feat: task cancellation (wip)

backend/src/app.py

@@ -36,7 +36,6 @@ class App(ChatMixin):
 
         self.replicate_client = replicate_token and replicate.Client(api_token=replicate_token) or None
         self.openrouter_client = openrouter_token and OpenRouter(api_key=openrouter_token) or None
-        
 
         self.agent_classes = [
             agents_mod.ExpertAgent,
@@ -332,6 +331,14 @@ class App(ChatMixin):
         )
         return run.id
 
+    async def cancel_agent_run(self, run_id):
+        """Cancel an ongoing agent run by ID."""
+        run = self.tmp.runs.get(run_id)
+        if run:
+            run.cancel()
+            return True
+        return False
+
     async def get_agent_runs(self, agent_id=None, user_id=None):
         runs = list(self.tmp.runs.values())
         if agent_id: