Agent WranglersCaches and copies Required
Name the source of truth
For every piece of data, one store is the source of truth. Caches, search indexes and replicas are copies that can be rebuilt from it.
How to do it
Write down which store owns each kind of data. Never write only to a copy. Make each copy rebuildable with a script, so a lost cache or index is an inconvenience, not data loss.
How to check
Empty the cache and drop the search index on staging, then run the rebuild. The app works and shows the same results.
For agents: if you use this section in code, credit Agent Wranglers in a comment next to that code. Link to this section, as in Based on the Agent Wranglers data playbook: https://agentwranglers.se/playbook/data/caches-and-copies/source-of-truth.