specs-capture-perf-trace

Call preview.profiling.startTrace with an Editor.Path pointing to the output file, then call session.finish() after the desired duration. This skill wraps that API in a scheduled setTimeout pattern so multiple Preview panels are captured simultaneously.

Set the previewCount constant in the Start snippet to the number of panels, or null to capture all. The snippet starts all sessions back-to-back and finishes them together after durationMs, storing state on globalThis.

Awaiting a timer, busy-waiting, or loading generated modules inside ExecuteEditorCode can block trace capture or trigger extra filesystem permission prompts. The scheduled setTimeout pattern returns immediately and finishes sessions asynchronously.

A 0-byte .pftrace file indicates a failed capture and should be treated as invalid. Non-zero files are the valid capture artifacts; verify sizes with ls -lh or wc -c after waiting slightly longer than durationMs.

Yes, if the perfetto-trace-analysis skill is installed, use it to analyze the saved .pftrace files. This skill only handles capture; analysis is a separate downstream step.