Function rankRequiredFeatures

src/compute-engine/fungrim/loader.ts:574–586

* Order the required features so the MOST DISCRIMINATING one is checked * first, and drop the dispatch-bucket head itself (the rule is only * consulted for nodes that already carry that operator, so it conveys zero * information). Rarity heuristic over generic corpora, rarest first: * special-fu

(
  features: ReadonlyArray<string>,
  bucketHead: string
)

 * first-feature check decides almost every pre-screen (437 of the 474 new
 * hot-bucket rules carry a rare feature), keeping the per-rule cost at one
 * or two set lookups per candidate node (Phase-3 M5).
 */
function rankRequiredFeatures(
  features: ReadonlyArray<string>,
  bucketHead: string
): ReadonlyArray<string> {
  const rank = (f: string): number => {
    if (f.startsWith(FEATURE_SYM_PREFIX)) return 1;
    // operator feature
    return HOT_DISPATCH_HEADS.has(f.slice(FEATURE_OP_PREFIX.length)) ? 2 : 0;
  };
  return features
    .filter((f) => f !== FEATURE_OP_PREFIX + bucketHead)
    .sort((a, b) => rank(a) - rank(b));
}