feat: add user startup warnings, add home directory check (#3056)

packages/cli/src/utils/userStartupWarnings.ts

@@ -0,0 +1,45 @@
+/**
+ * @license
+ * Copyright 2025 Google LLC
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+import fs from 'fs/promises';
+import * as os from 'os';
+
+type WarningCheck = {
+  id: string;
+  check: (workspaceRoot: string) => Promise<string | null>;
+};
+
+// Individual warning checks
+const homeDirectoryCheck: WarningCheck = {
+  id: 'home-directory',
+  check: async (workspaceRoot: string) => {
+    try {
+      const [workspaceRealPath, homeRealPath] = await Promise.all([
+        fs.realpath(workspaceRoot),
+        fs.realpath(os.homedir()),
+      ]);
+
+      if (workspaceRealPath === homeRealPath) {
+        return 'You are running Gemini CLI in your home directory. It is recommended to run in a project-specific directory.';
+      }
+      return null;
+    } catch (_err: unknown) {
+      return 'Could not verify the current directory due to a file system error.';
+    }
+  },
+};
+
+// All warning checks
+const WARNING_CHECKS: readonly WarningCheck[] = [homeDirectoryCheck];
+
+export async function getUserStartupWarnings(
+  workspaceRoot: string,
+): Promise<string[]> {
+  const results = await Promise.all(
+    WARNING_CHECKS.map((check) => check.check(workspaceRoot)),
+  );
+  return results.filter((msg) => msg !== null);
+}