Address code review feedback - improve MongoDB compatibility, transaction isolation, and process cleanup

Co-authored-by: hotlong <50353452+hotlong@users.noreply.github.com>

Author: Copilot

packages/drivers/memory/src/index.ts

@@ -575,8 +575,12 @@ export class MemoryDriver implements Driver {
     async beginTransaction(): Promise<any> {
         const txId = `tx_${Date.now()}_${Math.random().toString(36).substring(7)}`;
 
-        // Create a snapshot of the current store
-        const snapshot = new Map(this.store);
+        // Create a deep snapshot of the current store to ensure complete transaction isolation
+        // This prevents issues with nested objects and arrays being modified during the transaction
+        const snapshot = new Map<string, any>();
+        for (const [key, value] of this.store.entries()) {
+            snapshot.set(key, JSON.parse(JSON.stringify(value)));
+        }
 
         const transaction: MemoryTransaction = {
             id: txId,
@@ -676,9 +680,11 @@ export class MemoryDriver implements Driver {
         }
 
         // Set up auto-save timer
+        // Use unref() to allow Node.js process to exit gracefully when idle
         this.persistenceTimer = setInterval(() => {
             this.saveToDisk();
         }, autoSaveInterval);
+        this.persistenceTimer.unref();
     }
 
     /**

packages/drivers/mongo/src/index.ts

@@ -545,8 +545,10 @@ export class MongoDriver implements Driver {
         const result = await collection.findOneAndUpdate(filter, update, mongoOptions);
 
         // Map MongoDB document to API format (convert _id to id)
-        // MongoDB's findOneAndUpdate returns { value: document } in newer versions
-        const doc = result?.value || result;
+        // MongoDB driver v5+ returns { value: document, ok: number }
+        // Older versions (v4) return the document directly
+        // We handle both for backward compatibility
+        const doc = result?.value !== undefined ? result.value : result;
         return doc ? this.mapFromMongo(doc) : null;
     }