fix: reliably dispatch and return background tasks

agent/dispatch_mcp.py

@@ -11,6 +11,7 @@ from __future__ import annotations
 
 import asyncio
 import logging
+import os
 
 from mcp.server.fastmcp import FastMCP
 
@@ -51,8 +52,13 @@ async def _run_worker(worker: "TaskWorker", task_id: str):
     except ImportError:
         from task_registry import registry
 
+    timeout_seconds = float(os.environ.get("TASK_TIMEOUT_SECONDS", "180"))
     try:
-        await worker.run()
+        await asyncio.wait_for(worker.run(), timeout=timeout_seconds)
+    except asyncio.TimeoutError:
+        message = f"Timed out after {timeout_seconds:g} seconds"
+        logger.error("Task %s %s", task_id, message.lower())
+        registry.fail(task_id, message)
     except Exception as e:
         logger.exception("Task %s crashed: %s", task_id, e)
         registry.fail(task_id, str(e))