feat(channel): add message send retry mechanism with exponential backoff

- Add send_max_retries config option (default: 3, range: 0-10)
- Implement _send_with_retry in ChannelManager with 1s/2s/4s backoff
- Propagate CancelledError for graceful shutdown
- Fix telegram send_delta to raise exceptions for Manager retry
- Add comprehensive tests for retry logic
- Document channel settings in README

README.md

@@ -1157,6 +1157,38 @@ That's it! Environment variables, model routing, config matching, and `nanobot s
 
 </details>
 
+### Channel Settings
+
+Global settings that apply to all channels. Configure under the `channels` section in `~/.nanobot/config.json`:
+
+```json
+{
+  "channels": {
+    "sendProgress": true,
+    "sendToolHints": false,
+    "sendMaxRetries": 3,
+    "telegram": { ... }
+  }
+}
+```
+
+| Setting | Default | Description |
+|---------|---------|-------------|
+| `sendProgress` | `true` | Stream agent's text progress to the channel |
+| `sendToolHints` | `false` | Stream tool-call hints (e.g. `read_file("…")`) |
+| `sendMaxRetries` | `3` | Max retry attempts for message send failures (0-10) |
+
+#### Retry Behavior
+
+When a message fails to send, nanobot will automatically retry with exponential backoff:
+
+- **Attempts 1-3**: Retry delays are 1s, 2s, 4s
+- **Attempts 4+**: Retry delay caps at 4s
+- **Transient failures** (network hiccups, temporary API limits): Retry usually succeeds
+- **Permanent failures** (invalid token, channel banned): All retries fail
+
+> [!NOTE]
+> When a channel is completely unavailable, there's no way to notify the user since we cannot reach them through that channel. Monitor logs for "Failed to send to {channel} after N attempts" to detect persistent delivery failures.
 
 ### Web Search
 

nanobot/channels/manager.py

@@ -7,10 +7,14 @@ from typing import Any
 
 from loguru import logger
 
+from nanobot.bus.events import OutboundMessage
 from nanobot.bus.queue import MessageBus
 from nanobot.channels.base import BaseChannel
 from nanobot.config.schema import Config
 
+# Retry delays for message sending (exponential backoff: 1s, 2s, 4s)
+_SEND_RETRY_DELAYS = (1, 2, 4)
+
 
 class ChannelManager:
     """
@@ -129,15 +133,7 @@ class ChannelManager:
 
                 channel = self.channels.get(msg.channel)
                 if channel:
-                    try:
-                        if msg.metadata.get("_stream_delta") or msg.metadata.get("_stream_end"):
-                            await channel.send_delta(msg.chat_id, msg.content, msg.metadata)
-                        elif msg.metadata.get("_streamed"):
-                            pass
-                        else:
-                            await channel.send(msg)
-                    except Exception as e:
-                        logger.error("Error sending to {}: {}", msg.channel, e)
+                    await self._send_with_retry(channel, msg)
                 else:
                     logger.warning("Unknown channel: {}", msg.channel)
 
@@ -146,6 +142,41 @@ class ChannelManager:
             except asyncio.CancelledError:
                 break
 
+    async def _send_with_retry(self, channel: BaseChannel, msg: OutboundMessage) -> None:
+        """Send a message with retry on failure using exponential backoff.
+
+        Note: CancelledError is re-raised to allow graceful shutdown.
+        """
+        max_attempts = max(self.config.channels.send_max_retries, 1)
+
+        for attempt in range(max_attempts):
+            try:
+                if msg.metadata.get("_stream_delta") or msg.metadata.get("_stream_end"):
+                    await channel.send_delta(msg.chat_id, msg.content, msg.metadata)
+                elif msg.metadata.get("_streamed"):
+                    pass
+                else:
+                    await channel.send(msg)
+                return  # Send succeeded
+            except asyncio.CancelledError:
+                raise  # Propagate cancellation for graceful shutdown
+            except Exception as e:
+                if attempt == max_attempts - 1:
+                    logger.error(
+                        "Failed to send to {} after {} attempts: {} - {}",
+                        msg.channel, max_attempts, type(e).__name__, e
+                    )
+                    return
+                delay = _SEND_RETRY_DELAYS[min(attempt, len(_SEND_RETRY_DELAYS) - 1)]
+                logger.warning(
+                    "Send to {} failed (attempt {}/{}): {}, retrying in {}s",
+                    msg.channel, attempt + 1, max_attempts, type(e).__name__, delay
+                )
+                try:
+                    await asyncio.sleep(delay)
+                except asyncio.CancelledError:
+                    raise  # Propagate cancellation during sleep
+
     def get_channel(self, name: str) -> BaseChannel | None:
         """Get a channel by name."""
         return self.channels.get(name)

nanobot/channels/telegram.py

@@ -528,6 +528,7 @@ class TelegramChannel(BaseChannel):
                 buf.last_edit = now
             except Exception as e:
                 logger.warning("Stream initial send failed: {}", e)
+                raise  # Let ChannelManager handle retry
         elif (now - buf.last_edit) >= self._STREAM_EDIT_INTERVAL:
             try:
                 await self._call_with_retry(
@@ -536,8 +537,9 @@ class TelegramChannel(BaseChannel):
                     text=buf.text,
                 )
                 buf.last_edit = now
-            except Exception:
-                pass
+            except Exception as e:
+                logger.warning("Stream edit failed: {}", e)
+                raise  # Let ChannelManager handle retry
 
     async def _on_start(self, update: Update, context: ContextTypes.DEFAULT_TYPE) -> None:
         """Handle /start command."""

nanobot/config/schema.py

@@ -25,6 +25,7 @@ class ChannelsConfig(Base):
 
     send_progress: bool = True  # stream agent's text progress to the channel
     send_tool_hints: bool = False  # stream tool-call hints (e.g. read_file("…"))
+    send_max_retries: int = Field(default=3, ge=0, le=10)  # Max retry attempts for message send failures
 
 
 class AgentDefaults(Base):

pyproject.toml

@@ -120,3 +120,16 @@ ignore = ["E501"]
 [tool.pytest.ini_options]
 asyncio_mode = "auto"
 testpaths = ["tests"]
+
+[tool.coverage.run]
+source = ["nanobot"]
+omit = ["tests/*", "**/tests/*"]
+
+[tool.coverage.report]
+exclude_lines = [
+    "pragma: no cover",
+    "def __repr__",
+    "raise NotImplementedError",
+    "if __name__ == .__main__.:",
+    "if TYPE_CHECKING:",
+]

tests/channels/test_channel_plugins.py

@@ -2,8 +2,9 @@
 
 from __future__ import annotations
 
+import asyncio
 from types import SimpleNamespace
-from unittest.mock import patch
+from unittest.mock import AsyncMock, patch
 
 import pytest
 
@@ -262,3 +263,618 @@ def test_builtin_channel_init_from_dict():
     ch = TelegramChannel({"enabled": False, "token": "test-tok", "allowFrom": ["*"]}, bus)
     assert ch.config.token == "test-tok"
     assert ch.config.allow_from == ["*"]
+
+
+def test_channels_config_send_max_retries_default():
+    """ChannelsConfig should have send_max_retries with default value of 3."""
+    cfg = ChannelsConfig()
+    assert hasattr(cfg, 'send_max_retries')
+    assert cfg.send_max_retries == 3
+
+
+def test_channels_config_send_max_retries_upper_bound():
+    """send_max_retries should be bounded to prevent resource exhaustion."""
+    from pydantic import ValidationError
+
+    # Value too high should be rejected
+    with pytest.raises(ValidationError):
+        ChannelsConfig(send_max_retries=100)
+
+    # Negative should be rejected
+    with pytest.raises(ValidationError):
+        ChannelsConfig(send_max_retries=-1)
+
+    # Boundary values should be allowed
+    cfg_min = ChannelsConfig(send_max_retries=0)
+    assert cfg_min.send_max_retries == 0
+
+    cfg_max = ChannelsConfig(send_max_retries=10)
+    assert cfg_max.send_max_retries == 10
+
+    # Value above upper bound should be rejected
+    with pytest.raises(ValidationError):
+        ChannelsConfig(send_max_retries=11)
+
+
+# ---------------------------------------------------------------------------
+# _send_with_retry
+# ---------------------------------------------------------------------------
+
+@pytest.mark.asyncio
+async def test_send_with_retry_succeeds_first_try():
+    """_send_with_retry should succeed on first try and not retry."""
+    call_count = 0
+
+    class _FailingChannel(BaseChannel):
+        name = "failing"
+        display_name = "Failing"
+
+        async def start(self) -> None:
+            pass
+
+        async def stop(self) -> None:
+            pass
+
+        async def send(self, msg: OutboundMessage) -> None:
+            nonlocal call_count
+            call_count += 1
+            # Succeeds on first try
+
+    fake_config = SimpleNamespace(
+        channels=ChannelsConfig(send_max_retries=3),
+        providers=SimpleNamespace(groq=SimpleNamespace(api_key="")),
+    )
+
+    mgr = ChannelManager.__new__(ChannelManager)
+    mgr.config = fake_config
+    mgr.bus = MessageBus()
+    mgr.channels = {"failing": _FailingChannel(fake_config, mgr.bus)}
+    mgr._dispatch_task = None
+
+    msg = OutboundMessage(channel="failing", chat_id="123", content="test")
+    await mgr._send_with_retry(mgr.channels["failing"], msg)
+
+    assert call_count == 1
+
+
+@pytest.mark.asyncio
+async def test_send_with_retry_retries_on_failure():
+    """_send_with_retry should retry on failure up to max_retries times."""
+    call_count = 0
+
+    class _FailingChannel(BaseChannel):
+        name = "failing"
+        display_name = "Failing"
+
+        async def start(self) -> None:
+            pass
+
+        async def stop(self) -> None:
+            pass
+
+        async def send(self, msg: OutboundMessage) -> None:
+            nonlocal call_count
+            call_count += 1
+            raise RuntimeError("simulated failure")
+
+    fake_config = SimpleNamespace(
+        channels=ChannelsConfig(send_max_retries=3),
+        providers=SimpleNamespace(groq=SimpleNamespace(api_key="")),
+    )
+
+    mgr = ChannelManager.__new__(ChannelManager)
+    mgr.config = fake_config
+    mgr.bus = MessageBus()
+    mgr.channels = {"failing": _FailingChannel(fake_config, mgr.bus)}
+    mgr._dispatch_task = None
+
+    msg = OutboundMessage(channel="failing", chat_id="123", content="test")
+
+    # Patch asyncio.sleep to avoid actual delays
+    with patch("nanobot.channels.manager.asyncio.sleep", new_callable=AsyncMock) as mock_sleep:
+        await mgr._send_with_retry(mgr.channels["failing"], msg)
+
+    assert call_count == 3  # 3 total attempts (initial + 2 retries)
+    assert mock_sleep.call_count == 2  # 2 sleeps between retries
+
+
+@pytest.mark.asyncio
+async def test_send_with_retry_no_retry_when_max_is_zero():
+    """_send_with_retry should not retry when send_max_retries is 0."""
+    call_count = 0
+
+    class _FailingChannel(BaseChannel):
+        name = "failing"
+        display_name = "Failing"
+
+        async def start(self) -> None:
+            pass
+
+        async def stop(self) -> None:
+            pass
+
+        async def send(self, msg: OutboundMessage) -> None:
+            nonlocal call_count
+            call_count += 1
+            raise RuntimeError("simulated failure")
+
+    fake_config = SimpleNamespace(
+        channels=ChannelsConfig(send_max_retries=0),
+        providers=SimpleNamespace(groq=SimpleNamespace(api_key="")),
+    )
+
+    mgr = ChannelManager.__new__(ChannelManager)
+    mgr.config = fake_config
+    mgr.bus = MessageBus()
+    mgr.channels = {"failing": _FailingChannel(fake_config, mgr.bus)}
+    mgr._dispatch_task = None
+
+    msg = OutboundMessage(channel="failing", chat_id="123", content="test")
+
+    with patch("nanobot.channels.manager.asyncio.sleep", new_callable=AsyncMock):
+        await mgr._send_with_retry(mgr.channels["failing"], msg)
+
+    assert call_count == 1  # Called once but no retry (max(0, 1) = 1)
+
+
+@pytest.mark.asyncio
+async def test_send_with_retry_calls_send_delta():
+    """_send_with_retry should call send_delta when metadata has _stream_delta."""
+    send_delta_called = False
+
+    class _StreamingChannel(BaseChannel):
+        name = "streaming"
+        display_name = "Streaming"
+
+        async def start(self) -> None:
+            pass
+
+        async def stop(self) -> None:
+            pass
+
+        async def send(self, msg: OutboundMessage) -> None:
+            pass  # Should not be called
+
+        async def send_delta(self, chat_id: str, delta: str, metadata: dict | None = None) -> None:
+            nonlocal send_delta_called
+            send_delta_called = True
+
+    fake_config = SimpleNamespace(
+        channels=ChannelsConfig(send_max_retries=3),
+        providers=SimpleNamespace(groq=SimpleNamespace(api_key="")),
+    )
+
+    mgr = ChannelManager.__new__(ChannelManager)
+    mgr.config = fake_config
+    mgr.bus = MessageBus()
+    mgr.channels = {"streaming": _StreamingChannel(fake_config, mgr.bus)}
+    mgr._dispatch_task = None
+
+    msg = OutboundMessage(
+        channel="streaming", chat_id="123", content="test delta",
+        metadata={"_stream_delta": True}
+    )
+    await mgr._send_with_retry(mgr.channels["streaming"], msg)
+
+    assert send_delta_called is True
+
+
+@pytest.mark.asyncio
+async def test_send_with_retry_skips_send_when_streamed():
+    """_send_with_retry should not call send when metadata has _streamed flag."""
+    send_called = False
+    send_delta_called = False
+
+    class _StreamedChannel(BaseChannel):
+        name = "streamed"
+        display_name = "Streamed"
+
+        async def start(self) -> None:
+            pass
+
+        async def stop(self) -> None:
+            pass
+
+        async def send(self, msg: OutboundMessage) -> None:
+            nonlocal send_called
+            send_called = True
+
+        async def send_delta(self, chat_id: str, delta: str, metadata: dict | None = None) -> None:
+            nonlocal send_delta_called
+            send_delta_called = True
+
+    fake_config = SimpleNamespace(
+        channels=ChannelsConfig(send_max_retries=3),
+        providers=SimpleNamespace(groq=SimpleNamespace(api_key="")),
+    )
+
+    mgr = ChannelManager.__new__(ChannelManager)
+    mgr.config = fake_config
+    mgr.bus = MessageBus()
+    mgr.channels = {"streamed": _StreamedChannel(fake_config, mgr.bus)}
+    mgr._dispatch_task = None
+
+    # _streamed means message was already sent via send_delta, so skip send
+    msg = OutboundMessage(
+        channel="streamed", chat_id="123", content="test",
+        metadata={"_streamed": True}
+    )
+    await mgr._send_with_retry(mgr.channels["streamed"], msg)
+
+    assert send_called is False
+    assert send_delta_called is False
+
+
+@pytest.mark.asyncio
+async def test_send_with_retry_propagates_cancelled_error():
+    """_send_with_retry should re-raise CancelledError for graceful shutdown."""
+    class _CancellingChannel(BaseChannel):
+        name = "cancelling"
+        display_name = "Cancelling"
+
+        async def start(self) -> None:
+            pass
+
+        async def stop(self) -> None:
+            pass
+
+        async def send(self, msg: OutboundMessage) -> None:
+            raise asyncio.CancelledError("simulated cancellation")
+
+    fake_config = SimpleNamespace(
+        channels=ChannelsConfig(send_max_retries=3),
+        providers=SimpleNamespace(groq=SimpleNamespace(api_key="")),
+    )
+
+    mgr = ChannelManager.__new__(ChannelManager)
+    mgr.config = fake_config
+    mgr.bus = MessageBus()
+    mgr.channels = {"cancelling": _CancellingChannel(fake_config, mgr.bus)}
+    mgr._dispatch_task = None
+
+    msg = OutboundMessage(channel="cancelling", chat_id="123", content="test")
+
+    with pytest.raises(asyncio.CancelledError):
+        await mgr._send_with_retry(mgr.channels["cancelling"], msg)
+
+
+@pytest.mark.asyncio
+async def test_send_with_retry_propagates_cancelled_error_during_sleep():
+    """_send_with_retry should re-raise CancelledError during sleep."""
+    call_count = 0
+
+    class _FailingChannel(BaseChannel):
+        name = "failing"
+        display_name = "Failing"
+
+        async def start(self) -> None:
+            pass
+
+        async def stop(self) -> None:
+            pass
+
+        async def send(self, msg: OutboundMessage) -> None:
+            nonlocal call_count
+            call_count += 1
+            raise RuntimeError("simulated failure")
+
+    fake_config = SimpleNamespace(
+        channels=ChannelsConfig(send_max_retries=3),
+        providers=SimpleNamespace(groq=SimpleNamespace(api_key="")),
+    )
+
+    mgr = ChannelManager.__new__(ChannelManager)
+    mgr.config = fake_config
+    mgr.bus = MessageBus()
+    mgr.channels = {"failing": _FailingChannel(fake_config, mgr.bus)}
+    mgr._dispatch_task = None
+
+    msg = OutboundMessage(channel="failing", chat_id="123", content="test")
+
+    # Mock sleep to raise CancelledError
+    async def cancel_during_sleep(_):
+        raise asyncio.CancelledError("cancelled during sleep")
+
+    with patch("nanobot.channels.manager.asyncio.sleep", side_effect=cancel_during_sleep):
+        with pytest.raises(asyncio.CancelledError):
+            await mgr._send_with_retry(mgr.channels["failing"], msg)
+
+    # Should have attempted once before sleep was cancelled
+    assert call_count == 1
+
+
+# ---------------------------------------------------------------------------
+# ChannelManager - lifecycle and getters
+# ---------------------------------------------------------------------------
+
+class _ChannelWithAllowFrom(BaseChannel):
+    """Channel with configurable allow_from."""
+    name = "withallow"
+    display_name = "With Allow"
+
+    def __init__(self, config, bus, allow_from):
+        super().__init__(config, bus)
+        self.config.allow_from = allow_from
+
+    async def start(self) -> None:
+        pass
+
+    async def stop(self) -> None:
+        pass
+
+    async def send(self, msg: OutboundMessage) -> None:
+        pass
+
+
+class _StartableChannel(BaseChannel):
+    """Channel that tracks start/stop calls."""
+    name = "startable"
+    display_name = "Startable"
+
+    def __init__(self, config, bus):
+        super().__init__(config, bus)
+        self.started = False
+        self.stopped = False
+
+    async def start(self) -> None:
+        self.started = True
+
+    async def stop(self) -> None:
+        self.stopped = True
+
+    async def send(self, msg: OutboundMessage) -> None:
+        pass
+
+
+@pytest.mark.asyncio
+async def test_validate_allow_from_raises_on_empty_list():
+    """_validate_allow_from should raise SystemExit when allow_from is empty list."""
+    fake_config = SimpleNamespace(
+        channels=ChannelsConfig(),
+        providers=SimpleNamespace(groq=SimpleNamespace(api_key="")),
+    )
+
+    mgr = ChannelManager.__new__(ChannelManager)
+    mgr.config = fake_config
+    mgr.channels = {"test": _ChannelWithAllowFrom(fake_config, None, [])}
+    mgr._dispatch_task = None
+
+    with pytest.raises(SystemExit) as exc_info:
+        mgr._validate_allow_from()
+
+    assert "empty allowFrom" in str(exc_info.value)
+
+
+@pytest.mark.asyncio
+async def test_validate_allow_from_passes_with_asterisk():
+    """_validate_allow_from should not raise when allow_from contains '*'."""
+    fake_config = SimpleNamespace(
+        channels=ChannelsConfig(),
+        providers=SimpleNamespace(groq=SimpleNamespace(api_key="")),
+    )
+
+    mgr = ChannelManager.__new__(ChannelManager)
+    mgr.config = fake_config
+    mgr.channels = {"test": _ChannelWithAllowFrom(fake_config, None, ["*"])}
+    mgr._dispatch_task = None
+
+    # Should not raise
+    mgr._validate_allow_from()
+
+
+@pytest.mark.asyncio
+async def test_get_channel_returns_channel_if_exists():
+    """get_channel should return the channel if it exists."""
+    fake_config = SimpleNamespace(
+        channels=ChannelsConfig(),
+        providers=SimpleNamespace(groq=SimpleNamespace(api_key="")),
+    )
+
+    mgr = ChannelManager.__new__(ChannelManager)
+    mgr.config = fake_config
+    mgr.bus = MessageBus()
+    mgr.channels = {"telegram": _StartableChannel(fake_config, mgr.bus)}
+    mgr._dispatch_task = None
+
+    assert mgr.get_channel("telegram") is not None
+    assert mgr.get_channel("nonexistent") is None
+
+
+@pytest.mark.asyncio
+async def test_get_status_returns_running_state():
+    """get_status should return enabled and running state for each channel."""
+    fake_config = SimpleNamespace(
+        channels=ChannelsConfig(),
+        providers=SimpleNamespace(groq=SimpleNamespace(api_key="")),
+    )
+
+    mgr = ChannelManager.__new__(ChannelManager)
+    mgr.config = fake_config
+    mgr.bus = MessageBus()
+    ch = _StartableChannel(fake_config, mgr.bus)
+    mgr.channels = {"startable": ch}
+    mgr._dispatch_task = None
+
+    status = mgr.get_status()
+
+    assert status["startable"]["enabled"] is True
+    assert status["startable"]["running"] is False  # Not started yet
+
+
+@pytest.mark.asyncio
+async def test_enabled_channels_returns_channel_names():
+    """enabled_channels should return list of enabled channel names."""
+    fake_config = SimpleNamespace(
+        channels=ChannelsConfig(),
+        providers=SimpleNamespace(groq=SimpleNamespace(api_key="")),
+    )
+
+    mgr = ChannelManager.__new__(ChannelManager)
+    mgr.config = fake_config
+    mgr.bus = MessageBus()
+    mgr.channels = {
+        "telegram": _StartableChannel(fake_config, mgr.bus),
+        "slack": _StartableChannel(fake_config, mgr.bus),
+    }
+    mgr._dispatch_task = None
+
+    enabled = mgr.enabled_channels
+
+    assert "telegram" in enabled
+    assert "slack" in enabled
+    assert len(enabled) == 2
+
+
+@pytest.mark.asyncio
+async def test_stop_all_cancels_dispatcher_and_stops_channels():
+    """stop_all should cancel the dispatch task and stop all channels."""
+    fake_config = SimpleNamespace(
+        channels=ChannelsConfig(),
+        providers=SimpleNamespace(groq=SimpleNamespace(api_key="")),
+    )
+
+    mgr = ChannelManager.__new__(ChannelManager)
+    mgr.config = fake_config
+    mgr.bus = MessageBus()
+
+    ch = _StartableChannel(fake_config, mgr.bus)
+    mgr.channels = {"startable": ch}
+
+    # Create a real cancelled task
+    async def dummy_task():
+        while True:
+            await asyncio.sleep(1)
+
+    dispatch_task = asyncio.create_task(dummy_task())
+    mgr._dispatch_task = dispatch_task
+
+    await mgr.stop_all()
+
+    # Task should be cancelled
+    assert dispatch_task.cancelled()
+    # Channel should be stopped
+    assert ch.stopped is True
+
+
+@pytest.mark.asyncio
+async def test_start_channel_logs_error_on_failure():
+    """_start_channel should log error when channel start fails."""
+    class _FailingChannel(BaseChannel):
+        name = "failing"
+        display_name = "Failing"
+
+        async def start(self) -> None:
+            raise RuntimeError("connection failed")
+
+        async def stop(self) -> None:
+            pass
+
+        async def send(self, msg: OutboundMessage) -> None:
+            pass
+
+    fake_config = SimpleNamespace(
+        channels=ChannelsConfig(),
+        providers=SimpleNamespace(groq=SimpleNamespace(api_key="")),
+    )
+
+    mgr = ChannelManager.__new__(ChannelManager)
+    mgr.config = fake_config
+    mgr.bus = MessageBus()
+    mgr.channels = {}
+    mgr._dispatch_task = None
+
+    ch = _FailingChannel(fake_config, mgr.bus)
+
+    # Should not raise, just log error
+    await mgr._start_channel("failing", ch)
+
+
+@pytest.mark.asyncio
+async def test_stop_all_handles_channel_exception():
+    """stop_all should handle exceptions when stopping channels gracefully."""
+    class _StopFailingChannel(BaseChannel):
+        name = "stopfailing"
+        display_name = "Stop Failing"
+
+        async def start(self) -> None:
+            pass
+
+        async def stop(self) -> None:
+            raise RuntimeError("stop failed")
+
+        async def send(self, msg: OutboundMessage) -> None:
+            pass
+
+    fake_config = SimpleNamespace(
+        channels=ChannelsConfig(),
+        providers=SimpleNamespace(groq=SimpleNamespace(api_key="")),
+    )
+
+    mgr = ChannelManager.__new__(ChannelManager)
+    mgr.config = fake_config
+    mgr.bus = MessageBus()
+    mgr.channels = {"stopfailing": _StopFailingChannel(fake_config, mgr.bus)}
+    mgr._dispatch_task = None
+
+    # Should not raise even if channel.stop() raises
+    await mgr.stop_all()
+
+
+@pytest.mark.asyncio
+async def test_start_all_no_channels_logs_warning():
+    """start_all should log warning when no channels are enabled."""
+    fake_config = SimpleNamespace(
+        channels=ChannelsConfig(),
+        providers=SimpleNamespace(groq=SimpleNamespace(api_key="")),
+    )
+
+    mgr = ChannelManager.__new__(ChannelManager)
+    mgr.config = fake_config
+    mgr.bus = MessageBus()
+    mgr.channels = {}  # No channels
+    mgr._dispatch_task = None
+
+    # Should return early without creating dispatch task
+    await mgr.start_all()
+
+    assert mgr._dispatch_task is None
+
+
+@pytest.mark.asyncio
+async def test_start_all_creates_dispatch_task():
+    """start_all should create the dispatch task when channels exist."""
+    fake_config = SimpleNamespace(
+        channels=ChannelsConfig(),
+        providers=SimpleNamespace(groq=SimpleNamespace(api_key="")),
+    )
+
+    mgr = ChannelManager.__new__(ChannelManager)
+    mgr.config = fake_config
+    mgr.bus = MessageBus()
+
+    ch = _StartableChannel(fake_config, mgr.bus)
+    mgr.channels = {"startable": ch}
+    mgr._dispatch_task = None
+
+    # Cancel immediately after start to avoid running forever
+    async def cancel_after_start():
+        await asyncio.sleep(0.01)
+        if mgr._dispatch_task:
+            mgr._dispatch_task.cancel()
+
+    cancel_task = asyncio.create_task(cancel_after_start())
+
+    try:
+        await mgr.start_all()
+    except asyncio.CancelledError:
+        pass
+    finally:
+        cancel_task.cancel()
+        try:
+            await cancel_task
+        except asyncio.CancelledError:
+            pass
+
+    # Dispatch task should have been created
+    assert mgr._dispatch_task is not None
+