Compositing shows up in a trace as Layerize, Commit and PrePaint with no
indication of what caused it. The streaming profiler now snapshots
document.getAnimations() mid-capture and reports the running animations by
keyframe and target, which names the elements keeping the compositor busy
instead of leaving the trace to be guessed at.
A CPU sampling profile attributes native work to `(program)`, which during
streaming accounted for three quarters of all busy time and said nothing about
where it went. The timeline trace names that work, so the streaming report now
lists total and maximum time per trace event, skipping container events whose
duration already includes the work below them.
`getRuntimeKey` keys caches, stores, and persisted state across the whole UI,
so it runs on store reads, event handling, and render paths. Until the runtime
endpoint is explicitly initialised, every call re-derived the key by trimming
two injected globals and constructing three URL objects.
In a streaming capture this made `readInjectedLocalOrigin` the single most
expensive application function: 315 ms of self time, 12% of all main-thread
busy time. After the change it does not appear in the profile at all, and the
same capture went from two long tasks to none, with the longest task dropping
from 210 ms to 47 ms.
The key depends only on the active API base URL and two injected globals, and
`switchRuntimeEndpoint` writes the injected API base URL at runtime, so the
cache is validated against the raw untrimmed values rather than memoised
outright. That comparison allocates nothing and still recomputes as soon as any
input changes. Tests cover both directions, including an operation-count
assertion that repeated calls construct no URLs.
The streaming profiler also reports output-normalised metrics, because response
length varies between runs and makes per-second totals incomparable.
Adds `bun run profile:session`: creates a session, opens it in a real
browser, dispatches a prompt through the supported `openchamber session` CLI,
and records until the session reports itself idle. No input is synthesised, so
everything captured is the app reacting to its own event stream.
Streaming is judged by responsiveness rather than totals, so the report leads
with the long-task distribution, style recalculation and layout rates, frame
production, and the application's own stream counters.
Two failure modes are detected rather than reported as clean results. A session
belonging to a directory the browser is not viewing renders nothing and
produces a perfectly quiet profile, so the run verifies both new message
elements in the DOM and message-list render counters. And `RunTask` is only
emitted under the disabled-by-default timeline category, so a capture without
it reports zero long tasks; the missing-task case is now called out instead of
being shown as zero.
Metric helpers are shared with the idle profiler.
Bohdan Triapitsyn