Run a story from cron

The workflow behaviour: a story with a signature is a function, and yam workflow run prints its outputs on stdout as JSON so the command composes. The worked example, including the script a crontab line calls, is examples/cron/.

yam workflow run "Book a slot" --input location=Indiranagar | jq -r .booking

0 7 * * *  cd /srv/booking && ./book.sh >> /var/log/booking.log 2>&1

cron is the scheduler. Yam has none and will not: orchestration is external by design, so the boundary is an exit code and a run directory.

What makes it safe to leave running

• The environment policy. A story not marked idempotent is refused against a production configuration with exit 10 unless the caller passes --allow-side-effects. A scheduled job that books a slot has to have said, once, in the file, that it meant to.
• Checkpoints and audit are always on. A workflow that booked three of four slots cannot be re-run from the start. yam workflow run --resume <runId> --from <stepId> picks it up and refuses with exit 12 if the plan or the bindings moved since.
• Secrets come from the environment. YAM_INPUT_PASSWORD=… reaches the story, is redacted in every artifact, and never appears in the process list.
• Outputs come back even when the run failed. The exit code says whether it finished; the JSON says how far it got.

Exit codes a scheduled job branches on

Code	Meaning
0	finished, outputs on stdout
1	a step failed; partial outputs on stdout
6	finished, but a binding was healed on the way
10	refused: not idempotent against production
11	aborted under a compensation policy; the compensating story ran
12	resume refused: the plan or bindings changed since the checkpoint