test(dash): [PKG-DASH-05] isolate SDK paused-seek buffer metric deadlock

refactor/risks.json

@@ -2964,7 +2964,7 @@
     },
     {
       "id": "DASH-SEEK-01",
-      "title": "真实 dash.js 4.5.2 暂停 seek 到缓冲片段边界后可能持续 waiting",
+      "title": "dash.js 4.5.2 空裁剪漏更新缓冲量，稳定暂停 seek 后调度停滞",
       "confirmation": "reproduced",
       "status": "open",
       "owners": [
@@ -2974,9 +2974,12 @@
       "evidence": [
         "test/browser/dash-sdk.spec.js",
         "refactor/baselines/dash-sdk-checkpoint.json",
-        "refactor/changes/2026-09-12-PKG-DASH-05-sdk-checkpoint.md"
+        "refactor/changes/2026-09-12-PKG-DASH-05-sdk-checkpoint.md",
+        "refactor/changes/2026-09-12-PKG-DASH-05-seek-diagnosis.md",
+        "refactor/baselines/dash-seek-diagnosis.json",
+        "test/browser/dash-buffer-observer.js"
       ],
-      "compatibleResolution": "先比较实际 SDK、SourceBuffer/video 缓冲与暂停 seek 调度；不偏移公开 seek 目标，不吞异常或增加超时伪造通过。",
+      "compatibleResolution": "已用原生 SDK、SourceBuffer/调度指标和 SDK 5 空裁剪刷新的一行诊断回植确认根因。兼容处置尚未落地；不在核心伪造 timeupdate、不偏移 seek、不强制所有旧用户升级 SDK，也不将诊断补丁计为正式上游通过。",
       "closureCriteria": "原失败的新旧核心/插件组合有确定根因与对应修复/可验证环境边界；原生对照及原顺序、原目标回归成立，后续偶然通过不能关闭。"
     }
   ]