feat(java-spring): add java-cache skill

README.md

@@ -7,7 +7,7 @@ A Claude Code plugin marketplace with 3 focused plugins for Java developers. All
 | Plugin | Skills | Commands | Agents | Install when |
 |---|---|---|---|---|
 | `java-core` | 14 | 2 | `java-architect`, `java-build-resolver` | Every Java project |
-| `java-spring` | 8 | 2 | `java-spring-expert` | Spring Boot projects |
+| `java-spring` | 9 | 2 | `java-spring-expert` | Spring Boot projects |
 | `java-quality` | 3 | 1 | `java-security-reviewer`, `java-performance-reviewer`, `java-test-engineer` | Quality enforcement |
 
 ## Quick Setup (5 minutes)
@@ -77,6 +77,7 @@ Skills activate automatically based on context, or invoke them explicitly.
 | `/java-spring:java-openapi` | Generate or review OpenAPI/Swagger docs — `@Tag`, `@Operation`, `@Schema`, JWT auth scheme (springdoc v1/v2) |
 | `/java-spring:java-spring-ai` | Add AI features to Spring Boot — ChatClient, RAG, tool calling, memory (Spring AI 1.x / LangChain4J) |
 | `/java-spring:java-resilience` | Add Resilience4J patterns — circuit breaker, retry, rate limiter, bulkhead, timeout (Boot 2.x & 3.x) |
+| `/java-spring:java-cache` | Add or review Spring Cache — Caffeine (single-instance) or Redis (distributed), @Cacheable/@CacheEvict/@CachePut |
 
 ### java-quality
 

plugins/java-spring/skills/java-cache/SKILL.md

@@ -0,0 +1,110 @@
+---
+name: java-cache
+description: Use when the user asks to add caching, configure Redis or Caffeine cache, use @Cacheable/@CacheEvict/@CachePut, optimize repeated database or API calls, or review existing Spring Boot cache configuration.
+version: 1.0.0
+authors: [java-plugins contributors]
+tags: [java, spring-boot, cache, redis, caffeine, spring-cache]
+allowed-tools: [Read, Glob, Grep, Edit, Write]
+---
+
+# Spring Cache Skill
+
+Detect the cache provider in use, then apply the correct patterns.
+
+## Step 1 — Detect setup
+
+Check `pom.xml` or `build.gradle`:
+- `spring-boot-starter-data-redis` → Redis (Lettuce client by default)
+- `spring-boot-starter-cache` + `caffeine` → Caffeine (in-process)
+- `spring-boot-starter-cache` only → Simple (ConcurrentHashMap, dev only)
+- None present → offer to add (recommend Caffeine for single-instance, Redis for multi-instance/distributed)
+
+Check Spring Boot version:
+- Boot 3.x → Lettuce 6.x, Caffeine 3.x
+- Boot 2.x → Lettuce 5.x, Caffeine 2.x/3.x
+
+---
+
+## Mode: `review`
+
+User asks to review existing cache configuration. Check for:
+
+- [ ] `@EnableCaching` present on a `@Configuration` class — missing it silently disables all cache annotations
+- [ ] Cache names declared in `application.yml` with explicit TTL — no unnamed or unbounded caches
+- [ ] `@Cacheable` methods are on Spring-managed beans (not `private`, not called within the same class — proxy bypass)
+- [ ] Cache keys are deterministic — `@Cacheable(key = "#id")` not `#root.methodName` unless intentional
+- [ ] `@CacheEvict` present wherever data is mutated — missing eviction causes stale cache
+- [ ] `@CachePut` used to update cache on write — not a `@CacheEvict` + re-fetch pattern
+- [ ] Redis serialization configured — default JDK serialization is not readable/portable; use `GenericJackson2JsonRedisSerializer`
+- [ ] Redis TTL set — without `time-to-live`, entries never expire
+- [ ] Caffeine `maximumSize` set — without it, cache grows unbounded and causes OOM
+- [ ] Null values handled — `@Cacheable(unless = "#result == null")` to avoid caching nulls
+- [ ] Cache metrics exposed: `management.metrics.cache.instrument=true`
+
+---
+
+## Mode: `setup`
+
+User asks to add caching from scratch.
+
+### Caffeine (recommended for single-instance apps)
+1. Add `spring-boot-starter-cache` + `com.github.ben-manes.caffeine:caffeine`
+2. Add `@EnableCaching` to a `@Configuration` class
+3. Configure cache specs in `application.yml` — set `maximum-size` and `expire-after-write`
+4. Annotate service methods with `@Cacheable`, `@CacheEvict`, `@CachePut`
+
+### Redis (recommended for multi-instance / distributed)
+1. Add `spring-boot-starter-data-redis`
+2. Configure `spring.data.redis.host/port` (Boot 3.x) or `spring.redis.host/port` (Boot 2.x)
+3. Configure `RedisCacheConfiguration` bean — set TTL and use `GenericJackson2JsonRedisSerializer`
+4. Add `@EnableCaching` and annotate service methods
+
+See `references/patterns.md` for full configuration examples.
+
+---
+
+## Mode: `cacheable`
+
+User asks to cache the result of a method.
+
+1. Place `@Cacheable(cacheNames = "products", key = "#id")` on the service method
+2. The method must be on a Spring-managed bean and not `private`
+3. The method must not call itself (proxy bypass) — extract to a separate bean if needed
+4. Add `unless = "#result == null"` to avoid caching null results
+5. Ensure the return type is `Serializable` (Redis) or any object (Caffeine)
+6. Add a corresponding `@CacheEvict` on the update/delete method
+
+---
+
+## Mode: `evict`
+
+User asks to invalidate/evict cache entries on data changes.
+
+- `@CacheEvict(cacheNames = "products", key = "#id")` — evict a single entry on update/delete
+- `@CacheEvict(cacheNames = "products", allEntries = true)` — evict all entries (use sparingly)
+- `@CacheEvict(beforeInvocation = true)` — evict before method runs (use when method may throw)
+- For multi-cache eviction: `@Caching(evict = { @CacheEvict("products"), @CacheEvict("productList") })`
+
+---
+
+## Mode: `redis`
+
+User asks specifically for Redis cache configuration.
+
+1. Add `spring-boot-starter-data-redis`
+2. Configure connection: `spring.data.redis.host`, `spring.data.redis.port`, `spring.data.redis.password`
+3. Define `RedisCacheManager` bean with:
+   - `GenericJackson2JsonRedisSerializer` for values (human-readable, portable)
+   - `StringRedisSerializer` for keys
+   - Default TTL + per-cache TTL overrides
+4. Enable `@EnableCaching`
+5. For Redis Cluster: set `spring.data.redis.cluster.nodes`
+6. For Redis Sentinel: set `spring.data.redis.sentinel.master` and `nodes`
+
+---
+
+## Output format
+
+For **review mode**: list findings as `[CRITICAL] / [HIGH] / [MEDIUM] / [LOW]` with file:line references.
+
+For **implementation modes**: show exact Maven/Gradle dependency, full `application.yml` block, and complete Java configuration + annotated example. State minimum Spring Boot version where it differs.