test(hls): [PKG-HLS-SDK-01] preserve group stall evidence and verify ongoing playback

packages/artplayer-plugin-hls-control/ARCHITECTURE.md

@@ -135,6 +135,16 @@ HTTP without ArtPlayer/plugin or a Worker observer still reproduced crashes with
 both reset-first and SDK-first teardown. A passing no-worker control does not
 replace worker acceptance. See the 2026-09-14 HTTP teardown checkpoint in refactor.
 
+For the separate grouped-playback stall, `--switch-boundary switched|selected|immediate`
+compares completed SDK audio switching, selected UI/getter state, and same-call audio/level
+selection. The default remains switched. `--prefill` adds a controlled fully buffered
+fixture condition; it is not a player workaround. Both diagnostic and integration paths
+now require the clock and frame count to advance at the target height after high/low
+switches. Keep the original 7000ms height assertion and the failed trace even when a
+later control passes. Diagnostic private SDK fields are read-only, version-specific;
+never read load-level getters after SDK destruction. See the 2026-09-15 switch-boundary
+checkpoint in refactor for the reproduced empty-buffer failure and remaining attribution.
+
 ## Package file boundary
 
 The package .npmignore excludes src and tsconfig.json. The implementation config

refactor/changes/2026-09-15-PKG-HLS-SDK-01-switch-boundary.md

@@ -0,0 +1,75 @@
+# PKG-HLS-SDK-01 分组切换边界与持续播放
+
+来源 HEAD：`f37658d657dc89f4a1597ebd73b311529fc8e012`。任务仍为 doing，
+HLS-PLAYBACK-01 和独立的 HLS-CRASH-01 均未关闭。本轮没有生产源码、类型、
+依赖、媒体夹具或分发产物修改，没有改变 SDK 所有权或消费者配置。
+
+## 本轮取得的失败证据
+
+原分组集成场景再次复现 Firefox 155.0、Hls.js 1.7.2、发布核心、候选插件组合失败。
+SDK 音轨已为 high 组 index 0，但视频高度仍为 90，播放位置停在 0.999146，
+paused=false、ended=false、readyState=2、buffered=[]。原 7000ms 高度断言失败，
+发生在本次新增持续播放断言之前。该轮四项测试为三通过、一失败，不删失败或重试。
+
+该失败的 SDK error 数组为空。独立 trace 的 42 条媒体夹具请求均返回 200，
+最终切到 high 组后继续请求 French 音频，但没有再次请求 high 视频片段。
+早期自动选择阶段曾请求 high-01 至 high-05，不能写成整个测试从未请求 high 视频。
+这些事实将下一步收窄到加载/缓冲状态转换，但尚不足以认定 SDK 或核心的根因。
+
+失败报告和 trace 保留在独立的 hls-boundary-suite 路径，后续测试使用各自的输出
+目录。机器证据包含原始报告指纹、失败附件及从 trace 提取的完整夹具请求序列。
+较早 hls-sdk-validation.json 的历史失败保持原样。
+
+## 验证补强
+
+`test/browser/hls-sdk.spec.js` 原先返回 low 后只验证音轨数量与菜单。现在 high 和
+返回 low 均要求未暂停、目标高度、媒体时钟推进超过 0.3 秒、额外帧数超过两帧。
+没有额外 play/seek/reload，也没有扩大已有断言超时。检查新增观察和播放时间，
+因此不能把本轮销毁成功用于关闭此前独立的 Firefox 销毁崩溃。
+
+新增失败现场的 SDK 控制器状态、nextLoadPosition、独立缓冲区及加载/flush 事件。
+这些私有字段仅供固定 SDK 的只读诊断，不作为生产依赖或跨版本公共契约。
+SDK 销毁后不读取 currentLevel/loadLevel/nextLoadLevel：初版采集在成功销毁后读取
+nextLoadLevel 时出现失效 getter，导致诊断附件只有 diagnosticError。该两轮原始
+报告保留，最终轮明确检查附件没有 diagnosticError；不把它们当完整状态证据。
+
+## 可重跑对照
+
+`refactor/scripts/hls-sdk-diagnostic.mjs` 增加三个音轨/分组边界：
+
+- `--switch-boundary switched`：默认，保持等待 AUDIO_TRACK_SWITCHED。
+- `--switch-boundary selected`：插件宿主等待 UI 显示 French，直接宿主检查 audioTrack=1。
+- `--switch-boundary immediate`：同一次页面调用内选择音轨后立即选择 high。
+
+`--prefill` 等待单个原生 buffered 区间到达 duration-0.1；固定夹具视频 12 秒、
+音频 12.032 秒，因此允许编码尾部差异。它在初次选择 low 前等待，非 immediate
+模式还在选择 high 前等待。该受控对照不修改默认播放器，不是修复或延时兜底。
+
+```sh
+node refactor/scripts/hls-sdk-diagnostic.mjs --version 1.7.2 --iterations 3 --switch-boundary immediate --capture-before-destroy
+node refactor/scripts/hls-sdk-diagnostic.mjs --version 1.7.2 --iterations 2 --host published --plugin --switch-boundary selected --transport route --observe-workers --capture-before-destroy
+node refactor/scripts/hls-sdk-diagnostic.mjs --version 1.7.2 --iterations 2 --switch-boundary selected --prefill --capture-before-destroy
+yarn test:browser hls-sdk.spec.js --grep "group changes" --workers=1
+```
+
+19 个可读取的诊断迭代通过：早期三种宿主/边界九次；加入双向持续播放后的直接
+三次、发布核心两次、候选核心两次、prefill 两次、默认 switched 一次，共十次。
+全部使用 Windows Firefox 155.0 和固定 Hls.js 1.7.2。直接模式不加载 ArtPlayer 或
+插件。诊断宿主使用报告中哈希的既有 dist，集成用例使用源码选择的候选构建；
+本轮不声称重新构建或隔离安装了这些 dist。
+
+最初两轮共八次只打印 passed 后便在 JSON 序列化阶段失败，不能计入上述十九次。
+原因是新增 LEVEL_SWITCHING 的 details 为带循环引用的对象；已限定采集标量字段。
+不是播放器失败，也没有把未写出的报告认定为成功。
+
+## 最终验证与剩余
+
+最终三引擎分组用例八通过、四 Windows WebKit MSE 能力跳过，无重试；SDK 1.5.17
+与 1.7.2、新旧核心均包括在有 MSE 的八项中。原失败之后的中间轮另行保存，不能
+用最终通过覆盖或关闭原故障。定向 lint、固定 SDK 来源单测、严格工具链通过。
+Node 24.21.0、Yarn Classic 1.22.22；无新依赖，无重打包或远端执行。
+
+见 [机器证据](../baselines/hls-switch-boundary-validation.json)。完整目标仍需要解释
+空缓冲且不再请求视频的路径，结合新增控制器/缓冲事件建立更小的可重复案例，
+再决定归属与兼容修复；单次或多次通过不能关闭风险。Safari/真机/全部分发与
+三轮发布复盘仍按原门槛执行。回退本提交仅移除诊断和验收增强，不涉及运行时。

refactor/plan.md

@@ -569,7 +569,7 @@
 - PKG-HLS-02: [记录](hls-validation.md) [记录](baselines/hls-sdk.json) [记录](baselines/hls-validation.json) [记录](changes/2026-09-11-PKG-HLS-02-tests.md)
 - PKG-HLS-03: [记录](changes/2026-09-12-PKG-HLS-03-modules.md) [记录](baselines/hls-modules-validation.json) [记录](hls-validation.md)
 - PKG-HLS-04: [记录](changes/2026-09-12-PKG-HLS-04-types.md) [记录](baselines/hls-types-validation.json) [记录](hls-validation.md)
-- PKG-HLS-SDK-01: [记录](changes/2026-09-12-PKG-HLS-SDK-01-integration.md) [记录](baselines/hls-sdk-validation.json) [记录](baselines/hls-sdk-diagnostics.json) [记录](changes/2026-09-14-PKG-HLS-SDK-01-http-teardown.md) [记录](baselines/hls-http-teardown-validation.json)
+- PKG-HLS-SDK-01: [记录](changes/2026-09-12-PKG-HLS-SDK-01-integration.md) [记录](baselines/hls-sdk-validation.json) [记录](baselines/hls-sdk-diagnostics.json) [记录](changes/2026-09-14-PKG-HLS-SDK-01-http-teardown.md) [记录](baselines/hls-http-teardown-validation.json) [记录](changes/2026-09-15-PKG-HLS-SDK-01-switch-boundary.md) [记录](baselines/hls-switch-boundary-validation.json)
 - PKG-DASH-01: [记录](changes/2026-09-12-PKG-DASH-01-contract.md) [记录](baselines/dash-control-contract.md) [记录](baselines/dash-control-release.json)
 - PKG-DASH-02: [记录](changes/2026-09-12-PKG-DASH-02-tests.md) [记录](dash-validation.md) [记录](baselines/dash-validation.json)
 - PKG-DASH-03: [记录](changes/2026-09-12-PKG-DASH-03-runtime.md) [记录](baselines/dash-runtime.json) [记录](dash-validation.md)

refactor/progress.md

@@ -1,5 +1,19 @@
 # 进度与证据
 
+## PKG-HLS-SDK-01 分组切换与持续播放
+
+再次复现 Firefox/Hls.js 1.7.2/发布核心分组切换失败：音轨已更新，视频仍90高、
+约1秒、未暂停且缓冲区为空。独立trace中最终切组后没有新的视频片段请求，
+42条媒体请求均200；不是仅有菜单或网络错误的推断。保留三通过一失败的原轮。
+
+增加音轨选择/完成/同调用切组及整段缓冲对照，双向档位切换要求真实时钟和帧
+增长；19次有效诊断通过不能解释失败。修正两处诊断采集问题，失败报告独立保留。
+最终分组矩阵8通过、4 Windows WebKit MSE跳过；lint、来源单测和工具链通过。
+见[记录](changes/2026-09-15-PKG-HLS-SDK-01-switch-boundary.md)及
+[证据](baselines/hls-switch-boundary-validation.json)。任务和两项风险继续开放，
+总数203 done、21 doing、43 todo不变。后续围绕控制器/分轨缓冲状态定位，
+不更改消费者SDK参数或以反复通过宣布修复；未推送、部署或发布。
+
 ## PKG-ASR-05 首次媒体失败与恢复
 
 首次metadata之前的原生媒体失败、play拒绝、零音频资源、stop/destroy以及首个

refactor/risks.json

@@ -2832,7 +2832,9 @@
       "evidence": [
         "test/browser/hls-sdk.spec.js",
         "refactor/changes/2026-09-12-PKG-HLS-SDK-01-integration.md",
-        "refactor/baselines/hls-sdk-validation.json"
+        "refactor/baselines/hls-sdk-validation.json",
+        "refactor/changes/2026-09-15-PKG-HLS-SDK-01-switch-boundary.md",
+        "refactor/baselines/hls-switch-boundary-validation.json"
       ],
       "compatibleResolution": "区分 SDK、测试媒体/时序和宿主问题，保留真实档位/解码断言及 trace；不扩大等待或只验证菜单。",
       "closureCriteria": "直接 Hls 与新旧核心对照定位切换停滞，验证处置和正常/连续组切换，不能以重复通过关闭。"

refactor/scripts/hls-sdk-diagnostic.mjs

@@ -10,13 +10,14 @@ import { observeWorkers } from '../../test/helpers/worker-observer.js'
 import { ensureArchive, hash, readMember, refactorDir } from './releases.mjs'
 
 // Direct SDK control: no ArtPlayer or plugin is loaded, and no worker output is substituted.
-export async function diagnose({ version = '1.7.2', iterations = 5, transport = 'http', teardown = 'reset-first', worker = true, host = 'direct', plugin = false, sdkLogs = false, workerObserver = false, captureBeforeDestroy = false } = {}) {
+export async function diagnose({ version = '1.7.2', iterations = 5, transport = 'http', teardown = 'reset-first', worker = true, host = 'direct', plugin = false, sdkLogs = false, workerObserver = false, captureBeforeDestroy = false, switchBoundary = 'switched', prefill = false } = {}) {
   const runnerSHA256 = hash(fs.readFileSync(new URL(import.meta.url)))
   const observerSHA256 = hash(fs.readFileSync(new URL('../../test/helpers/worker-observer.js', import.meta.url)))
   assert(Number.isInteger(iterations) && iterations > 0 && iterations <= 50)
   assert(['http', 'route'].includes(transport))
   assert(['reset-first', 'sdk-first'].includes(teardown))
   assert(['direct', 'published', 'candidate'].includes(host))
+  assert(['switched', 'selected', 'immediate'].includes(switchBoundary))
   assert(!plugin || host !== 'direct', 'Plugin comparison requires an ArtPlayer host')
   const matrix = JSON.parse(fs.readFileSync(path.join(refactorDir, 'baselines/hls-sdk-matrix.json')))
   const release = matrix.releases.find(item => item.version === version)
@@ -98,7 +99,7 @@ export async function diagnose({ version = '1.7.2', iterations = 5, transport =
           let art
           const records = []
           const buffer = ranges => Array.from({ length: ranges.length }, (_, index) => [ranges.start(index), ranges.end(index)])
-          const state = () => ({ time: video.currentTime, readyState: video.readyState, height: video.videoHeight, paused: video.paused, buffered: buffer(video.buffered), seekable: buffer(video.seekable) })
+          const state = () => ({ time: video.currentTime, readyState: video.readyState, height: video.videoHeight, paused: video.paused, frames: video.getVideoPlaybackQuality().totalVideoFrames, buffered: buffer(video.buffered), seekable: buffer(video.seekable) })
           const record = (event, data) => {
             records.push({ at: performance.now(), event, data, media: state() })
             if (records.length > 400)
@@ -108,8 +109,8 @@ export async function diagnose({ version = '1.7.2', iterations = 5, transport =
           function attach(element) {
             video = element
             hls = new window.Hls({ enableWorker: worker, startLevel: 0, debug: sdkLogs ? logger : false })
-            for (const key of ['ERROR', 'AUDIO_TRACKS_UPDATED', 'AUDIO_TRACK_SWITCHED', 'LEVEL_SWITCHED', 'FRAG_BUFFERED', 'BUFFER_FLUSHED']) {
+            for (const key of ['ERROR', 'AUDIO_TRACKS_UPDATED', 'AUDIO_TRACK_SWITCHING', 'AUDIO_TRACK_SWITCHED', 'LEVEL_SWITCHING', 'LEVEL_SWITCHED', 'FRAG_BUFFERED', 'BUFFER_FLUSHED']) {
-              hls.on(window.Hls.Events[key], (_, data) => record(key, { id: data.id, level: data.level, fatal: data.fatal, details: data.details, frag: data.frag && { type: data.frag.type, sn: data.frag.sn, level: data.frag.level }, tracks: data.audioTracks?.map(track => ({ id: track.id, name: track.name, group: track.groupId })) }))
+              hls.on(window.Hls.Events[key], (_, data) => record(key, { id: data.id, level: typeof data.level === 'number' ? data.level : undefined, fatal: data.fatal, details: typeof data.details === 'string' ? data.details : undefined, frag: data.frag && { type: data.frag.type, sn: data.frag.sn, level: data.frag.level }, tracks: data.audioTracks?.map(track => ({ id: track.id, name: track.name, group: track.groupId })) }))
             }
             for (const name of ['waiting', 'stalled', 'seeking', 'seeked', 'playing', 'pause', 'ended', 'loadedmetadata', 'canplay', 'error'])
               video.addEventListener(name, () => record(name))
@@ -143,6 +144,7 @@ export async function diagnose({ version = '1.7.2', iterations = 5, transport =
             get hls() { return hls },
             get video() { return video },
             records,
+            record,
             state,
             destroy() {
               record('destroy:start', teardown)
@@ -170,21 +172,60 @@ export async function diagnose({ version = '1.7.2', iterations = 5, transport =
         await wait(() => window.direct.video?.readyState >= 3)
         await page.evaluate(() => window.direct.video.play())
         await wait(() => window.direct.video.currentTime > 0.3)
+        if (prefill) {
+          entry.phase = 'initial-prefill'
+          await wait(() => {
+            const video = window.direct.video
+            return video.buffered.length === 1 && video.buffered.end(0) >= video.duration - 0.1
+          })
+        }
         entry.phase = 'low-group'
         await page.evaluate(() => {
           window.direct.hls.currentLevel = 0
         })
         await wait(() => window.direct.hls.audioTracks.length === 2 && window.direct.hls.audioTracks.every(track => track.groupId === 'low'))
-        await page.evaluate(() => {
+        await page.evaluate((switchBoundary) => {
           window.direct.mark = performance.now()
           window.direct.hls.audioTrack = 1
-        })
+          if (switchBoundary === 'immediate') {
-        await wait(() => window.direct.records.some(item => item.at >= window.direct.mark && item.event === 'AUDIO_TRACK_SWITCHED' && item.data.id === 1))
+            window.direct.record('high-group:requested', { boundary: switchBoundary, audioTrack: window.direct.hls.audioTrack })
+            window.direct.hls.currentLevel = 1
+          }
+        }, switchBoundary)
+        if (switchBoundary === 'switched') {
+          await wait(() => window.direct.records.some(item => item.at >= window.direct.mark && item.event === 'AUDIO_TRACK_SWITCHED' && item.data.id === 1))
+        }
+        else if (switchBoundary === 'selected') {
+          if (plugin)
+            await expect(page.locator('.art-control-hls-audio .art-selector-value')).toHaveText('French', { timeout: 7000 })
+          else
+            await wait(() => window.direct.hls.audioTrack === 1)
+        }
         entry.phase = 'high-group'
-        await page.evaluate(() => {
+        if (switchBoundary !== 'immediate') {
-          window.direct.hls.currentLevel = 1
+          if (prefill) {
-        })
+            entry.phase = 'low-prefill'
+            await wait(() => {
+              const video = window.direct.video
+              return video.buffered.length === 1 && video.buffered.end(0) >= video.duration - 0.1
+            })
+            entry.phase = 'high-group'
+          }
+          await page.evaluate((switchBoundary) => {
+            window.direct.record('high-group:requested', { boundary: switchBoundary, audioTrack: window.direct.hls.audioTrack })
+            window.direct.hls.currentLevel = 1
+          }, switchBoundary)
+        }
         await wait(() => window.direct.video.videoHeight === 180 && window.direct.hls.audioTrack === 0)
+        entry.phase = 'high-group-playback'
+        await page.evaluate(() => {
+          window.direct.playbackStart = window.direct.state()
+        })
+        await wait(() => {
+          const current = window.direct.state()
+          return !current.paused && current.height === 180 && current.time > window.direct.playbackStart.time + 0.3 && current.frames > window.direct.playbackStart.frames + 2
+        })
+        entry.highPlayback = await page.evaluate(() => ({ start: window.direct.playbackStart, end: window.direct.state() }))
         entry.phase = 'commentary-track'
         await page.evaluate(() => {
           window.direct.hls.audioTrack = 2
@@ -195,6 +236,16 @@ export async function diagnose({ version = '1.7.2', iterations = 5, transport =
           window.direct.hls.currentLevel = 0
         })
         await wait(() => window.direct.hls.audioTracks.length === 2)
+        entry.phase = 'return-low-playback'
+        await wait(() => window.direct.video.videoHeight === 90)
+        await page.evaluate(() => {
+          window.direct.playbackStart = window.direct.state()
+        })
+        await wait(() => {
+          const current = window.direct.state()
+          return !current.paused && current.height === 90 && current.time > window.direct.playbackStart.time + 0.3 && current.frames > window.direct.playbackStart.frames + 2
+        })
+        entry.lowPlayback = await page.evaluate(() => ({ start: window.direct.playbackStart, end: window.direct.state() }))
         if (captureBeforeDestroy) {
           entry.phase = 'capture-before-destroy'
           entry.beforeDestroy = await page.evaluate(() => ({ coreLoaded: typeof window.Artplayer, pluginLoaded: typeof window.artplayerPluginHlsControl, media: window.direct.state(), sdk: { version: window.Hls.version, workerEnabled: window.direct.hls.config.enableWorker, level: window.direct.hls.currentLevel, audioTrack: window.direct.hls.audioTrack }, events: window.direct.records }))
@@ -214,7 +265,7 @@ export async function diagnose({ version = '1.7.2', iterations = 5, transport =
       finally {
         entry.failurePhase = entry.status === 'failed' ? entry.phase : undefined
         entry.phase = 'final-state'
-        entry.state = await page.evaluate(() => ({ coreLoaded: typeof window.Artplayer, pluginLoaded: typeof window.artplayerPluginHlsControl, workers: window.workerEvidence, media: window.direct?.state(), events: window.direct?.records, sdk: { version: window.Hls?.version, level: window.direct?.hls.currentLevel, audioTrack: window.direct?.hls.audioTrack } })).catch(error => ({ error: error.message }))
+        entry.state = await page.evaluate(() => ({ coreLoaded: typeof window.Artplayer, pluginLoaded: typeof window.artplayerPluginHlsControl, workers: window.workerEvidence, media: window.direct?.state(), events: window.direct?.records, sdk: { version: window.Hls?.version, level: window.direct?.hls.currentLevel, audioTrack: window.direct?.hls.audioTrack, mainState: window.direct?.hls.streamController?.state, audioState: window.direct?.hls.audioStreamController?.state } })).catch(error => ({ error: error.message }))
         entry.phase = 'trace-stop'
         await context.tracing.stop({ path: path.join(directory, `${iteration}.zip`) }).catch((error) => {
           entry.traceError = error.message
@@ -236,14 +287,14 @@ export async function diagnose({ version = '1.7.2', iterations = 5, transport =
     await browser?.close()
     server.closeAllConnections()
     await new Promise(resolve => server.close(resolve))
-    fs.writeFileSync(path.join(directory, 'report.json'), `${JSON.stringify({ version, iterations, transport, teardown, worker, host, plugin, sdkLogs, workerObserver, captureBeforeDestroy, runnerSHA256, observerSHA256, browserVersion, release, inputs: Object.fromEntries([...files].map(([file, bytes]) => [file, hash(bytes)])), results }, null, 2)}\n`)
+    fs.writeFileSync(path.join(directory, 'report.json'), `${JSON.stringify({ version, iterations, transport, teardown, worker, host, plugin, sdkLogs, workerObserver, captureBeforeDestroy, switchBoundary, prefill, runnerSHA256, observerSHA256, browserVersion, release, inputs: Object.fromEntries([...files].map(([file, bytes]) => [file, hash(bytes)])), results }, null, 2)}\n`)
     console.log(`Diagnostic report: ${directory}`)
   }
   return results
 }
 
-const { values } = parseArgs({ options: { 'version': { type: 'string', default: '1.7.2' }, 'iterations': { type: 'string', default: '5' }, 'transport': { type: 'string', default: 'http' }, 'teardown': { type: 'string', default: 'reset-first' }, 'no-worker': { type: 'boolean', default: false }, 'host': { type: 'string', default: 'direct' }, 'plugin': { type: 'boolean', default: false }, 'sdk-logs': { type: 'boolean', default: false }, 'observe-workers': { type: 'boolean', default: false }, 'capture-before-destroy': { type: 'boolean', default: false } } })
+const { values } = parseArgs({ options: { 'version': { type: 'string', default: '1.7.2' }, 'iterations': { type: 'string', default: '5' }, 'transport': { type: 'string', default: 'http' }, 'teardown': { type: 'string', default: 'reset-first' }, 'host': { type: 'string', default: 'direct' }, 'no-worker': { type: 'boolean', default: false }, 'plugin': { type: 'boolean', default: false }, 'sdk-logs': { type: 'boolean', default: false }, 'observe-workers': { type: 'boolean', default: false }, 'capture-before-destroy': { type: 'boolean', default: false }, 'switch-boundary': { type: 'string', default: 'switched' }, 'prefill': { type: 'boolean', default: false } } })
-diagnose({ version: values.version, iterations: Number(values.iterations), transport: values.transport, teardown: values.teardown, worker: !values['no-worker'], host: values.host, plugin: values.plugin, sdkLogs: values['sdk-logs'], workerObserver: values['observe-workers'], captureBeforeDestroy: values['capture-before-destroy'] }).then((results) => {
+diagnose({ version: values.version, iterations: Number(values.iterations), transport: values.transport, teardown: values.teardown, worker: !values['no-worker'], host: values.host, plugin: values.plugin, sdkLogs: values['sdk-logs'], workerObserver: values['observe-workers'], captureBeforeDestroy: values['capture-before-destroy'], switchBoundary: values['switch-boundary'], prefill: values.prefill }).then((results) => {
   process.exitCode = results.some(result => result.status !== 'passed') ? 1 : 0
 }).catch((error) => {
   console.error(error)

refactor/tasks.json

@@ -2149,7 +2149,9 @@
         "baselines/hls-sdk-validation.json",
         "baselines/hls-sdk-diagnostics.json",
         "changes/2026-09-14-PKG-HLS-SDK-01-http-teardown.md",
-        "baselines/hls-http-teardown-validation.json"
+        "baselines/hls-http-teardown-validation.json",
+        "changes/2026-09-15-PKG-HLS-SDK-01-switch-boundary.md",
+        "baselines/hls-switch-boundary-validation.json"
       ]
     },
     {

test/browser/hls-sdk.spec.js

@@ -41,12 +41,18 @@ test.beforeAll(async () => {
 test.afterEach(async ({ page }, testInfo) => {
   const state = await page.evaluate(() => {
     const video = window.art?.video
+    const hls = window.art?.hls
+    const ranges = buffered => buffered && Array.from({ length: buffered.length }, (_, index) => [buffered.start(index), buffered.end(index)])
+    const controller = source => source && ({ state: source.state, level: source.level, nextLoadPosition: source.nextLoadPosition, altAudio: source.altAudio, buffered: ranges(source.mediaBuffer?.buffered), frag: source.fragCurrent && { sn: source.fragCurrent.sn, level: source.fragCurrent.level, type: source.fragCurrent.type } })
     return {
       workers: window.workerEvidence,
       errors: window.sdkErrors,
       events: window.sdkEvents,
       supported: window.Hls?.isSupported(),
       destroyed: window.destroyedEngines,
+      controllers: { main: controller(hls?.streamController), audio: controller(hls?.audioStreamController) },
+      sdk: !window.destroyedEngines && hls ? { currentLevel: hls.currentLevel, loadLevel: hls.loadLevel, nextLoadLevel: hls.nextLoadLevel, mediaSourceState: hls.bufferController?.mediaSource?.readyState } : { destroyed: window.destroyedEngines },
+      buffers: hls?.bufferController?.sourceBuffers?.map(([type, source]) => ({ type, updating: source?.updating, buffered: ranges(source?.buffered) })),
       tracks: window.art?.hls?.audioTracks?.map(track => ({ id: track.id, name: track.name, groupId: track.groupId })),
       media: video && { time: video.currentTime, paused: video.paused, ended: video.ended, readyState: video.readyState, height: video.videoHeight, buffered: Array.from({ length: video.buffered.length }, (_, index) => [video.buffered.start(index), video.buffered.end(index)]) },
     }
@@ -81,8 +87,8 @@ async function open(page, testInfo, release, core, plugin = 'candidate', manifes
         art.hls = hls
         const mediaState = () => ({ time: video.currentTime, paused: video.paused, readyState: video.readyState, height: video.videoHeight, buffered: Array.from({ length: video.buffered.length }, (_, index) => [video.buffered.start(index), video.buffered.end(index)]) })
         hls.on(window.Hls.Events.ERROR, (_, data) => window.sdkErrors.push({ type: data.type, details: data.details, fatal: data.fatal, media: mediaState() }))
-        for (const key of ['AUDIO_TRACKS_UPDATED', 'AUDIO_TRACK_SWITCHED', 'LEVEL_SWITCHED', 'MEDIA_ATTACHED', 'MEDIA_DETACHED'])
+        for (const key of ['AUDIO_TRACKS_UPDATED', 'AUDIO_TRACK_SWITCHED', 'LEVEL_SWITCHED', 'MEDIA_ATTACHED', 'MEDIA_DETACHED', 'BUFFER_FLUSHING', 'BUFFER_FLUSHED', 'FRAG_LOADING', 'FRAG_BUFFERED'])
-          hls.on(window.Hls.Events[key], (_, data) => window.sdkEvents.push({ key, id: data.id, level: data.level, tracks: data.audioTracks?.map(track => ({ id: track.id, name: track.name, groupId: track.groupId })), media: mediaState() }))
+          hls.on(window.Hls.Events[key], (_, data) => window.sdkEvents.push({ key, id: data.id, level: data.level, type: data.type, frag: data.frag && { sn: data.frag.sn, level: data.frag.level, type: data.frag.type }, tracks: data.audioTracks?.map(track => ({ id: track.id, name: track.name, groupId: track.groupId })), media: mediaState() }))
         hls.on(window.Hls.Events.DESTROYING, () => window.destroyedEngines++)
         hls.loadSource(url)
         hls.attachMedia(video)
@@ -112,6 +118,14 @@ async function destroyed(page) {
   expect(await page.evaluate(() => ({ media: window.art.hls.media, children: document.querySelector('.player').childElementCount, errors: window.sdkErrors.filter(error => error.fatal) }))).toEqual({ media: null, children: 0, errors: [] })
 }
 
+async function playbackAdvances(page, height) {
+  const start = await page.evaluate(() => ({ time: window.art.video.currentTime, frames: window.art.video.getVideoPlaybackQuality().totalVideoFrames }))
+  await expect.poll(() => page.evaluate(({ start, height }) => {
+    const video = window.art.video
+    return !video.paused && video.videoHeight === height && video.currentTime > start.time + 0.3 && video.getVideoPlaybackQuality().totalVideoFrames > start.frames + 2
+  }, { start, height })).toBe(true)
+}
+
 for (const release of matrix.releases) {
   test(`SDK ${release.version}: MSE capability and unsupported cleanup`, async ({ page, browserName }, testInfo) => {
     await open(page, testInfo, release, 'candidate')
@@ -165,6 +179,7 @@ for (const release of matrix.releases) {
         await expect.poll(() => page.evaluate(() => window.art.hls.audioTracks.map(track => ({ id: track.id, name: track.name, group: track.groupId })))).toEqual([{ id: 0, name: 'French', group: 'high' }, { id: 1, name: 'English', group: 'high' }, { id: 2, name: 'Commentary', group: 'high' }])
         await expect.poll(() => page.evaluate(() => ({ index: window.art.hls.audioTrack, height: window.art.video.videoHeight }))).toEqual({ index: 0, height: 180 })
         await expect(page.locator('.art-control-hls-audio .art-selector-value')).toHaveText('French')
+        await playbackAdvances(page, 180)
         await page.evaluate(() => {
           window.art.controls.show = true
         })
@@ -179,6 +194,7 @@ for (const release of matrix.releases) {
         })
         await expect.poll(() => page.evaluate(() => window.art.hls.audioTracks.length)).toBe(2)
         await expect(control.locator('.art-selector-item')).toHaveCount(2)
+        await playbackAdvances(page, 90)
         await destroyed(page)
       })
       test(`${core} core: actual SDK detaches and reattaches to the same media`, async ({ page }, testInfo) => {