fix(cli): Group cancelled tool call responses to prevent API errors (#3333)

2 files changed, 114 insertions, 8 deletions

diff --git a/packages/cli/src/ui/hooks/useGeminiStream.test.tsx b/packages/cli/src/ui/hooks/useGeminiStream.test.tsx
index 1ccf3123..6a41234b 100644
--- a/packages/cli/src/ui/hooks/useGeminiStream.test.tsx
+++ b/packages/cli/src/ui/hooks/useGeminiStream.test.tsx
@@ -604,6 +604,112 @@ describe('useGeminiStream', () => {
     });
   });
 
+  it('should group multiple cancelled tool call responses into a single history entry', async () => {
+    const cancelledToolCall1: TrackedCancelledToolCall = {
+      request: {
+        callId: 'cancel-1',
+        name: 'toolA',
+        args: {},
+        isClientInitiated: false,
+      },
+      tool: {
+        name: 'toolA',
+        description: 'descA',
+        getDescription: vi.fn(),
+      } as any,
+      status: 'cancelled',
+      response: {
+        callId: 'cancel-1',
+        responseParts: [
+          { functionResponse: { name: 'toolA', id: 'cancel-1' } },
+        ],
+        resultDisplay: undefined,
+        error: undefined,
+      },
+      responseSubmittedToGemini: false,
+    };
+    const cancelledToolCall2: TrackedCancelledToolCall = {
+      request: {
+        callId: 'cancel-2',
+        name: 'toolB',
+        args: {},
+        isClientInitiated: false,
+      },
+      tool: {
+        name: 'toolB',
+        description: 'descB',
+        getDescription: vi.fn(),
+      } as any,
+      status: 'cancelled',
+      response: {
+        callId: 'cancel-2',
+        responseParts: [
+          { functionResponse: { name: 'toolB', id: 'cancel-2' } },
+        ],
+        resultDisplay: undefined,
+        error: undefined,
+      },
+      responseSubmittedToGemini: false,
+    };
+    const allCancelledTools = [cancelledToolCall1, cancelledToolCall2];
+    const client = new MockedGeminiClientClass(mockConfig);
+
+    let capturedOnComplete:
+      | ((completedTools: TrackedToolCall[]) => Promise<void>)
+      | null = null;
+
+    mockUseReactToolScheduler.mockImplementation((onComplete) => {
+      capturedOnComplete = onComplete;
+      return [[], mockScheduleToolCalls, mockMarkToolsAsSubmitted];
+    });
+
+    renderHook(() =>
+      useGeminiStream(
+        client,
+        [],
+        mockAddItem,
+        mockSetShowHelp,
+        mockConfig,
+        mockOnDebugMessage,
+        mockHandleSlashCommand,
+        false,
+        () => 'vscode' as EditorType,
+        () => {},
+        () => Promise.resolve(),
+      ),
+    );
+
+    // Trigger the onComplete callback with multiple cancelled tools
+    await act(async () => {
+      if (capturedOnComplete) {
+        await capturedOnComplete(allCancelledTools);
+      }
+    });
+
+    await waitFor(() => {
+      // The tools should be marked as submitted locally
+      expect(mockMarkToolsAsSubmitted).toHaveBeenCalledWith([
+        'cancel-1',
+        'cancel-2',
+      ]);
+
+      // Crucially, addHistory should be called only ONCE
+      expect(client.addHistory).toHaveBeenCalledTimes(1);
+
+      // And that single call should contain BOTH function responses
+      expect(client.addHistory).toHaveBeenCalledWith({
+        role: 'user',
+        parts: [
+          ...(cancelledToolCall1.response.responseParts as Part[]),
+          ...(cancelledToolCall2.response.responseParts as Part[]),
+        ],
+      });
+
+      // No message should be sent back to the API for a turn with only cancellations
+      expect(mockSendMessageStream).not.toHaveBeenCalled();
+    });
+  });
+
   it('should not flicker streaming state to Idle between tool completion and submission', async () => {
     const toolCallResponseParts: PartListUnion = [
       { text: 'tool 1 final response' },
diff --git a/packages/cli/src/ui/hooks/useGeminiStream.ts b/packages/cli/src/ui/hooks/useGeminiStream.ts
index e2226761..bba01bc9 100644
--- a/packages/cli/src/ui/hooks/useGeminiStream.ts
+++ b/packages/cli/src/ui/hooks/useGeminiStream.ts
@@ -636,20 +636,20 @@ export const useGeminiStream = (
           const responsesToAdd = geminiTools.flatMap(
             (toolCall) => toolCall.response.responseParts,
           );
+          const combinedParts: Part[] = [];
           for (const response of responsesToAdd) {
-            let parts: Part[];
             if (Array.isArray(response)) {
-              parts = response;
+              combinedParts.push(...response);
             } else if (typeof response === 'string') {
-              parts = [{ text: response }];
+              combinedParts.push({ text: response });
             } else {
-              parts = [response];
+              combinedParts.push(response);
             }
-            geminiClient.addHistory({
-              role: 'user',
-              parts,
-            });
           }
+          geminiClient.addHistory({
+            role: 'user',
+            parts: combinedParts,
+          });
         }
 
         const callIdsToMarkAsSubmitted = geminiTools.map(