test(voice): add comprehensive flow tests for voice channel fixes

Tests cover the actual code paths changed in voice fixes:

_on_packet DAVE passthrough (8 tests):
- Known SSRC + DAVE decrypt success → buffered
- Unknown SSRC + DAVE → skip DAVE, passthrough to Opus
- DAVE "Unencrypted" error → passthrough, not dropped
- DAVE other error → packet dropped
- No DAVE session → direct decode
- Bot's own SSRC → ignored (echo prevention)
- Multiple SSRCs → separate buffers

SSRC auto-mapping (6 tests):
- Single allowed user → auto-mapped
- Multiple allowed users → no auto-map
- No allowlist → sole non-bot member inferred
- Unallowed user → rejected
- Only bot in channel → no map
- Auto-map persists across checks

Buffer lifecycle (4 tests):
- Known SSRC completed utterance
- Short buffer ignored
- Recent audio waits
- Stale unknown buffer discarded

TTS playback (10 tests):
- play_tts calls play_in_voice_channel in VC
- play_tts falls through when not in VC
- play_tts wrong channel no match
- Voice input dedup (runner skips)
- Text + voice_mode combinations
- Error/empty response skipped
- Agent TTS tool dedup

UDP keepalive (2 tests):
- Interval within bounds
- Silence frame actually sent via send_packet

tests/gateway/test_voice_command.py

@@ -2037,3 +2037,530 @@ class TestDisconnectVoiceCleanup:
         assert len(adapter._voice_receivers) == 0
         assert len(adapter._voice_listen_tasks) == 0
         assert len(adapter._voice_timeout_tasks) == 0
+
+
+# =====================================================================
+# Discord Voice Channel Flow Tests
+# =====================================================================
+
+
+class TestVoiceReception:
+    """Audio reception: SSRC mapping, DAVE passthrough, buffer lifecycle."""
+
+    @staticmethod
+    def _make_receiver(allowed_ids=None, members=None, dave=False, bot_id=9999):
+        from gateway.platforms.discord import VoiceReceiver
+        vc = MagicMock()
+        vc._connection.secret_key = [0] * 32
+        vc._connection.dave_session = MagicMock() if dave else None
+        vc._connection.ssrc = bot_id
+        vc._connection.add_socket_listener = MagicMock()
+        vc._connection.remove_socket_listener = MagicMock()
+        vc._connection.hook = None
+        vc.user = SimpleNamespace(id=bot_id)
+        vc.channel = MagicMock()
+        vc.channel.members = members or []
+        receiver = VoiceReceiver(vc, allowed_user_ids=allowed_ids)
+        return receiver
+
+    @staticmethod
+    def _fill_buffer(receiver, ssrc, duration_s=1.0, age_s=3.0):
+        """Add PCM data to buffer. 48kHz stereo 16-bit = 192000 bytes/sec."""
+        size = int(192000 * duration_s)
+        receiver._buffers[ssrc] = bytearray(b"\x00" * size)
+        receiver._last_packet_time[ssrc] = time.monotonic() - age_s
+
+    # -- Known SSRC (normal flow) --
+
+    def test_known_ssrc_returns_completed(self):
+        receiver = self._make_receiver()
+        receiver.start()
+        receiver.map_ssrc(100, 42)
+        self._fill_buffer(receiver, 100)
+        completed = receiver.check_silence()
+        assert len(completed) == 1
+        assert completed[0][0] == 42
+        assert len(receiver._buffers[100]) == 0  # cleared
+
+    def test_known_ssrc_short_buffer_ignored(self):
+        receiver = self._make_receiver()
+        receiver.start()
+        receiver.map_ssrc(100, 42)
+        self._fill_buffer(receiver, 100, duration_s=0.1)  # too short
+        completed = receiver.check_silence()
+        assert len(completed) == 0
+
+    def test_known_ssrc_recent_audio_waits(self):
+        receiver = self._make_receiver()
+        receiver.start()
+        receiver.map_ssrc(100, 42)
+        self._fill_buffer(receiver, 100, age_s=0.0)  # just arrived
+        completed = receiver.check_silence()
+        assert len(completed) == 0
+
+    # -- Unknown SSRC + DAVE passthrough --
+
+    def test_unknown_ssrc_no_automap_no_completed(self):
+        """Unknown SSRC, no members to infer — buffer cleared, not returned."""
+        receiver = self._make_receiver(dave=True, members=[])
+        receiver.start()
+        self._fill_buffer(receiver, 100)
+        completed = receiver.check_silence()
+        assert len(completed) == 0
+        assert len(receiver._buffers[100]) == 0
+
+    def test_unknown_ssrc_late_speaking_event(self):
+        """Audio buffered before SPEAKING → SPEAKING maps → next check returns it."""
+        receiver = self._make_receiver(dave=True)
+        receiver.start()
+        self._fill_buffer(receiver, 100, age_s=0.0)  # still receiving
+        # No user yet
+        assert receiver.check_silence() == []
+        # SPEAKING event arrives
+        receiver.map_ssrc(100, 42)
+        # Silence kicks in
+        receiver._last_packet_time[100] = time.monotonic() - 3.0
+        completed = receiver.check_silence()
+        assert len(completed) == 1
+        assert completed[0][0] == 42
+
+    # -- SSRC auto-mapping --
+
+    def test_automap_single_allowed_user(self):
+        members = [
+            SimpleNamespace(id=9999, name="Bot"),
+            SimpleNamespace(id=42, name="Alice"),
+        ]
+        receiver = self._make_receiver(allowed_ids={"42"}, members=members)
+        receiver.start()
+        self._fill_buffer(receiver, 100)
+        completed = receiver.check_silence()
+        assert len(completed) == 1
+        assert completed[0][0] == 42
+        assert receiver._ssrc_to_user[100] == 42
+
+    def test_automap_multiple_allowed_users_no_map(self):
+        members = [
+            SimpleNamespace(id=9999, name="Bot"),
+            SimpleNamespace(id=42, name="Alice"),
+            SimpleNamespace(id=43, name="Bob"),
+        ]
+        receiver = self._make_receiver(allowed_ids={"42", "43"}, members=members)
+        receiver.start()
+        self._fill_buffer(receiver, 100)
+        completed = receiver.check_silence()
+        assert len(completed) == 0
+
+    def test_automap_no_allowlist_single_member(self):
+        """No allowed_user_ids → sole non-bot member inferred."""
+        members = [
+            SimpleNamespace(id=9999, name="Bot"),
+            SimpleNamespace(id=42, name="Alice"),
+        ]
+        receiver = self._make_receiver(allowed_ids=None, members=members)
+        receiver.start()
+        self._fill_buffer(receiver, 100)
+        completed = receiver.check_silence()
+        assert len(completed) == 1
+        assert completed[0][0] == 42
+
+    def test_automap_unallowed_user_rejected(self):
+        """User in channel but not in allowed list — not mapped."""
+        members = [
+            SimpleNamespace(id=9999, name="Bot"),
+            SimpleNamespace(id=42, name="Alice"),
+        ]
+        receiver = self._make_receiver(allowed_ids={"99"}, members=members)
+        receiver.start()
+        self._fill_buffer(receiver, 100)
+        completed = receiver.check_silence()
+        assert len(completed) == 0
+
+    def test_automap_only_bot_in_channel(self):
+        """Only bot in channel — no one to map to."""
+        members = [SimpleNamespace(id=9999, name="Bot")]
+        receiver = self._make_receiver(allowed_ids=None, members=members)
+        receiver.start()
+        self._fill_buffer(receiver, 100)
+        completed = receiver.check_silence()
+        assert len(completed) == 0
+
+    def test_automap_persists_across_calls(self):
+        """Auto-mapped SSRC stays mapped for subsequent checks."""
+        members = [
+            SimpleNamespace(id=9999, name="Bot"),
+            SimpleNamespace(id=42, name="Alice"),
+        ]
+        receiver = self._make_receiver(allowed_ids={"42"}, members=members)
+        receiver.start()
+        self._fill_buffer(receiver, 100)
+        receiver.check_silence()
+        assert receiver._ssrc_to_user[100] == 42
+        # Second utterance — should use cached mapping
+        self._fill_buffer(receiver, 100)
+        completed = receiver.check_silence()
+        assert len(completed) == 1
+        assert completed[0][0] == 42
+
+    # -- Stale buffer cleanup --
+
+    def test_stale_unknown_buffer_discarded(self):
+        """Buffer with no user and very old timestamp is discarded."""
+        receiver = self._make_receiver()
+        receiver.start()
+        receiver._buffers[200] = bytearray(b"\x00" * 100)
+        receiver._last_packet_time[200] = time.monotonic() - 10.0
+        receiver.check_silence()
+        assert 200 not in receiver._buffers
+
+    # -- Pause / resume (echo prevention) --
+
+    def test_paused_receiver_ignores_packets(self):
+        receiver = self._make_receiver()
+        receiver.start()
+        receiver.pause()
+        receiver._on_packet(b"\x00" * 100)
+        assert len(receiver._buffers) == 0
+
+    def test_resumed_receiver_accepts_packets(self):
+        receiver = self._make_receiver()
+        receiver.start()
+        receiver.pause()
+        receiver.resume()
+        assert receiver._paused is False
+
+    # -- _on_packet DAVE passthrough behavior --
+
+    def _make_receiver_with_nacl(self, dave_session=None, mapped_ssrcs=None):
+        """Create a receiver that can process _on_packet with mocked NaCl + Opus."""
+        from gateway.platforms.discord import VoiceReceiver
+        vc = MagicMock()
+        vc._connection.secret_key = [0] * 32
+        vc._connection.dave_session = dave_session
+        vc._connection.ssrc = 9999
+        vc._connection.add_socket_listener = MagicMock()
+        vc._connection.remove_socket_listener = MagicMock()
+        vc._connection.hook = None
+        vc.user = SimpleNamespace(id=9999)
+        vc.channel = MagicMock()
+        vc.channel.members = []
+        receiver = VoiceReceiver(vc)
+        receiver.start()
+        # Pre-map SSRCs if provided
+        if mapped_ssrcs:
+            for ssrc, uid in mapped_ssrcs.items():
+                receiver.map_ssrc(ssrc, uid)
+        return receiver
+
+    @staticmethod
+    def _build_rtp_packet(ssrc=100, seq=1, timestamp=960):
+        """Build a minimal valid RTP packet for _on_packet.
+
+        We need: RTP header (12 bytes) + encrypted payload + 4-byte nonce.
+        NaCl decrypt is mocked so payload content doesn't matter.
+        """
+        import struct
+        # RTP header: version=2, payload_type=0x78, no extension, no CSRC
+        header = struct.pack(">BBHII", 0x80, 0x78, seq, timestamp, ssrc)
+        # Fake encrypted payload (NaCl will be mocked) + 4 byte nonce
+        payload = b"\x00" * 20 + b"\x00\x00\x00\x01"
+        return header + payload
+
+    def _inject_mock_decoder(self, receiver, ssrc):
+        """Pre-inject a mock Opus decoder for the given SSRC."""
+        mock_decoder = MagicMock()
+        mock_decoder.decode.return_value = b"\x00" * 3840
+        receiver._decoders[ssrc] = mock_decoder
+        return mock_decoder
+
+    def test_on_packet_dave_known_user_decrypt_ok(self):
+        """Known SSRC + DAVE decrypt success → audio buffered."""
+        dave = MagicMock()
+        dave.decrypt.return_value = b"\xf8\xff\xfe"
+        receiver = self._make_receiver_with_nacl(
+            dave_session=dave, mapped_ssrcs={100: 42}
+        )
+        self._inject_mock_decoder(receiver, 100)
+
+        with patch("nacl.secret.Aead") as mock_aead:
+            mock_aead.return_value.decrypt.return_value = b"\xf8\xff\xfe"
+            receiver._on_packet(self._build_rtp_packet(ssrc=100))
+
+        assert 100 in receiver._buffers
+        assert len(receiver._buffers[100]) > 0
+        dave.decrypt.assert_called_once()
+
+    def test_on_packet_dave_unknown_ssrc_passthrough(self):
+        """Unknown SSRC + DAVE → skip DAVE, attempt Opus decode (passthrough)."""
+        dave = MagicMock()
+        receiver = self._make_receiver_with_nacl(dave_session=dave)
+        self._inject_mock_decoder(receiver, 100)
+
+        with patch("nacl.secret.Aead") as mock_aead:
+            mock_aead.return_value.decrypt.return_value = b"\xf8\xff\xfe"
+            receiver._on_packet(self._build_rtp_packet(ssrc=100))
+
+        dave.decrypt.assert_not_called()
+        assert 100 in receiver._buffers
+        assert len(receiver._buffers[100]) > 0
+
+    def test_on_packet_dave_unencrypted_error_passthrough(self):
+        """DAVE decrypt 'Unencrypted' error → use data as-is, don't drop."""
+        dave = MagicMock()
+        dave.decrypt.side_effect = Exception(
+            "Failed to decrypt: DecryptionFailed(UnencryptedWhenPassthroughDisabled)"
+        )
+        receiver = self._make_receiver_with_nacl(
+            dave_session=dave, mapped_ssrcs={100: 42}
+        )
+        self._inject_mock_decoder(receiver, 100)
+
+        with patch("nacl.secret.Aead") as mock_aead:
+            mock_aead.return_value.decrypt.return_value = b"\xf8\xff\xfe"
+            receiver._on_packet(self._build_rtp_packet(ssrc=100))
+
+        assert 100 in receiver._buffers
+        assert len(receiver._buffers[100]) > 0
+
+    def test_on_packet_dave_other_error_drops(self):
+        """DAVE decrypt non-Unencrypted error → packet dropped."""
+        dave = MagicMock()
+        dave.decrypt.side_effect = Exception("KeyRotationFailed")
+        receiver = self._make_receiver_with_nacl(
+            dave_session=dave, mapped_ssrcs={100: 42}
+        )
+
+        with patch("nacl.secret.Aead") as mock_aead:
+            mock_aead.return_value.decrypt.return_value = b"\xf8\xff\xfe"
+            receiver._on_packet(self._build_rtp_packet(ssrc=100))
+
+        assert len(receiver._buffers.get(100, b"")) == 0
+
+    def test_on_packet_no_dave_direct_decode(self):
+        """No DAVE session → decode directly."""
+        receiver = self._make_receiver_with_nacl(dave_session=None)
+        self._inject_mock_decoder(receiver, 100)
+
+        with patch("nacl.secret.Aead") as mock_aead:
+            mock_aead.return_value.decrypt.return_value = b"\xf8\xff\xfe"
+            receiver._on_packet(self._build_rtp_packet(ssrc=100))
+
+        assert 100 in receiver._buffers
+        assert len(receiver._buffers[100]) > 0
+
+    def test_on_packet_bot_own_ssrc_ignored(self):
+        """Bot's own SSRC → dropped (echo prevention)."""
+        receiver = self._make_receiver_with_nacl()
+        with patch("nacl.secret.Aead"):
+            receiver._on_packet(self._build_rtp_packet(ssrc=9999))
+        assert len(receiver._buffers) == 0
+
+    def test_on_packet_multiple_ssrcs_separate_buffers(self):
+        """Different SSRCs → separate buffers."""
+        receiver = self._make_receiver_with_nacl(dave_session=None)
+        self._inject_mock_decoder(receiver, 100)
+        self._inject_mock_decoder(receiver, 200)
+
+        with patch("nacl.secret.Aead") as mock_aead:
+            mock_aead.return_value.decrypt.return_value = b"\xf8\xff\xfe"
+            receiver._on_packet(self._build_rtp_packet(ssrc=100))
+            receiver._on_packet(self._build_rtp_packet(ssrc=200))
+
+        assert 100 in receiver._buffers
+        assert 200 in receiver._buffers
+
+
+class TestVoiceTTSPlayback:
+    """TTS playback: play_tts in VC, dedup, fallback."""
+
+    @staticmethod
+    def _make_discord_adapter():
+        from gateway.platforms.discord import DiscordAdapter
+        from gateway.config import PlatformConfig, Platform
+        config = PlatformConfig(enabled=True, extra={})
+        config.token = "fake-token"
+        adapter = object.__new__(DiscordAdapter)
+        adapter.platform = Platform.DISCORD
+        adapter.config = config
+        adapter._voice_clients = {}
+        adapter._voice_text_channels = {}
+        adapter._voice_receivers = {}
+        return adapter
+
+    # -- play_tts behavior --
+
+    @pytest.mark.asyncio
+    async def test_play_tts_plays_in_vc(self):
+        """play_tts calls play_in_voice_channel when bot is in VC."""
+        adapter = self._make_discord_adapter()
+        mock_vc = MagicMock()
+        mock_vc.is_connected.return_value = True
+        adapter._voice_clients[111] = mock_vc
+        adapter._voice_text_channels[111] = 123
+
+        played = []
+        async def fake_play(gid, path):
+            played.append((gid, path))
+            return True
+        adapter.play_in_voice_channel = fake_play
+
+        result = await adapter.play_tts(chat_id="123", audio_path="/tmp/tts.ogg")
+        assert result.success is True
+        assert played == [(111, "/tmp/tts.ogg")]
+
+    @pytest.mark.asyncio
+    async def test_play_tts_fallback_when_not_in_vc(self):
+        """play_tts sends as file attachment when bot is not in VC."""
+        adapter = self._make_discord_adapter()
+        from gateway.platforms.base import SendResult
+        adapter.send_voice = AsyncMock(return_value=SendResult(success=False, error="no client"))
+        result = await adapter.play_tts(chat_id="123", audio_path="/tmp/tts.ogg")
+        assert result.success is False
+        adapter.send_voice.assert_called_once()
+
+    @pytest.mark.asyncio
+    async def test_play_tts_wrong_channel_no_match(self):
+        """play_tts doesn't match if chat_id is for a different channel."""
+        adapter = self._make_discord_adapter()
+        mock_vc = MagicMock()
+        mock_vc.is_connected.return_value = True
+        adapter._voice_clients[111] = mock_vc
+        adapter._voice_text_channels[111] = 123
+
+        from gateway.platforms.base import SendResult
+        adapter.send_voice = AsyncMock(return_value=SendResult(success=True))
+        # Different chat_id — shouldn't match VC
+        result = await adapter.play_tts(chat_id="999", audio_path="/tmp/tts.ogg")
+        adapter.send_voice.assert_called_once()
+
+    # -- Runner dedup --
+
+    @staticmethod
+    def _make_runner():
+        from gateway.run import GatewayRunner
+        runner = object.__new__(GatewayRunner)
+        runner._voice_mode = {}
+        runner.adapters = {}
+        return runner
+
+    def _call_should_reply(self, runner, voice_mode, msg_type, response="Hello", agent_msgs=None):
+        from gateway.platforms.base import MessageType, MessageEvent, SessionSource
+        from gateway.config import Platform
+        runner._voice_mode["ch1"] = voice_mode
+        source = SessionSource(
+            platform=Platform.DISCORD, chat_id="ch1",
+            user_id="1", user_name="test", chat_type="channel",
+        )
+        event = MessageEvent(source=source, text="test", message_type=msg_type)
+        return runner._should_send_voice_reply(event, response, agent_msgs or [])
+
+    def test_voice_input_runner_skips(self):
+        """Voice input: runner skips — base adapter handles via play_tts."""
+        from gateway.platforms.base import MessageType
+        runner = self._make_runner()
+        assert self._call_should_reply(runner, "all", MessageType.VOICE) is False
+
+    def test_text_input_voice_all_runner_fires(self):
+        """Text input + voice_mode=all: runner generates TTS."""
+        from gateway.platforms.base import MessageType
+        runner = self._make_runner()
+        assert self._call_should_reply(runner, "all", MessageType.TEXT) is True
+
+    def test_text_input_voice_off_no_tts(self):
+        """Text input + voice_mode=off: no TTS."""
+        from gateway.platforms.base import MessageType
+        runner = self._make_runner()
+        assert self._call_should_reply(runner, "off", MessageType.TEXT) is False
+
+    def test_text_input_voice_only_no_tts(self):
+        """Text input + voice_mode=voice_only: no TTS for text."""
+        from gateway.platforms.base import MessageType
+        runner = self._make_runner()
+        assert self._call_should_reply(runner, "voice_only", MessageType.TEXT) is False
+
+    def test_error_response_no_tts(self):
+        """Error response: no TTS regardless of voice_mode."""
+        from gateway.platforms.base import MessageType
+        runner = self._make_runner()
+        assert self._call_should_reply(runner, "all", MessageType.TEXT, response="Error: boom") is False
+
+    def test_empty_response_no_tts(self):
+        """Empty response: no TTS."""
+        from gateway.platforms.base import MessageType
+        runner = self._make_runner()
+        assert self._call_should_reply(runner, "all", MessageType.TEXT, response="") is False
+
+    def test_agent_tts_tool_dedup(self):
+        """Agent already called text_to_speech tool: runner skips."""
+        from gateway.platforms.base import MessageType
+        runner = self._make_runner()
+        agent_msgs = [{"role": "assistant", "tool_calls": [
+            {"id": "1", "type": "function", "function": {"name": "text_to_speech", "arguments": "{}"}}
+        ]}]
+        assert self._call_should_reply(runner, "all", MessageType.TEXT, agent_msgs=agent_msgs) is False
+
+
+class TestUDPKeepalive:
+    """UDP keepalive prevents Discord from dropping the voice session."""
+
+    def test_keepalive_interval_is_reasonable(self):
+        from gateway.platforms.discord import DiscordAdapter
+        interval = DiscordAdapter._KEEPALIVE_INTERVAL
+        assert 5 <= interval <= 30, f"Keepalive interval {interval}s should be between 5-30s"
+
+    @pytest.mark.asyncio
+    async def test_keepalive_sends_silence_frame(self):
+        """Listen loop sends silence frame via send_packet after interval."""
+        from gateway.platforms.discord import DiscordAdapter
+        from gateway.config import PlatformConfig, Platform
+
+        config = PlatformConfig(enabled=True, extra={})
+        config.token = "fake"
+        adapter = object.__new__(DiscordAdapter)
+        adapter.platform = Platform.DISCORD
+        adapter.config = config
+        adapter._voice_clients = {}
+        adapter._voice_text_channels = {}
+        adapter._voice_receivers = {}
+        adapter._voice_listen_tasks = {}
+
+        # Mock VC and receiver
+        mock_vc = MagicMock()
+        mock_vc.is_connected.return_value = True
+        mock_conn = MagicMock()
+        adapter._voice_clients[111] = mock_vc
+        mock_vc._connection = mock_conn
+
+        from gateway.platforms.discord import VoiceReceiver
+        mock_receiver_vc = MagicMock()
+        mock_receiver_vc._connection.secret_key = [0] * 32
+        mock_receiver_vc._connection.dave_session = None
+        mock_receiver_vc._connection.ssrc = 9999
+        mock_receiver_vc._connection.add_socket_listener = MagicMock()
+        mock_receiver_vc._connection.remove_socket_listener = MagicMock()
+        mock_receiver_vc._connection.hook = None
+        receiver = VoiceReceiver(mock_receiver_vc)
+        receiver.start()
+        adapter._voice_receivers[111] = receiver
+
+        # Set keepalive interval very short for test
+        original_interval = DiscordAdapter._KEEPALIVE_INTERVAL
+        DiscordAdapter._KEEPALIVE_INTERVAL = 0.1
+
+        try:
+            # Run listen loop briefly
+            import asyncio
+            loop_task = asyncio.create_task(adapter._voice_listen_loop(111))
+            await asyncio.sleep(0.3)
+            receiver._running = False  # stop loop
+            await asyncio.sleep(0.1)
+            loop_task.cancel()
+            try:
+                await loop_task
+            except asyncio.CancelledError:
+                pass
+
+            # send_packet should have been called with silence frame
+            mock_conn.send_packet.assert_called_with(b'\xf8\xff\xfe')
+        finally:
+            DiscordAdapter._KEEPALIVE_INTERVAL = original_interval