050106-elysia-cache-tagslisted

# Elysia Cache Tags ## When to use When you need fine-grained cache invalidation beyond simple key-based TTL. Tags let you invalidate related cache entries in bulk. ## References | Topic | File | |---|---| | 3-level tag system | `references/tag-levels.md` | | Cache-aside with tags | `references/remember-with-tags.md` | | Invalidation chains | `references/invalidation-chains.md` | | Signed URL caching | `references/signed-url-cache.md` | ## Quick checklist - [ ] Level 1: entity-specific tag (`cache:tags:{domain}:{entityId}`) - [ ] Level 2: domain collection tag (`cache:tags:{domain}`) - [ ] Level 3: cross-domain tag (`cache:tags:cross:{scope}`) - [ ] Use `setWithTags(key, data, tags, ttl)` when storing cached values - [ ] Use `invalidateTags([tag1, tag2, ...])` to batch-invalidate - [ ] Tag sets TTL = 2x value TTL (ensures tags outlive their members) - [ ] For signed URLs, cache the URL for 3500s (just under the 3600s expiry)