garrytan/cron-scheduler

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}."

Multi-source brains: use sync --all, not per-source entries

When the brain has 2+ active sources (anything gbrain sources list shows with a non-null local_path that isn't archived), use one consolidated cron line instead of N per-source entries.

Preferred (multi-source):

*/5 * * * * gbrain sync --all --parallel 4 --workers 4 --skip-failed

This replaces N per-source lines AND auto-picks-up future sources without a crontab edit. Concurrency budget: parallel × workers × 2 ≈ 32 connections during the wave (each per-file worker opens its own 2-connection pool). Stay under your Postgres max_connections setting.

Avoid (legacy): separate gbrain sync --source default and gbrain sync --source zion-brain entries staggered by 5 minutes. They require manual deconfliction every time a new source is added, and a slow source can race a fast source on the legacy global gbrain-sync lock (v0.40.3.0+ uses per-source gbrain-sync:<sourceId> locks but the per-source cron pattern doesn't benefit from the parallelism that --all --parallel actually delivers).

gbrain doctor surfaces the recommended line as a sync_consolidation check whenever it detects 2+ active sources. Paste-ready from there.

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)
• Separate per-source gbrain sync --source <id> cron entries when gbrain sync --all --parallel N --workers N would replace them with one line that auto-picks-up future sources.