fix: port PINNED_HUB_CANDIDATES to benchmark.ts for stable hub identity (#2039)

benchmark.ts called selectHubTargets(dbPath) with no pinned-candidate list,
so it always fell back to the most-connected qualifying node. query-benchmark.ts
already solved this drift with PINNED_HUB_CANDIDATES, but the list was never
ported over, so benchmark.ts's hub identity could still silently shift between
versions whenever the most-connected function changed.

Move PINNED_HUB_CANDIDATES into scripts/lib/hub-selection.ts as a shared
export (single source of truth instead of a second copy that could drift),
and have both benchmark.ts and query-benchmark.ts import and pass it to
selectHubTargets().

Author: carlos-alm

scripts/benchmark.ts

@@ -17,7 +17,7 @@ import { fileURLToPath } from 'node:url';
 import { resolveBenchmarkExcludes, resolveBenchmarkSource, srcImport } from './lib/bench-config.js';
 import { isWorker, workerEngine, workerTargets, forkEngines } from './lib/fork-engine.js';
 import { round1, timeMedian, timeMedianWithValue } from './lib/bench-timing.js';
-import { selectHubTargets } from './lib/hub-selection.js';
+import { PINNED_HUB_CANDIDATES, selectHubTargets } from './lib/hub-selection.js';
 
 // ── Parent process: fork one child per engine, assemble final output ─────
 if (!isWorker()) {
@@ -173,7 +173,7 @@ try {
 
 // ── Query benchmarks ────────────────────────────────────────────────
 console.error(`  [${engine}] Benchmarking queries...`);
-const targets = workerTargets() || selectHubTargets(dbPath);
+const targets = workerTargets() || selectHubTargets(dbPath, PINNED_HUB_CANDIDATES);
 console.error(`    hub=${targets.hub}, leaf=${targets.leaf}`);
 
 async function benchQuery(fn, ...args) {

scripts/lib/hub-selection.ts

@@ -30,6 +30,16 @@ import Database from 'better-sqlite3';
 // a candidate's name — mirrors CALLABLE_SYMBOL_KINDS in src/shared/kinds.ts.
 export const HUB_CANDIDATE_KINDS: readonly string[] = ['function', 'method'];
 
+// Pinned hub targets — stable function names expected to exist across
+// versions. Auto-selecting the most-connected node makes version-to-version
+// comparison meaningless whenever the most-connected function changes (e.g.
+// a barrel/type file gets added or removed, or a new heavily-called utility
+// shifts the ranking) — pinning keeps "the hub" identity stable so
+// back-to-back benchmark runs measure the same node. Shared by both
+// query-benchmark.ts and benchmark.ts so the two scripts can't drift apart
+// on which names they consider stable.
+export const PINNED_HUB_CANDIDATES: readonly string[] = ['buildGraph', 'openDb', 'loadConfig'];
+
 export interface HubTargets {
 	hub: string;
 	hubFile: string;

scripts/query-benchmark.ts

@@ -18,7 +18,7 @@ import { fileURLToPath } from 'node:url';
 import { resolveBenchmarkExcludes, resolveBenchmarkSource, srcImport } from './lib/bench-config.js';
 import { isWorker, workerEngine, workerTargets, forkEngines } from './lib/fork-engine.js';
 import { round1, timeMedian } from './lib/bench-timing.js';
-import { selectHubTargets, type HubTargets } from './lib/hub-selection.js';
+import { PINNED_HUB_CANDIDATES, selectHubTargets, type HubTargets } from './lib/hub-selection.js';
 
 // ── Parent process: fork one child per engine, assemble final output ─────
 if (!isWorker()) {
@@ -118,11 +118,6 @@ const RUNS = 5;
 // before timing so the metric reflects warm-call latency, not cold-start.
 const WARMUP_RUNS = 3;
 
-// Pinned hub targets — stable function names that exist across versions.
-// Auto-selecting the most-connected node makes version-to-version comparison
-// meaningless when barrel/type files get added or removed.
-const PINNED_HUB_CANDIDATES = ['buildGraph', 'openDb', 'loadConfig'];
-
 async function benchDepths(fn, name, depths) {
 	const result = {};
 	for (const depth of depths) {

tests/unit/hub-selection.test.ts

@@ -13,7 +13,7 @@ import os from 'node:os';
 import path from 'node:path';
 import Database from 'better-sqlite3';
 import { afterAll, beforeAll, describe, expect, it } from 'vitest';
-import { selectHubTargets } from '../../scripts/lib/hub-selection.js';
+import { PINNED_HUB_CANDIDATES, selectHubTargets } from '../../scripts/lib/hub-selection.js';
 import { initSchema } from '../../src/db/index.js';
 
 function insertNode(db, name, kind, file, line) {
@@ -82,6 +82,17 @@ describe('selectHubTargets', () => {
     expect(targets.hubFile).toBe('src/domain/graph/builder.ts');
   });
 
+  it('resolves via the shared PINNED_HUB_CANDIDATES list used by both benchmark scripts', () => {
+    // query-benchmark.ts and benchmark.ts both pass this exact export to
+    // selectHubTargets — exercise it directly (not just a single-item
+    // ['buildGraph'] stand-in) so a typo or ordering change in the shared
+    // list is caught here rather than only at benchmark run time.
+    expect(PINNED_HUB_CANDIDATES.length).toBeGreaterThan(0);
+    const targets = selectHubTargets(dbPath, PINNED_HUB_CANDIDATES);
+    expect(targets.hub).toBe('buildGraph');
+    expect(targets.hubFile).toBe('src/domain/graph/builder.ts');
+  });
+
   it('excludes a constant-kind node from the most-connected fallback even with more raw edges', () => {
     // No pinned candidates supplied — falls back to the most-connected
     // qualifying (function/method) node. constBuildGraph has 3 edges (more