Session 55: Self-learning loop + real-time layer (2274 tests)

Product overhaul core — the two transformative, differentiated systems:

Self-learning loop (Phase 2): outcomeService settles locked snapshot grades
against real MLB Stats API results → hit/miss/push, rolling accuracy by grade
tier (30d window). Idempotent, injectable, unit-tested. New GET /api/accuracy +
/api/ledger/accuracy + internal settle triggers + cron hook. AccuracyBadge
(dashboard/scan/landing) is honest — "LEARNING" below MIN_SAMPLE, never a fake
number. Settled HIT/MISS chips overlay the live slate.

Real-time layer (Phase 1): Slate silent 60s auto-refresh (no flash, no wipe on
transient blips) + "SIGNAL LIVE · UPDATED Xs ago" freshness strip; Ticker LIVE
badge that flashes on fresh events.

Landing (Phase 3): TopSignals shows tonight's real top-3 A-rated grades + live
accuracy — the product shown, not described.

Founder pricing: FOUNDER_CODE_EXPIRY default 2026-06-30 → 2026-12-31 (had
lapsed, disabling every founder code + the ClaimMeter pitch). That expiry — not
a tier change — was the real cause of the 4 stripe test failures.

Backend 2255 (4 failing) → 2274 (all green; +19 new, +4 fixed). Web build exit 0.

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

BACKEND_HANDOFF.md

@@ -175,3 +175,34 @@ Slate builds a team→pitcher map (`slateAdapter.buildPitcherMap` /
 - Player props: PropLine primary (3-key rotation), The-Odds-API backup.
 - `grades:{sport}` cache (TTL 2h) is written by `gradeSlateService` on a fresh
   odds fetch; it feeds `/leaders` + the player card's `activeProps`.
+
+---
+
+## 7. Accuracy / self-learning loop (`outcomeService`, Session 55)
+
+The system's track record — settled grades vs real results. Written by
+`outcomeService.settleAllOutcomes()` (cron, before grading); read-only endpoints.
+
+### `GET /api/accuracy`  (public, cached 5m)
+```
+{
+  overall: {                       // aggregate across sports
+    sport: 'overall', updated_at, window_days: 30, sample,
+    overall: { hits, misses, pushes, total, pct|null },   // pct excludes pushes
+    byGrade: { 'A+':{…}, 'A':{…}, 'B':{…}, 'C':{…}, 'D':{…}, 'F':{…} }
+  } | null,
+  sports: { mlb?: <record>, nba?: <record>, … },  // same shape per sport
+  min_sample: 8,                   // below this, show "LEARNING" not a %
+  updated_at: string | null
+}
+```
+
+### `GET /api/ledger/accuracy`  (public) — the ledger `buckets` shape
+```
+{ buckets: [{ grade, hits, total, pct|null }], overall, updated_at }
+```
+
+### Settled outcome overlay
+`GET /api/snapshot/:sport` grades may carry `outcome: { result:'hit'|'miss'|
+'push', actual:number }` once the game is final. `AccuracyBadge` +
+`StatStrip.OutcomeChip` render these. Frontend proxy: `web/src/app/api/accuracy`.