Two crews finishing together in one project: the older run's writer could
reach the file after the newer one and leave the older run as "the last".
record_last_run now compares finished_at (recorded_at when absent) with
the record already there and keeps the later-finished run; the same run
recorded again (a refreshed grant) and a record without a comparable time
never block the run just finished. No lock file: the file is a convenience
pointer and the compare closes the ordering, leaving a microsecond window
between read and replace that two runs finishing in the same instant
could hit — either is then a fair "last run".
Test: the older writer replaces after the newer one; the newer stays.
88 passed.
Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
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