RADIANCE_CALIB_TOKENS=12000000 is a pooled floor and calib-7168.jsonl carries 10.03M tokens, so
round 1 of a corpus push seals nothing by construction. The gate PR #84 added failed exactly
there, one round too early, while the drain was already running.
Now round_verdict() separates the cases: 'shrink' (the tap lost bytes) fails the run, 'flat' says
so and continues, 'grew' continues, 'done' stops. A run that never sees the engine's completion
line still exits non-zero on max rounds, and the rig marker remains the lock that stops a push
into anything that is not the rig.
Test: round_verdict's four verdicts, behaviorally.
Frank