stress (Haiku, Opus 5.5/High reviewer): 5/5 pass, 0 product defects.
h1 4 writers same project, no race, hashes consistent (npm test 5 failures are seed's planted bugs); h2 12/12 in 17 s, no cross-talk (no 429 seen); h3 8/8 all tests pass; h4 lock refused r2 cleanly, one linear history, lock released; h5 5 queued turns in order, files right.
HARNESS FIX: rapid mode never sent /session-controls, so h5 ran at default permission + medium effort; driver now queues it before the burst.
