feat: task cancellation (wip)

backend/src/agent.py

@@ -137,6 +137,11 @@ class AgentRun:
         self.events = []
         self.event_listeners = {}
         self.output = None
+        
+        # Cancellation tracking
+        self.task = None  # For asyncio tasks
+        self.thread = None  # For threads
+        self.cancelled = False
 
         app.tmp.runs[self.id] = self
         
@@ -216,6 +221,36 @@ class AgentRun:
             "output": self.output,
         }
 
+    def cancel(self):
+        """Cancel the agent run and stop any ongoing inference."""
+        if self.cancelled or self.done:
+            return
+        
+        self.cancelled = True
+        print(f"Cancelling agent run {self.id}")
+        
+        # Cancel asyncio task if exists
+        if self.task and not self.task.done():
+            self.task.cancel()
+        
+        # Thread cannot be forcefully cancelled, but we can signal
+        if self.thread and self.thread.is_alive():
+            # The thread should be checking self.cancelled in its loop
+            print(f"Signalled thread to stop for run {self.id}")
+        
+        # Close the stream and mark as done
+        self.close()
+        
+        # Emit cancellation event
+        self.emit_event("cancelled", {"runId": self.id, "agentId": self.agent_id})
+        
+        # Broadcast cancellation event
+        self.app.emit_event("run-cancelled", {
+            "runId": self.id,
+            "agentId": self.agent_id,
+            "endTime": int(time.time()),
+        })
+
     def close(self):
         if self.done:
             return