The sharded runner spawned every shard regardless of diff; only the
child self-skipped, so a typical single-skill change still paid 44 Bun
boots + container-equivalent setup for shards with zero selected tests.
The parent now computes selection once (mirroring e2e-helpers exactly:
EVALS_ALL -> run-all, empty union -> run-all, git errors propagate the
fail-closed throw) and drops shards where no selected test name maps in.
Mapping = quoted E2E map keys in the file's source UNION keys whose dep
list registers the file (constructed-name families need the second
direction). FAIL-OPEN everywhere it matters: run-all, non-skill-e2e
files, unreadable source, zero mapped names all keep the shard — the
child filter stays authoritative, so a parent bug can only run extra.
New taxonomy status skipped-by-diff (never conflated with
never-started); selection banner prints once; --list is selection-aware.
C6 lands in the same commit: a HARD tier-alignment test — every paid
skill-e2e file must be parent-mappable or provably fail-open-safe.
Note: this change-set's 14 dep-list registrations in touchfiles-data.ts
rode along in f945c841 (concurrent-agent staging); they belong to this
change logically.
Demo: selection of one test -> 'running 3 of 44 shards, 41
skipped-by-diff'. 13 new $0 tests via injected seams.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
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