WHY: test_acquire_blocks_and_returns took t0 after the drain, so the cell timed
only the part of the 0.05 s refill that happened after the scheduler returned to
it. Observed red in a loaded full-suite run at 7c36185:
'assert 0.03909331373870373 >= 0.04' -- 10.9 ms of untimed prefix. Deterministic
repro: pre-fix cell + 11 ms injected gap -> 0.03897/0.03912, rc 1.
FIX: t0 now precedes try_acquire(1.0), which is where the bucket sets _last, so
dt is >= 0.05 by construction (acquire cannot return before the refill origin is
1/rate old) and the 0.04 floor has ~10 ms of margin instead of 1 ms.
MEASURED: repo cell 9 passed; pre control rc 1 dt 0.03897-0.03912; post control
rc 0; same-gap in-process dt pre 0.039119 / post 0.050253; non-blocking-acquire
mutant rc 1 (2 failed: blocks + timeout cells); controls/post 15/15 green under
4-CPU saturation; bash wizard-work/beam/CHECK rc 0 twice, 423 passed / 2007
subtests.
CHECK: python3 /root/.hermes/wizard-outputs/volt/2026-10-28-q122/verify.py
ledger
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