Pause playback while transmitting and declare microphone use.

macOS refuses capture without a usage string, and queued remote audio was still handed to the speaker after push-to-talk began.

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

station/behavior_test.go

@@ -360,6 +360,32 @@ func TestRemoteAudioAndTalker(t *testing.T) {
 	}
 }
 
+func TestPlaybackPausesWhenTransmitting(t *testing.T) {
+	in := login(t, "DL1ABC", "key", 20, 7, []string{"OPUS"})
+	enc, err := opus.NewEncoder()
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer enc.Close()
+	pkt, err := enc.Encode(make([]int16, opus.FrameSamples))
+	if err != nil {
+		t.Fatal(err)
+	}
+	in.refl.writeUDP(t, 101, 7, 1, appendBytes(nil, pkt))
+	in.refl.writeUDP(t, 101, 7, 2, appendBytes(nil, pkt))
+	if _, err := in.st.WaitPlayback(t.Context(), 2*opus.FrameSamples-1); err != nil {
+		t.Fatal(err)
+	}
+	in.st.HoldButton()
+	in.refl.writeFrame(t, 105, appendStr(appendU32(nil, 20), "DB0XYZ"))
+	if _, err := in.st.Wait(t.Context(), func(s station.State) bool { return s.Transmitting }); err != nil {
+		t.Fatal(err)
+	}
+	if pcm := in.st.TakePlayback(); len(pcm) != 0 {
+		t.Fatalf("playback %d samples, want none while transmitting", len(pcm))
+	}
+}
+
 func TestMicrophoneIsNotPlayed(t *testing.T) {
 	in := login(t, "DL1ABC", "key", 20, 7, []string{"OPUS"})
 	in.st.HoldButton()

station/session.go

@@ -163,12 +163,12 @@ func (s *Station) session(ctx context.Context, conn net.Conn) error {
 		case <-ctx.Done():
 			timer.Stop()
 			return ctx.Err()
-		case <-tcpErr:
+		case err := <-tcpErr:
 			timer.Stop()
-			return errors.New("tcp closed")
-		case <-udpFail:
+			return err
+		case err := <-udpFail:
 			timer.Stop()
-			return errors.New("udp closed")
+			return err
 		case tcpf = <-tcpCh:
 			timer.Stop()
 			reason = "tcp"
@@ -465,12 +465,14 @@ func (s *Station) endTransmit() {
 		copy(frame, s.mic)
 		s.mic = nil
 		if pkt, err := s.enc.Encode(frame); err == nil {
+			// A lost datagram ends the session when the receive timer expires.
 			_ = s.sendUDP(udpAudio, appendBlob(nil, pkt))
 		}
 	} else {
 		s.mic = nil
 	}
 	if s.udp != nil {
+		// A lost datagram ends the session when the receive timer expires.
 		_ = s.sendUDP(udpFlush, nil)
 	}
 }
@@ -511,6 +513,7 @@ func (s *Station) publish() {
 		s.state.Transmitting = tx
 		if tx {
 			s.state.Talker = s.cfg.callsign
+			s.play = nil
 		} else {
 			s.state.Talker = s.remoteTalker
 		}

station/station.go

@@ -151,6 +151,7 @@ func (s *Station) WriteMicrophone(pcm []int16) {
 		if err != nil {
 			continue
 		}
+		// A lost datagram ends the session when the receive timer expires.
 		_ = s.sendUDP(udpAudio, appendBlob(nil, pkt))
 	}
 }
@@ -159,6 +160,10 @@ func (s *Station) WriteMicrophone(pcm []int16) {
 func (s *Station) TakePlayback() []int16 {
 	s.mu.Lock()
 	defer s.mu.Unlock()
+	if s.transmitting() {
+		s.play = nil
+		return nil
+	}
 	out := s.play
 	s.play = nil
 	return out