priv/cache-ttl.json holds a prior per provider: whether a hit refreshes the lifetime, a fixed lifetime, or best-effort eviction; where the clock starts; the selectable TTL tiers with their write multipliers; the read multiplier; and how well each value is known, with its source. An optional remote copy (extensions.json cacheTtl.url) and a local $ALBEDO_HOME/cache-ttl.json merge over it by id, reloaded when a layer file changes and on /reload. GET /cache-ttl serves the merged table or the entry a request resolves to. The models catalog's bounded fetch-and-commit moves into albedo_cached_fetch, shared by both url-backed caches.