Cache Invalidation Policy

Caching introduces an obligation to know when the cache is wrong. Time-based expiry is simple and crude — it discards good answers on schedule while leaving bad ones valid until the timer runs. Source-based invalidation is correct and requires knowing which records an answer derived from, which is only possible if that derivation was recorded. The failure mode of getting this wrong is specific: an answer that remains fluent and cited while describing a policy that has since been amended.

Centralpoint records which sources a governed answer was built from, so invalidation follows the sources rather than a timer. When a record moves to a new version, the answers derived from its predecessor are identifiable by that link, which turns cache correctness into a lifecycle question rather than a scheduling one.