v27.1.0

Added

• Three new analyses on result.cpu derived from the same Chrome trace.json that's already collected when --cpu is on. scriptCosts produces the per-URL parse / compile / execute / total breakdown that Lighthouse's bootup-time audit shows, sorted by total descending. forcedReflows walks the main-thread task tree for Layout / UpdateLayoutTree events nested inside JS-driven tasks (EventDispatch, FunctionCall, TimerFire, FireAnimationFrame, …) — every match is a synchronous reflow caused by JavaScript reading a layout-triggering property mid-handler, reported with the script that triggered it. nonCompositedAnimations surfaces Animation events whose compositeFailed bitmask is non-zero, returning the unsupported properties (top, box-shadow, filter, …) so consumers can see what to swap for the GPU-friendly equivalent. Each new analysis is wrapped in its own try / catch so a bug in one can't poison the existing categories / events / urls payload

Fixed

• Replace the unmaintained @sitespeed.io/tracium dependency (extracted from Lighthouse circa 2017, last release 0.3.3) with an in-tree ESM port at lib/chrome/trace/. The algorithm is a 1:1 port; output of computeMainThreadTasks is byte-equivalent for any trace, so existing result.cpu.{categories,events,urls} consumers see no change. Pulling the parser inline lets new analyses ship at Browsertime's release cadence without a second npm publish step in between
• Modernise the trace-event classifier. The original list only knew about ~30 event names, so on busy 2026-era pages roughly half the trace fell through to "other" — on a sample cnet run that meant 1.3 s of "other" hiding RunTask, v8.run, IntersectionObserverController::computeIntersections, PrePaint, Commit, Layerize, v8.callFunction, V8.DeserializeContext and friends. The expanded list draws from modern Lighthouse + the WebPageTest-derived map in waterfall-tools + direct sampling of real traces, and a new groupForEvent() lookup adds V8.GC* prefix matching so future V8 GC phases auto-classify
• Bump chrome-har to 1.3.0 to pick up the new _renderBlocking field on each entry, lifting Chrome's CDP renderBlockingStatus (Chrome 108+) so downstream HAR consumers can see which resources blocked first paint without inferring it from the trace.