feat(cache): add build-tag-gated Redis cache backend

Add optional Redis cache support via `go build -tags redis`, following
the same paired-stub pattern as OTel and Tailscale. The Cache[V] interface
is unchanged; Redis and in-memory implementations are injected at startup
without altering usage logic.

- Add RedisCache[V] implementation with JSON serialization, fail-open on errors
- Add gateway_redis.go / gateway_redis_noop.go paired wiring files
- Refactor GroupWriterCache and ContextFileInterceptor to accept injected caches
- Add GOCLAW_REDIS_DSN env var, docker-compose.redis.yml overlay
- Update Dockerfile and GitHub Actions with ENABLE_REDIS build arg
- Add Redis variant to CI matrix (5 variants: latest, otel, tsnet, redis, full)

cmd/gateway.go

@@ -346,6 +346,10 @@ func runGateway() {
 		initOTelExporter(context.Background(), cfg, traceCollector)
 	}
 
+	// Redis cache: compiled via build tags. Build with 'go build -tags redis' to enable.
+	redisClient := initRedisClient(cfg)
+	defer shutdownRedis(redisClient)
+
 	// Wire cron retry config from config.json
 	cronRetryCfg := cfg.Cron.ToRetryConfig()
 	// Apply retry config via type assertion on the concrete cron store.
@@ -575,7 +579,7 @@ func runGateway() {
 	}
 
 	var mcpPool *mcpbridge.Pool
-	contextFileInterceptor, delegateMgr, mcpPool = wireExtras(pgStores, agentRouter, providerRegistry, msgBus, pgStores.Sessions, toolsReg, toolPE, skillsLoader, hasMemory, traceCollector, workspace, cfg.Gateway.InjectionAction, cfg, sandboxMgr, dynamicLoader)
+	contextFileInterceptor, delegateMgr, mcpPool = wireExtras(pgStores, agentRouter, providerRegistry, msgBus, pgStores.Sessions, toolsReg, toolPE, skillsLoader, hasMemory, traceCollector, workspace, cfg.Gateway.InjectionAction, cfg, sandboxMgr, dynamicLoader, redisClient)
 	if mcpPool != nil {
 		defer mcpPool.Stop()
 	}

cmd/gateway_managed.go

@@ -44,18 +44,22 @@ func wireExtras(
 	appCfg *config.Config,
 	sandboxMgr sandbox.Manager,
 	dynamicLoader *tools.DynamicToolLoader,
+	redisClient any, // nil when built without -tags redis or when Redis is unconfigured
 ) (*tools.ContextFileInterceptor, *tools.DelegateManager, *mcpbridge.Pool) {
-	// 1. Context file interceptor (created before resolver so callbacks can reference it)
+	// 1. Build cache instances (in-memory or Redis depending on build tags)
+	agentCtxCache, userCtxCache, gwCache := makeCaches(redisClient)
+
+	// 1a. Context file interceptor (created before resolver so callbacks can reference it)
 	var contextFileInterceptor *tools.ContextFileInterceptor
 	var delegateMgr *tools.DelegateManager
 	if stores.Agents != nil {
-		contextFileInterceptor = tools.NewContextFileInterceptor(stores.Agents, workspace)
+		contextFileInterceptor = tools.NewContextFileInterceptor(stores.Agents, workspace, agentCtxCache, userCtxCache)
 	}
 
 	// 1b. Group writer cache (wraps ListGroupFileWriters with TTL cache)
 	var groupWriterCache *store.GroupWriterCache
 	if stores.Agents != nil {
-		groupWriterCache = store.NewGroupWriterCache(stores.Agents)
+		groupWriterCache = store.NewGroupWriterCache(stores.Agents, gwCache)
 	}
 
 	// 2. User seeding callback: seeds per-user context files on first chat

cmd/gateway_redis.go

@@ -0,0 +1,56 @@
+//go:build redis
+
+package cmd
+
+import (
+	"log/slog"
+
+	"github.com/redis/go-redis/v9"
+
+	"github.com/nextlevelbuilder/goclaw/internal/cache"
+	"github.com/nextlevelbuilder/goclaw/internal/config"
+	"github.com/nextlevelbuilder/goclaw/internal/store"
+)
+
+// initRedisClient creates a Redis client when built with -tags redis.
+// Returns nil (typed as any) if GOCLAW_REDIS_DSN is empty or connection fails.
+func initRedisClient(cfg *config.Config) any {
+	dsn := cfg.Database.RedisDSN
+	if dsn == "" {
+		slog.Debug("Redis available but not configured (set GOCLAW_REDIS_DSN)")
+		return nil
+	}
+	client, err := cache.NewRedisClient(dsn)
+	if err != nil {
+		slog.Warn("Redis connection failed, falling back to in-memory cache", "error", err)
+		return nil
+	}
+	slog.Info("Redis cache connected")
+	return client
+}
+
+// makeCaches creates typed cache instances backed by Redis (or in-memory if client is nil).
+func makeCaches(raw any) (
+	agentCtxCache cache.Cache[[]store.AgentContextFileData],
+	userCtxCache cache.Cache[[]store.AgentContextFileData],
+	groupWriterCache cache.Cache[[]store.GroupFileWriterData],
+) {
+	client, _ := raw.(*redis.Client)
+	if client == nil {
+		slog.Info("cache backend: in-memory (Redis not connected)")
+		return cache.NewInMemoryCache[[]store.AgentContextFileData](),
+			cache.NewInMemoryCache[[]store.AgentContextFileData](),
+			cache.NewInMemoryCache[[]store.GroupFileWriterData]()
+	}
+	slog.Info("cache backend: redis")
+	return cache.NewRedisCache[[]store.AgentContextFileData](client, "ctx:agent"),
+		cache.NewRedisCache[[]store.AgentContextFileData](client, "ctx:user"),
+		cache.NewRedisCache[[]store.GroupFileWriterData](client, "grp:writers")
+}
+
+// shutdownRedis closes the Redis client connection.
+func shutdownRedis(raw any) {
+	if client, ok := raw.(*redis.Client); ok && client != nil {
+		client.Close()
+	}
+}

cmd/gateway_redis_noop.go

@@ -0,0 +1,30 @@
+//go:build !redis
+
+package cmd
+
+import (
+	"log/slog"
+
+	"github.com/nextlevelbuilder/goclaw/internal/cache"
+	"github.com/nextlevelbuilder/goclaw/internal/config"
+	"github.com/nextlevelbuilder/goclaw/internal/store"
+)
+
+// initRedisClient is a no-op when built without the "redis" tag.
+// Build with `go build -tags redis` to enable Redis cache.
+func initRedisClient(_ *config.Config) any { return nil }
+
+// makeCaches returns in-memory cache instances when Redis is not compiled in.
+func makeCaches(_ any) (
+	agentCtxCache cache.Cache[[]store.AgentContextFileData],
+	userCtxCache cache.Cache[[]store.AgentContextFileData],
+	groupWriterCache cache.Cache[[]store.GroupFileWriterData],
+) {
+	slog.Info("cache backend: in-memory")
+	return cache.NewInMemoryCache[[]store.AgentContextFileData](),
+		cache.NewInMemoryCache[[]store.AgentContextFileData](),
+		cache.NewInMemoryCache[[]store.GroupFileWriterData]()
+}
+
+// shutdownRedis is a no-op when built without the "redis" tag.
+func shutdownRedis(_ any) {}