feat(h5): web 联网能力、实时查询路由与 session Finish 对齐

- 新增 web 能力并挂载 platform/web（web_search/fetch_url）
- 实时查询强制 web skill，router fallback 与 await session Finish
- Session Broker 覆盖率/指标、stream replay 与相关单测/E2E 脚本

Co-authored-by: Cursor <cursoragent@cursor.com>

capabilities.mjs

@@ -123,6 +123,13 @@ export const CAPABILITY_CATALOG = [
     risk: 'low',
     category: 'productivity',
   },
+  {
+    key: 'web',
+    label: '网页搜索',
+    description: '联网搜索与抓取（platform/web：web_search、fetch_url）',
+    risk: 'medium',
+    category: 'knowledge',
+  },
   {
     key: 'computer',
     label: '电脑控制',
@@ -182,6 +189,7 @@ export const DEFAULT_USER_CAPABILITIES = Object.fromEntries(
       extension_admin: false,
       apps: false,
       todo: false,
+      web: true,
       computer: false,
       charts: false,
       aider: false,
@@ -401,6 +409,9 @@ export function buildAgentExtensionPolicy(
   if (capabilities.todo) {
     extensions.push(makeExtension('platform', 'todo', []));
   }
+  if (capabilities.web) {
+    extensions.push(makeExtension('platform', 'web', ['web_search', 'fetch_url']));
+  }
   if (capabilities.computer) {
     extensions.push(makeExtension('builtin', 'computercontroller', []));
   }