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Reports, tools and agents ​

profiler.report() returns plain JSON about the frames in the buffer (ten seconds by default). This one is from a debuff game on a 165 Hz display:

json
{
  "frames": 558,
  "seconds": 3.47,
  "fps": 160.88,
  "budgetMs": 9.09,
  "displayIntervalMs": 6.06,
  "intervalMs": { "p50": 6.1, "p95": 6.2, "p99": 12.1, "max": 30.3 },
  "cpuMs": { "p50": 0.2, "p95": 0.6, "max": 1.4 },
  "hitches": 3,
  "causes": { "unknown": 2, "script": 1 },
  "worst": [],
  "spans": { "update": 0.04, "render": 0.09 },
  "perFrame": { "draws": 1, "uploads": 1, "uploadBytes": 0 },
  "overheadMs": 0.053,
  "support": { "attribution": true, "heap": true, "contexts": true },
  "warnings": []
}
  • intervalMs is what players feel. Watch p95 and p99, not the average.
  • cpuMs is what your frame code costs.
  • worst holds up to 10 verdicts, slowest first.
  • support says what this browser reports, so you know how much to trust the causes.
  • warnings says what myaku couldn't see. Check it before trusting a quiet report.

Warnings ​

Myaku would rather tell you it's blind than show a healthy-looking graph it can't vouch for. profiler.warnings(), the report's warnings and the overlay all list:

  • No frames recorded. The game kept its own reference to requestAnimationFrame from before myaku loaded. Load myaku first.
  • No canvas context seen. The game created its context before myaku loaded, so draws, uploads and compiles aren't counted. Load myaku first.
  • More than 16 span names. The rest are added up under other, not dropped.
  • Heap too coarse. Some browsers report the heap rarely or in big steps, which can't show garbage collection. Myaku checks that readings actually change. When they don't, support.heap is false and unknown verdicts say GC can't be ruled out.

From browser automation ​

Myaku exposes itself as window.__MYAKU__, so Playwright or Puppeteer can read it after playing:

ts
await page.goto("http://localhost:5173");
await page.waitForTimeout(5000);
const report = await page.evaluate(() => window.__MYAKU__.report());
expect(report.intervalMs.p95).toBeLessThan(20);

From coding agents ​

In debuff projects, the MCP server's game_profile tool returns the report from the running game, and the explain-stutter prompt walks an agent through it: read the worst verdicts, open the code they point at, fix it, and measure again.