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docs: add live play-url session cache implementation plan

Upgrade Monitor refreshPlayURL to session coalesce + TTL reuse,
and add Media opening lock with the same ensure pattern.
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xiaosi 2 weeks ago
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      docs/superpowers/plans/2026-09-03-live-playurl-session-cache.md

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docs/superpowers/plans/2026-09-03-live-playurl-session-cache.md

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# Live play-url Session Cache Implementation Plan
> **For agentic workers:** REQUIRED SUB-SKILL: Use superpowers:subagent-driven-development (recommended) or superpowers:executing-plans to implement this plan task-by-task. Steps use checkbox (`- [ ]`) syntax for tracking.
**Goal:** Coalesce in-flight `/play-url` by `streamSessionId`, reuse addresses until 30s before expiry, and stop duplicate fetches from open/phase/heartbeat on Monitor and Media.
**Architecture:** Keep page-local logic (no shared helper). Upgrade `useMonitorLive.refreshPlayURL` to session-scoped ensure semantics (`force` for retry/renewal). Add Media `opening` lock plus the same ensure pattern with `playUrlExpiresAt`. LivePlayer startup-404 same-URL behavior stays unchanged.
**Tech Stack:** Vue 3, existing `@/api/live` `getLivePlayURL`
**Spec:** `docs/superpowers/specs/2026-09-03-live-playurl-session-cache-design.md`
---
### Task 1: Monitor ensurePlayUrl via refreshPlayURL upgrade
**Files:**
- Modify: `src/composables/useMonitorLive.js`
- [ ] **Step 1: Add fresh-window alias and session-scoped promise fields**
Near existing constants, keep `PLAY_REFRESH_LEAD_MS = 30_000` and add:
```js
const PLAY_URL_FRESH_MS = PLAY_REFRESH_LEAD_MS
```
Replace:
```js
let playURLRequest = null
```
with:
```js
let playURLRequest = null
let playURLRequestSessionId = ''
```
In `clearPlaybackOnly` and `resetLocal`, clear both:
```js
playURLRequest = null
playURLRequestSessionId = ''
```
(Keep existing clears of `live.playUrl` / `live.playUrlExpiresAt`.)
- [ ] **Step 2: Rewrite `refreshPlayURLOnce` + `refreshPlayURL` to ensure semantics**
Replace the current `refreshPlayURLOnce` / `refreshPlayURL` pair with:
```js
async function refreshPlayURLOnce({ fromRetry = false, force = false } = {}) {
if (disposed || live.stopping || !live.dockId || !live.session?.id) return false
const dockId = live.dockId
const sessionId = live.session.id
const forceFetch = force || fromRetry
if (
!forceFetch &&
live.playUrl &&
live.playUrlExpiresAt * 1000 - Date.now() > PLAY_URL_FRESH_MS
) {
return true
}
const play = await getLivePlayURL(dockId, sessionId)
if (disposed || live.stopping || !live.session || live.session.id !== sessionId) return false
live.playUrl = play.playUrl || ''
const nowSec = Math.floor(Date.now() / 1000)
live.playUrlExpiresAt = Number(play.expiresAt) || nowSec + PLAY_EXPIRE_FALLBACK_SEC
if (!fromRetry) live.playRetryCount = 0
schedulePlayRefresh()
return true
}
function refreshPlayURL(options = {}) {
const sessionId = live.session?.id
if (!sessionId) return Promise.resolve(false)
const forceFetch = Boolean(options.force || options.fromRetry)
if (
!forceFetch &&
live.playUrl &&
live.playUrlExpiresAt * 1000 - Date.now() > PLAY_URL_FRESH_MS
) {
return Promise.resolve(true)
}
if (playURLRequest && playURLRequestSessionId === sessionId) {
return playURLRequest
}
playURLRequestSessionId = sessionId
playURLRequest = refreshPlayURLOnce(options).finally(() => {
if (playURLRequestSessionId === sessionId) {
playURLRequest = null
playURLRequestSessionId = ''
}
})
return playURLRequest
}
```
- [ ] **Step 3: Force renewals on schedule + error rebuild; leave cold paths default**
In `schedulePlayRefresh` timer callback, change:
```js
await refreshPlayURL()
```
to:
```js
await refreshPlayURL({ force: true })
```
Keep these as default (non-force) so they coalesce/reuse:
- `openLive` streaming branch: `await refreshPlayURL()`
- `pollPhaseOnce` streaming branch: `await refreshPlayURL()`
- heartbeat when `streaming && !live.playUrl`: `await refreshPlayURL()`
Keep error rebuild as:
```js
await refreshPlayURL({ fromRetry: true })
```
(`fromRetry` already implies force in Step 2.)
Do **not** change `live.opening` guards, stop gate, 57006, or TLS/403 paths.
- [ ] **Step 4: Static check**
```bash
rg -n "PLAY_URL_FRESH_MS|playURLRequestSessionId|force: true|fromRetry|refreshPlayURL" src/composables/useMonitorLive.js
```
Expected:
- `PLAY_URL_FRESH_MS` defined
- coalesce keyed by `playURLRequestSessionId`
- TTL short-circuit in `refreshPlayURL`
- `schedulePlayRefresh` uses `{ force: true }`
- `onPlayError` still `{ fromRetry: true }`
- open/phase/heartbeat cold paths still `refreshPlayURL()` without force
- [ ] **Step 5: Commit**
```bash
git add src/composables/useMonitorLive.js
git commit -m "feat: coalesce monitor play-url by session with TTL reuse"
```
---
### Task 2: MediaView opening lock + ensurePlayUrl
**Files:**
- Modify: `src/views/MediaView/MediaView.vue`
- [ ] **Step 1: Extend activeLive + module locals**
In `activeLive` reactive, add:
```js
playUrlExpiresAt: 0,
```
Near other module lets (`heartbeatTimer`, `openSeq`, …), add:
```js
const PLAY_URL_FRESH_MS = 30_000
const PLAY_EXPIRE_FALLBACK_SEC = 270
let playUrlPromise = null
let playUrlSessionId = ''
let opening = false
```
Update `resetActiveLive` to also clear cache keys and expiry:
```js
function resetActiveLive() {
clearHeartbeat()
playUrlPromise = null
playUrlSessionId = ''
opening = false
activeLive.id = ''
activeLive.dockId = ''
activeLive.sessionId = ''
activeLive.playUrl = ''
activeLive.playUrlExpiresAt = 0
activeLive.phase = ''
activeLive.leaseExpiresAt = 0
}
```
(`closeActiveLive` already bumps `openSeq` then `resetActiveLive` — that clears promise/cache.)
- [ ] **Step 2: Add `ensurePlayUrl` helper**
Place after `resetActiveLive` / before `scheduleHeartbeat`:
```js
async function ensurePlayUrl(dockId, sessionId, { force = false } = {}) {
if (!dockId || !sessionId) return null
if (
!force &&
activeLive.sessionId === sessionId &&
activeLive.playUrl &&
activeLive.playUrlExpiresAt * 1000 - Date.now() > PLAY_URL_FRESH_MS
) {
return {
playUrl: activeLive.playUrl,
expiresAt: activeLive.playUrlExpiresAt,
}
}
if (playUrlPromise && playUrlSessionId === sessionId) {
return playUrlPromise
}
const seq = openSeq
playUrlSessionId = sessionId
playUrlPromise = getLivePlayURL(dockId, sessionId)
.then((play) => {
if (disposed || seq !== openSeq || activeLive.sessionId !== sessionId) return play
const nowSec = Math.floor(Date.now() / 1000)
const expiresAt = Number(play?.expiresAt) || nowSec + PLAY_EXPIRE_FALLBACK_SEC
if (play?.playUrl) {
activeLive.playUrl = play.playUrl
activeLive.playUrlExpiresAt = expiresAt
}
return play
})
.finally(() => {
if (playUrlSessionId === sessionId) {
playUrlPromise = null
playUrlSessionId = ''
}
})
return playUrlPromise
}
```
- [ ] **Step 3: Wire `openLive` with opening lock + ensure**
Replace `openLive` with:
```js
async function openLive(stream) {
if (disposed || !stream?.dockId || opening) return
if (activeLive.id === stream.id && activeLive.playUrl) {
await closeActiveLive()
return
}
opening = true
try {
// closeActiveLive 会 bump openSeq,使旧 in-flight join 失效;之后再取本次 seq
await closeActiveLive()
const seq = ++openSeq
try {
const result = await joinLiveWithRetry(stream.dockId, {}, {
shouldContinue: () => seq === openSeq && !disposed,
})
const session = result?.session
const sessionId = session?.id
if (seq !== openSeq || disposed) {
if (sessionId) await safeLeave(stream.dockId, sessionId)
return
}
if (!sessionId) {
ui.toast('直播会话无效')
return
}
activeLive.id = stream.id
activeLive.dockId = stream.dockId
activeLive.sessionId = sessionId
activeLive.phase = session.phase || ''
activeLive.playUrl = ''
activeLive.playUrlExpiresAt = 0
scheduleHeartbeat(result.leaseExpiresAt)
if (session.phase !== 'streaming') {
ui.toast('直播正在启动,请稍后重试')
return
}
const play = await ensurePlayUrl(stream.dockId, sessionId)
if (seq !== openSeq || disposed || activeLive.sessionId !== sessionId) return
if (play?.playUrl && !play.playUrl.startsWith('fake://')) {
// ensurePlayUrl already wrote playUrl/expiresAt when session matched;
// keep toast branch for empty/fake
if (!activeLive.playUrl) {
activeLive.playUrl = play.playUrl
}
} else if (!activeLive.playUrl) {
ui.toast('控制面已验证,当前未配置可播放媒体流')
}
} catch (e) {
if (seq !== openSeq || disposed || e?.code === 'ABORTED') return
if (isLeaseInvalidError(e)) {
await rejoinAfterLeaseInvalid(stream.id, stream.dockId)
return
}
await closeActiveLive()
ui.toast(e.message || '打开直播失败')
}
} finally {
opening = false
}
}
```
Note: `closeActiveLive` clears `opening` via `resetActiveLive`. That is OK **before** the outer `finally` sets `opening = false` again; do **not** rely on reset to keep opening true across join — the outer `opening = true` must be set **before** `closeActiveLive`, and `resetActiveLive` currently clears `opening`.
**Important implementation detail:** either:
1. **Preferred:** do **not** clear `opening` inside `resetActiveLive`; only clear it in `openLive` finally / unmount, **or**
2. Set `opening = true` **after** `await closeActiveLive()`.
Use option **2** to minimize surprise (toggle-close path unaffected):
```js
async function openLive(stream) {
if (disposed || !stream?.dockId || opening) return
if (activeLive.id === stream.id && activeLive.playUrl) {
await closeActiveLive()
return
}
await closeActiveLive()
if (disposed) return
opening = true
const seq = ++openSeq
try {
const result = await joinLiveWithRetry(stream.dockId, {}, {
shouldContinue: () => seq === openSeq && !disposed && opening,
})
// ... same session handling as above from session extract onward ...
} catch (e) {
// same as above
} finally {
opening = false
}
}
```
And in `resetActiveLive`, **do clear** `playUrlPromise` / `playUrlSessionId` / `playUrlExpiresAt`, but **do not** clear `opening` (leave that to `openLive` finally). Explicitly:
```js
function resetActiveLive() {
clearHeartbeat()
playUrlPromise = null
playUrlSessionId = ''
activeLive.id = ''
activeLive.dockId = ''
activeLive.sessionId = ''
activeLive.playUrl = ''
activeLive.playUrlExpiresAt = 0
activeLive.phase = ''
activeLive.leaseExpiresAt = 0
}
```
- [ ] **Step 4: Heartbeat may ensure when streaming and missing playUrl**
Inside `scheduleHeartbeat` success path, after updating phase, add:
```js
if (result?.session?.phase === 'streaming' && !activeLive.playUrl) {
try {
await ensurePlayUrl(dockId, sessionId)
} catch (playErr) {
if (disposed || activeLive.sessionId !== sessionId) return
if (isLeaseInvalidError(playErr)) {
await rejoinAfterLeaseInvalid(streamId, dockId)
return
}
console.warn('[media] ensure play-url after heartbeat failed', playErr)
}
}
```
- [ ] **Step 5: Static check**
```bash
rg -n "PLAY_URL_FRESH_MS|ensurePlayUrl|playUrlPromise|playUrlSessionId|opening|playUrlExpiresAt" src/views/MediaView/MediaView.vue
```
Expected: opening guard; ensurePlayUrl TTL + coalesce; openLive uses ensure; reset clears promise/session/expiry; heartbeat can ensure when missing playUrl.
- [ ] **Step 6: Commit**
```bash
git add src/views/MediaView/MediaView.vue
git commit -m "feat: cache media play-url by session and debounce open"
```
---
### Task 3: Build, deploy, smoke
**Files:** none (verify only)
- [ ] **Step 1: Build**
```bash
npm run build
```
Expected: success.
- [ ] **Step 2: Push + deploy**
```bash
git push origin main
tar -C dist -czf - . | ssh -o BatchMode=yes jg-serv1 'rm -rf /usr/share/nginx/laic-frontend/dist/* && tar -C /usr/share/nginx/laic-frontend/dist -xzf -'
```
- [ ] **Step 3: Manual smoke**
1. Monitor 开播:进入 streaming 后,短时间同一 `streamSessionId``/play-url` 不应出现多份并发;未过期不要无故重拉。
2. Media 开播:同样;连点播放不会并行多个 join。
3. 启动期 HLS 404:仅同 URL 重载,不因此刷 `/play-url`
4. 临期或播放错误 force/fromRetry 才会重新 GET。
5. 切走直播 / 关页后无过期回写;stop / 57006 / TLS·403 回归正常。
---
## Self-review vs spec
| Spec requirement | Task |
|------------------|------|
| Session in-flight coalesce | Task 1 + 2 |
| TTL >30s reuse | Task 1 + 2 (`PLAY_URL_FRESH_MS`) |
| open / phase / heartbeat unified ensure | Task 1; Media open + heartbeat gap fill in Task 2 |
| force only for renew / retry | Task 1 Step 3 |
| opening debounce on Media | Task 2 |
| clear promise on close/dispose | Task 1 clears; Task 2 resetActiveLive |
| write only if session still matches | both tasks |
| LivePlayer 404 unchanged | no LivePlayer edits |
| build/deploy/smoke | Task 3 |
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