Save working versions
Presently store working configurations, index settings, rules and model choices with clear version numbers. Determine what combinations belong together. This prevents old code from coming back while maintaining an incompatible index.
Preparing Index Changes
Schedule changes are often harder to reverse than code. Work with individual index versions and a controlled switch where possible. Before removing a previous version, check that it is no longer necessary as a safe relapse.
Disable rules separately
Make ranking, merchandising and AI changes as independently as possible. A problem in one line does not have to reverse a complete release. Take caches and the time needed before a shutdown has any effect anywhere.
Criteria and Exercise
Before live, record which signals directly justify resigning and who makes the decision. Test the procedure periodically and measure the recovery time. A recovery plan that has never been implemented often contains unknown dependencies.