Every wrong turn in this work came from trusting a number whose validity had
not been established: a throttled renderer reporting zero rendering work, a
trace category that was never enabled reporting zero long tasks, a scenario
that rendered nothing reporting a perfectly quiet profile, and an 'after'
measured without a matching 'before', which made a no-op change look like a
fix.
The performance skill now puts measurement validity ahead of measurement,
requires a baseline from the unchanged build through the identical scenario,
directs native work to the timeline trace rather than the sampler, requires
unvalidated changes to be reverted and recorded as rejected, and says when to
stop optimising a path that is already inside budget. It also points at the
repository's capture commands.
The sync skill gains the invariant behind the cache-thrash loop: an entry
acquired during render but protected only after commit is unprotected for the
whole render pass, capacity should be a soft target, eviction must not run on
the acquisition path, and raising a limit relocates a cliff instead of removing
it.
Bohdan Triapitsyn
d3576117da