Engine (scripts/lib/shard-engine.ts) gains the W2 primitives: per-shard
tmp/Chromium sandbox + async cleanup backstop, log-path allocation and
full-stream log capture, one duration-seed reader/writer with a lane
predicate, LanePolicy (seed predicate + zero-execution verdict),
strictShardStatus, and the shared CLI flag loop. runShardChild takes an
optional companion (signal/settle) and waits a bounded 250ms to reap a
wall-killed child.
Free lane stops spawning shards itself: runFreeShard uses runShardChild
with trackShardBrowser as the companion (win32 path unchanged: no process
group, no negative-pid kill). Its sync state-dir removal stays lane policy.
Paid lane uses the sandbox, log, seed, verdict and flag primitives; the
hollow-shard guard applies PAID_LANE_POLICY. Lane outcomes are unchanged
(free keeps >= 0 seeds and file-count zero-exec rule; paid keeps > 0 seeds,
warning under selection and passed-empty under EVALS_ALL).
paid-free-boundary's closure assertion now names the engine module, where
the strict classifier lives.
The shared shard engine grows from the existing strict-output module
(runShardChild, killProcessGroup, signal forwarding, strict classifier).
scripts/test-strict-output.ts stays as a re-export so existing importers,
mock.module paths and the strict-output/run-shard-child tests are unchanged.
The engine inherits the global touchfile entry; the free runner's CLI-routing
fixture copies the new module.
garrytan