test(sdk): track宿主伪造归属键被快照覆盖的权威性回归

Co-Authored-By: Claude Code <noreply@anthropic.com>

sdk/test/index.test.ts

@@ -152,6 +152,45 @@ describe("index 入口", () => {
     expect(ev.grant_ref).toBe(null);
   });
 
+  it("track 归属权威性回归（T5 审查遗留）：宿主伪造归属键被快照覆盖，业务字段原样保留", async () => {
+    await loadSdk([["init", { siteId: "site-auth", endpoint: "/e", flushMs: 60000 }]]);
+    g.ctk!("track", {
+      event_id: "e-evil",
+      event_name: "page_stay",
+      occurred_at: new Date().toISOString(),
+      path: "/x",
+      title: "t",
+      properties: {},
+      site_id: "evil-site", // 宿主伪造归属键：spread 宿主在前、归属在后（index.ts track 分支）
+      session_id: "evil-sess",
+    });
+    g.ctk!("flush");
+
+    // 信封 site_id 恒取 init 配置（transport.envelope 读 cfg.siteId）——
+    // 伪造的 evil-site 批次根本不存在
+    expect(bodiesOf("evil-site")).toHaveLength(0);
+    const bodies = bodiesOf("site-auth");
+    expect(bodies).toHaveLength(1); // 伪造键被覆盖 → 与 page_view/sdk_loaded 同四元组，单组子批
+    const evs = bodies[0].events;
+    expect(evs.map((e: { event_name: string }) => e.event_name)).toEqual([
+      "page_view",
+      "sdk_loaded",
+      "page_stay",
+    ]);
+    const ev = evs[2] as Record<string, unknown>;
+    // 事件归属四元组来自 PageSession 快照（非宿主伪造值）
+    expect(ev.site_id).toBe("site-auth");
+    expect(ev.session_id).toMatch(UUID_RE);
+    expect(ev.session_id).toBe(evs[0].session_id); // 与初始 page_view 同会话（非 evil-sess）
+    expect(ev.visitor_id).toBe(evs[0].visitor_id);
+    expect(ev.page_id).toBe(evs[0].page_id);
+    // 信封归属同取分组键（事件顶层快照字段）：亦非伪造值
+    expect(bodies[0].session_id).toBe(evs[0].session_id);
+    // 宿主业务字段不被归属展开覆盖
+    expect(ev.event_id).toBe("e-evil");
+    expect(ev.properties).toEqual({});
+  });
+
   it("init 接线 business（T5）：产品页路径下队列 [page_view,sdk_loaded,product_view]；wa.me 点击 → contact_click beacon 冒烟", async () => {
     setUrl("/product/hydraulic-press-100t/");
     await loadSdk([["init", { siteId: "site-biz", endpoint: "/e", flushMs: 60000 }]]);