fix(core): improve shutdown cleanup, socket/stream robustness, and memory/cache handling

ts/security/classes.contentscanner.ts

@@ -182,7 +182,14 @@ export class ContentScanner {
     }
     return ContentScanner.instance;
   }
-  
+
+  /**
+   * Reset the singleton instance (for shutdown/testing)
+   */
+  public static resetInstance(): void {
+    ContentScanner.instance = undefined;
+  }
+
   /**
    * Scan an email for malicious content
    * @param email The email to scan

ts/security/classes.ipreputationchecker.ts

@@ -65,6 +65,8 @@ export class IPReputationChecker {
   private reputationCache: LRUCache<string, IReputationResult>;
   private options: Required<IIPReputationOptions>;
   private storageManager?: any; // StorageManager instance
+  private saveCacheTimer: ReturnType<typeof setTimeout> | null = null;
+  private static readonly SAVE_CACHE_DEBOUNCE_MS = 30_000;
   
   // Default DNSBL servers
   private static readonly DEFAULT_DNSBL_SERVERS = [
@@ -143,7 +145,20 @@ export class IPReputationChecker {
     }
     return IPReputationChecker.instance;
   }
-  
+
+  /**
+   * Reset the singleton instance (for shutdown/testing)
+   */
+  public static resetInstance(): void {
+    if (IPReputationChecker.instance) {
+      if (IPReputationChecker.instance.saveCacheTimer) {
+        clearTimeout(IPReputationChecker.instance.saveCacheTimer);
+        IPReputationChecker.instance.saveCacheTimer = null;
+      }
+    }
+    IPReputationChecker.instance = undefined;
+  }
+
   /**
    * Check an IP address's reputation
    * @param ip IP address to check
@@ -213,12 +228,9 @@ export class IPReputationChecker {
       // Update cache with result
       this.reputationCache.set(ip, result);
       
-      // Save cache if enabled
+      // Schedule debounced cache save if enabled
       if (this.options.enableLocalCache) {
-        // Fire and forget the save operation
-        this.saveCache().catch(error => {
-          logger.log('error', `Failed to save IP reputation cache: ${error.message}`);
-        });
+        this.debouncedSaveCache();
       }
       
       // Log the reputation check
@@ -447,6 +459,21 @@ export class IPReputationChecker {
     });
   }
   
+  /**
+   * Schedule a debounced cache save (at most once per SAVE_CACHE_DEBOUNCE_MS)
+   */
+  private debouncedSaveCache(): void {
+    if (this.saveCacheTimer) {
+      return; // already scheduled
+    }
+    this.saveCacheTimer = setTimeout(() => {
+      this.saveCacheTimer = null;
+      this.saveCache().catch(error => {
+        logger.log('error', `Failed to save IP reputation cache: ${error.message}`);
+      });
+    }, IPReputationChecker.SAVE_CACHE_DEBOUNCE_MS);
+  }
+
   /**
    * Save cache to disk or storage manager
    */

ts/security/classes.securitylogger.ts

@@ -83,7 +83,14 @@ export class SecurityLogger {
     }
     return SecurityLogger.instance;
   }
-  
+
+  /**
+   * Reset the singleton instance (for shutdown/testing)
+   */
+  public static resetInstance(): void {
+    SecurityLogger.instance = undefined;
+  }
+
   /**
    * Log a security event
    * @param event The security event to log