The coverage lane's wall clock was pinned by a few compiler- and
subprocess-bound suites whose v8 instrumentation tax is a multiple of
their runtime while contributing nothing the per-file thresholds need:
typert generator fixtures (whole-workspace compiler analysis; its src is
threshold-excluded) and three scripts/ child-process fixture suites
(scripts/ sources are never coverage-measured; in-process imports are
covered by their owning package tests).
Split ci-coverage into two parallel gates: the instrumented run sets
DSH_COVERAGE_EXEMPT_HEAVY=1 and vitest.config.ts drops the exempt suites
from both projects (CLI --exclude cannot reach per-project include
resolution); a second uninstrumented gate runs exactly those suites, so
the aggregate still executes every test. Membership contract and the
filter/exclude pairs live in scripts/coverage-exempt.ts.
Local 6-worker A/B: instrumented gate 900s -> 260s wall; exempt gate
262s wall runs beside it, so the lane converges near the slower of the
two (~4.4min vs ~7min single-gate). DSH_GATE_CONCURRENCY now has two
schedulable gates in this lane.
