Read integrity, as-of context, and the shadow matchup resolve (A1-A7)

Seven orders of measurement-first repair. The served grade does not move.

A0/A1 — the unordered page walk returned the right COUNT and the wrong ROWS:
410-617 of 2,490 duplicated with an equal number never returned, while
rows.length matched the server exactly. safePaginate orders on a real unique
key, verifies the tuple at runtime, and THROWS on a query error instead of
treating it as end-of-data. Both hits PROVES are withdrawn: they were drawn
through that reader, and defense_by_direction's distinct-n was likely below
the gate floor all along.

A2/A2b — rolled across every reader: 11 FAIL -> 0. Composite keys pulled from
pg_index (the context tables are dated-composite and had no single unique
column). The unordered helper is deleted, not parked.

A3 — ledgerService and retentionService defaulted the SAME env var to
DIFFERENT versions, so no ledger row ever carried the marker eligibility
requires. One source now. model_snapshots settlement moved onto the cron:
15,484 -> 28,894 settled, repaired-champion 0 -> 7,556.

A4 — hitsFactorContext takes an as-of cutoff. Refusal over reconstruction: no
row at-or-before the date means the factor does not apply, never the nearest
row. Live path unchanged, proven 400/400 on real rows.

A5 — factor_inputs freezes what the factor READ, never the multiplier, so an
audit can recompute and check. It also recorded the finding: the three hits
factors have NEVER fired. prop.opponent and prop.opposing_pitcher are read by
the resolver and written by nothing.

A6/A7 — matchupKeys resolves those keys from the posted lineup plus the
schedule's probable pitchers, and fires the factors into a SHADOW freeze:
248 fires on 308 props, 245 of which would move the grade. The served
forecast is untouched. specs/a8-shadow-factor-gate.md pre-registers the test
that decides whether they ever go live.

Nothing is turned on. CALIBRATION_DEPLOYED stays []. Both verdicts stay
withdrawn. 4,772 tests / 371 suites green, web build exit 0, read-integrity
harness 34/34.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

scripts/backfill-context.js

@@ -29,30 +29,45 @@ const { createClient } = require('@supabase/supabase-js');
 const ctx = require('../src/services/lineupContextService');
 const mlb = require('../src/services/adapters/mlbStatsAdapter');
 const { knownNumber } = require('../src/utils/known');
+const { paginate } = require('../src/utils/safePaginate');
+const { uniqueKeyFor } = require('../src/utils/tableKeys');
 
 const SB_URL = process.env.SUPABASE_URL;
 const SB_KEY = process.env.SUPABASE_SERVICE_ROLE_KEY || process.env.SUPABASE_SERVICE_KEY;
 const SEASON = Number(process.env.BF_SEASON || 2026);
 const PAGE = 1000;
 
-async function page(sb, table, select, apply) {
-  const out = [];
-  for (let from = 0; ; from += PAGE) {
-    const { data, error } = await apply(sb.from(table).select(select)).range(from, from + PAGE - 1);
-    if (error) throw error;
-    if (!data || data.length === 0) break;
-    out.push(...data);
-    if (data.length < PAGE) break;
-  }
-  return out;
+// ── THE SAFE WALK (Fix A2/A2b) ────────────────────────────────────────────
+// This script used to walk pages with `.range()` and NO ORDER BY. Measured on
+// production, that returned the correct row COUNT and the wrong ROWS: up to
+// 33.6% of a read came back twice while an equal share never came back at all,
+// so `rows.length` looked perfect while a fifth of the sample was missing.
+//
+// `pageSafe` routes every read through `src/utils/safePaginate`: a stable ORDER
+// BY on the table's real UNIQUE key — single OR composite, looked up from
+// `src/utils/tableKeys` rather than assumed — a runtime tuple-uniqueness check,
+// and a THROWN error instead of a silent stop. The old unordered helper is gone
+// rather than left beside it, because a dead broken helper is an invitation.
+async function pageSafe(sb, table, select, apply, key = uniqueKeyFor(table)) {
+  return paginate(() => apply(sb.from(table).select(select)),
+    { key, pageSize: PAGE, label: `${table}` });
 }
 
+/** THE MEASURED READS — main() and the harness call the same functions. */
+const READS = {
+  ledger: (sb) => pageSafe(sb, 'ledger_entries', 'id, player_key, player_name, stat, outcome, quarantine_reason',
+    (q) => q.eq('sport', 'mlb').is('user_id', null).in('stat', ['hits', 'total_bases'])
+      .in('outcome', ['hit', 'miss'])),
+  platoonHeld: (sb) => pageSafe(sb, 'platoon_splits', 'as_of_date, sport, season, player_key',
+    (q) => q.eq('sport', 'mlb')),
+};
+
 async function main() {
   if (!SB_URL || !SB_KEY) throw new Error('SUPABASE_URL / service key required');
   const sb = createClient(SB_URL, SB_KEY, { auth: { persistSession: false } });
 
   // Every hitter who appears on a CLEAN settled row — the true denominator.
-  const led = await page(sb, 'ledger_entries', 'player_key, player_name, stat, outcome, quarantine_reason',
+  const led = await pageSafe(sb, 'ledger_entries', 'id, player_key, player_name, stat, outcome, quarantine_reason',
     (q) => q.eq('sport', 'mlb').is('user_id', null).in('stat', ['hits', 'total_bases'])
       .in('outcome', ['hit', 'miss']));
   const need = new Map();
@@ -61,7 +76,7 @@ async function main() {
     if (!need.has(r.player_key)) need.set(r.player_key, r.player_name);
   }
 
-  const have = new Set((await page(sb, 'platoon_splits', 'player_key', (q) => q.eq('sport', 'mlb')))
+  const have = new Set((await pageSafe(sb, 'platoon_splits', 'as_of_date, sport, season, player_key', (q) => q.eq('sport', 'mlb')))
     .map((r) => r.player_key));
   const missing = [...need.entries()].filter(([k]) => !have.has(k));
 
@@ -100,4 +115,9 @@ async function main() {
   process.exit(0);
 }
 
-main().catch((e) => { console.error(e); process.exit(1); });
+if (require.main === module) {
+  main().catch((e) => { console.error(e); process.exit(1); });
+}
+
+// Exported so the read-integrity harness measures THE REAL FUNCTION.
+module.exports = { READS: (typeof READS !== 'undefined' ? READS : undefined), READS_LEDGER: (typeof READS_LEDGER !== 'undefined' ? READS_LEDGER : undefined) };