fix(sdk): stayIntervalMs边界守卫——0/NaN钳制下限防事件灌入

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

sdk/src/stay.ts

@@ -24,7 +24,9 @@ export interface StayOptions {
 }
 
 export function startStayTracking(t: Transport, ps: PageSession, opts: StayOptions = {}): void {
-  const stayIntervalMs = opts.stayIntervalMs ?? 15_000;
+  // 边界守卫：0/负数等有限小值钳制下限 1s（防 setInterval 高频 cut 灌入事件）；
+  // NaN/Infinity 非有限值——NaN 绕过 ?? 的 nullish 判定直传，须显式回落默认 15s。
+  const stayIntervalMs = Math.max(1_000, Number.isFinite(opts.stayIntervalMs) ? opts.stayIntervalMs! : 15_000);
   let intervalStart: number | null = null; // performance.now 基准；null=无 open 区间
   let lastCutEnd: number | null = null; // 最近一次 cut 的 perf 端点——重开回溯的钳制上界
   let lastAct = Date.now(); // 墙钟活动戳（沿 events.ts 冻结语义；页面加载即活动）

sdk/test/stay.test.ts

@@ -254,4 +254,34 @@ describe("stay / startStayTracking", () => {
     expect(stays[0].properties.active_ms).toBe(30_000); // 活动窗 [0,30s] 整段
     expect(stays[0].properties.flush_reason).toBe("periodic"); // 失活悬置属周期结算
   });
+
+  it("stayIntervalMs 边界守卫：NaN 回落默认 15s；0 钳制下限 ≥1s（防高频 cut 灌入）", () => {
+    // NaN：非 nullish，绕过 ?? 默认值——须回落 15s 语义（16s 恰一条 [0,15s] periodic）
+    let t = mkTransport("stay-nan");
+    let ps = new PageSession(t);
+    startStayTracking(t, ps, { stayIntervalMs: NaN });
+    advance(16_000);
+    t.flush();
+    let stays = staysOf(fetchedEvents("stay-nan"));
+    expect(stays).toHaveLength(1);
+    expect(stays[0].properties.active_ms).toBe(15_000);
+    expect(stays[0].properties.flush_reason).toBe("periodic");
+
+    // 0：无守卫时 setInterval(0) 每毫秒 cut 灌入事件；钳到下限后 5s 内切分有界。
+    // 首秒 tick/cut 同瞬触发顺序不定——断言保持顺序无关：条数有界、区间 ≥1s、相邻不重叠
+    t = mkTransport("stay-zero");
+    ps = new PageSession(t);
+    startStayTracking(t, ps, { stayIntervalMs: 0 });
+    advance(5_000);
+    t.flush();
+    stays = staysOf(fetchedEvents("stay-zero")).sort(
+      (a, b) => a.properties.active_from - b.properties.active_from
+    );
+    expect(stays.length).toBeGreaterThanOrEqual(1);
+    expect(stays.length).toBeLessThanOrEqual(5); // 下限 1s 一刀 → 至多 5 条
+    for (const s of stays) expect(s.properties.active_ms).toBeGreaterThanOrEqual(1_000);
+    for (let i = 1; i < stays.length; i++) {
+      expect(stays[i].properties.active_from).toBeGreaterThanOrEqual(stays[i - 1].properties.active_to); // lastCutEnd 钳制不重叠
+    }
+  });
 });