docs(review): add PR 69 browser QA packet

docs/reviews/pr-69/summary.md

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+# PR #69 — Race Story polish review
+
+Result: **NEEDS CHANGES**
+
+- Reviewer harness: Codex, including browser QA against the hermetic seeded preview
+- Implementer harness: Cursor
+- Scope: issue #68 — Race Story UX polish
+
+## Blocking findings
+
+1. **Existing E2E coverage fails.** `npm run test:e2e` has one failure in `tests/race-hub.spec.ts`: it still expects the existing missing-positions notice, but the PR replaces it with new empty-state copy without updating the E2E assertion. The issue's definition of done requires existing suites to stay green.
+2. **Chapter selection is not visibly synchronized for data with partial position coverage.** Browser QA on the seeded `session_key=9472` route showed that clicking either chapter leaves both cards unhighlighted. `chapterStartScrub` clamps a chapter outside the position chart's time window to 0 or 1, while `activeChapterIndex` checks the unclamped timestamps. The scrubber and active card therefore disagree. This is a direct miss on the active-chapter highlight/jump acceptance criterion.
+
+## Gates
+
+- `go test ./...` — pass
+- `npm run test` — pass, 393/393 across 51 files
+- `npm run build` — pass (`tsc --noEmit` + Vite build)
+- `npm run test:e2e` — **fail**, 27/28 (missing-positions assertion)
+- `npm run test:visual` — pass, 15/15 including new Race Story snapshots
+- `git diff --check origin/main...HEAD` — pass
+- Browser QA — desktop and mobile rendered without console warnings/errors; the map control was correctly absent when seeded replay data was unavailable
+
+## Visual artifacts
+
+- `screenshots/race-story-desktop.png`
+- `screenshots/race-story-mobile.png`
+
+## Acceptance-criteria assessment
+
+- Chapter-strip styling, scroll affordances, cards, and responsive layout: visually verified
+- Segmented playback controls: visually verified
+- Map unavailable state: verified; no dead panel or map toggle in seeded data
+- Graph full-width fallback and responsive rendering: visually verified
+- Chapter band/axis/label polish: present in the rendered chart
+- Empty-state card pattern: present
+- Active chapter highlight synchronization: **not met in browser QA**
+- Existing test suites stay green: **not met** (one E2E failure)
+
+## Non-blocking note
+
+The PR adds shared empty-state styles to `frontend/src/styles/app.css`, although the issue explicitly says not to edit that file. Keep the fix scoped to the Race Story style files if practical.