Address the three findings from the 2026-08-24 re-review of #6455, plus
one finding from a follow-up adversarial review:
- The switch trace now opens inside commitGuardedNavigation, only after
the navigation guard accepts — a refused click can no longer leave an
orphan trace that a later history navigation would settle with
inflated time. The commit flow is extracted and dependency-injected;
new unit tests pin guard ordering and the refusal→history-back case.
- The perf-log 4 KiB cap now bounds bytes on disk: one byte is reserved
for the newline writeln! appends. New boundary test measures the file.
- The channel↔Projects benchmark gates readiness on a new
data-projects-hydrating marker (driven by the surface's query fan via
isLoading, so disabled queries never wedge it) instead of the shell
header, verifies member inflation on both inflated channels, uses a
prefixed ready-selector for general, and reports each switch direction
as its own median so a one-leg regression cannot hide.
- A settle wait that hits its 5s deadline while the render is still
pending now records with settleWaitTruncated instead of posing as an
honest settled paint — the >deadline tail is what the tracer exists
to expose. Also removes the dead ChannelSwitchFetchTrace type.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Signed-off-by: Max Lampert <maxwell@squareup.com>
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