* perf(harness): add 2D-highway frame-time measurement + capture the R3c gate (H0)
scripts/perf-baseline.mjs gains a `--song` mode: it wraps requestAnimationFrame
before any page script, TAGS the frames the highway actually painted (via
highway.addDrawHook), starts playback, and reports draw-frame p50/p95/p99 over
`--frames` seconds across `--runs` runs. Tagging is the point — ~half the rAF
callbacks are other cheap loops (~0.1 ms); averaging them in would hide a
renderer regression, so only draw frames are counted.
This is the metric the plan says gates the highway.js split (R3c) but the harness
never measured (it did server latency + boot + heap only, and the R0 numbers were
against an empty library). docs/perf-baseline.md now records the pre-lift baseline
on the Arcturus feedpak: p50 ~2.2 ms, p95 spread 2.7-3.2 ms across 3 runs. The
H-container lift (next) re-runs this on the same box and must stay within noise.
Maintainer/CI-only tooling; the existing no-`--song` run is unchanged.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
* perf(harness): close page on error + MD040 fence + CHANGELOG (CodeRabbit)
- frameTimeOnce now closes its page in a finally, so a failing run doesn't leak
the page until the final browser.close() (CodeRabbit).
- fenced code block gets a bash language hint (MD040).
- CHANGELOG mentions the new --song frame-time mode.
---------
Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
