fix: preserve real cancellation in MCP paths

nanobot/agent/loop.py

@@ -81,6 +81,7 @@ from nanobot.session.manager import (
     replay_max_messages_for_context,
 )
 from nanobot.triggers.local_turns import LocalTriggerTurnCoordinator
+from nanobot.utils.cancellation import task_is_cancelling
 from nanobot.utils.document import extract_documents, reference_non_image_attachments
 from nanobot.utils.helpers import image_placeholder_text
 from nanobot.utils.helpers import truncate_text as truncate_text_fn
@@ -998,8 +999,11 @@ class AgentLoop:
                 except asyncio.CancelledError:
                     # Preserve real task cancellation so shutdown can complete cleanly.
                     # Only ignore non-task CancelledError signals that may leak from integrations.
-                    if not self._running or asyncio.current_task().cancelling():
+                    if not self._running or task_is_cancelling():
                         raise
+                    logger.warning(
+                        "Ignoring leaked CancelledError while consuming inbound messages"
+                    )
                     continue
                 except Exception as e:
                     logger.warning("Error consuming inbound message: {}, continuing...", e)

nanobot/agent/tools/mcp.py

@@ -30,6 +30,7 @@ from nanobot.security.network import (
     resolve_url_target,
     validate_url_target,
 )
+from nanobot.utils.cancellation import task_is_cancelling
 
 # Transient connection errors that warrant a single retry.
 # These typically happen when an MCP server restarts or a network
@@ -487,8 +488,7 @@ class MCPToolWrapper(_MCPWrapperBase):
             except asyncio.CancelledError:
                 # MCP SDK's anyio cancel scopes can leak CancelledError on timeout/failure.
                 # Re-raise only if our task was externally cancelled (e.g. /stop).
-                task = asyncio.current_task()
-                if task is not None and task.cancelling() > 0:
+                if task_is_cancelling():
                     raise
                 logger.warning("MCP tool '{}' was cancelled by server/SDK", self._name)
                 return ToolResult.error("(MCP tool call was cancelled)")
@@ -650,8 +650,7 @@ class MCPResourceWrapper(_MCPWrapperBase):
                 )
                 return f"(MCP resource read timed out after {self._resource_timeout}s)"
             except asyncio.CancelledError:
-                task = asyncio.current_task()
-                if task is not None and task.cancelling() > 0:
+                if task_is_cancelling():
                     raise
                 logger.warning("MCP resource '{}' was cancelled by server/SDK", self._name)
                 return "(MCP resource read was cancelled)"
@@ -764,8 +763,7 @@ class MCPPromptWrapper(_MCPWrapperBase):
                 )
                 return f"(MCP prompt call timed out after {self._prompt_timeout}s)"
             except asyncio.CancelledError:
-                task = asyncio.current_task()
-                if task is not None and task.cancelling() > 0:
+                if task_is_cancelling():
                     raise
                 logger.warning("MCP prompt '{}' was cancelled by server/SDK", self._name)
                 return "(MCP prompt call was cancelled)"
@@ -1145,6 +1143,8 @@ async def connect_missing_servers(state: Any, registry: ToolRegistry) -> None:
             else:
                 logger.warning("No MCP servers connected successfully (will retry next message)")
         except asyncio.CancelledError:
+            if task_is_cancelling():
+                raise
             logger.warning("MCP connection cancelled (will retry next message)")
         except BaseException as e:
             logger.warning("Failed to connect MCP servers (will retry next message): {}", e)
@@ -1411,7 +1411,7 @@ async def _close_server(state: Any, server_name: str) -> None:
     try:
         await stack.aclose()
     except asyncio.CancelledError:
-        if asyncio.current_task().cancelling() > 0:
+        if task_is_cancelling():
             raise
         logger.debug("MCP server '{}' cleanup error (can be ignored)", server_name)
     except (RuntimeError, BaseExceptionGroup):
@@ -1428,7 +1428,7 @@ async def close_mcp_servers(state: Any) -> None:
             try:
                 await connection.aclose()
             except asyncio.CancelledError:
-                if asyncio.current_task().cancelling() > 0:
+                if task_is_cancelling():
                     raise
                 logger.debug("MCP server '{}' cleanup error (can be ignored)", name)
             except (RuntimeError, BaseExceptionGroup):

nanobot/utils/cancellation.py

@@ -0,0 +1,10 @@
+"""Async cancellation helpers."""
+
+from __future__ import annotations
+
+import asyncio
+
+
+def task_is_cancelling() -> bool:
+    task = asyncio.current_task()
+    return task is not None and task.cancelling() > 0