Book Comparison Phase 1-3(backend): fenced per-book store + honest gated crown

Per-book prices existed only transiently (odds cache, ~1h, raw names, grade-path
input); every grade-path persistence point collapses to one book. The
/api/books feature was built+mounted but non-functional (fed FLAT rows to a
GROUPED comparator -> always empty).

Phase 1: bookPriceStore captures per-book prices from `props` BEFORE dedupeProps,
keyed nameKey|stat, into bookprices:{sport} (SNAP_TTL) in snapshotService. Fenced:
reads props, writes its own key, read by nothing on the grade path. Grade proven
byte-identical (test + no-grade-path-reference grep test).

Phase 2: scripts/measure-book-spread.js reports same-line best-vs-worst spread
(cents + implied-prob pts), per sport, never pooled. Pre-registered crown
threshold: median >=8c OR >=2pp. Runs post-deploy on real data.

Phase 3 (backend): compareProp is honest-absent (single-book/flat -> no crown)
and the crown is gated (BOOK_CROWN_ENABLED, default OFF until Phase 2 clears).
/api/books repointed to the snapshot-locked store (fallback odds cache),
nameKey-matched; `source` field is the deploy fingerprint.

HELD unchanged: dedupeProps, snapshot dedup, selector, grade, champion,
challengers, ranking, edge_pct/ev_pct. UI routing of BookComparison + crown
treatment deferred to post-measurement (gated on Phase 2). Full suite 3834 green,
web build exit 0.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01VsztNChZ7vEvSR61AuMhD1

src/services/bookComparisonService.js

@@ -30,22 +30,73 @@ function oddsForSide(line, side) {
   return raw == null ? null : Number(raw);
 }
 
+// Book Comparison order — the crown is PRE-REGISTERED and threshold-gated. It
+// stays OFF until Phase 2's spread measurement (scripts/measure-book-spread.js)
+// confirms the median same-line spread clears the bar (≥8¢ OR ≥2 implied-prob
+// pts). A crown over a flat market is a claim of edge that does not exist.
+function crownEnabled(opts) {
+  if (opts && opts.crownEnabled != null) return !!opts.crownEnabled;
+  return process.env.BOOK_CROWN_ENABLED === '1';
+}
+
+// Render every book row honestly, with NO crown. Used for single-book props,
+// props with no shared line, and whenever the crown flag is off.
+function honestGrid(prop, side, books) {
+  const rows = books.map((b) => ({
+    book: b.book,
+    line: b.line ?? null,
+    over_odds: b.over_odds ?? null,
+    under_odds: b.under_odds ?? null,
+    isBest: false,
+  }));
+  return {
+    player: prop.player,
+    stat: prop.stat_type || prop.stat,
+    line: prop.line ?? (books[0] && books[0].line) ?? null,
+    side,
+    books: rows,
+    bestBook: null,
+    bestOdds: null,
+    bookCount: new Set(books.map((b) => b.book)).size,
+    savings: 0,
+    crowned: false,
+  };
+}
+
 /**
  * Compare one grouped prop across its books for a given side.
- * Returns null when there are no usable book lines.
+ * Returns null when there are no usable book rows at all.
+ *
+ * HONEST-ABSENT: a single-book prop renders that one book — no crown, no implied
+ * second price, no savings claim. The crown fires ONLY among ≥2 books posting
+ * the SAME line with DIFFERING prices, and ONLY when the flag is enabled (Phase 2
+ * gate). Comparing prices across different lines is meaningless (Data Semantics).
  */
-function compareProp(prop, side = 'over') {
+function compareProp(prop, side = 'over', opts = {}) {
   const books = (prop?.lines || prop?.books || []).filter((b) => b && b.book);
-  const priced = books.filter((b) => Number.isFinite(oddsForSide(b, side)));
-  if (priced.length === 0) return null;
+  if (books.length === 0) return null;
 
-  let best = priced[0];
-  for (const b of priced) {
+  const priced = books.filter((b) => Number.isFinite(oddsForSide(b, side)));
+  // Single priced book, or crown disabled → honest grid, no crown.
+  if (priced.length < 2 || !crownEnabled(opts)) return honestGrid(prop, side, books);
+
+  // Crown only among books at the SAME line (the shared-line comparison set).
+  const byLine = {};
+  for (const b of priced) { const L = String(b.line); (byLine[L] = byLine[L] || []).push(b); }
+  let shared = [];
+  for (const rows of Object.values(byLine)) { if (rows.length > shared.length) shared = rows; }
+  const distinctBooks = new Set(shared.map((b) => b.book));
+  const distinctPrices = new Set(shared.map((b) => oddsForSide(b, side)));
+  // Fewer than 2 books at one line, or all books post the identical price →
+  // nothing to crown. Render honestly.
+  if (distinctBooks.size < 2 || distinctPrices.size < 2) return honestGrid(prop, side, books);
+
+  let best = shared[0];
+  for (const b of shared) {
     if (americanToDecimal(oddsForSide(b, side)) > americanToDecimal(oddsForSide(best, side))) best = b;
   }
-
   const bestDecimal = americanToDecimal(oddsForSide(best, side));
-  const avgDecimal = average(priced.map((b) => americanToDecimal(oddsForSide(b, side))));
+  const avgDecimal = average(shared.map((b) => americanToDecimal(oddsForSide(b, side))));
   const savings = Math.round((bestDecimal - avgDecimal) * 100 * 100) / 100; // per $100, 2dp
 
   return {
@@ -53,17 +104,19 @@ function compareProp(prop, side = 'over') {
     stat: prop.stat_type || prop.stat,
     line: best.line ?? prop.line ?? null,
     side,
-    books: priced.map((b) => ({
+    // Show all books; crown only the best AT THE SHARED LINE.
+    books: books.map((b) => ({
       book: b.book,
       line: b.line ?? null,
       over_odds: b.over_odds ?? null,
       under_odds: b.under_odds ?? null,
-      isBest: b.book === best.book,
+      isBest: b.book === best.book && Number(b.line) === Number(best.line),
     })),
     bestBook: best.book,
     bestOdds: oddsForSide(best, side),
-    bookCount: priced.length,
+    bookCount: distinctBooks.size,
     savings,
+    crowned: true,
   };
 }
 
@@ -72,12 +125,15 @@ function compareProp(prop, side = 'over') {
  * shopping matters most). Drops props with a single book (nothing to
  * compare). `limit` caps the result.
  */
-function bestLines(props, { side = 'over', limit = 20 } = {}) {
+function bestLines(props, { side = 'over', limit = 20, crownEnabled: ce } = {}) {
   if (!Array.isArray(props)) return [];
+  // "Best lines tonight" is inherently a crown claim — when the crown is gated
+  // off (Phase 2 not yet cleared) it makes no such claim.
+  if (!crownEnabled({ crownEnabled: ce })) return [];
   const out = [];
   for (const prop of props) {
-    const cmp = compareProp(prop, side);
-    if (cmp && cmp.bookCount >= 2) out.push(cmp);
+    const cmp = compareProp(prop, side, { crownEnabled: ce });
+    if (cmp && cmp.crowned && cmp.bookCount >= 2) out.push(cmp);
   }
   out.sort((a, b) => b.savings - a.savings);
   return limit > 0 ? out.slice(0, limit) : out;

src/services/bookPriceStore.js

@@ -0,0 +1,92 @@
+'use strict';
+
+/**
+ * bookPriceStore — DISPLAY-ONLY per-book price capture (Book Comparison order,
+ * Phase 1).
+ *
+ * WHY THIS EXISTS: `normalizeProps` emits one row per book, but every
+ * persistence point on the GRADE path collapses to a single book
+ * (gradeSlateService.dedupeProps keeps the first book per line;
+ * snapshotService.indexOdds keeps one row per player|stat; the grades cache,
+ * snapshot, and ledger each lock one price). The only place per-book prices
+ * survived was the transient odds cache (`odds:{sport}:{utcDate}`, ~1h TTL,
+ * raw player names, grade-path INPUT). This module captures them at snapshot
+ * time into a snapshot-locked, normalized-key, display-only store.
+ *
+ * STRUCTURAL FENCE (not a comment — an enforced property):
+ *   1. This module ONLY reads a props array and RETURNS a new object. It never
+ *      mutates the props it is handed (a bookPriceStore.test.js case deep-freezes
+ *      the input and asserts capture succeeds).
+ *   2. Its output is written to its OWN Redis key (`bookprices:{sport}`), read by
+ *      NOTHING on the grade path — not gradeSlateService, snapshotService's dedup,
+ *      indexOdds, any challenger, the ledger, edge_pct/ev_pct, or the selector.
+ *      A test greps the grade-path files and asserts zero `bookprices` references.
+ *   3. In runSnapshot the capture is a leaf `cacheSet` whose result is assigned to
+ *      no variable used downstream — the grade-byte-identical test proves the
+ *      graded slate is unchanged whether or not the capture runs.
+ *
+ * So no value this file produces can ever reach a grade, a locked line, a
+ * challenger, the ledger, or the hero. It is a pure display leaf.
+ */
+
+const { nameKey, normalizeName } = require('../utils/playerName');
+
+/** Canonical lookup key for a graded prop's book rows. */
+function bookKey(player, statType) {
+  return `${nameKey(player)}|${String(statType || '').toLowerCase()}`;
+}
+
+/**
+ * Group a flat multi-book props array (oddsNormalizer shape) into one entry per
+ * normalized player+stat, each carrying every real book row. Rows with no price
+ * on EITHER side are dropped (nothing to compare — honest-absent, never a
+ * fabricated price). Never mutates `props`.
+ *
+ * @returns {{ updated_at, props: Array, count }}
+ */
+function captureBookPrices(props, opts = {}) {
+  const now = opts.now || (() => new Date().toISOString());
+  const ts = now();
+  const byKey = new Map();
+
+  for (const p of props || []) {
+    if (!p || !p.player || !p.stat_type || p.line == null || !p.book) continue;
+    // A row with neither price is not a comparable book row.
+    if (p.over_odds == null && p.under_odds == null) continue;
+
+    const stat = String(p.stat_type).toLowerCase();
+    const key = bookKey(p.player, stat);
+    if (!byKey.has(key)) {
+      byKey.set(key, {
+        key,
+        player: normalizeName(p.player).display || p.player,
+        stat_type: stat,
+        books: [],
+      });
+    }
+    const entry = byKey.get(key);
+    // A book appears once per line. Keep the FIRST row for a given book+line
+    // (mirrors dedupeProps' first-wins, applied here only for display de-dup —
+    // it does NOT feed grading).
+    const bl = `${p.book}|${p.line}`;
+    if (entry.books.some((b) => `${b.book}|${b.line}` === bl)) continue;
+    entry.books.push({
+      book: p.book,
+      line: Number(p.line),
+      over_odds: p.over_odds ?? null,
+      under_odds: p.under_odds ?? null,
+    });
+  }
+
+  const out = [...byKey.values()];
+  return { updated_at: ts, props: out, count: out.length };
+}
+
+/** Books posting a given line for a prop entry (shared-line comparison set). */
+function booksAtLine(entry, line) {
+  if (!entry || !Array.isArray(entry.books) || line == null) return [];
+  const L = Number(line);
+  return entry.books.filter((b) => Number(b.line) === L);
+}
+
+module.exports = { captureBookPrices, bookKey, booksAtLine };

src/services/snapshotService.js

@@ -284,6 +284,10 @@ async function runSnapshot(sport, opts = {}) {
     // suite that doesn't know about this dep can never make a live ESPN call.
     // Session 64 — model-snapshot retention. Injectable; null disables it.
     retention: opts.retention !== undefined ? opts.retention : require('./retentionService'),
+    // Book Comparison order (Phase 1) — DISPLAY-ONLY per-book price capture.
+    // Fenced: written to its own `bookprices:{sport}` key, read by nothing on
+    // the grade path. Injectable; a failure never touches grading.
+    captureBookPrices: opts.captureBookPrices || require('./bookPriceStore').captureBookPrices,
     refreshTeamStats: opts.refreshTeamStats
       || (process.env.NODE_ENV === 'test'
         ? async () => null
@@ -335,6 +339,21 @@ async function runSnapshot(sport, opts = {}) {
     console.warn(`[snapshot] game binding failed for ${sp} (rows without a real game time will be skipped):`, e.message);
   }
 
+  // Book Comparison order (Phase 1) — CAPTURE PER-BOOK PRICES BEFORE DEDUP.
+  // `props` still carries one row per book here (dedupeProps runs downstream
+  // inside gradeAndCacheSlate). The capture only READS props and writes its own
+  // `bookprices:{sport}` key at SNAP_TTL — long enough to outlive the cron gap
+  // (the 1h odds cache would blank between runs). Best-effort and structurally
+  // fenced: nothing on the grade path reads this key, and the graded slate is
+  // byte-identical whether or not this runs (bookPriceStore.test.js locks it).
+  try {
+    const bookStore = deps.captureBookPrices(props, { now: deps.now });
+    await deps.cacheSet(`bookprices:${sp}`, bookStore, SNAP_TTL);
+    console.log(`[snapshot] book prices ${sp}: ${bookStore.count} props with book rows captured`);
+  } catch (e) {
+    console.warn(`[snapshot] book-price capture failed for ${sp} (display-only, grading continues):`, e.message);
+  }
+
   // Session 63 — REFRESH TEAM STATS BEFORE GRADING.
   // `refreshTeamStats` is the ONLY writer of `team_stats:{sport}:{abbr}`, which
   // is the ONLY source of `opp_rank_stat` — and it had zero production callers,