User asked to measure everything so we can pinpoint the lag/ECONNRESET at 70 concurrent uploads. All additive instrumentation, no upload-behavior change.
main process: the eventloop-delay log line now also reports cpu=X%core (process.cpuUsage delta over wall time; >100% means multiple cores), rss, per-hoster live connection distribution (active-by-hoster), cumulative transient (ECONNRESET-class) error count, and pending count — pulled from a new UploadManager.getDiagnostics(). This shows whether the main thread is CPU-bound and which hoster is oversubscribed.
renderer: a PerformanceObserver('longtask') plus a requestAnimationFrame frame-time monitor log 'renderer-perf' every 5s while uploading — fps, jankFrames (>33ms), worstFrame, longtask count and max. This is the direct renderer ground truth (real frame rate under load), which the component-timing harness could not capture. Low fps / high jank => renderer is blocked; ~60fps while it still feels laggy => the cpu/eld numbers in the same log decide CPU-bound vs IO-bound in the main process.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
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