fix(cli): gemini command stuck in git bash (#6397)

Co-authored-by: Arya Gummadi <aryagummadi@google.com>

integration-tests/stdin-context.test.ts

@@ -67,4 +67,31 @@ describe('stdin context', () => {
       'Expected the model to identify the secret word from stdin',
     ).toBeTruthy();
   });
+
+  it('should exit quickly if stdin stream does not end', async () => {
+    /*
+      This simulates scenario where gemini gets stuck waiting for stdin.
+      This happens in situations where process.stdin.isTTY is false
+      even though gemini is intended to run interactively.
+    */
+
+    const rig = new TestRig();
+    await rig.setup('should exit quickly if stdin stream does not end');
+
+    try {
+      await rig.run({ stdinDoesNotEnd: true });
+      throw new Error('Expected rig.run to throw an error');
+    } catch (error: unknown) {
+      expect(error).toBeInstanceOf(Error);
+      const err = error as Error;
+
+      expect(err.message).toContain('Process exited with code 1');
+      expect(err.message).toContain('No input provided via stdin.');
+      console.log('Error message:', err.message);
+    }
+    const lastRequest = rig.readLastApiRequest();
+    expect(lastRequest).toBeNull();
+
+    // If this test times out, runs indefinitely, it's a regression.
+  }, 3000);
 });