Multi-core simulation: grain movement and heat across a worker pool (t88 phase 3)

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

tools/perf-measure.js

@@ -13,20 +13,25 @@ function perfWrap(names, data) {
   }
   return () => { for (const name of names) window[name] = originals[name]; };
 }
-function perfSim(names, scene, w, h) {
+async function perfSim(names, scene, w, h) {
   // Five full periods warm even the 120-tick cold pass without forcing conditional calls.
   for (let k = 0; k < 600; k++) simTick();
   perfScene(scene, w, h);
+  await startThreads();
   const start = perfState(), data = {}, restore = perfWrap(names, data), n = 240;
+  const threadData = {}, restoreThread = perfWrap(['threadWait'], threadData);
+  if (simPool) simPool.activeMax = 0;
   const t = performance.now();
   try { for (let k = 0; k < n; k++) simTick(); }
-  finally { restore(); }
+  finally { restore(); restoreThread(); }
   const total = (performance.now() - t) / n;
   const steps = {};
   for (const [name, d] of Object.entries(data)) steps[name] = {
     ms_per_tick: d.ms / n, ms_per_call: d.calls ? d.ms / d.calls : null, calls: d.calls
   };
-  return { total_ms: total, ticks: n, start, end: perfState(), steps,
+  return { total_ms: total, main_thread_ms: total, polling_ms: threadData.threadWait.ms / n,
+    main_compute_ms: total - threadData.threadWait.ms / n,
+    workers: simPool ? simPool.workers.length : 0, active_workers: simPool ? simPool.activeMax : 0, ticks: n, start, end: perfState(), steps,
     rest_ms: total - Object.values(data).reduce((s, d) => s + d.ms / n, 0) };
 }
 async function perfRender(lighting, overlays) {