docs(plan): pre-PR checklist + deferred e2e-coverage effort (spike)

Record the canonical pre-PR checklist (items 1-10), mark the ~0-PTS threshold
done, and capture the playback-lifecycle e2e tests as a separate deferred effort
(the current e2e suite is UI/skin-expectation only).

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

.claude/plans/spf-non-zero-pts-timestamp-offset-spike.md

@@ -33,6 +33,28 @@ The design of record is `internal/design/spf/presentation-timeline-model.md`
 **KEEP** = lasting, review it; **TODO** = designed, not built; **REVIEW** = needs
 your detailed pass; **DEFERRED** = later/open.
 
+### Pre-PR checklist (canonical — before converting the spike to a PR)
+Working order agreed 2026-07-14: 1→3 first.
+1. [x] **~0-PTS threshold** — DONE (uncommitted). `NEAR_ZERO_ORIGIN_THRESHOLD = 1`s (absolute)
+   in the derive: shared/per-type origin `< 1s` (incl. negatives) → `0` → native, no relocation.
+   Loader stamp already no-ops on derived `0`. 13 derive tests + full suite green.
+2. [ ] **Rebase `--onto main` below the live PR** — branch stacked on `feat/spf-hls-live`;
+   isolate the relocation commits; manual fixups where anchor/relocation meet. Back up first.
+3. [ ] **Live-vs-VOD mutual-exclusion gate** — relocation composed unconditionally; must not
+   both fire with `anchorPresentationTimeline` on a live source. (Post-rebase / live-integration.)
+4. [ ] **Track-id-matched parser** for muxed `clcp` (presumptive first-box → `findMediaTrack`).
+5. [ ] **Barrier-liveness bound** — shared-`min` stamp `awaitDefined` unbounded → hang edge case.
+6. [ ] **Load-behavior coordinate-assumption audit** — loader planning/flush keyed off `currentTime`.
+7. [ ] **Negative-DTS on Chromium** — headline risk; looks validated (shared-`min` keeps DTS ≥ 0 +
+   cross-browser smoke played to end, no append errors) — confirm + note in PR.
+8. [ ] **Composition opt-in / tree-shaking + Tier-0 bundle measure** (currently baked-in w/ markers).
+9. [ ] **Commit cleanup** — reword `(spike)`/`wip` commits; resolve `StepDeps` typing (tighten vs leave).
+10. [ ] **Docs** — flip `presentation-timeline-model.md` to `implemented`; update stale
+    `features/non-zero-pts-support.md`; write PR description.
+- Deferred (separate effort): playback-lifecycle **e2e** (see "E2E coverage" below).
+
+Detail for each item is in the sections below (TODO / REVIEW / DEFERRED).
+
 ### Landed (committed)
 - mp4 box parser + decode-time origin — `cf8aaca45`
 - presentation timeline coordinate model doc (+ reactor rearchitecture) — `555f9fdac`, `ae1b0beee`
@@ -146,6 +168,35 @@ Apple stalled at the end + wouldn't loop. Two compounding causes, two narrow fix
 - Env: `pnpm size` leaves `packages/spf/tsdown.config.ts` swapped to the single-entry
   size config (breaks `build` + sandbox until `git restore`d). Interrupted-restore bug.
 
+### E2E coverage — SEPARATE EFFORT (do NOT bake into the current suite yet)
+The existing `apps/e2e` suite is entirely **UI/skin-expectation** tests (controls, keyboard,
+gestures, captions, visual snapshots); nothing asserts **playback lifecycle** (reaches
+`ended`, loops, 0-based timeline). Playback-lifecycle e2e is a NEW category — track it with
+the media-renderer-reliability effort ([[project_e2e_renderer_reliability]]), not here.
+Cross-browser validation of this work currently lives in the git-ignored sandbox smoke script
+`apps/sandbox/src/spf-non-zero-pts/eos-smoke.mjs` (chromium/firefox/webkit × apple/muxclip, all
+green 2026-07-14; needs a sandbox server on :5173) —
+reusable driving pattern: mute, seek-to-near-end for speed, bounded polls, never `await
+media.play()`.
+Candidates when this lands:
+- **General `SimpleHlsMedia` lifecycle** (NOT spike-coupled; landable independently): plays
+  through to `ended` + loops, across the 3 browsers, on the existing `simple-hls-video` +
+  `hlsFmp4` page. Assert the **outcome** (reaches `ended` within N s via seek-to-near-end),
+  never "the nudge fired" — the outcome holds whether or not Chrome's freeze occurs, so it's
+  CI-stable.
+- **Non-zero-PTS relocation correctness** (spike): 0-based `currentTime`/`seekable`/`buffered`
+  + active caption cue brackets the 0-based playhead. The owned Mux clip
+  (`asset_start_time=60`) works and we control it.
+- **`recover-end-stall` on skewed A/V** (spike): reaches `ended` + loops on a source that
+  actually reproduces the tiny-final-segment / audio-clock freeze. **Prereq: an OWNED skewed
+  asset.** Apple `bipbop_adv_example_hevc` reproduces it but is a third-party CDN + HEVC (forces
+  the `avcOnly` pin); the Mux clip's ~0.6ms skew does NOT reproduce the freeze. Without an owned
+  skewed / tiny-final-segment asset this test is either flaky (Apple CDN) or doesn't exercise
+  the fix.
+- e2e media-source convention: external streams centralized in `apps/e2e/fixtures/resources.ts`;
+  pages generated by `scripts/generate-pages.ts` from `fixtures/media.ts`; parametrized across
+  chromium/webkit/firefox.
+
 ## Problems the other branch surfaced — keep in view (likely changed, not gone)
 
 1. **Initial-load stall** (anchor-shift / origin-seek / flush mis-coordination) —