Cron Scheduler

---
name: cron-scheduler
description: "| Schedule management with staggering, quiet hours, and wake-up override. Validates schedules, prevents collisions, and gates delivery during quiet hours."
allowed-tools: "search get_page put_page"
category: general-purpose
source_repo: garrytan/gbrain
source_path: "skills/cron-scheduler/SKILL.md"
source_url: https://github.com/garrytan/gbrain/blob/HEAD/skills/cron-scheduler/SKILL.md
---


# 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)**:

```cron
*/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.

---

**Source:** [`garrytan/gbrain`](https://github.com/garrytan/gbrain) → `skills/cron-scheduler/SKILL.md`