A repeated task needs two different clocks: the scheduled invocation time and the period of data the run examines. Record a named time zone, the user's intended local hour, the window start and end, and how to handle late-arriving records. Calendar time and a fixed number of elapsed hours are different contracts. Daylight-saving changes, holidays, and missed runs can alter what 'yesterday' means. The prompt should receive resolved timestamps from the scheduler or application, then state them in the output. It must not calculate an authoritative billing or operations window by guessing from the model's own clock.
Make this comfortable
Recurring prompts: bind local time and data windows
Operational case
North Pier's review runs at 08:15 in the depot's local time. The reporting window ends at the previous local midnight, so an 08:15 run does not silently include morning updates that have not yet settled. A late scan may arrive after the cutoff; the next run marks it as a revision to an earlier window rather than quietly rewriting yesterday's report. The application supplies the exact start and end instants and the time-zone identifier. If the schedule misses a day, the run reports the uncovered interval before computing changes.
Local schedule: 08:15, depot time zone.
Resolved data window: [start instant, end instant).
Late scan: label as revision to prior window.
Missed run: identify uncovered interval before comparison.
Every report prints resolved cutoff and invocation time.Performance and operating cost
Window filtering is O(N) without an index on event time and closer to O(log N + W) for W matching events with a suitable index. Explicit time windows add a small amount of prompt text but prevent costly duplicate or missing record reviews. A zero-length or overlapping interval is a validation error. Test local-time transitions against the actual scheduler because providers differ in how they handle a clock hour that is skipped or repeated.
Common Mistakes
- Do not use the model's current date as the only source of a reporting cutoff.
- Do not assume a daily schedule always spans exactly 24 elapsed hours.
- Do not hide a missed interval behind a normal-looking report.
Connected lessons
- Prompt engineering applications
- Prompt Engineering
- Research prompts: bind claims to a date and evidence record
- Retrieved evidence: reconcile versions and conflicting facts
- Incident impact: window, denominator, and scope
- Recurring prompts: define the trigger and stop condition
- Recurring prompts: validate fresh inputs and empty states
- Recurring prompts: survive retries without duplicate effects
- Recurring prompts: notify only on actionable changes
- Recurring prompts: renew authority for sensitive actions
- Recurring prompts: make every run replayable and auditable
- Project: build a North Pier recurring review
- Recurring prompt workflow decisions
Continue with: Calendar prompts: resolve availability, zone, and duration.
prompt engineering
recurring workflows