Session 52: Coming Soon teaser + infrastructure verification (2239 tests)

Phase 1 — Push-to-Book teaser (feature not live; teaser only):
- StatStrip: "BOOK IT ⟶" per graded prop (hover: "Push-to-Book coming soon").
- GradeResultCard: "PUSH-TO-BOOK · COMING SOON" footer.

Phase 2 — infrastructure verification:
- snapshotScheduler logs armed AND disarmed state (incl SNAPSHOT_CRON) so
  container logs disambiguate off-vs-crashed.
- NEW GET /api/internal/snapshot/status (internal-key gated): cron_armed,
  cron_hours_utc, last_snapshot per sport (gradeCount/deltaCount), redis_keys
  existence map, ticker_count. The post-deploy pipeline health probe.
- Finding: Redis AOF/RDB persistence is a server-side (Coolify) config the app
  can't set/verify — documented.

Phase 3 — delta pipeline (verified sound, no fix needed):
- runSnapshot already rotates :latest->:previous and diffs locked lines; added
  opt-in SNAPSHOT_DEBUG=1 [deltas] log + a trace test asserting :previous is
  preserved verbatim and the delta math is correct.

Backend 2234 -> 2239 tests (+5), 192 suites. Web build clean (exit 0).

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

tests/unit/snapshotService.test.js

@@ -123,10 +123,15 @@ describe('runSnapshot (fully injected)', () => {
       { player: 'Aaron Judge', stat_type: 'total_bases', line, direction: 'over', grade: 'A+', confidence: 80 },
     ])(sport, props, opts);
     await svc.runSnapshot('mlb', d);
+    const firstLatest = cache.store['snapshot:mlb:latest'];
     line = 2.5; // line moved +1.0
     const r2 = await svc.runSnapshot('mlb', d);
     expect(cache.store['snapshot:mlb:previous']).toBeTruthy();
     expect(r2.deltas).toBe(1);
+    // Session 52 trace: the previous snapshot is preserved verbatim so the next
+    // run can diff against the exact locked lines (the delta pipeline's input).
+    expect(cache.store['snapshot:mlb:previous']).toEqual(firstLatest);
+    expect(cache.store['snapshot:mlb:latest'].deltas[0]).toMatchObject({ delta: 1, gradedLine: 1.5, currentLine: 2.5 });
   });
 
   it('pushes ticker events (capped) into ticker:items', async () => {