fix(agent): stop session-owned exec processes

nanobot/agent/loop.py

@@ -788,9 +788,9 @@ class AgentLoop:
             logger.warning("Command '{}' matched but dispatch returned None", raw)
 
     async def _cancel_active_tasks(self, key: str) -> int:
-        """Cancel and await all active tasks and subagents for *key*.
+        """Cancel and await all active work for *key*.
 
-        Returns the total number of cancelled tasks + subagents.
+        Returns the total number of cancelled tasks, subagents, and exec sessions.
         """
         tasks = tuple(self._active_tasks.pop(key, set()))
         cancelled = sum(1 for t in tasks if not t.done() and t.cancel())
@@ -798,7 +798,8 @@ class AgentLoop:
             with suppress(asyncio.CancelledError, Exception):
                 await t
         sub_cancelled = await self.subagents.cancel_by_session(key)
-        return cancelled + sub_cancelled
+        exec_cancelled = await self._exec_session_manager.terminate_by_owner(key)
+        return cancelled + sub_cancelled + exec_cancelled
 
     async def discard_session(self, key: str) -> None:
         """Stop active work for *key* and forget its cached session."""