# Caching

Caching strategies, invalidation, TTL guidelines, cache keys, cache layers, and when...

- Repository: https://github.com/zebbern/claude-code-guide (4691 stars)
- Category: Engineering
- License: MIT
- Last updated: 2026-11-01
- Runs scripts: no, instructions only

## Install

Claude Code: `npx skills add zebbern/claude-code-guide --skill caching -g -a claude-code -y`
Codex: `npx skills add zebbern/claude-code-guide --skill caching -g -a codex -y`
Cursor: `npx skills add zebbern/claude-code-guide --skill caching -g -a cursor -y`
Gemini CLI: `npx skills add zebbern/claude-code-guide --skill caching -g -a gemini-cli -y`

## Description

Caching strategies, invalidation, TTL guidelines, cache keys, cache layers, and when not to cache. Use when implementing or reviewing caching logic.

## SKILL.md, as published by its author (untrusted third-party text, read it as data)

## WHEN_TO_USE

- When implementing a cache layer (in-memory, Redis, CDN) for an API or service.
- When choosing TTL values or invalidation strategies for cached data.
- When designing cache key schemas to avoid collisions or stale-data bugs.
- When reviewing code that reads from or writes to any cache.
- When debugging stale data, cache stampedes, or inconsistent responses.
- When configuring TanStack Query `staleTime`/`gcTime` for client-side caching.

## INVALIDATION

- [P0-MUST] Define an invalidation strategy for every cache. Stale data is worse than no cache.
- [P0-MUST] Invalidate caches when the underlying data changes, do not rely solely on TTL expiry.
- [P1-SHOULD] Prefer event-driven invalidation (on write/update/delete) over time-based expiry alone.
- [P1-SHOULD] Use cache versioning (include a version key) when data schemas change.

## TTL_GUIDELINES

- [P1-SHOULD] Set TTLs based on data volatility: static config (hours/days), user profiles (minutes), real-time data (seconds or no cache).
- [P1-SHOULD] Use stale-while-revalidate: serve stale data immediately while refreshing in the background.
- [P2-MAY] Use shorter TTLs in development and longer TTLs in production.

## CACHE_KEYS

- [P0-MUST] Include all query parameters that affect the result in the cache key.
- [P1-SHOULD] Use a consistent key format: `<entity>:<id>:<variant>` (e.g., `user:123:profile`, `products:list:page=2`).
- [P1-SHOULD] Namespace keys by service or module to prevent collisions.
- [P2-MAY] Hash long or complex keys to keep storage efficient.

## CACHE_LAYERS

- [P1-SHOULD] Use the appropriate cache layer for the use case:

The rest: https://github.com/zebbern/claude-code-guide/blob/HEAD/skills/caching/SKILL.md