Cron Scheduling

Handles cron expressions and scheduled tasks across node-cron, Spring @Scheduled, and Python's APScheduler. The skill covers the standard five-field cron syntax, timezone handling, and crucially, distributed locking patterns with Redlock and ShedLock to prevent duplicate runs when you're running multiple instances. It's opinionated about separating concerns: use this for time-based scheduling, but reach for job queues when you need worker-based processing or one-off delayed tasks. The anti-patterns section is genuinely useful, calling out things like missing error handling and hardcoded schedules that will bite you in production.