feat: validate eviction policy in cache config (#223)

Signed-off-by: cryo <[email protected]>
Co-authored-by: Huamin Chen <[email protected]>

Author: cryo-zd

src/semantic-router/pkg/cache/cache_factory.go

@@ -74,6 +74,13 @@ func ValidateCacheConfig(config CacheConfig) error {
 		if config.MaxEntries < 0 {
 			return fmt.Errorf("max_entries cannot be negative for in-memory cache, got: %d", config.MaxEntries)
 		}
+		// Validate eviction policy
+		switch config.EvictionPolicy {
+		case "", FIFOEvictionPolicyType, LRUEvictionPolicyType, LFUEvictionPolicyType:
+			// "" is allowed, treated as FIFO by default
+		default:
+			return fmt.Errorf("unsupported eviction_policy: %s", config.EvictionPolicy)
+		}
 	case MilvusCacheType:
 		if config.BackendConfigPath == "" {
 			return fmt.Errorf("backend_config_path is required for Milvus cache backend")

src/semantic-router/pkg/cache/cache_test.go

@@ -220,6 +220,7 @@ development:
 					SimilarityThreshold: 0.8,
 					MaxEntries:          1000,
 					TTLSeconds:          3600,
+					EvictionPolicy:      "lru",
 				}
 
 				err := cache.ValidateCacheConfig(config)
@@ -294,6 +295,21 @@ development:
 				Expect(err.Error()).To(ContainSubstring("max_entries cannot be negative"))
 			})
 
+			It("should return error for unsupported eviction_policy value in memory backend", func() {
+				config := cache.CacheConfig{
+					BackendType:         cache.InMemoryCacheType,
+					Enabled:             true,
+					SimilarityThreshold: 0.8,
+					MaxEntries:          1000,
+					TTLSeconds:          3600,
+					EvictionPolicy:      "random", // unsupported
+				}
+
+				err := cache.ValidateCacheConfig(config)
+				Expect(err).To(HaveOccurred())
+				Expect(err.Error()).To(ContainSubstring("unsupported eviction_policy"))
+			})
+
 			It("should return error for Milvus backend without config path", func() {
 				config := cache.CacheConfig{
 					BackendType:         cache.MilvusCacheType,