Suppress rare-event 0.5 unders (juiced, no-edge) — config-driven grade + board fix

Betting-logic audit: the CONSENSUS-vs-MODEL board flooded with fake reads like
"DOUBLES u0.5 · MODEL 0.2 · +edge" — the juiced under side of rare counting-stat
markets (doubles/triples/HR/SB), which is never a takeable edge and violates the
no-unders-default doctrine.

Report finding (item 3/4): the doubles projection is REAL per-player, not a flat
fallback — 'doubles' maps to a real game-log field (MLB_LOG_FIELD doubles→
doubles) and the live values varied (0.03/0.16/0.2/0.22). So no projection-gate
refusal for fakeness; the problem is purely structural (a rare event's real
projection always sits below a 0.5 line, so the under always "wins").

Fix (config-driven — src/config/rareEventMarkets.js, tunable stat list + line
threshold):
- Grade layer (analyzeViaEngine1): a rare-event UNDER at ≤0.5 is always REFUSED
  (grade null + suppressed flag/reason). A rare-event OVER at ≤0.5 is refused
  UNLESS the model genuinely projects the event above the line — because a
  0.2-over-0.5 carries the SAME |edge| as the suppressed under and would just
  take its rank on the board. The over grades normally once projection > line.
- Board layer (marketBreadth.collectBreadth): drops null-model rows so a
  suppressed/ungraded prop can't rank a "MODEL —" placeholder onto the board.

10 suppression tests + config locks; also fixed a settingsPage book assertion
left over from the ESPN→theScore swap. Suite 274/3289 green, web build exit 0.

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

src/config/rareEventMarkets.js

@@ -0,0 +1,65 @@
+'use strict';
+
+/**
+ * Rare-event markets (betting-logic audit, 2026-07-19).
+ *
+ * On a 0.5-line rare counting stat — doubles, triples, home runs, stolen bases —
+ * the UNDER is the juiced side the book wants action on: the event just usually
+ * doesn't happen, so a real projection of (say) 0.2 always "favors" under 0.5,
+ * but there's no takeable edge (the book prices it -250+). Surfacing those
+ * unders floods the board with fake B-grade "under 0.5" reads and violates the
+ * standing no-unders-default doctrine.
+ *
+ * So we SUPPRESS the under side on these markets at/below the line threshold —
+ * it is not graded. The OVER side still grades normally and only surfaces when
+ * the model genuinely projects the event above the line.
+ *
+ * Config-driven (a stat list + a line threshold) so it's tunable without
+ * touching grade logic. CommonJS so it's unit-testable + requireable everywhere.
+ */
+
+// Low-frequency counting stats where a 0.5 under is structurally a bad bet.
+const RARE_EVENT_STATS = ['doubles', 'triples', 'home_runs', 'stolen_bases'];
+
+// The under is suppressed only at/below this line (0.5 is the juiced rare line;
+// a 1.5+ line is a different market where an under can be a real read).
+const RARE_EVENT_LINE_MAX = 0.5;
+
+function isRareEventStat(statType) {
+  return RARE_EVENT_STATS.includes(String(statType || '').toLowerCase());
+}
+
+/** True when this prop is a rare-event UNDER at/below the line threshold —
+ *  the juiced side, always refused. Needs no projection. */
+function isSuppressedRareUnder(statType, line, direction) {
+  const dir = String(direction || '').toLowerCase();
+  const ln = Number(line);
+  return dir === 'under'
+    && isRareEventStat(statType)
+    && Number.isFinite(ln)
+    && ln <= RARE_EVENT_LINE_MAX;
+}
+
+/** True when this prop is a rare-event OVER at/below the threshold that the
+ *  model does NOT genuinely project (projection <= line). Refusing it is what
+ *  keeps the board clean — a 0.2-projection over 0.5 carries the SAME |edge| as
+ *  the suppressed under, so if we let it grade it just takes the under's place.
+ *  The over is a real read only when the model projects ABOVE the line. */
+function isSuppressedRareOver(statType, line, direction, projection) {
+  const dir = String(direction || '').toLowerCase();
+  if (dir !== 'over') return false;
+  const ln = Number(line);
+  const proj = Number(projection);
+  return isRareEventStat(statType)
+    && Number.isFinite(ln)
+    && ln <= RARE_EVENT_LINE_MAX
+    && !(Number.isFinite(proj) && proj > ln);
+}
+
+module.exports = {
+  RARE_EVENT_STATS,
+  RARE_EVENT_LINE_MAX,
+  isRareEventStat,
+  isSuppressedRareUnder,
+  isSuppressedRareOver,
+};