From 5a05fb0dd002481343aaab7736a871904bb07c6f Mon Sep 17 00:00:00 2001
From: Sandy Tao <sandytao520@icloud.com>
Date: Fri, 12 Sep 2025 16:44:24 -0700
Subject: [PATCH] fix(core): stop streaming request on loop detection (#8377)

---
 packages/core/src/core/client.test.ts | 69 +++++++++++++++++++++++++++
 packages/core/src/core/client.ts      |  6 ++-
 2 files changed, 74 insertions(+), 1 deletion(-)

diff --git a/packages/core/src/core/client.test.ts b/packages/core/src/core/client.test.ts
index 5d030f3ad0..77be6cf4c2 100644
--- a/packages/core/src/core/client.test.ts
+++ b/packages/core/src/core/client.test.ts
@@ -2405,6 +2405,75 @@ ${JSON.stringify(
       // Assert
       expect(mockCheckNextSpeaker).not.toHaveBeenCalled();
     });
+
+    it('should create linked abort signal and pass it to turn.run', async () => {
+      // Arrange
+      const mockStream = (async function* () {
+        yield { type: 'content', value: 'Hello' };
+      })();
+      mockTurnRunFn.mockReturnValue(mockStream);
+
+      const mockChat: Partial<GeminiChat> = {
+        addHistory: vi.fn(),
+        getHistory: vi.fn().mockReturnValue([]),
+      };
+      client['chat'] = mockChat as GeminiChat;
+
+      const originalSignal = new AbortController().signal;
+
+      // Act
+      const stream = client.sendMessageStream(
+        [{ text: 'Hi' }],
+        originalSignal,
+        'prompt-id-signal',
+      );
+      for await (const _ of stream) {
+        // consume stream
+      }
+
+      // Assert
+      expect(mockTurnRunFn).toHaveBeenCalledWith(
+        expect.any(String),
+        [{ text: 'Hi' }],
+        expect.not.objectContaining({ signal: originalSignal }),
+      );
+    });
+
+    it('should abort linked signal when loop is detected', async () => {
+      // Arrange
+      vi.spyOn(client['loopDetector'], 'turnStarted').mockResolvedValue(false);
+      vi.spyOn(client['loopDetector'], 'addAndCheck')
+        .mockReturnValueOnce(false)
+        .mockReturnValueOnce(true);
+
+      const mockStream = (async function* () {
+        yield { type: 'content', value: 'First event' };
+        yield { type: 'content', value: 'Second event' };
+      })();
+      mockTurnRunFn.mockReturnValue(mockStream);
+
+      const mockChat: Partial<GeminiChat> = {
+        addHistory: vi.fn(),
+        getHistory: vi.fn().mockReturnValue([]),
+      };
+      client['chat'] = mockChat as GeminiChat;
+
+      // Act
+      const stream = client.sendMessageStream(
+        [{ text: 'Hi' }],
+        new AbortController().signal,
+        'prompt-id-loop',
+      );
+
+      const events = [];
+      for await (const event of stream) {
+        events.push(event);
+      }
+
+      // Assert
+      expect(events).toContainEqual({ type: GeminiEventType.LoopDetected });
+      expect(client['loopDetector'].addAndCheck).toHaveBeenCalledTimes(2);
+    });
   });
 
   describe('generateContent', () => {
diff --git a/packages/core/src/core/client.ts b/packages/core/src/core/client.ts
index 810f87de25..de4b065bb0 100644
--- a/packages/core/src/core/client.ts
+++ b/packages/core/src/core/client.ts
@@ -489,6 +489,9 @@ export class GeminiClient {
 
     const turn = new Turn(this.getChat(), prompt_id);
 
+    const controller = new AbortController();
+    const linkedSignal = AbortSignal.any([signal, controller.signal]);
+
     const loopDetected = await this.loopDetector.turnStarted(signal);
     if (loopDetected) {
       yield { type: GeminiEventType.LoopDetected };
@@ -514,10 +517,11 @@ export class GeminiClient {
       this.currentSequenceModel = modelToUse;
     }
 
-    const resultStream = turn.run(modelToUse, request, signal);
+    const resultStream = turn.run(modelToUse, request, linkedSignal);
     for await (const event of resultStream) {
       if (this.loopDetector.addAndCheck(event)) {
         yield { type: GeminiEventType.LoopDetected };
+        controller.abort();
         return turn;
       }
       yield event;