The instrument was over half this PR and the source of nearly every review
finding, and the benchmark that actually validates the perf work does not
depend on it: member-heavy-switch.perf.ts times click -> ready itself with
performance.now() and DOM readiness, and never reads a tracer export.
Its remaining value was a dev console line, against a failure mode of
reporting a number that never happened — which is worse than reporting
nothing, because it sends someone chasing a regression that does not exist.
The live baselines it produced are already recorded in the PR description
and stand on their own; they justified the fixes, and the fixes are the
deliverable.
Removed: channelSwitchPerf.ts and its tests, useChannelSwitchTraceMarks,
switch-settle-after-paint.spec.ts, the fetch attribution in the window
queryFn, the trace hooks in commitGuardedNavigation/useAppNavigation, and
the community-init reset.
Kept, because the perf fixes build on them:
- member-heavy-switch.perf.ts plus the inflateChannelMembers bridge knob —
the high-membership benchmark
- useChannelTimelineLoading — the per-channel loading latch
- commitGuardedNavigation — the shared guard/no-op commit flow
- the Projects hydration marker the harness gates readiness on
- routing Pulse note actions through goChannel, so that DM entry goes
through the same navigation guard as every other one
Signed-off-by: Max Lampert <maxwell@squareup.com>
8a8e01cfb0