diff --git a/nanobot/channels/matrix.py b/nanobot/channels/matrix.py
index 7e84626..89e7616 100644
--- a/nanobot/channels/matrix.py
+++ b/nanobot/channels/matrix.py
@@ -1,7 +1,17 @@
 import asyncio
 from typing import Any
 
-from nio import AsyncClient, AsyncClientConfig, InviteEvent, MatrixRoom, RoomMessageText
+from loguru import logger
+from nio import (
+    AsyncClient,
+    AsyncClientConfig,
+    InviteEvent,
+    JoinError,
+    MatrixRoom,
+    RoomMessageText,
+    RoomSendError,
+    SyncError,
+)
 
 from nanobot.bus.events import OutboundMessage
 from nanobot.channels.base import BaseChannel
@@ -21,6 +31,7 @@ class MatrixChannel(BaseChannel):
         self._sync_task: asyncio.Task | None = None
 
     async def start(self) -> None:
+        """Start Matrix client and begin sync loop."""
         self._running = True
 
         store_path = get_data_dir() / "matrix-store"
@@ -40,11 +51,24 @@ class MatrixChannel(BaseChannel):
         self.client.access_token = self.config.access_token
         self.client.device_id = self.config.device_id
 
-        self.client.add_event_callback(self._on_message, RoomMessageText)
-        self.client.add_event_callback(self._on_room_invite, InviteEvent)
+        self._register_event_callbacks()
+        self._register_response_callbacks()
 
         if self.config.device_id:
-            self.client.load_store()
+            try:
+                self.client.load_store()
+            except Exception as e:
+                logger.warning(
+                    "Matrix store load failed ({}: {}); sync token restore is disabled and "
+                    "restart may replay recent messages.",
+                    type(e).__name__,
+                    str(e),
+                )
+        else:
+            logger.warning(
+                "Matrix device_id is empty; sync token restore is disabled and restart may "
+                "replay recent messages."
+            )
 
         self._sync_task = asyncio.create_task(self._sync_loop())
 
@@ -85,9 +109,48 @@ class MatrixChannel(BaseChannel):
             ignore_unverified_devices=True,
         )
 
+    def _register_event_callbacks(self) -> None:
+        """Register Matrix event callbacks used by this channel."""
+        self.client.add_event_callback(self._on_message, RoomMessageText)
+        self.client.add_event_callback(self._on_room_invite, InviteEvent)
+
+    def _register_response_callbacks(self) -> None:
+        """Register response callbacks for operational error observability."""
+        self.client.add_response_callback(self._on_sync_error, SyncError)
+        self.client.add_response_callback(self._on_join_error, JoinError)
+        self.client.add_response_callback(self._on_send_error, RoomSendError)
+
+    @staticmethod
+    def _is_auth_error(errcode: str | None) -> bool:
+        """Return True if the Matrix errcode indicates auth/token problems."""
+        return errcode in {"M_UNKNOWN_TOKEN", "M_FORBIDDEN", "M_UNAUTHORIZED"}
+
+    async def _on_sync_error(self, response: SyncError) -> None:
+        """Log sync errors with clear severity."""
+        if self._is_auth_error(response.status_code) or response.soft_logout:
+            logger.error("Matrix sync failed: {}", response)
+            return
+        logger.warning("Matrix sync warning: {}", response)
+
+    async def _on_join_error(self, response: JoinError) -> None:
+        """Log room-join errors from invite handling."""
+        if self._is_auth_error(response.status_code):
+            logger.error("Matrix join failed: {}", response)
+            return
+        logger.warning("Matrix join warning: {}", response)
+
+    async def _on_send_error(self, response: RoomSendError) -> None:
+        """Log message send failures."""
+        if self._is_auth_error(response.status_code):
+            logger.error("Matrix send failed: {}", response)
+            return
+        logger.warning("Matrix send warning: {}", response)
+
     async def _sync_loop(self) -> None:
         while self._running:
             try:
+                # full_state applies only to the first sync inside sync_forever and helps
+                # rebuild room state when restoring from stored sync tokens.
                 await self.client.sync_forever(timeout=30000, full_state=True)
             except asyncio.CancelledError:
                 break