Fix title-race chart: persist the diary, dedupe restarts, date axis

The chart looked broken because its data was: history lived in memory,
so every deploy wiped it (yesterday's points were gone), and each boot
plus the +5min refit appended a fresh point labeled with the same last
result — leaving two identical flat segments on an index axis.

- model_history table: every diary point persists with the finished-
  result signature it was computed from; restored at boot
- points only append when the finished set actually changes — refit
  and boot recomputes update the snapshot without spamming the diary
- one-time rebuild when nothing is persisted: replay finished results
  in kickoff order, re-running the sim after each with later results
  masked, so the historical points are recreated faithfully
- chart x-axis shows localized dates instead of raw indices

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

server/src/db/db.ts

@@ -139,6 +139,13 @@ CREATE TABLE IF NOT EXISTS inplay_history (
   PRIMARY KEY (fixture_num, minute, home_score, away_score)
 );
 
+CREATE TABLE IF NOT EXISTS model_history (
+  t     TEXT NOT NULL,
+  label TEXT NOT NULL,
+  top   TEXT NOT NULL,
+  key   TEXT NOT NULL
+);
+
 CREATE TABLE IF NOT EXISTS ingest_log (
   id     INTEGER PRIMARY KEY AUTOINCREMENT,
   source TEXT NOT NULL,
@@ -473,3 +480,27 @@ export function getMatchExt<T = unknown>(fixtureNum: number): { data: T; updated
   if (!row) return null;
   return { data: JSON.parse(row.json) as T, updatedAt: row.updated_at };
 }
+
+// ---- title-race diary (championship odds after each result) ----
+// Persisted so the Predict chart survives restarts; `key` is the finished-
+// result signature the point was computed from (dedupes boot recomputes).
+
+export interface ModelHistoryRecord {
+  t: string;
+  label: string;
+  top: { team: string; champion: number }[];
+  key: string;
+}
+
+export function saveModelHistory(p: { t: string; label: string; top: { team: string; champion: number }[] }, key: string): void {
+  db()
+    .prepare('INSERT INTO model_history (t, label, top, key) VALUES (?, ?, ?, ?)')
+    .run(p.t, p.label, JSON.stringify(p.top), key);
+}
+
+export function allModelHistory(): ModelHistoryRecord[] {
+  const rows = db()
+    .prepare('SELECT t, label, top, key FROM model_history ORDER BY t DESC LIMIT 200')
+    .all() as unknown as { t: string; label: string; top: string; key: string }[];
+  return rows.reverse().map((r) => ({ t: r.t, label: r.label, top: JSON.parse(r.top) as ModelHistoryRecord['top'], key: r.key }));
+}

server/src/index.ts

@@ -10,7 +10,7 @@ import { startScheduler } from './ingest/scheduler';
 import { ModelEngine } from './model';
 import { buildPreview, buildTeamProfile } from './preview';
 import { buildScoreboard, snapshotCheck } from './scoreboard';
-import { db, healthAll, oddsFor, latestOddsAll, dbCounts, inplayHistory, recordInplay, getMatchExt, getMatchProvider, allFixtureResults, saveFixtureResult } from './db/db';
+import { db, healthAll, oddsFor, latestOddsAll, dbCounts, inplayHistory, recordInplay, getMatchExt, getMatchProvider, allFixtureResults, saveFixtureResult, allModelHistory, saveModelHistory } from './db/db';
 import { inPlayProbs } from '../../src/lib/model/inplay';
 import { PushNotifier, pushEnabled, subscribe as pushSubscribe, unsubscribe as pushUnsubscribe, vapidPublicKey } from './push';
 import type { EspnSummary } from './ingest/espnNormalize';
@@ -45,8 +45,9 @@ export function buildServer() {
     if (state.applyScore(r.fixture_num, r.home_score, r.away_score, r.status as MatchStatus, null, 'seed')) restored++;
   }
   if (restored) console.log(`[state] restored ${restored} fixture result(s) from the DB`);
-  const model = new ModelEngine(STATIC_DIR);
+  const model = new ModelEngine(STATIC_DIR, { load: allModelHistory, save: saveModelHistory });
   model.refitTeamDc(state.allFixtures()); // current Team-DC from day one (covers restarts mid-tournament)
+  model.rebuildHistory(state.allFixtures()); // one-time diary replay when nothing is persisted yet
   model.recompute(state.allFixtures());
   const clients = new Set<WebSocket>();