diff --git a/packages/cli/src/ui/hooks/useGeminiStream.test.tsx b/packages/cli/src/ui/hooks/useGeminiStream.test.tsx
index 5f89083a..bf0f4fc0 100644
--- a/packages/cli/src/ui/hooks/useGeminiStream.test.tsx
+++ b/packages/cli/src/ui/hooks/useGeminiStream.test.tsx
@@ -448,6 +448,7 @@ describe('useGeminiStream', () => {
           callId: 'call1',
           responseParts: [{ text: 'tool 1 response' }],
           error: undefined,
+          errorType: undefined,
           resultDisplay: 'Tool 1 success display',
         },
         tool: {
@@ -655,6 +656,7 @@ describe('useGeminiStream', () => {
         ],
         resultDisplay: undefined,
         error: undefined,
+        errorType: undefined,
       },
       responseSubmittedToGemini: false,
     };
@@ -679,6 +681,7 @@ describe('useGeminiStream', () => {
         ],
         resultDisplay: undefined,
         error: undefined,
+        errorType: undefined,
       },
       responseSubmittedToGemini: false,
     };
@@ -775,6 +778,7 @@ describe('useGeminiStream', () => {
           callId: 'call1',
           responseParts: toolCallResponseParts,
           error: undefined,
+          errorType: undefined,
           resultDisplay: 'Tool 1 success display',
         },
         endTime: Date.now(),
@@ -1128,6 +1132,7 @@ describe('useGeminiStream', () => {
           responseParts: [{ text: 'Memory saved' }],
           resultDisplay: 'Success: Memory saved',
           error: undefined,
+          errorType: undefined,
         },
         tool: {
           name: 'save_memory',
@@ -1649,4 +1654,262 @@ describe('useGeminiStream', () => {
       );
     });
   });
+
+  describe('Concurrent Execution Prevention', () => {
+    it('should prevent concurrent submitQuery calls', async () => {
+      let resolveFirstCall!: () => void;
+      let resolveSecondCall!: () => void;
+      
+      const firstCallPromise = new Promise<void>((resolve) => {
+        resolveFirstCall = resolve;
+      });
+      
+      const secondCallPromise = new Promise<void>((resolve) => {
+        resolveSecondCall = resolve;
+      });
+
+      // Mock a long-running stream for the first call
+      const firstStream = (async function* () {
+        yield { type: ServerGeminiEventType.Content, value: 'First call content' };
+        await firstCallPromise; // Wait until we manually resolve
+        yield { type: ServerGeminiEventType.Finished, value: 'STOP' };
+      })();
+
+      // Mock a stream for the second call (should not be used)
+      const secondStream = (async function* () {
+        yield { type: ServerGeminiEventType.Content, value: 'Second call content' };
+        await secondCallPromise;
+        yield { type: ServerGeminiEventType.Finished, value: 'STOP' };
+      })();
+
+      let callCount = 0;
+      mockSendMessageStream.mockImplementation(() => {
+        callCount++;
+        if (callCount === 1) {
+          return firstStream;
+        } else {
+          return secondStream;
+        }
+      });
+
+      const { result } = renderTestHook();
+
+      // Start first call
+      const firstCallResult = act(async () => {
+        await result.current.submitQuery('First query');
+      });
+
+      // Wait a bit to ensure first call has started
+      await new Promise(resolve => setTimeout(resolve, 10));
+
+      // Try to start second call while first is still running
+      const secondCallResult = act(async () => {
+        await result.current.submitQuery('Second query');
+      });
+
+      // Resolve both calls
+      resolveFirstCall();
+      resolveSecondCall();
+
+      await Promise.all([firstCallResult, secondCallResult]);
+
+      // Verify only one call was made to sendMessageStream
+      expect(mockSendMessageStream).toHaveBeenCalledTimes(1);
+      expect(mockSendMessageStream).toHaveBeenCalledWith(
+        'First query',
+        expect.any(AbortSignal),
+        expect.any(String),
+      );
+
+      // Verify only the first query was added to history
+      const userMessages = mockAddItem.mock.calls.filter(
+        call => call[0].type === MessageType.USER
+      );
+      expect(userMessages).toHaveLength(1);
+      expect(userMessages[0][0].text).toBe('First query');
+    });
+
+    it('should allow subsequent calls after first call completes', async () => {
+      // Mock streams that complete immediately
+      mockSendMessageStream
+        .mockReturnValueOnce((async function* () {
+          yield { type: ServerGeminiEventType.Content, value: 'First response' };
+          yield { type: ServerGeminiEventType.Finished, value: 'STOP' };
+        })())
+        .mockReturnValueOnce((async function* () {
+          yield { type: ServerGeminiEventType.Content, value: 'Second response' };
+          yield { type: ServerGeminiEventType.Finished, value: 'STOP' };
+        })());
+
+      const { result } = renderTestHook();
+
+      // First call
+      await act(async () => {
+        await result.current.submitQuery('First query');
+      });
+
+      // Second call after first completes
+      await act(async () => {
+        await result.current.submitQuery('Second query');
+      });
+
+      // Both calls should have been made
+      expect(mockSendMessageStream).toHaveBeenCalledTimes(2);
+      expect(mockSendMessageStream).toHaveBeenNthCalledWith(1,
+        'First query',
+        expect.any(AbortSignal),
+        expect.any(String),
+      );
+      expect(mockSendMessageStream).toHaveBeenNthCalledWith(2,
+        'Second query',
+        expect.any(AbortSignal),
+        expect.any(String),
+      );
+    });
+
+    it('should reset execution flag even when query preparation fails', async () => {
+      const { result } = renderTestHook();
+
+      // First call with empty query (should fail in preparation)
+      await act(async () => {
+        await result.current.submitQuery('   '); // Empty trimmed query
+      });
+
+      // Second call should work normally
+      mockSendMessageStream.mockReturnValue((async function* () {
+        yield { type: ServerGeminiEventType.Content, value: 'Valid response' };
+        yield { type: ServerGeminiEventType.Finished, value: 'STOP' };
+      })());
+
+      await act(async () => {
+        await result.current.submitQuery('Valid query');
+      });
+
+      // The second call should have been made
+      expect(mockSendMessageStream).toHaveBeenCalledTimes(1);
+      expect(mockSendMessageStream).toHaveBeenCalledWith(
+        'Valid query',
+        expect.any(AbortSignal),
+        expect.any(String),
+      );
+    });
+
+    it('should reset execution flag when user cancels', async () => {
+      let resolveCancelledStream!: () => void;
+      const cancelledStreamPromise = new Promise<void>((resolve) => {
+        resolveCancelledStream = resolve;
+      });
+
+      // Mock a stream that can be cancelled
+      const cancelledStream = (async function* () {
+        yield { type: ServerGeminiEventType.Content, value: 'Cancelled content' };
+        await cancelledStreamPromise;
+        yield { type: ServerGeminiEventType.UserCancelled };
+      })();
+
+      mockSendMessageStream.mockReturnValueOnce(cancelledStream);
+
+      const { result } = renderTestHook();
+
+      // Start first call
+      const firstCallResult = act(async () => {
+        await result.current.submitQuery('First query');
+      });
+
+      // Wait a bit then resolve to trigger cancellation
+      await new Promise(resolve => setTimeout(resolve, 10));
+      resolveCancelledStream();
+      await firstCallResult;
+
+      // Now try a second call - should work
+      mockSendMessageStream.mockReturnValue((async function* () {
+        yield { type: ServerGeminiEventType.Content, value: 'Second response' };
+        yield { type: ServerGeminiEventType.Finished, value: 'STOP' };
+      })());
+
+      await act(async () => {
+        await result.current.submitQuery('Second query');
+      });
+
+      // Both calls should have been made
+      expect(mockSendMessageStream).toHaveBeenCalledTimes(2);
+    });
+
+    it('should reset execution flag when an error occurs', async () => {
+      // Mock a stream that throws an error
+      mockSendMessageStream.mockReturnValueOnce((async function* () {
+        yield { type: ServerGeminiEventType.Content, value: 'Error content' };
+        throw new Error('Stream error');
+      })());
+
+      const { result } = renderTestHook();
+
+      // First call that will error
+      await act(async () => {
+        await result.current.submitQuery('Error query');
+      });
+
+      // Second call should work normally
+      mockSendMessageStream.mockReturnValue((async function* () {
+        yield { type: ServerGeminiEventType.Content, value: 'Success response' };
+        yield { type: ServerGeminiEventType.Finished, value: 'STOP' };
+      })());
+
+      await act(async () => {
+        await result.current.submitQuery('Success query');
+      });
+
+      // Both calls should have been attempted
+      expect(mockSendMessageStream).toHaveBeenCalledTimes(2);
+    });
+
+    it('should handle rapid multiple concurrent calls correctly', async () => {
+      let resolveStream!: () => void;
+      const streamPromise = new Promise<void>((resolve) => {
+        resolveStream = resolve;
+      });
+
+      // Mock a long-running stream
+      const longStream = (async function* () {
+        yield { type: ServerGeminiEventType.Content, value: 'Long running content' };
+        await streamPromise;
+        yield { type: ServerGeminiEventType.Finished, value: 'STOP' };
+      })();
+
+      mockSendMessageStream.mockReturnValue(longStream);
+
+      const { result } = renderTestHook();
+
+      // Start multiple concurrent calls
+      const calls = [
+        act(async () => { await result.current.submitQuery('Query 1'); }),
+        act(async () => { await result.current.submitQuery('Query 2'); }),
+        act(async () => { await result.current.submitQuery('Query 3'); }),
+        act(async () => { await result.current.submitQuery('Query 4'); }),
+        act(async () => { await result.current.submitQuery('Query 5'); }),
+      ];
+
+      // Wait a bit then resolve the stream
+      await new Promise(resolve => setTimeout(resolve, 10));
+      resolveStream();
+
+      // Wait for all calls to complete
+      await Promise.all(calls);
+
+      // Only the first call should have been made
+      expect(mockSendMessageStream).toHaveBeenCalledTimes(1);
+      expect(mockSendMessageStream).toHaveBeenCalledWith(
+        'Query 1',
+        expect.any(AbortSignal),
+        expect.any(String),
+      );
+
+      // Only one user message should have been added
+      const userMessages = mockAddItem.mock.calls.filter(
+        call => call[0].type === MessageType.USER
+      );
+      expect(userMessages).toHaveLength(1);
+      expect(userMessages[0][0].text).toBe('Query 1');
+    });
+  });
 });
diff --git a/packages/cli/src/ui/hooks/useGeminiStream.ts b/packages/cli/src/ui/hooks/useGeminiStream.ts
index 85614d3b..43fccdb6 100644
--- a/packages/cli/src/ui/hooks/useGeminiStream.ts
+++ b/packages/cli/src/ui/hooks/useGeminiStream.ts
@@ -97,6 +97,7 @@ export const useGeminiStream = (
   const [initError, setInitError] = useState<string | null>(null);
   const abortControllerRef = useRef<AbortController | null>(null);
   const turnCancelledRef = useRef(false);
+  const isSubmittingQueryRef = useRef(false);
   const [isResponding, setIsResponding] = useState<boolean>(false);
   const [thought, setThought] = useState<ThoughtSummary | null>(null);
   const [pendingHistoryItemRef, setPendingHistoryItem] =
@@ -622,6 +623,11 @@ export const useGeminiStream = (
       options?: { isContinuation: boolean },
       prompt_id?: string,
     ) => {
+      // Prevent concurrent executions of submitQuery
+      if (isSubmittingQueryRef.current) {
+        return;
+      }
+
       if (
         (streamingState === StreamingState.Responding ||
           streamingState === StreamingState.WaitingForConfirmation) &&
@@ -629,6 +635,9 @@ export const useGeminiStream = (
       )
         return;
 
+      // Set the flag to indicate we're now executing
+      isSubmittingQueryRef.current = true;
+
       const userMessageTimestamp = Date.now();
 
       // Reset quota error flag when starting a new query (not a continuation)
@@ -653,6 +662,7 @@ export const useGeminiStream = (
       );
 
       if (!shouldProceed || queryToSend === null) {
+        isSubmittingQueryRef.current = false;
         return;
       }
 
@@ -677,6 +687,7 @@ export const useGeminiStream = (
         );
 
         if (processingStatus === StreamProcessingStatus.UserCancelled) {
+          isSubmittingQueryRef.current = false;
           return;
         }
 
@@ -708,6 +719,7 @@ export const useGeminiStream = (
         }
       } finally {
         setIsResponding(false);
+        isSubmittingQueryRef.current = false;
       }
     },
     [