feat(ui): move user identity display to header (#18216)

# Conflicts:
#	packages/cli/src/ui/AppContainer.tsx

packages/cli/src/ui/components/UserIdentity.tsx

@@ -0,0 +1,61 @@
+/**
+ * @license
+ * Copyright 2025 Google LLC
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+import type React from 'react';
+import { useMemo } from 'react';
+import { Box, Text } from 'ink';
+import { theme } from '../semantic-colors.js';
+import {
+  type Config,
+  UserAccountManager,
+  AuthType,
+} from '@google/gemini-cli-core';
+
+interface UserIdentityProps {
+  config: Config;
+}
+
+export const UserIdentity: React.FC<UserIdentityProps> = ({ config }) => {
+  const authType = config.getContentGeneratorConfig()?.authType;
+
+  const { email, tierName } = useMemo(() => {
+    if (!authType) {
+      return { email: undefined, tierName: undefined };
+    }
+    const userAccountManager = new UserAccountManager();
+    return {
+      email: userAccountManager.getCachedGoogleAccount(),
+      tierName: config.getUserTierName(),
+    };
+  }, [config, authType]);
+
+  if (!authType) {
+    return null;
+  }
+
+  return (
+    <Box marginY={1} flexDirection="column">
+      <Box>
+        <Text color={theme.text.primary}>
+          {authType === AuthType.LOGIN_WITH_GOOGLE ? (
+            <Text>
+              <Text bold>Logged in with Google{email ? ':' : ''}</Text>
+              {email ? ` ${email}` : ''}
+            </Text>
+          ) : (
+            `Authenticated with ${authType}`
+          )}
+        </Text>
+        <Text color={theme.text.secondary}> /auth</Text>
+      </Box>
+      {tierName && (
+        <Text color={theme.text.primary}>
+          <Text bold>Plan:</Text> {tierName}
+        </Text>
+      )}
+    </Box>
+  );
+};