_submit_with_guard persists a `claimed` receipt before the worker runs, and
run_one_job only owns the terminal writes once it starts. Two exits in
between left the row `claimed` forever (a permanently in-flight attempt
for a run that never happened): a fire claim raising anything other than
OSError in _process_due_job, and a failure in _submit_with_guard after
create_execution returned (note_cron_execution, context copy). Both now
close the receipt through a best-effort settle_unstarted_execution in
cron/executions.py (the ledger owner; scheduler.py is a capped facade); the
claim failure still re-raises so the real error surfaces.
Co-authored-by: PRELVAS94 <86016656+PRELVAS94@users.noreply.github.com>
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