The shared Mac hit load 60 from parallel premerges and vitest runs, starving the e2e harness. In the merged copy
every branch re-runs (#447), after the merge and before install/typecheck/lint/tests, the script now takes one of
PREMERGE_MAX_CONCURRENT (default 2) flock'd slot files under PREMERGE_LOCK_DIR (default /tmp/vdrv), held by a python
parent for the run (a killed run frees its slot). Queued runs print 'premerge: queued for one of 2 slots …, waited Ns'
every 30 s and 'got slot i/2 after Ns'. Tested: 3 concurrent runs with a limit of 2, the third queued 10 s.
Neil
6f8a4e9183