Two patterns that keep a real ~1,000-page PHP site alive on shared cPanel hosting - no shell, no SSH, no cron. Everything below runs in your browser as a simulation of the production pattern. Code: lazy-cron · guarded-deploy-workers
A worker is one PHP file uploaded to the web root and hit with a secret token. Pick a scenario and run it - the abort and rollback paths are the feature.
Every simulated request passes the job queue. The first request after a window opens claims it with one conditional UPDATE; concurrent requests hit the lock and move on. Fast-forward to see idle traffic self-heal a missed window.