diff --git a/apps/ai-game-creator-shell/src/services/clientAuth.ts b/apps/ai-game-creator-shell/src/services/clientAuth.ts
index c0b5e0750..65d0650da 100644
--- a/apps/ai-game-creator-shell/src/services/clientAuth.ts
+++ b/apps/ai-game-creator-shell/src/services/clientAuth.ts
@@ -13,6 +13,8 @@ import type {
 import {
   API_RESPONSE_ENVELOPE_HEADER,
   API_RESPONSE_ENVELOPE_VERSION,
+  isApiResponse,
+  parseApiErrorMessage,
   unwrapApiResponse,
 } from '../../../../packages/shared/src/http';
 import {
@@ -138,6 +140,18 @@ export function getClientAuthErrorMessage(error: unknown, fallback: string) {
   return error instanceof Error ? error.message : fallback;
 }
 
+/**
+ * 旧形态错误体：未带 `x-genarrative-response-envelope` 时后端返回
+ * `{ error: { code, message }, meta }`，没有 `ok` 字段，但 message 同样是给用户看的原因。
+ */
+function isLegacyApiErrorBody(value: unknown) {
+  if (typeof value !== 'object' || value === null || Array.isArray(value)) {
+    return false;
+  }
+  const record = value as Record<string, unknown>;
+  return 'error' in record || 'message' in record || 'code' in record;
+}
+
 async function readAuthErrorMessage(response: Response, fallback: string) {
   const httpFallback = getClientAuthHttpErrorMessage(response.status, fallback);
   const text = await readClientHttpResponseText(response, {
@@ -150,15 +164,27 @@ async function readAuthErrorMessage(response: Response, fallback: string) {
   try {
     parsed = JSON.parse(text) as unknown;
   } catch {
+    // 非 JSON（代理错误页、纯文本）不把内部英文原样抛给用户。
     return httpFallback;
   }
-  try {
-    unwrapApiResponse(parsed);
-  } catch (error) {
-    const message = error instanceof Error ? error.message.trim() : '';
-    return message && message !== '请求失败' ? message : httpFallback;
+  if (isApiResponse(parsed)) {
+    try {
+      unwrapApiResponse(parsed);
+    } catch (error) {
+      const message = error instanceof Error ? error.message.trim() : '';
+      return message && message !== '请求失败' ? message : httpFallback;
+    }
+    return httpFallback;
   }
-  return httpFallback;
+  if (!isLegacyApiErrorBody(parsed)) {
+    return httpFallback;
+  }
+  // 旧形态错误体仍按共享契约解析，否则“手机号或密码错误”这类明确原因会退化成固定文案。
+  const legacyMessage = parseApiErrorMessage(text, httpFallback).trim();
+  // 共享解析器在认不出结构时会回显原始 JSON，这里不允许把它当成用户可见文案。
+  return legacyMessage && legacyMessage !== text.trim()
+    ? legacyMessage
+    : httpFallback;
 }
 
 async function requestAuthJson<T>(
diff --git a/apps/ai-game-creator-shell/tests/appSurface/auth.suite.ts b/apps/ai-game-creator-shell/tests/appSurface/auth.suite.ts
index bfb771cb0..586a4e0a7 100644
--- a/apps/ai-game-creator-shell/tests/appSurface/auth.suite.ts
+++ b/apps/ai-game-creator-shell/tests/appSurface/auth.suite.ts
@@ -1156,6 +1156,94 @@ export function registerAuthTests() {
     expect(screen.queryByText(/Unexpected|Failed to deserialize/u)).toBeNull();
   });
 
+  it('shows the backend reason when the password login is rejected', async () => {
+    vi.spyOn(globalThis, 'fetch').mockImplementation(
+      async (input: RequestInfo | URL) => {
+        const url = String(input);
+        if (url === '/api/auth/refresh') {
+          return new Response('', { status: 401 });
+        }
+        if (url === '/api/auth/entry') {
+          return new Response(
+            JSON.stringify({
+              ok: false,
+              data: null,
+              error: { code: 'unauthorized', message: '手机号或密码错误' },
+              meta: { apiVersion: '2026-06-16', routeVersion: 'v1' },
+            }),
+            {
+              status: 401,
+              headers: { 'Content-Type': 'application/json' },
+            },
+          );
+        }
+        throw new Error(`unexpected fetch ${url}`);
+      },
+    );
+
+    render(
+      React.createElement(AuthenticatedClient, null, () =>
+        React.createElement('main', { 'aria-label': '已登录' }, 'ready'),
+      ),
+    );
+
+    await screen.findByRole('main', { name: '登录' });
+    fireEvent.click(screen.getByRole('button', { name: '密码登录' }));
+    fireEvent.change(screen.getByLabelText('手机号'), {
+      target: { value: '15801783533' },
+    });
+    fireEvent.change(screen.getByLabelText('密码'), {
+      target: { value: 'wrong-password' },
+    });
+    fireEvent.click(screen.getByRole('button', { name: '登录' }));
+
+    expect(await screen.findByText('手机号或密码错误')).not.toBeNull();
+    expect(screen.queryByText('登录失败')).toBeNull();
+  });
+
+  it('keeps the backend reason when the error body carries no envelope', async () => {
+    vi.spyOn(globalThis, 'fetch').mockImplementation(
+      async (input: RequestInfo | URL) => {
+        const url = String(input);
+        if (url === '/api/auth/refresh') {
+          return new Response('', { status: 401 });
+        }
+        if (url === '/api/auth/entry') {
+          return new Response(
+            JSON.stringify({
+              error: { code: 'unauthorized', message: '手机号或密码错误' },
+              meta: { apiVersion: '2026-06-16', routeVersion: 'v1' },
+            }),
+            {
+              status: 401,
+              headers: { 'Content-Type': 'application/json' },
+            },
+          );
+        }
+        throw new Error(`unexpected fetch ${url}`);
+      },
+    );
+
+    render(
+      React.createElement(AuthenticatedClient, null, () =>
+        React.createElement('main', { 'aria-label': '已登录' }, 'ready'),
+      ),
+    );
+
+    await screen.findByRole('main', { name: '登录' });
+    fireEvent.click(screen.getByRole('button', { name: '密码登录' }));
+    fireEvent.change(screen.getByLabelText('手机号'), {
+      target: { value: '15801783533' },
+    });
+    fireEvent.change(screen.getByLabelText('密码'), {
+      target: { value: 'wrong-password' },
+    });
+    fireEvent.click(screen.getByRole('button', { name: '登录' }));
+
+    expect(await screen.findByText('手机号或密码错误')).not.toBeNull();
+    expect(screen.queryByText('登录失败')).toBeNull();
+  });
+
   it('shows a clear login service error instead of raw Load failed', async () => {
     vi.spyOn(globalThis, 'fetch').mockImplementation(
       async (input: RequestInfo | URL) => {