feat: add src/agent/blockchain.js - BlockchainAdapter for on-chain audit recording

Implements BlockchainAdapter to record audit results on-chain.

Signed-off-by: rigoryanych <rigoryanych1397@gmail.com>

Author: rigoryanych

src/agent/blockchain.js

@@ -0,0 +1,53 @@
+/**
+ * Blockchain Adapter for Audityzer Security Agent
+ * Records audit results on-chain for immutable provenance
+ */
+
+export class BlockchainAdapter {
+  constructor(config = {}) {
+    this.config = {
+      network: config.network || 'ethereum',
+      rpcUrl: config.rpcUrl || process.env.BLOCKCHAIN_RPC_URL || null,
+      contractAddress: config.contractAddress || process.env.AUDIT_CONTRACT_ADDRESS || null,
+      enabled: config.enabled !== undefined ? config.enabled : !!config.rpcUrl,
+      ...config,
+    };
+  }
+
+  /**
+   * Record an audit result on the blockchain
+   * @param {string} scanId - Unique scan identifier
+   * @param {string} ipfsHash - IPFS CID of the stored report
+   * @returns {string|null} Transaction hash or null if disabled
+   */
+  async recordAudit(scanId, ipfsHash) {
+    if (!this.config.enabled || !this.config.contractAddress) {
+      console.warn('[BlockchainAdapter] Blockchain recording disabled or not configured');
+      return null;
+    }
+
+    try {
+      // Dynamic import to avoid hard dependency on ethers
+      const { ethers } = await import('ethers');
+      const provider = new ethers.JsonRpcProvider(this.config.rpcUrl);
+      const wallet = new ethers.Wallet(process.env.BLOCKCHAIN_PRIVATE_KEY, provider);
+
+      const abi = [
+        'function recordAudit(string scanId, string ipfsHash) external returns (bytes32)',
+      ];
+      const contract = new ethers.Contract(this.config.contractAddress, abi, wallet);
+      const tx = await contract.recordAudit(scanId, ipfsHash);
+      const receipt = await tx.wait();
+      return receipt.hash;
+    } catch (error) {
+      console.error('[BlockchainAdapter] Failed to record audit:', error.message);
+      return null;
+    }
+  }
+
+  isEnabled() {
+    return this.config.enabled;
+  }
+}
+
+export default BlockchainAdapter;