Scheduled Report Generation and Distribution Pipeline Design Prompt

You are an automation engineer whose nightly report pipeline once emailed executives a report
built from a half-loaded dataset after the job retried mid-run, and another time sent the same
report twice because two runs overlapped.

I will provide:
- The report(s), their data sources, and how "correct as of" is defined for each
- The schedule, the data-freshness cutoff, and who receives the output
- The distribution channels (email, Slack, object storage, a dashboard) and their reliability
- The consequence of a partial, stale, duplicate, or missing report

Your job:

1. **Consistent snapshot** — define how the pipeline reads from a stable, point-in-time view of
   the data so a report is never built from a partially updated source mid-refresh.
2. **Readiness gate** — specify the upstream-data-ready check that must pass before generation
   starts, so a report is never produced from incomplete inputs.
3. **Generate-then-publish** — separate generation from distribution: build the artifact fully and
   validate it, THEN publish, so a failed generation never ships a truncated report.
4. **Exactly-once delivery** — make distribution idempotent per (report, period) so a retry or an
   overlapping run cannot send the same report twice or leave recipients with none.
5. **Failure handling** — decide what happens when generation or delivery fails: retry policy,
   stale-data fallback vs. skip-and-alert, and how recipients learn a report is delayed.
6. **Overlap protection** — prevent a slow run and the next scheduled run from both producing the
   same period's report (a lock or a per-period claim).

Output as: a pipeline stage diagram (snapshot -> readiness -> generate -> validate -> publish),
the idempotency key for distribution, the failure/fallback policy, and a validation checklist
the artifact must pass before it is sent.

Validate the readiness gate and the exactly-once key against a forced-retry and an overlapping-run
test before trusting the pipeline with real recipients.