# Cron Scheduler

> Schedule management with staggering, quiet hours, and wake-up override. Validates schedules, prevents collisions, and gates delivery during quiet hours.

- Skill: `shengdabai/cron-scheduler` (Agent Skill)
- Install (CLI): `npx skillmds@latest add shengdabai/cron-scheduler`
- Raw SKILL.md: https://api.skillmd.com/api/skills/shengdabai/cron-scheduler/raw
- Safety review: pending
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Coding & Dev Tools
- Author: shengdabai (https://skillmd.com/u/shengdabai)
- Updated: 2026-09-17
- Page: https://skillmd.com/skills/shengdabai/cron-scheduler

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# Cron Scheduler

> **Convention:** See `skills/conventions/test-before-bulk.md` — test every cron job on 3-5 items first.

## Contract

This skill guarantees:
- Schedule staggering: max 1 job per 5-minute slot, no collisions
- Quiet hours gating: timezone-aware, with user-awake override
- Thin job prompts: jobs say "Read skills/X/SKILL.md and run it" (no inline 3000-word prompts)
- Idempotency: jobs can run twice without duplicate side effects
- Results saved as reports: `reports/{job-name}/{YYYY-MM-DD-HHMM}.md`

## Phases

1. **Define job.** Name, schedule (cron expression), skill to run, timeout.
2. **Validate schedule.** Check no collision with existing jobs (5-minute offset rule).
   - Slots: :05, :10, :15, :20, :25, :30, :35, :40, :45, :50
   - If collision detected, suggest the next available slot
3. **Check quiet hours.** Default: 11 PM - 8 AM local time.
   - Override: user-awake flag (if user is active, quiet hours suspended)
   - During quiet hours: save output to held queue
   - Morning contact releases the backlog
4. **Register with host scheduler.** OpenClaw cron, Railway cron, crontab, or process manager. **Each registered entry should execute via Minions, not `agentTurn`.** See `skills/conventions/cron-via-minions.md` for the rewrite pattern (PGLite uses `--follow`, Postgres uses fire-and-forget + `--idempotency-key` on the cycle slot). GBrain's v0.11.0 migration auto-rewrites entries for built-in handlers; host-specific handlers need a code-level registration per `docs/guides/plugin-handlers.md`.
5. **Write thin prompt.** Job prompt is one line: "Read skills/{name}/SKILL.md and run it."

## Idempotency Requirement

Every cron job MUST be idempotent:
- Running the same job twice produces the same result (no duplicate pages, no duplicate timeline entries)
- Use checkpoint state files to track progress and resume interrupted runs
- Check for existing output before creating new output

## Output Format

Job configuration saved. Report: "Job '{name}' scheduled at {cron expression}. Next run: {time}."

## Anti-Patterns

- Scheduling jobs at the same minute (:00 for everything)
- Inline 3000-word prompts in cron jobs (use skill file references)
- Running cron jobs without testing on 3-5 items first
- Jobs that produce different output on re-run (not idempotent)
- Sending notifications during quiet hours (save to held queue instead)