Correct hnsw.ef_search and relaxed_order comments

Flooring ef_search at 40 is a product choice (never worse than the GUC
default); pgvector itself accepts 1..1000. relaxed_order can slightly
disorder dense-channel ranks that feed RRF — that trade-off is intentional
for selective-filter recall, not a free re-sort.

Author: TheGreatAxios

src/services/search.test.ts

@@ -242,7 +242,7 @@ describe("deriveHybridEvidence", () => {
 });
 
 describe("hnswEfSearch", () => {
-  it("clamps to pgvector's [40, 1000] bounds", () => {
+  it("clamps to the product floor of 40 and the GUC max of 1000", () => {
     expect(hnswEfSearch(0)).toBe(40);
     expect(hnswEfSearch(1)).toBe(40);
     expect(hnswEfSearch(40)).toBe(40);

src/services/search.ts

@@ -479,8 +479,9 @@ const iterativeScanSupport = new WeakMap<RawSql, boolean>();
 
 /**
  * The hnsw.ef_search value for a dense query: the overfetch limit clamped
- * to pgvector's bounds — never below the GUC's default (40), never above
- * its hard maximum (1000). Non-finite input falls back to the default.
+ * into [40, 1000]. pgvector accepts 1..1000 (default 40); flooring at 40 is
+ * a product choice so we never run worse than the GUC default, and 1000 is
+ * the GUC hard max. Non-finite input falls back to the default.
  */
 export function hnswEfSearch(overfetchLimit: number): number {
   const limit = Number.isFinite(overfetchLimit) ? Math.floor(overfetchLimit) : 40;
@@ -573,7 +574,9 @@ export async function fetchDenseCandidates(
   // exist. ef_search widens the fixed candidate pool; iterative_scan
   // (pgvector >= 0.8) additionally keeps scanning until the limit is
   // satisfied. Both are SET LOCAL, so nothing leaks into pooled session
-  // state. relaxed_order is safe downstream: RRF fuses by rank and re-sorts.
+  // state. relaxed_order can slightly disorder the dense channel's neighbor
+  // ranks (and those ranks ARE the dense RRF input) — intentional trade-off
+  // for selective-filter recall over strict distance order.
   const rows = await rawSql.begin(async (tx) => {
     await tx.unsafe(`SET LOCAL hnsw.ef_search = ${efSearch}`);
     const support = iterativeScanSupport.get(rawSql);