diff --git a/app/api/cron/blockchain-sync/route.ts b/app/api/cron/blockchain-sync/route.ts
new file mode 100644
index 0000000..6622fc3
--- /dev/null
+++ b/app/api/cron/blockchain-sync/route.ts
@@ -0,0 +1,25 @@
+import { NextResponse } from "next/server";
+import { BlockchainSyncService } from "@/lib/blockchain-sync.service";
+
+export const maxDuration = 300; // max Vercel timeout 5 minutes
+
+export async function GET(request: Request) {
+  try {
+    // Optionally verify cron secret here if configured
+    const authHeader = request.headers.get("authorization");
+    if (
+      process.env.CRON_SECRET &&
+      authHeader !== `Bearer ${process.env.CRON_SECRET}`
+    ) {
+      return new NextResponse("Unauthorized", { status: 401 });
+    }
+
+    const service = new BlockchainSyncService();
+    await service.runSyncJob();
+
+    return NextResponse.json({ success: true });
+  } catch (error) {
+    console.error("[Cron/BlockchainSync] Error running job:", error);
+    return NextResponse.json({ error: "Internal Server Error" }, { status: 500 });
+  }
+}
diff --git a/lib/blockchain-sync.repository.ts b/lib/blockchain-sync.repository.ts
new file mode 100644
index 0000000..503b911
--- /dev/null
+++ b/lib/blockchain-sync.repository.ts
@@ -0,0 +1,63 @@
+import { neon } from "@neondatabase/serverless";
+import crypto from "crypto";
+
+let sql: ReturnType<typeof neon> | null = null;
+
+function getSql() {
+  if (!sql) {
+    if (!process.env.DATABASE_URL) {
+      throw new Error("DATABASE_URL environment variable is not set");
+    }
+    sql = neon(process.env.DATABASE_URL);
+  }
+  return sql;
+}
+
+export interface SyncLogParams {
+  snippetId: string;
+  transactionHash?: string | null;
+  discrepancyType: string;
+  resolution: string;
+}
+
+export class BlockchainSyncRepository {
+  async logSyncDiscrepancy(params: SyncLogParams): Promise<void> {
+    await getSql()`
+      INSERT INTO blockchain_sync_log (
+        snippet_id,
+        transaction_hash,
+        discrepancy_type,
+        resolution
+      ) VALUES (
+        ${params.snippetId},
+        ${params.transactionHash ?? null},
+        ${params.discrepancyType},
+        ${params.resolution}
+      )
+    `;
+  }
+
+  async getAllSnippets(): Promise<any[]> {
+    return getSql()`
+      SELECT id, owner, updated_at 
+      FROM snippets
+    `;
+  }
+
+  async getSnippetByid(snippetId: string): Promise<any> {
+    const result = await getSql()`
+      SELECT id, owner, updated_at 
+      FROM snippets 
+      WHERE id = ${snippetId}
+    `;
+    return result[0];
+  }
+
+  async updateSnippetOwner(snippetId: string, newOwner: string, updatedAt: Date): Promise<void> {
+    await getSql()`
+      UPDATE snippets 
+      SET owner = ${newOwner}, updated_at = ${updatedAt.toISOString()} 
+      WHERE id = ${snippetId}
+    `;
+  }
+}
diff --git a/lib/blockchain-sync.service.ts b/lib/blockchain-sync.service.ts
new file mode 100644
index 0000000..2b9a294
--- /dev/null
+++ b/lib/blockchain-sync.service.ts
@@ -0,0 +1,85 @@
+import { BlockchainSyncRepository } from "./blockchain-sync.repository";
+import { BlockchainEventListenerRepository } from "./blockchain-event-listener.repository";
+
+export class BlockchainSyncService {
+  constructor(
+    private readonly syncRepo = new BlockchainSyncRepository(),
+    private readonly eventRepo = new BlockchainEventListenerRepository()
+  ) {}
+
+  /**
+   * Fetches the latest on-chain state for a snippet.
+   * Includes a retry mechanism for transient network failures.
+   */
+  async fetchBlockchainState(snippetId: string, retries = 3): Promise<any> {
+    for (let i = 0; i < retries; i++) {
+      try {
+        // In a real scenario, this queries Stellar Horizon for the latest transaction
+        // referencing the snippetId. 
+        // We mock the network call for illustration.
+        await new Promise(res => setTimeout(res, 100)); // Simulate network latency
+
+        // Mock response
+        return {
+          owner: "mock-onchain-owner-wallet",
+          timestamp: new Date().toISOString(),
+          transactionHash: "mock-tx-hash",
+          isAuthoritative: true
+        };
+      } catch (error) {
+        if (i === retries - 1) {
+          console.error(`[BlockchainSyncService] Permanent failure fetching state for ${snippetId}`, error);
+          throw error;
+        }
+        console.warn(`[BlockchainSyncService] Transient failure fetching state for ${snippetId}. Retrying...`);
+        await new Promise(res => setTimeout(res, 500 * (i + 1))); // Exponential backoff
+      }
+    }
+  }
+
+  async runSyncJob(): Promise<void> {
+    console.log("[BlockchainSyncService] Starting sync job...");
+    const snippets = await this.syncRepo.getAllSnippets();
+
+    for (const snippet of snippets) {
+      try {
+        await this.reconcileSnippet(snippet);
+      } catch (error) {
+        console.error(`[BlockchainSyncService] Failed to reconcile snippet ${snippet.id}:`, error);
+        // Log permanent failure or just continue to be resilient
+      }
+    }
+    console.log("[BlockchainSyncService] Sync job completed.");
+  }
+
+  async reconcileSnippet(snippet: any): Promise<void> {
+    const onChainState = await this.fetchBlockchainState(snippet.id);
+    if (!onChainState) return;
+
+    // Detect discrepancy
+    if (snippet.owner !== onChainState.owner) {
+      const dbUpdatedAt = new Date(snippet.updated_at).getTime();
+      const onChainUpdatedAt = new Date(onChainState.timestamp).getTime();
+
+      let resolution = "";
+
+      if (onChainUpdatedAt > dbUpdatedAt && onChainState.isAuthoritative) {
+        // Safe reconciliation: on-chain data is newer and authoritative
+        await this.syncRepo.updateSnippetOwner(snippet.id, onChainState.owner, new Date(onChainState.timestamp));
+        resolution = "UPDATED_DB";
+      } else {
+        // Do not overwrite newer application state
+        resolution = "PRESERVED_APP_STATE";
+      }
+
+      await this.syncRepo.logSyncDiscrepancy({
+        snippetId: snippet.id,
+        transactionHash: onChainState.transactionHash,
+        discrepancyType: "OWNERSHIP_MISMATCH",
+        resolution
+      });
+      
+      console.log(`[BlockchainSyncService] Discrepancy resolved for ${snippet.id}: ${resolution}`);
+    }
+  }
+}
diff --git a/lib/stellar-auth.ts b/lib/stellar-auth.ts
index 556abc4..c58f77b 100644
--- a/lib/stellar-auth.ts
+++ b/lib/stellar-auth.ts
@@ -1,3 +1,5 @@
+import { validateStellarAddress } from "./stellar-wallet-validation";
+
 /**
  * Verify wallet signature using Stellar SDK
  */
@@ -7,6 +9,11 @@ export async function verifyWalletSignature(
   publicKey: string,
 ): Promise<{ valid: boolean; error?: string }> {
   try {
+    // Validate the Stellar wallet address first
+    if (!validateStellarAddress(publicKey)) {
+      return { valid: false, error: "Invalid Stellar wallet address" };
+    }
+
     // Import Stellar SDK
     const StellarSdk = require("stellar-sdk");
 
diff --git a/lib/stellar-wallet-validation.ts b/lib/stellar-wallet-validation.ts
new file mode 100644
index 0000000..e5f8926
--- /dev/null
+++ b/lib/stellar-wallet-validation.ts
@@ -0,0 +1,35 @@
+import * as StellarSdk from 'stellar-sdk';
+
+/**
+ * Validates a Stellar wallet address (public key).
+ * 
+ * @param address - The Stellar wallet address to validate (e.g., G...)
+ * @returns true if valid
+ * @throws Error if the address is malformed or invalid
+ */
+export function validateStellarAddress(address: string): boolean {
+  if (!address || typeof address !== 'string') {
+    throw new Error("Invalid Stellar wallet address");
+  }
+  
+  if (!StellarSdk.StrKey.isValidEd25519PublicKey(address)) {
+    throw new Error("Invalid Stellar wallet address");
+  }
+  
+  return true;
+}
+
+/**
+ * Validates a Stellar wallet address (public key) safely without throwing.
+ * 
+ * @param address - The Stellar wallet address to validate (e.g., G...)
+ * @returns true if valid, false otherwise
+ */
+export function isValidStellarAddress(address: string): boolean {
+  try {
+    if (!address || typeof address !== 'string') return false;
+    return StellarSdk.StrKey.isValidEd25519PublicKey(address);
+  } catch {
+    return false;
+  }
+}
diff --git a/lib/stellar.ts b/lib/stellar.ts
index fde9b2d..5587d87 100644
--- a/lib/stellar.ts
+++ b/lib/stellar.ts
@@ -11,6 +11,7 @@ import {
   buildSnippetMemo,
   generateSnippetMemoRef,
 } from "@/lib/snippet-memo";
+import { validateStellarAddress } from "@/lib/stellar-wallet-validation";
 
 const STELLAR_NETWORK = process.env.NEXT_PUBLIC_STELLAR_NETWORK || "testnet";
 const STELLAR_SECRET_KEY = process.env.STELLAR_SECRET_KEY || "";
@@ -61,6 +62,16 @@ export async function submitTransactionWithConfirmation({
   memo?: StellarSdk.Memo;
   metadata?: Record<string, unknown>;
 }): Promise<StellarSubmitResult> {
+  // Validate the wallet address
+  try {
+    validateStellarAddress(walletAddress);
+  } catch (error: any) {
+    return {
+      success: false,
+      error: `Invalid Stellar wallet address: ${error.message}`,
+    };
+  }
+
   const key = secretKey || STELLAR_SECRET_KEY;
 
   if (!key) {
@@ -160,6 +171,16 @@ export async function submitOwnershipTransferMemoToStellar({
   oldOwnerWalletAddress: string;
   newOwnerWalletAddress: string;
 }): Promise<StellarSubmitResult> {
+  try {
+    validateStellarAddress(oldOwnerWalletAddress);
+    validateStellarAddress(newOwnerWalletAddress);
+  } catch (error: any) {
+    return {
+      success: false,
+      error: `Invalid Stellar wallet address: ${error.message}`,
+    };
+  }
+
   const key = secretKey || STELLAR_SECRET_KEY;
 
   // Fall back to deterministic mock when no key configured.
diff --git a/scripts/add-blockchain-sync-log.sql b/scripts/add-blockchain-sync-log.sql
new file mode 100644
index 0000000..4df0b53
--- /dev/null
+++ b/scripts/add-blockchain-sync-log.sql
@@ -0,0 +1,8 @@
+CREATE TABLE IF NOT EXISTS blockchain_sync_log (
+  id SERIAL PRIMARY KEY,
+  snippet_id VARCHAR(64) NOT NULL,
+  transaction_hash VARCHAR(64),
+  discrepancy_type VARCHAR(50),
+  resolution VARCHAR(50),
+  synced_at TIMESTAMP DEFAULT NOW()
+);
diff --git a/validiation/stellar-wallet-validation.test.ts b/validiation/stellar-wallet-validation.test.ts
new file mode 100644
index 0000000..f6ca208
--- /dev/null
+++ b/validiation/stellar-wallet-validation.test.ts
@@ -0,0 +1,62 @@
+import { validateStellarAddress, isValidStellarAddress } from '../lib/stellar-wallet-validation';
+
+describe('Stellar Wallet Validation', () => {
+  const validAddress = 'GB3T5Y73X7P54R3F2R2L63K3627HXYF475V5RKTF5ZQ22J4LZRVKZ2B5';
+  const invalidAddress = 'GB3T5Y73X7P54R3F2R2L63K3627HXYF475V5RKTF5ZQ22J4LZRVKZ2B'; // Too short
+  const malformedAddress = 'invalid-address';
+  const secretKey = 'SA3T5Y73X7P54R3F2R2L63K3627HXYF475V5RKTF5ZQ22J4LZRVKZ2B5'; // Starting with S
+  
+  describe('validateStellarAddress', () => {
+    it('should return true for a valid Stellar address', () => {
+      expect(validateStellarAddress(validAddress)).toBe(true);
+    });
+
+    it('should throw for an invalid Stellar address length', () => {
+      expect(() => validateStellarAddress(invalidAddress)).toThrow('Invalid Stellar wallet address');
+    });
+
+    it('should throw for a malformed address', () => {
+      expect(() => validateStellarAddress(malformedAddress)).toThrow('Invalid Stellar wallet address');
+    });
+
+    it('should throw if secret key is passed instead of public key', () => {
+      expect(() => validateStellarAddress(secretKey)).toThrow('Invalid Stellar wallet address');
+    });
+
+    it('should throw for empty string', () => {
+      expect(() => validateStellarAddress('')).toThrow('Invalid Stellar wallet address');
+    });
+    
+    it('should throw for null or undefined', () => {
+      expect(() => validateStellarAddress(null as any)).toThrow('Invalid Stellar wallet address');
+      expect(() => validateStellarAddress(undefined as any)).toThrow('Invalid Stellar wallet address');
+    });
+  });
+
+  describe('isValidStellarAddress', () => {
+    it('should return true for a valid Stellar address', () => {
+      expect(isValidStellarAddress(validAddress)).toBe(true);
+    });
+
+    it('should return false for an invalid Stellar address length', () => {
+      expect(isValidStellarAddress(invalidAddress)).toBe(false);
+    });
+
+    it('should return false for a malformed address', () => {
+      expect(isValidStellarAddress(malformedAddress)).toBe(false);
+    });
+
+    it('should return false if secret key is passed instead of public key', () => {
+      expect(isValidStellarAddress(secretKey)).toBe(false);
+    });
+
+    it('should return false for empty string', () => {
+      expect(isValidStellarAddress('')).toBe(false);
+    });
+    
+    it('should return false for null or undefined', () => {
+      expect(isValidStellarAddress(null as any)).toBe(false);
+      expect(isValidStellarAddress(undefined as any)).toBe(false);
+    });
+  });
+});
diff --git a/vercel.json b/vercel.json
index 8bf0afb..484d91e 100644
--- a/vercel.json
+++ b/vercel.json
@@ -15,6 +15,10 @@
     {
       "path": "/api/cron/stellar-recovery",
       "schedule": "*/2 * * * *"
+    },
+    {
+      "path": "/api/cron/blockchain-sync",
+      "schedule": "*/15 * * * *"
     }
   ]
 }