Problem
context.test.parallel_js: multi-age cooperative nursery retains old-owner graph asserts that gc_cooperative_timeouts is exactly zero. The cooperative collector intentionally uses a bounded 100 ms rendezvous and retries after a peer misses that deadline. Under a 10-shard Debug unit run this assertion failed twice (expected 0, found 2) while the graph, collection, parking, promotion, cleanup, and denominator invariants all completed.
A nearby moving-nursery test already documents the scheduler-stable contract: every elected attempt has exactly one terminal outcome, so attempts == collections + timeouts; the retry count depends on host scheduling.
Evidence
- conservative 10-shard run: 1,530 passed, 1 expected platform skip, 1 failed, 0 leaked; 1,532/1,532 accounted; 608.7 s wall
- prior history-LPT warmup: same test and assertion failed (
expected 0, found 2) - successful multi-age collections, peer parks, promotion, final graph value, and clean collector/conductor state remained independently asserted
Acceptance
- Preserve the multi-age collection, promotion, peer-park, graph-integrity, and cleanup assertions.
- Assert exact cooperative terminal-outcome accounting relative to the test baseline instead of requiring zero bounded retries.
- Pass focused repeats and the complete sharded unit gate with exact denominator/leak accounting.