessageType_TAP_SNAPSHOT,
+		Payload: &pb.UartMessage_TapSnapshotRequest{
+			TapSnapshotRequest: &pb.TapSnapshotRequest{ClientId: clientID},
+		},
+	}
+	body, err := proto.Marshal(msg)
+	if err != nil {
+		return nil, fmt.Errorf("encode: %w", err)
+	}
+	payload := append([]byte{byte(pb.MessageType_TAP_SNAPSHOT)}, body...)
+	respPayload, err := m.exchangePayloadPoll(payload, "TAP_SNAPSHOT")
+	if err != nil {
+		return nil, err
+	}
+	return decodeTapSnapshotPayload(respPayload)
+}
+
+func decodeTapSnapshotPayload(payload []byte) (*pb.TapSnapshotResponse, error) {
+	if len(payload) < 1 {
+		return nil, fmt.Errorf("empty response payload")
+	}
+	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_TAP_SNAPSHOT {
+		return nil, fmt.Errorf("unexpected type %v", msg.GetType())
+	}
+	r := msg.GetTapSnapshotResponse()
+	if r == nil {
+		return nil, fmt.Errorf("missing tap_snapshot_response")
+	}
+	return r, nil
+}
+
 func (m *managedSerial) accelStreamVia(
 	portFn func(func(*serialPort) error) error,
 	req *pb.AccelStreamRequest,
@@ -325,6 +383,52 @@ func (s *serialPort) AccelStream(req *pb.AccelStreamRequest) (*pb.AccelStreamRes
 	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) readTapSnapshot(clientID uint32) (*pb.TapSnapshotResponse, error) {
+	msg := &pb.UartMessage{
+		Type: pb.MessageType_TAP_SNAPSHOT,
+		Payload: &pb.UartMessage_TapSnapshotRequest{
+			TapSnapshotRequest: &pb.TapSnapshotRequest{ClientId: clientID},
+		},
+	}
+	body, err := proto.Marshal(msg)
+	if err != nil {
+		return nil, fmt.Errorf("encode: %w", err)
+	}
+	payload := append([]byte{byte(pb.MessageType_TAP_SNAPSHOT)}, body...)
+	respPayload, err := s.exchangePayload(payload, "TAP_SNAPSHOT")
+	if err != nil {
+		return nil, err
+	}
+	return decodeTapSnapshotPayload(respPayload)
+}
+
 func (s *serialPort) accelDeadzone(req *pb.AccelDeadzoneRequest) (*pb.AccelDeadzoneResponse, error) {
 	msg := &pb.UartMessage{
 		Type: pb.MessageType_ACCEL_DEADZONE,