feat: add matrix (Element) chat channel support

nanobot/channels/matrix.py

@@ -0,0 +1,79 @@
+import asyncio
+from typing import Any
+
+from nio import AsyncClient, MatrixRoom, RoomMessageText
+
+from nanobot.channels.base import BaseChannel
+from nanobot.bus.events import OutboundMessage
+
+
+class MatrixChannel(BaseChannel):
+    """
+    Matrix (Element) channel using long-polling sync.
+    """
+
+    name = "matrix"
+
+    def __init__(self, config: Any, bus):
+        super().__init__(config, bus)
+        self.client: AsyncClient | None = None
+        self._sync_task: asyncio.Task | None = None
+
+    async def start(self) -> None:
+        self._running = True
+
+        self.client = AsyncClient(
+             homeserver=self.config.homeserver,
+             user=self.config.user_id,
+            )
+        
+        self.client.access_token = self.config.access_token
+
+        self.client.add_event_callback(
+            self._on_message,
+            RoomMessageText
+        )
+
+        self._sync_task = asyncio.create_task(self._sync_loop())
+
+    async def stop(self) -> None:
+        self._running = False
+        if self._sync_task:
+            self._sync_task.cancel()
+        if self.client:
+            await self.client.close()
+
+    async def send(self, msg: OutboundMessage) -> None:
+        if not self.client:
+            return
+
+        await self.client.room_send(
+            room_id=msg.chat_id,
+            message_type="m.room.message",
+            content={"msgtype": "m.text", "body": msg.content},
+        )
+
+    async def _sync_loop(self) -> None:
+        while self._running:
+            try:
+                await self.client.sync(timeout=30000)
+            except asyncio.CancelledError:
+                break
+            except Exception:
+                await asyncio.sleep(2)
+
+    async def _on_message(
+        self,
+        room: MatrixRoom,
+        event: RoomMessageText
+    ) -> None:
+        # Ignore self messages
+        if event.sender == self.config.user_id:
+            return
+
+        await self._handle_message(
+            sender_id=event.sender,
+            chat_id=room.room_id,
+            content=event.body,
+            metadata={"room": room.display_name},
+        )