diff --git a/internal/api/handlers/management/handler.go b/internal/api/handlers/management/handler.go
index d3ccbda6..613c9841 100644
--- a/internal/api/handlers/management/handler.go
+++ b/internal/api/handlers/management/handler.go
@@ -24,8 +24,15 @@ import (
 type attemptInfo struct {
 	count        int
 	blockedUntil time.Time
+	lastActivity time.Time // track last activity for cleanup
 }
 
+// attemptCleanupInterval controls how often stale IP entries are purged
+const attemptCleanupInterval = 1 * time.Hour
+
+// attemptMaxIdleTime controls how long an IP can be idle before cleanup
+const attemptMaxIdleTime = 2 * time.Hour
+
 // Handler aggregates config reference, persistence path and helpers.
 type Handler struct {
 	cfg                 *config.Config
@@ -47,7 +54,7 @@ func NewHandler(cfg *config.Config, configFilePath string, manager *coreauth.Man
 	envSecret, _ := os.LookupEnv("MANAGEMENT_PASSWORD")
 	envSecret = strings.TrimSpace(envSecret)
 
-	return &Handler{
+	h := &Handler{
 		cfg:                 cfg,
 		configFilePath:      configFilePath,
 		failedAttempts:      make(map[string]*attemptInfo),
@@ -57,6 +64,38 @@ func NewHandler(cfg *config.Config, configFilePath string, manager *coreauth.Man
 		allowRemoteOverride: envSecret != "",
 		envSecret:           envSecret,
 	}
+	h.startAttemptCleanup()
+	return h
+}
+
+// startAttemptCleanup launches a background goroutine that periodically
+// removes stale IP entries from failedAttempts to prevent memory leaks.
+func (h *Handler) startAttemptCleanup() {
+	go func() {
+		ticker := time.NewTicker(attemptCleanupInterval)
+		defer ticker.Stop()
+		for range ticker.C {
+			h.purgeStaleAttempts()
+		}
+	}()
+}
+
+// purgeStaleAttempts removes IP entries that have been idle beyond attemptMaxIdleTime
+// and whose ban (if any) has expired.
+func (h *Handler) purgeStaleAttempts() {
+	now := time.Now()
+	h.attemptsMu.Lock()
+	defer h.attemptsMu.Unlock()
+	for ip, ai := range h.failedAttempts {
+		// Skip if still banned
+		if !ai.blockedUntil.IsZero() && now.Before(ai.blockedUntil) {
+			continue
+		}
+		// Remove if idle too long
+		if now.Sub(ai.lastActivity) > attemptMaxIdleTime {
+			delete(h.failedAttempts, ip)
+		}
+	}
 }
 
 // NewHandler creates a new management handler instance.
@@ -149,6 +188,7 @@ func (h *Handler) Middleware() gin.HandlerFunc {
 					h.failedAttempts[clientIP] = aip
 				}
 				aip.count++
+				aip.lastActivity = time.Now()
 				if aip.count >= maxFailures {
 					aip.blockedUntil = time.Now().Add(banDuration)
 					aip.count = 0
diff --git a/internal/cache/signature_cache.go b/internal/cache/signature_cache.go
index c1326629..d4a864e0 100644
--- a/internal/cache/signature_cache.go
+++ b/internal/cache/signature_cache.go
@@ -26,11 +26,17 @@ const (
 
 	// MinValidSignatureLen is the minimum length for a signature to be considered valid
 	MinValidSignatureLen = 50
+
+	// SessionCleanupInterval controls how often stale sessions are purged
+	SessionCleanupInterval = 10 * time.Minute
 )
 
 // signatureCache stores signatures by sessionId -> textHash -> SignatureEntry
 var signatureCache sync.Map
 
+// sessionCleanupOnce ensures the background cleanup goroutine starts only once
+var sessionCleanupOnce sync.Once
+
 // sessionCache is the inner map type
 type sessionCache struct {
 	mu      sync.RWMutex
@@ -45,6 +51,9 @@ func hashText(text string) string {
 
 // getOrCreateSession gets or creates a session cache
 func getOrCreateSession(sessionID string) *sessionCache {
+	// Start background cleanup on first access
+	sessionCleanupOnce.Do(startSessionCleanup)
+
 	if val, ok := signatureCache.Load(sessionID); ok {
 		return val.(*sessionCache)
 	}
@@ -53,6 +62,40 @@ func getOrCreateSession(sessionID string) *sessionCache {
 	return actual.(*sessionCache)
 }
 
+// startSessionCleanup launches a background goroutine that periodically
+// removes sessions where all entries have expired.
+func startSessionCleanup() {
+	go func() {
+		ticker := time.NewTicker(SessionCleanupInterval)
+		defer ticker.Stop()
+		for range ticker.C {
+			purgeExpiredSessions()
+		}
+	}()
+}
+
+// purgeExpiredSessions removes sessions with no valid (non-expired) entries.
+func purgeExpiredSessions() {
+	now := time.Now()
+	signatureCache.Range(func(key, value any) bool {
+		sc := value.(*sessionCache)
+		sc.mu.Lock()
+		// Remove expired entries
+		for k, entry := range sc.entries {
+			if now.Sub(entry.Timestamp) > SignatureCacheTTL {
+				delete(sc.entries, k)
+			}
+		}
+		isEmpty := len(sc.entries) == 0
+		sc.mu.Unlock()
+		// Remove session if empty
+		if isEmpty {
+			signatureCache.Delete(key)
+		}
+		return true
+	})
+}
+
 // CacheSignature stores a thinking signature for a given session and text.
 // Used for Claude models that require signed thinking blocks in multi-turn conversations.
 func CacheSignature(sessionID, text, signature string) {
diff --git a/internal/runtime/executor/cache_helpers.go b/internal/runtime/executor/cache_helpers.go
index 5272686b..b6de886d 100644
--- a/internal/runtime/executor/cache_helpers.go
+++ b/internal/runtime/executor/cache_helpers.go
@@ -1,10 +1,68 @@
 package executor
 
-import "time"
+import (
+	"sync"
+	"time"
+)
 
 type codexCache struct {
 	ID     string
 	Expire time.Time
 }
 
-var codexCacheMap = map[string]codexCache{}
+// codexCacheMap stores prompt cache IDs keyed by model+user_id.
+// Protected by codexCacheMu. Entries expire after 1 hour.
+var (
+	codexCacheMap = make(map[string]codexCache)
+	codexCacheMu  sync.RWMutex
+)
+
+// codexCacheCleanupInterval controls how often expired entries are purged.
+const codexCacheCleanupInterval = 15 * time.Minute
+
+// codexCacheCleanupOnce ensures the background cleanup goroutine starts only once.
+var codexCacheCleanupOnce sync.Once
+
+// startCodexCacheCleanup launches a background goroutine that periodically
+// removes expired entries from codexCacheMap to prevent memory leaks.
+func startCodexCacheCleanup() {
+	go func() {
+		ticker := time.NewTicker(codexCacheCleanupInterval)
+		defer ticker.Stop()
+		for range ticker.C {
+			purgeExpiredCodexCache()
+		}
+	}()
+}
+
+// purgeExpiredCodexCache removes entries that have expired.
+func purgeExpiredCodexCache() {
+	now := time.Now()
+	codexCacheMu.Lock()
+	defer codexCacheMu.Unlock()
+	for key, cache := range codexCacheMap {
+		if cache.Expire.Before(now) {
+			delete(codexCacheMap, key)
+		}
+	}
+}
+
+// getCodexCache retrieves a cached entry, returning ok=false if not found or expired.
+func getCodexCache(key string) (codexCache, bool) {
+	codexCacheCleanupOnce.Do(startCodexCacheCleanup)
+	codexCacheMu.RLock()
+	cache, ok := codexCacheMap[key]
+	codexCacheMu.RUnlock()
+	if !ok || cache.Expire.Before(time.Now()) {
+		return codexCache{}, false
+	}
+	return cache, true
+}
+
+// setCodexCache stores a cache entry.
+func setCodexCache(key string, cache codexCache) {
+	codexCacheCleanupOnce.Do(startCodexCacheCleanup)
+	codexCacheMu.Lock()
+	codexCacheMap[key] = cache
+	codexCacheMu.Unlock()
+}
diff --git a/internal/runtime/executor/codex_executor.go b/internal/runtime/executor/codex_executor.go
index 0788e4f1..8e7c8df9 100644
--- a/internal/runtime/executor/codex_executor.go
+++ b/internal/runtime/executor/codex_executor.go
@@ -457,14 +457,14 @@ func (e *CodexExecutor) cacheHelper(ctx context.Context, from sdktranslator.Form
 	if from == "claude" {
 		userIDResult := gjson.GetBytes(req.Payload, "metadata.user_id")
 		if userIDResult.Exists() {
-			var hasKey bool
 			key := fmt.Sprintf("%s-%s", req.Model, userIDResult.String())
-			if cache, hasKey = codexCacheMap[key]; !hasKey || cache.Expire.Before(time.Now()) {
+			var ok bool
+			if cache, ok = getCodexCache(key); !ok {
 				cache = codexCache{
 					ID:     uuid.New().String(),
 					Expire: time.Now().Add(1 * time.Hour),
 				}
-				codexCacheMap[key] = cache
+				setCodexCache(key, cache)
 			}
 		}
 	} else if from == "openai-response" {
diff --git a/internal/usage/logger_plugin.go b/internal/usage/logger_plugin.go
index e4371e8d..38177d7d 100644
--- a/internal/usage/logger_plugin.go
+++ b/internal/usage/logger_plugin.go
@@ -87,6 +87,10 @@ type modelStats struct {
 	Details       []RequestDetail
 }
 
+// maxDetailsPerModel limits the number of request details retained per model
+// to prevent unbounded memory growth. Oldest entries are dropped when exceeded.
+const maxDetailsPerModel = 1000
+
 // RequestDetail stores the timestamp and token usage for a single request.
 type RequestDetail struct {
 	Timestamp time.Time  `json:"timestamp"`
@@ -221,6 +225,11 @@ func (s *RequestStatistics) updateAPIStats(stats *apiStats, model string, detail
 	modelStatsValue.TotalRequests++
 	modelStatsValue.TotalTokens += detail.Tokens.TotalTokens
 	modelStatsValue.Details = append(modelStatsValue.Details, detail)
+	// Prevent unbounded growth by dropping oldest entries when limit exceeded
+	if len(modelStatsValue.Details) > maxDetailsPerModel {
+		excess := len(modelStatsValue.Details) - maxDetailsPerModel
+		modelStatsValue.Details = modelStatsValue.Details[excess:]
+	}
 }
 
 // Snapshot returns a copy of the aggregated metrics for external consumption.