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>

session-stream-store.test.mjs

@@ -0,0 +1,88 @@
+import assert from 'node:assert/strict';
+import test from 'node:test';
+import { createSessionStreamStore } from './session-stream-store.mjs';
+
+function createMockPool() {
+  let clock = 1;
+  const events = [];
+  return {
+    events,
+    async query(sql, params = []) {
+      if (sql.includes('INSERT INTO h5_session_stream_events')) {
+        const createdAt = clock++;
+        events.push({
+          id: params[0],
+          user_id: params[1],
+          agent_session_id: params[2],
+          event_type: params[3],
+          payload_json: params[4],
+          upstream_event_id: params[5],
+          created_at: createdAt,
+        });
+        return [{ insertId: 1 }];
+      }
+      if (sql.includes('WHERE id = ? AND agent_session_id = ?')) {
+        const row = events.find((item) => item.id === params[0]);
+        return [[row ? { created_at: row.created_at } : undefined].filter(Boolean)];
+      }
+      if (sql.includes('created_at > ?')) {
+        const after = Number(params[2]);
+        const rows = events
+          .filter(
+            (item) =>
+              item.agent_session_id === params[0] &&
+              item.user_id === params[1] &&
+              Number(item.created_at) > after,
+          )
+          .sort((a, b) => Number(a.created_at) - Number(b.created_at));
+        return [rows];
+      }
+      if (sql.includes('ORDER BY created_at ASC, id ASC')) {
+        const rows = events
+          .filter(
+            (item) => item.agent_session_id === params[0] && item.user_id === params[1],
+          )
+          .sort((a, b) => Number(a.created_at) - Number(b.created_at))
+          .slice(0, params[2]);
+        return [rows];
+      }
+      if (sql.includes('ORDER BY created_at DESC, id DESC')) {
+        const row = events
+          .filter(
+            (item) => item.agent_session_id === params[0] && item.user_id === params[1],
+          )
+          .sort((a, b) => Number(b.created_at) - Number(a.created_at))[0];
+        return [[row].filter(Boolean)];
+      }
+      throw new Error(`unexpected sql: ${sql}`);
+    },
+  };
+}
+
+test('session stream store append and replay with cursor', async () => {
+  const pool = createMockPool();
+  const store = createSessionStreamStore({ pool });
+  const first = await store.appendEvent({
+    userId: 'user-1',
+    sessionId: 'sess-1',
+    payload: { type: 'Message', message: { role: 'assistant', content: [] } },
+    id: 'evt-1',
+  });
+  await store.appendEvent({
+    userId: 'user-1',
+    sessionId: 'sess-1',
+    payload: { type: 'Finish' },
+    id: 'evt-2',
+  });
+
+  const head = await store.listEventsForUser('user-1', 'sess-1');
+  assert.equal(head.events.length, 2);
+
+  const tail = await store.listEventsForUser('user-1', 'sess-1', { afterEventId: 'evt-1' });
+  assert.equal(tail.events.length, 1);
+  assert.equal(tail.events[0].payload.type, 'Finish');
+  assert.equal(tail.cursorMiss, false);
+
+  const miss = await store.listEventsForUser('user-1', 'sess-1', { afterEventId: 'missing' });
+  assert.equal(miss.cursorMiss, true);
+});