feat(qmd): add GPU and CPU benchmark for Auto selection

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

shared/qmd/qmd-benchmark.mjs

@@ -0,0 +1,86 @@
+// shared/qmd/qmd-benchmark.mjs — measures warm QMD search latency and embedding throughput on one device.
+import { mkdtempSync, mkdirSync, rmSync, writeFileSync } from 'node:fs';
+import { availableParallelism, tmpdir } from 'node:os';
+import { join } from 'node:path';
+import { pathToFileURL } from 'node:url';
+import { parseArgs } from 'node:util';
+import { MODELS, importQmd, qmdPackageDir } from './qmd-lib.mjs';
+
+export function passes({ querySeconds, chunksPerSecond }, env = process.env) {
+  const maxQuery = Number(env.QMD_BENCHMARK_MAX_QUERY_SECONDS) || 5;
+  const minChunks = Number(env.QMD_BENCHMARK_MIN_CHUNKS_PER_SECOND) || 20;
+  return querySeconds <= maxQuery && chunksPerSecond >= minChunks;
+}
+
+const TOPICS = ['invoice rounding', 'upload retries', 'trial expiry', 'cache invalidation', 'session tokens'];
+
+export function fixtureDocuments(count) {
+  return Array.from({ length: count }, (_, index) => {
+    const topic = TOPICS[index % TOPICS.length];
+    const sections = Array.from({ length: 6 }, (__, section) =>
+      `## ${topic} part ${section}\n\n` + (`This section ${index}-${section} explains how ${topic} behaves when the service handles request ${index * 7 + section}. ` +
+      `It lists the edge cases, the configuration keys, and the error messages that operators see during incidents.\n`).repeat(2));
+    return { name: `doc-${String(index).padStart(3, '0')}.md`, text: `# ${topic} ${index}\n\n${sections.join('\n')}` };
+  });
+}
+
+export function describeDevices({ gpu, devices, threads }) {
+  const gpus = gpu ? `${String(gpu).toUpperCase()}: ${devices.join(', ') || 'unnamed device'}` : 'no GPU';
+  return `${gpus}; CPU threads: ${threads}`;
+}
+
+// llama.cpp's automatic backend uses every GPU of the chosen backend; nothing here narrows the device set.
+async function detect() {
+  const { getLlama } = await import(pathToFileURL(join(qmdPackageDir(), 'node_modules', 'node-llama-cpp', 'dist', 'index.js')).href);
+  const llama = await getLlama({ gpu: 'auto' });
+  const gpu = llama.gpu;
+  const devices = gpu ? await llama.getGpuDeviceNames() : [];
+  await llama.dispose();
+  return { gpu, devices, threads: availableParallelism() };
+}
+
+async function measure(device) {
+  for (const [key, value] of Object.entries({ QMD_EMBED_MODEL: MODELS.embed, QMD_RERANK_MODEL: MODELS.rerank, QMD_GENERATE_MODEL: MODELS.generate })) {
+    process.env[key] = value;
+  }
+  const work = mkdtempSync(join(tmpdir(), 'ai-config-qmd-bench-'));
+  try {
+    const docs = join(work, 'docs');
+    mkdirSync(docs);
+    for (const doc of fixtureDocuments(100)) writeFileSync(join(docs, doc.name), doc.text);
+    const { createStore } = await importQmd();
+    const store = await createStore({ dbPath: join(work, 'index.sqlite'), config: { collections: { bench: { path: docs, pattern: '**/*.md' } } } });
+    try {
+      await store.update();
+      await store.searchVector('warm up the embedding model', { limit: 1 });
+      const embedded = await store.embed({ collection: 'bench' });
+      const chunksPerSecond = embedded.chunksEmbedded / Math.max(embedded.durationMs / 1000, 0.001);
+      const question = 'Which part explains how upload retries behave during incidents?';
+      await store.search({ query: question, collections: ['bench'], limit: 5 });
+      const times = [];
+      for (let run = 0; run < 3; run += 1) {
+        const started = performance.now();
+        await store.search({ query: `${question} (${run})`, collections: ['bench'], limit: 5, candidateLimit: 40 });
+        times.push((performance.now() - started) / 1000);
+      }
+      const querySeconds = times.sort((a, b) => a - b)[1];
+      const result = { device, querySeconds: Number(querySeconds.toFixed(3)), chunksPerSecond: Number(chunksPerSecond.toFixed(1)) };
+      return { ...result, passed: passes(result) };
+    } finally {
+      await store.close();
+    }
+  } finally {
+    rmSync(work, { recursive: true, force: true });
+  }
+}
+
+async function main() {
+  const { values } = parseArgs({ options: { detect: { type: 'boolean' }, device: { type: 'string' } } });
+  if (values.detect) return console.log(JSON.stringify(await detect()));
+  if (!['gpu', 'cpu'].includes(values.device)) throw new Error('--device gpu|cpu or --detect is required');
+  console.log(JSON.stringify(await measure(values.device)));
+}
+
+if (import.meta.url === pathToFileURL(process.argv[1] || '').href) {
+  main().catch((error) => { console.error(`qmd-benchmark: ${error.message}`); process.exit(1); });
+}