fix(cli): conditionally suppress console output in headless and non-interactive modes

packages/cli/src/gemini.tsx

@@ -272,7 +272,7 @@ export async function main() {
   const isDebugMode = cliConfig.isDebugMode(argv);
   const consolePatcher = new ConsolePatcher({
     stderr: true,
-    suppressConsoleOutput: isHeadlessMode() ? true : false,
+    suppressConsoleOutput: isHeadlessMode() && !isDebugMode,
     debugMode: isDebugMode,
     onNewMessage: (msg) => {
       coreEvents.emitConsoleLog(msg.type, msg.content);

packages/cli/src/nonInteractiveCli.ts

@@ -27,6 +27,7 @@ import {
   CoreEvent,
   createWorkingStdio,
   recordToolCallInteractions,
+  isHeadlessMode,
   ToolErrorType,
   Scheduler,
   ROOT_SCHEDULER_ID,
@@ -63,9 +64,10 @@ export async function runNonInteractive({
   resumedSessionData,
 }: RunNonInteractiveParams): Promise<void> {
   return promptIdContext.run(prompt_id, async () => {
+    const suppressConsoleOutput = isHeadlessMode() && !config.getDebugMode();
     const consolePatcher = new ConsolePatcher({
       stderr: true,
-      suppressConsoleOutput: true,
+      suppressConsoleOutput,
       debugMode: config.getDebugMode(),
       onNewMessage: (msg) => {
         coreEvents.emitConsoleLog(msg.type, msg.content);

packages/cli/src/ui/utils/ConsolePatcher.test.ts

@@ -43,6 +43,26 @@ describe('ConsolePatcher', () => {
     console.error = originalError;
   });
 
+  it('should NOT suppress console.error even when suppressConsoleOutput is true', () => {
+    const originalError = console.error;
+    const errorSpy = vi.spyOn(console, 'error').mockImplementation(() => {});
+
+    patcher = new ConsolePatcher({
+      debugMode: false,
+      suppressConsoleOutput: true,
+      stderr: true,
+    });
+    patcher.patch();
+
+    console.error('test error');
+
+    expect(errorSpy).toHaveBeenCalled();
+
+    patcher.cleanup();
+    errorSpy.mockRestore();
+    console.error = originalError;
+  });
+
   it('should NOT suppress output when suppressConsoleOutput is true but debugMode is true', () => {
     const originalError = console.error;
     const errorSpy = vi.spyOn(console, 'error').mockImplementation(() => {});

packages/cli/src/ui/utils/ConsolePatcher.ts

@@ -50,7 +50,11 @@ export class ConsolePatcher {
   private patchConsoleMethod =
     (type: 'log' | 'warn' | 'error' | 'debug' | 'info') =>
     (...args: unknown[]) => {
-      if (this.params.suppressConsoleOutput && !this.params.debugMode) {
+      if (
+        this.params.suppressConsoleOutput &&
+        !this.params.debugMode &&
+        type !== 'error'
+      ) {
         return;
       }