diff --git a/integration-tests/mixed-input-crash.test.ts b/integration-tests/mixed-input-crash.test.ts
new file mode 100644
index 0000000000..e2db647316
--- /dev/null
+++ b/integration-tests/mixed-input-crash.test.ts
@@ -0,0 +1,62 @@
+/**
+ * @license
+ * Copyright 2025 Google LLC
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+import { describe, it, expect } from 'vitest';
+import { TestRig } from './test-helper.js';
+
+describe('mixed input crash prevention', () => {
+  it('should not crash when using mixed prompt inputs', async () => {
+    const rig = new TestRig();
+    rig.setup('should not crash when using mixed prompt inputs');
+
+    // Test: echo "say '1'." | gemini --prompt-interactive="say '2'." say '3'.
+    const stdinContent = "say '1'.";
+
+    try {
+      await rig.run(
+        { stdin: stdinContent },
+        '--prompt-interactive',
+        "say '2'.",
+        "say '3'.",
+      );
+      throw new Error('Expected the command to fail, but it succeeded');
+    } 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(
+        '--prompt-interactive flag cannot be used when input is piped',
+      );
+      expect(err.message).not.toContain('setRawMode is not a function');
+      expect(err.message).not.toContain('unexpected critical error');
+    }
+
+    const lastRequest = rig.readLastApiRequest();
+    expect(lastRequest).toBeNull();
+  });
+
+  it('should provide clear error message for mixed input', async () => {
+    const rig = new TestRig();
+    rig.setup('should provide clear error message for mixed input');
+
+    try {
+      await rig.run(
+        { stdin: 'test input' },
+        '--prompt-interactive',
+        'test prompt',
+      );
+      throw new Error('Expected the command to fail, but it succeeded');
+    } catch (error: unknown) {
+      expect(error).toBeInstanceOf(Error);
+      const err = error as Error;
+
+      expect(err.message).toContain(
+        '--prompt-interactive flag cannot be used when input is piped',
+      );
+    }
+  });
+});
diff --git a/packages/cli/src/gemini.test.tsx b/packages/cli/src/gemini.test.tsx
index 3ed8d6ea80..7d6a522572 100644
--- a/packages/cli/src/gemini.test.tsx
+++ b/packages/cli/src/gemini.test.tsx
@@ -174,6 +174,15 @@ describe('gemini.tsx main function kitty protocol', () => {
       (process.stdin as any).setRawMode = vi.fn();
     }
     setRawModeSpy = vi.spyOn(process.stdin, 'setRawMode');
+
+    Object.defineProperty(process.stdin, 'isTTY', {
+      value: true,
+      configurable: true,
+    });
+    Object.defineProperty(process.stdin, 'isRaw', {
+      value: false,
+      configurable: true,
+    });
   });
 
   it('should call setRawMode and detectAndEnableKittyProtocol when isInteractive is true', async () => {
diff --git a/packages/cli/src/gemini.tsx b/packages/cli/src/gemini.tsx
index 9b4a3acf8f..af2d0d6c9b 100644
--- a/packages/cli/src/gemini.tsx
+++ b/packages/cli/src/gemini.tsx
@@ -209,9 +209,17 @@ export async function main() {
     argv,
   );
 
+  // Check for invalid input combinations early to prevent crashes
+  if (argv.promptInteractive && !process.stdin.isTTY) {
+    console.error(
+      'Error: The --prompt-interactive flag cannot be used when input is piped from stdin.',
+    );
+    process.exit(1);
+  }
+
   const wasRaw = process.stdin.isRaw;
   let kittyProtocolDetectionComplete: Promise<boolean> | undefined;
-  if (config.isInteractive() && !wasRaw) {
+  if (config.isInteractive() && !wasRaw && process.stdin.isTTY) {
     // Set this as early as possible to avoid spurious characters from
     // input showing up in the output.
     process.stdin.setRawMode(true);
@@ -248,13 +256,6 @@ export async function main() {
     validateDnsResolutionOrder(settings.merged.advanced?.dnsResolutionOrder),
   );
 
-  if (argv.promptInteractive && !process.stdin.isTTY) {
-    console.error(
-      'Error: The --prompt-interactive flag is not supported when piping input from stdin.',
-    );
-    process.exit(1);
-  }
-
   if (config.getListExtensions()) {
     console.log('Installed extensions:');
     for (const extension of extensions) {