feat(cli): disable folder trust in headless mode (#18407)

packages/core/src/utils/headless.ts

@@ -0,0 +1,45 @@
+/**
+ * @license
+ * Copyright 2025 Google LLC
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+import process from 'node:process';
+
+/**
+ * Options for headless mode detection.
+ */
+export interface HeadlessModeOptions {
+  /** Explicit prompt string or flag. */
+  prompt?: string | boolean;
+  /** Initial query positional argument. */
+  query?: string | boolean;
+}
+
+/**
+ * Detects if the CLI is running in a "headless" (non-interactive) mode.
+ *
+ * Headless mode is triggered by:
+ * 1. process.env.CI being set to 'true'.
+ * 2. process.stdout not being a TTY.
+ * 3. Presence of an explicit prompt flag.
+ *
+ * @param options - Optional flags and arguments from the CLI.
+ * @returns true if the environment is considered headless.
+ */
+export function isHeadlessMode(options?: HeadlessModeOptions): boolean {
+  if (process.env['GEMINI_CLI_INTEGRATION_TEST'] === 'true') {
+    return (
+      !!options?.prompt ||
+      (!!process.stdin && !process.stdin.isTTY) ||
+      (!!process.stdout && !process.stdout.isTTY)
+    );
+  }
+  return (
+    process.env['CI'] === 'true' ||
+    process.env['GITHUB_ACTIONS'] === 'true' ||
+    !!options?.prompt ||
+    (!!process.stdin && !process.stdin.isTTY) ||
+    (!!process.stdout && !process.stdout.isTTY)
+  );
+}