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/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
 		}