cron-schedulinglisted

# Cron Scheduling Skill ## Domain Context **What is this skill?** This skill provides cron job architecture patterns for web applications: Inngest schedule integration, Vercel Cron configuration, retry logic, monitoring and alerting for failed crons, and idempotency requirements. Load when designing scheduled tasks, configuring cron triggers, debugging missed or duplicate executions, or implementing monitoring for recurring jobs. > A cron that runs twice is worse than a cron that doesn't run. Idempotency is not optional. ## Coverage This skill covers cron expression syntax and scheduling precision, Vercel Cron configuration (`vercel.json` cron routes), Inngest scheduled function patterns (cron triggers vs event-driven), idempotency guarantees for scheduled jobs, retry and failure handling for cron-triggered work, monitoring and alerting for missed or failed cron executions, timezone handling in cron schedules, and the decision framework for choosing between Vercel Cron, Inngest schedules, and external cron services. ## Philosophy Cron jobs are the most deceptively simple infrastructure in web applications. The expression `0 9 * * *` looks trivial, but the implementation must handle: what happens when the job runs twice (deploy overlap), what happens when the job fails silently (no monitoring), what happens when the job takes longer than the interval (overlap), and what happens at DST transitions (timezone drift). Every anti-pattern in this skill was observed in producti