test(multiple-subtitles): [PKG-MULTI-SUB-09] isolate old-core source seeking from caption loss

refactor/changes/2026-09-14-PKG-MULTI-SUB-09-switch-order.md

@@ -0,0 +1,81 @@
+# PKG-MULTI-SUB-09: distinguish source seeking from caption loss
+
+Baseline: efed847cdfcbe5110e88b31527c46e622bcc83ee. This task closes the
+misattributed switching finding with independent native evidence and corrects
+integration sequencing. No production code, public type, dependency, version,
+lockfile or built artifact changes. PKG-MULTI-SUB-05 remains doing.
+
+## Root cause evidence
+
+The original WebKit failures retained a valid Translation cue at1..3 seconds,
+but the actual media clock was approximately0.002 seconds, with no active cues.
+The subtitle was correctly absent at that time; the intended seek to1.5 had not
+landed. Those reports predate currentTime instrumentation.
+
+`multiple-subtitles-switch.spec.js` compares no plugin, current plugin, and actual
+npm plugin1.2.0 on cores5.3.0/5.4.0/candidate. Each case plays real local media,
+enters/exits native fullscreen, then performs three source changes. It captures
+native currentTime writes and media events, Promise settlement state, first seek
+completion and a second seek only if the first missed after native seeking ended.
+The property probe forwards to the original native getter/setter; it does not
+intercept or replace source operations. Outcomes and full traces are stored in
+[multiple-subtitles-switch-validation.json](../baselines/multiple-subtitles-switch-validation.json).
+
+The first WebKit run confirms5 misses in18 old-core source changes, including
+both no-plugin old-core controls. All9 candidate-core changes land correctly.
+Old core promises sometimes resolve while video.seeking is still true, allowing
+the caller's new seek to overlap native restoration. After the restoration has
+ended, a fresh seek reaches the cue interval and both old/new plugins display it.
+Candidate source/switch.ts already waits for native seeking to finish and uses
+the position restoration logic covered by BASE-LIFE-44/CORE-19. No plugin-level
+seek retry, clock rewrite, blanket source reload or global core patch is needed.
+
+The actual-main three-engine trace run has no missed first seeks in81 changes,
+but old WebKit hosts still settle during native seeking in6 of18 changes. This
+variation is retained; it is an intermittent old-host race, not proof that the
+initial misses were fixed by rerunning. All27 candidate-core changes in that run
+have seeking=false at settlement and honor the first caller seek.
+
+## Test sequencing and validation
+
+The caption combination test now waits for video.seeking=false after switchUrl
+before testing the separate user seek/caption behavior. The immediate old-call
+path is retained in the independent ordering test above, including its misses.
+This wait is a predicate on real native state, not a fixed delay or a silent
+retry of the acceptance assertion. It does not claim old switchUrl promises have
+been changed or all historical playback contracts are correct.
+
+One later full run exposed an unrelated fixture sequence: it started exiting
+fullscreen when the document property changed but before the public enter event
+arrived, resulting in old-core notifications[false,false]. The normal enter/exit
+scenario now waits for the entering event before requesting exit; the original
+strict final[true,false] assertion remains. The failed trace is retained. No
+production fullscreen correction is claimed by this test-sequencing adjustment.
+
+- Initial source WebKit ordering probe:9 cases pass their observation/candidate
+  assertions, including the5 old first-seek misses noted above.
+- Actual core and plugin main artifacts, three engines:84 cases,83 passing
+  assertions,1 fullscreen-sequencing failure. All27 ordering cases pass, and the
+  run also includes explicitly labelled historical overlap/offset defects.
+- After the entering-event predicate correction, the affected timed-combination
+  matrix is rerun unchanged otherwise:9/9 pass across three cores and engines.
+  Do not describe this as a fresh84-case all-green run.
+- The two changed browser scripts pass lint;50 CI regression tests pass. Final
+  plan/risk and risk-validator checks cover the completed task state.
+
+MULTI-SUB-SWITCH-01 is resolved as a classified old-core seeking issue already
+handled in the candidate core, with the original calls and failures preserved.
+This does not resolve MULTI-SUB-MERGE-01 or complete device/distribution acceptance.
+Use the actual loaded core/plugin hashes when comparing future runs; the fixture
+supports both source builds and the existing explicit artifact map.
+
+## Maintenance and rollback
+
+Keep source readiness, actual seek landing and caption rendering distinct when
+debugging media failures. Run the ordering probe with/without the plugin before
+adding plugin retries for an underlying player clock problem. Keep candidate
+first-seek assertions strict; old observations must never count as correct calls.
+Both suites run under yarn test:browser. A normal core/plugin build was not needed
+because production bytes are unchanged; the checked artifacts came from the prior
+completed implementation commits. Revert this independent task09 commit to remove
+the new probe and integration predicates. Local commit only, no push/publication.

refactor/plan.md

@@ -2,9 +2,9 @@
 
 > 由 tasks.json 生成。请修改数据后运行 `node refactor/scripts/plan.mjs --write`，不要手改本表。
 
-基线：`40fcda6a37d0049d42e49c1e64e70d4fd9ba5f7f`。总任务 248 项，范围 22 个包及工作区/示例。
+基线：`40fcda6a37d0049d42e49c1e64e70d4fd9ba5f7f`。总任务 249 项，范围 22 个包及工作区/示例。
 
-状态：todo 55 / doing 17 / blocked 0 / done 176 / deferred 0。风险 L/M/H 表示兼容风险，不表示工期。
+状态：todo 55 / doing 17 / blocked 0 / done 177 / deferred 0。风险 L/M/H 表示兼容风险，不表示工期。
 
 前置依赖是启动条件；验收是完成条件。任务可以继续拆分，但不能复用或悄悄删除旧 ID。
 
@@ -14,7 +14,7 @@
 
 | 包 | 基线版本 | 任务 |
 | --- | --- | --- |
-| artplayer | 5.4.1 | CORE-01, CORE-02, CORE-03, CORE-04, CORE-05, CORE-06, CORE-07, CORE-08, CORE-09, CORE-10, CORE-11, CORE-12, CORE-13, CORE-14, CORE-15, CORE-16, CORE-17, CORE-18, CORE-19, CORE-20, CORE-21, CORE-23, CORE-22, CORE-24, SITE-BUILD-01, CORE-25, ENG-12, CORE-SUBTITLE-OFFSET-01 |
+| artplayer | 5.4.1 | CORE-01, CORE-02, CORE-03, CORE-04, CORE-05, CORE-06, CORE-07, CORE-08, CORE-09, CORE-10, CORE-11, CORE-12, CORE-13, CORE-14, CORE-15, CORE-16, CORE-17, CORE-18, CORE-19, CORE-20, CORE-21, CORE-23, CORE-22, CORE-24, SITE-BUILD-01, CORE-25, ENG-12, CORE-SUBTITLE-OFFSET-01, PKG-MULTI-SUB-09 |
 | artplayer-plugin-ads | 2.1.0 | PKG-ADS-01, PKG-ADS-02, PKG-ADS-03, PKG-ADS-04, PKG-ADS-05, PKG-ADS-06 |
 | artplayer-plugin-ambilight | 1.1.0 | PKG-AMBILIGHT-01, PKG-AMBILIGHT-02, PKG-AMBILIGHT-03, PKG-AMBILIGHT-04, PKG-AMBILIGHT-PROXY-01, PKG-AMBILIGHT-05, PKG-AMBILIGHT-06, PKG-FACTORY-01 |
 | artplayer-plugin-asr | 2.1.0 | PKG-ASR-01, PKG-ASR-02, PKG-ASR-03, PKG-ASR-04, PKG-ASR-05, PKG-ASR-06, PKG-ASR-07, PKG-ASR-08, PKG-ASR-09 |
@@ -28,7 +28,7 @@
 | artplayer-plugin-document-pip | 1.1.0 | PKG-DPIP-01, PKG-DPIP-02, PKG-DPIP-03, PKG-DPIP-04, PKG-DPIP-05, PKG-DPIP-06 |
 | artplayer-plugin-hls-control | 1.1.0 | PKG-HLS-01, PKG-HLS-02, PKG-HLS-03, PKG-HLS-04, PKG-HLS-SDK-01, PKG-HLS-05, PKG-HLS-06 |
 | artplayer-plugin-jassub | 1.1.0 | PKG-JASSUB-01, PKG-JASSUB-02, PKG-JASSUB-03, PKG-JASSUB-04, PKG-JASSUB-05, PKG-JASSUB-06, PKG-JASSUB-07, PKG-JASSUB-08, PKG-JASSUB-09 |
-| artplayer-plugin-multiple-subtitles | 1.2.0 | PKG-MULTI-SUB-01, PKG-MULTI-SUB-02, PKG-MULTI-SUB-03, PKG-MULTI-SUB-04, PKG-MULTI-SUB-07, PKG-MULTI-SUB-08, PKG-MULTI-SUB-05, PKG-MULTI-SUB-06 |
+| artplayer-plugin-multiple-subtitles | 1.2.0 | PKG-MULTI-SUB-01, PKG-MULTI-SUB-02, PKG-MULTI-SUB-03, PKG-MULTI-SUB-04, PKG-MULTI-SUB-07, PKG-MULTI-SUB-08, PKG-MULTI-SUB-05, PKG-MULTI-SUB-06, PKG-MULTI-SUB-09 |
 | artplayer-plugin-vast | 1.2.0 | PKG-VAST-01, PKG-VAST-02, PKG-VAST-03, PKG-VAST-04, PKG-VAST-05, PKG-VAST-06 |
 | artplayer-plugin-vtt-thumbnail | 1.1.0 | PKG-VTT-THUMB-01, PKG-VTT-THUMB-02, PKG-VTT-THUMB-03, PKG-VTT-THUMB-04, PKG-VTT-THUMB-05, PKG-VTT-THUMB-06 |
 | artplayer-proxy-canvas | 1.1.0 | PKG-AMBILIGHT-PROXY-01, PKG-CANVAS-01, PKG-CANVAS-02, PKG-CANVAS-03, PKG-CANVAS-04, PKG-CANVAS-05, PKG-CANVAS-06, PKG-FACTORY-01 |
@@ -229,7 +229,8 @@
 | PKG-MULTI-SUB-07 | artplayer-plugin-multiple-subtitles<br>修复字幕内嵌时间戳序列化 | PKG-MULTI-SUB-03 | 保留数字时间戳节点、修正无效 NaN 输出、明确旧/新字幕输出差异 | 旧九份实现可复现，候选有效内嵌时间戳及文字/CSS/原生字幕通过，公开工厂与选择接口不变 | H | done |
 | PKG-MULTI-SUB-08 | artplayer-plugin-multiple-subtitles<br>修复字幕实体解码与嵌套标签包装 | PKG-MULTI-SUB-04, PKG-MULTI-SUB-07 | 使用解析器既有实体表入口修复多余分号；保护字面文本并以兄弟节点包装标签，保留CSS钩子和时间戳 | 冻结旧实现复现、实体/双重编码/标签/选择重置回归、新旧核心真实字幕显示通过；vendor原文与来源校验不变，类型/分发兼容 | M | done |
 | PKG-MULTI-SUB-05 | artplayer-plugin-multiple-subtitles<br>验证新旧核心和组合 | PKG-MULTI-SUB-04, CORE-22, PKG-MULTI-SUB-07, PKG-MULTI-SUB-08 | 与核心字幕/偏移/全屏组合，旧名称调用不变 | 最终核心与原支持范围核心分别通过；设备/SDK 缺证据不能标完成 | H | doing |
-| PKG-MULTI-SUB-06 | artplayer-plugin-multiple-subtitles<br>验证分发并同步文档 | PKG-MULTI-SUB-05, ENG-07, CORE-SUBTITLE-OFFSET-01 | multiple.subtitles.js、parser 来源许可及打包边界 | tarball 入口/资源、类型、8082 demo 和 README 一致，有回退记录 | H | todo |
+| PKG-MULTI-SUB-06 | artplayer-plugin-multiple-subtitles<br>验证分发并同步文档 | PKG-MULTI-SUB-05, ENG-07, CORE-SUBTITLE-OFFSET-01, PKG-MULTI-SUB-09 | multiple.subtitles.js、parser 来源许可及打包边界 | tarball 入口/资源、类型、8082 demo 和 README 一致，有回退记录 | H | todo |
+| PKG-MULTI-SUB-09 | artplayer-plugin-multiple-subtitles, artplayer<br>定位旧核心切源寻址与字幕显示边界 | PKG-MULTI-SUB-08, CORE-19 | 无插件及旧新插件对照、真实事件轨迹、原切源失败归因和组合测试顺序 | 保留旧核心立即寻址观察，候选首次寻址与正常字幕组合通过；不把原生时钟失败误归为字幕丢失 | M | done |
 
 ## 5 包迁移：artplayer-plugin-jassub
 
@@ -647,3 +648,4 @@
 - PKG-AUTO-THUMB-10: [记录](changes/2026-09-14-PKG-AUTO-THUMB-10-encoding.md) [记录](baselines/auto-thumbnail-encoding-validation.json)
 - ENG-LINT-01: [记录](changes/2026-09-14-ENG-LINT-01-manifest-order.md) [记录](baselines/manifest-lint-validation.json)
 - CORE-SUBTITLE-OFFSET-01: [记录](changes/2026-09-14-CORE-SUBTITLE-OFFSET-01-paused.md) [记录](baselines/subtitle-offset-validation.json)
+- PKG-MULTI-SUB-09: [记录](changes/2026-09-14-PKG-MULTI-SUB-09-switch-order.md) [记录](baselines/multiple-subtitles-switch-validation.json)

refactor/progress.md

@@ -1,5 +1,20 @@
 # 进度与证据
 
+## PKG-MULTI-SUB-09 切源显示问题归因完成
+
+失败时字幕cue仍在1至3秒，媒体却停在约0.002秒；新增无插件/候选插件/旧1.2.0
+对照并记录原生currentTime写入、事件和Promise状态。首轮WebKit27次切源中旧
+核心18次有5次立即seek未到达，两个无插件旧核心组也复现；候选9次全部到达。
+正式main三引擎81次切源无失位，但旧WebKit仍有6次在seeking中结算；候选27次
+均在原生定位结束后结算并兑现首个seek。确认是已有旧核心寻址问题，候选CORE-19
+路径已处理，无需在多字幕插件追加重试或改时钟。原失败及立即调用路径完整留证。
+84项正式产物矩阵83断言通过，1项测试未等待全屏进入通知即退出而失败；保留
+严格true/false顺序断言，补事件谓词后受影响9项三引擎全通过，不声称重跑84项。
+脚本lint与CI50项通过。见[归因记录](changes/2026-09-14-PKG-MULTI-SUB-09-switch-order.md)
+和[证据](baselines/multiple-subtitles-switch-validation.json)。关闭误归因的SWITCH风险，
+无生产、声明、依赖、版本或构建产物修改；249项为177 done、17 doing、55 todo。
+任务05仍未完成，下一步处理旧5.1核心的双语渲染适配，再补剩余组合与分发验收。
+
 ## CORE-SUBTITLE-OFFSET-01 暂停字幕偏移修复完成
 
 原生video/track探针确认Firefox155暂停时cue时间更新后活动标记陈旧；候选核心

refactor/risk-table.md

@@ -266,4 +266,4 @@
 | AUTO-THUMB-ENCODE-TIMEOUT-01 | resolved / 源码/产物事实 | Pending JPEG encoding has no bounded lifetime after frame readiness finishes | PKG-AUTO-THUMB-10 |
 | MULTI-SUB-MARKUP-01 | resolved / 已复现 | Semantic cue nodes receive HTML wrappers inside their annotation fields | PKG-MULTI-SUB-08 |
 | MULTI-SUB-OFFSET-01 | resolved / 已复现 | Paused Firefox subtitle offset leaves out-of-time native cues active and captions visible | PKG-MULTI-SUB-05, CORE-SUBTITLE-OFFSET-01 |
-| MULTI-SUB-SWITCH-01 | open / 待取证 | Intermittent WebKit core5.3.0 caption loss after selected-track source switch | PKG-MULTI-SUB-05 |
+| MULTI-SUB-SWITCH-01 | resolved / 已复现 | Intermittent WebKit core5.3.0 caption loss after selected-track source switch | PKG-MULTI-SUB-05, PKG-MULTI-SUB-09 |

refactor/risks.json

@@ -6028,21 +6028,30 @@
     {
       "id": "MULTI-SUB-SWITCH-01",
       "title": "Intermittent WebKit core5.3.0 caption loss after selected-track source switch",
-      "confirmation": "unverified",
-      "workspaceState": "One Windows WebKit26.6 run lost Translation after switchUrl and seek1.5; diagnostic rerun passed without a production change. Root cause and reproducibility are unresolved; do not mark accepted or fixed. Expanded153 offset/lifecycle run again lost the selected caption after source switch on published5.3.0 and5.4.0 in WebKit, while candidate core passed. Root cause remains unclassified; the offset fix does not close this issue.",
-      "compatibleResolution": "Inspect native track loading and source-switch ordering with deterministic state evidence; distinguish historical host failure from fixture ordering and candidate regression.",
+      "confirmation": "reproduced",
+      "workspaceState": "Original failing snapshots kept the1..3 cue intact but video time was near0.002. Independent no-plugin and published1.2/current-plugin WebKit traces reproduce5 old-core first-seek misses, with promises sometimes settled during native seeking. Candidate already waits and honors every first seek. Actual main three-engine probes and corrected normal caption sequencing pass; old race observations remain explicit.",
+      "compatibleResolution": "Classify the old-host source/native-seek race separately from caption rendering; preserve immediate-call probes, require candidate first seeks, and wait for real native source completion before independent caption-seek assertions.",
       "closureCriteria": "Root cause classified with targeted evidence, any required fix validated, and changed candidate/old-core combination rerun without hiding the original failure.",
-      "status": "open",
+      "status": "resolved",
       "owners": [
-        "PKG-MULTI-SUB-05"
+        "PKG-MULTI-SUB-05",
+        "PKG-MULTI-SUB-09"
       ],
       "evidence": [
         "refactor/changes/2026-09-14-PKG-MULTI-SUB-05-combinations.md",
         "refactor/baselines/multiple-subtitles-combinations-validation.json",
         "test/browser/multiple-subtitles-combinations.spec.js",
         "refactor/changes/2026-09-14-CORE-SUBTITLE-OFFSET-01-paused.md",
-        "refactor/baselines/subtitle-offset-validation.json"
-      ]
+        "refactor/baselines/subtitle-offset-validation.json",
+        "refactor/changes/2026-09-14-PKG-MULTI-SUB-09-switch-order.md",
+        "refactor/baselines/multiple-subtitles-switch-validation.json",
+        "test/browser/multiple-subtitles-switch.spec.js"
+      ],
+      "resolutionEvidence": [
+        "refactor/changes/2026-09-14-PKG-MULTI-SUB-09-switch-order.md",
+        "refactor/baselines/multiple-subtitles-switch-validation.json"
+      ],
+      "resolutionRationale": "No-plugin controls reproduce the same miss and a settled seek restores correct old/new captions without changing plugin data. Candidate source code already provides the necessary readiness guard (BASE-LIFE-44/CORE-19 context). This resolves the suspected plugin-switch defect; it does not approve every historical source call or complete package task05."
     }
   ]
 }

refactor/tasks.json

@@ -2430,7 +2430,8 @@
       "dependsOn": [
         "PKG-MULTI-SUB-05",
         "ENG-07",
-        "CORE-SUBTITLE-OFFSET-01"
+        "CORE-SUBTITLE-OFFSET-01",
+        "PKG-MULTI-SUB-09"
       ],
       "status": "todo",
       "risk": "H",
@@ -5157,6 +5158,27 @@
         "changes/2026-09-14-CORE-SUBTITLE-OFFSET-01-paused.md",
         "baselines/subtitle-offset-validation.json"
       ]
+    },
+    {
+      "id": "PKG-MULTI-SUB-09",
+      "phase": "5 包迁移：artplayer-plugin-multiple-subtitles",
+      "title": "定位旧核心切源寻址与字幕显示边界",
+      "scope": [
+        "artplayer-plugin-multiple-subtitles",
+        "artplayer"
+      ],
+      "dependsOn": [
+        "PKG-MULTI-SUB-08",
+        "CORE-19"
+      ],
+      "status": "done",
+      "risk": "M",
+      "deliverable": "无插件及旧新插件对照、真实事件轨迹、原切源失败归因和组合测试顺序",
+      "acceptance": "保留旧核心立即寻址观察，候选首次寻址与正常字幕组合通过；不把原生时钟失败误归为字幕丢失",
+      "evidence": [
+        "changes/2026-09-14-PKG-MULTI-SUB-09-switch-order.md",
+        "baselines/multiple-subtitles-switch-validation.json"
+      ]
     }
   ]
 }