```

feat: 增强URL基础地址验证功能

- 在app-instance/frontend/lib/api.ts中实现更严格的URL验证逻辑，
  包括检查是否以斜杠开头、包含空格字符，以及使用URL构造函数进行验证

- 在app-instance/frontend/lib/auth-portal.ts中应用相同的URL验证改进，
  提升认证门户的基础地址处理安全性

- 在auth-portal/src/lib/auth-client.ts中增强前端跳转URL构建功能，
  添加错误处理机制并在URL构造失败时抛出相应异常

- 统一三个文件中的normalizeBaseUrl函数实现，确保一致的输入验证行为
```

app-instance/frontend/lib/api.ts

@@ -79,7 +79,15 @@ function isBrowser(): boolean {
 function normalizeBaseUrl(value?: string | null): string | null {
   const trimmed = value?.trim();
   if (!trimmed) return null;
-  return trimmed.replace(/\/+$/, '');
+  if (trimmed.startsWith('/') || /\s/.test(trimmed)) return null;
+  const hasScheme = /^[a-z][a-z0-9+.-]*:\/\//i.test(trimmed);
+  const candidate = hasScheme ? trimmed : `http://${trimmed}`;
+  try {
+    const url = new URL(candidate);
+    return url.toString().replace(/\/+$/, '');
+  } catch {
+    return null;
+  }
 }
 
 export function buildAuthHandoffUrl(response: TokenResponse, nextPath: string): string | null {

app-instance/frontend/lib/auth-portal.ts

@@ -6,7 +6,15 @@ const AUTH_PORTAL_PORT = process.env.NEXT_PUBLIC_AUTH_PORTAL_PORT?.trim() || '30
 function normalizeBaseUrl(value?: string | null): string | null {
   const trimmed = value?.trim();
   if (!trimmed) return null;
-  return trimmed.replace(/\/+$/, '');
+  if (trimmed.startsWith('/') || /\s/.test(trimmed)) return null;
+  const hasScheme = /^[a-z][a-z0-9+.-]*:\/\//i.test(trimmed);
+  const candidate = hasScheme ? trimmed : `http://${trimmed}`;
+  try {
+    const url = new URL(candidate);
+    return url.toString().replace(/\/+$/, '');
+  } catch {
+    return null;
+  }
 }
 
 function getPortalBaseUrl(): string {
@@ -28,4 +36,3 @@ export function buildAuthPortalUrl(path: '/login' | '/register', nextPath?: stri
   }
   return url.toString();
 }
-

app-instance/frontend/lib/auth-url.test.ts

@@ -0,0 +1,51 @@
+import { afterEach, describe, expect, it, vi } from 'vitest';
+
+import { buildAuthHandoffUrl } from './api';
+
+afterEach(() => {
+  vi.unstubAllEnvs();
+  vi.resetModules();
+});
+
+describe('auth URL handling', () => {
+  it('builds auth portal URLs when configured portal host has no scheme', async () => {
+    vi.stubEnv('NEXT_PUBLIC_AUTH_PORTAL_URL', 'auth.example.com');
+    const { buildAuthPortalUrl } = await import('./auth-portal');
+
+    expect(buildAuthPortalUrl('/login', '/mcp')).toBe('http://auth.example.com/login?next=%2Fmcp');
+  });
+
+  it('builds a handoff URL when backend returns a hostname without scheme', () => {
+    const url = buildAuthHandoffUrl({
+      access_token: 'token',
+      refresh_token: '',
+      token_type: 'bearer',
+      user_id: 'u1',
+      username: 'u1',
+      role: 'owner',
+      handoff_code: 'handoff-1',
+      backend_connection: {
+        frontend_base_url: 'workspace.example.com:8088',
+      },
+    }, '/mcp');
+
+    expect(url).toBe('http://workspace.example.com:8088/handoff?code=handoff-1&next=%2Fmcp');
+  });
+
+  it('rejects malformed handoff base URLs instead of throwing URL constructor errors', () => {
+    const url = buildAuthHandoffUrl({
+      access_token: 'token',
+      refresh_token: '',
+      token_type: 'bearer',
+      user_id: 'u1',
+      username: 'u1',
+      role: 'owner',
+      handoff_code: 'handoff-1',
+      backend_connection: {
+        frontend_base_url: 'http://',
+      },
+    }, '/mcp');
+
+    expect(url).toBeNull();
+  });
+});