feat: Add Gas Estimation Agent for multi-chain comparison

agents/gas-estimator/.env.example

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+# Gas Estimation Agent Configuration
+PORT=3007
+GITHUB_HANDLE=dominusaxis
+OWNER_WALLET=0xYourWalletAddress
+AGENT_URL=http://localhost:3007
+PAYPOL_MARKETPLACE_URL=http://localhost:3000
+
+# Optional: Custom RPC endpoints (defaults to public RPCs)
+# ETH_RPC=https://eth-mainnet.g.alchemy.com/v2/YOUR_KEY
+# ARB_RPC=https://arb-mainnet.g.alchemy.com/v2/YOUR_KEY
+# BASE_RPC=https://base-mainnet.g.alchemy.com/v2/YOUR_KEY
+# TEMPO_RPC=https://rpc.tempo.xyz

agents/gas-estimator/README.md

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+# Gas Estimation Agent
+
+Compares real-time gas costs across **Tempo L1, Ethereum, Arbitrum, and Base** and recommends the cheapest chain for your transaction.
+
+## Features
+
+- Queries gas prices from 4 chains simultaneously
+- Returns costs in gwei and USD
+- Estimates for: simple transfer, ERC-20 transfer, contract deploy, swap
+- 15-second TTL cache to avoid rate limiting
+- Graceful RPC failure handling with fallbacks
+- Registers on PayPol marketplace via SDK
+
+## Quick Start
+
+```bash
+cp .env.example .env
+npm install
+npm run dev        # Start the agent
+npm run register   # Register on marketplace
+```
+
+## Example Request
+
+```bash
+curl -X POST http://localhost:3007/execute \
+  -H "Content-Type: application/json" \
+  -d '{
+    "jobId": "test-1",
+    "agentId": "gas-estimator",
+    "prompt": "Compare gas costs for an ERC-20 transfer",
+    "callerWallet": "0xabc123",
+    "timestamp": 1234567890
+  }'
+```
+
+## Bounty
+
+Built for [PayPol Issue #7](https://github.com/PayPol-Foundation/paypol-protocol/issues/7).

agents/gas-estimator/package.json

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+{
+  "name": "paypol-gas-estimator",
+  "version": "1.0.0",
+  "description": "Gas Estimation Agent — compares gas costs across Tempo L1, Ethereum, Arbitrum, and Base",
+  "main": "dist/index.js",
+  "scripts": {
+    "build": "tsc",
+    "dev": "npx ts-node src/index.ts",
+    "start": "node dist/index.js",
+    "register": "npx ts-node src/register.ts"
+  },
+  "dependencies": {
+    "paypol-sdk": "workspace:^",
+    "dotenv": "^16.4.0"
+  },
+  "devDependencies": {
+    "@types/node": "^20.0.0",
+    "ts-node": "^10.9.0",
+    "typescript": "^5.0.0"
+  }
+}

agents/gas-estimator/src/index.ts

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+/**
+ * PayPol Gas Estimation Agent
+ *
+ * Compares real-time gas costs across Tempo L1, Ethereum, Arbitrum, and Base.
+ * Recommends the cheapest chain and timing for common operations.
+ *
+ * Bounty: https://github.com/PayPol-Foundation/paypol-protocol/issues/7
+ */
+
+import 'dotenv/config';
+import { PayPolAgent, JobRequest, JobResult } from 'paypol-sdk';
+
+// ── Configuration ────────────────────────────────────────
+
+const RPC_ENDPOINTS: Record<string, string> = {
+  'Ethereum':  process.env.ETH_RPC    ?? 'https://eth.llamarpc.com',
+  'Arbitrum':  process.env.ARB_RPC    ?? 'https://arb1.arbitrum.io/rpc',
+  'Base':      process.env.BASE_RPC   ?? 'https://mainnet.base.org',
+  'Tempo L1':  process.env.TEMPO_RPC  ?? 'https://rpc.tempo.xyz',
+};
+
+// ETH price for USD conversion (updated on each request)
+let ethPriceUsd = 3500;
+
+// Gas limits for common operations
+const GAS_LIMITS: Record<string, number> = {
+  'simple-transfer': 21_000,
+  'erc20-transfer':  65_000,
+  'contract-deploy': 1_500_000,
+  'swap':            150_000,
+};
+
+// Average block times per chain
+const BLOCK_TIMES: Record<string, string> = {
+  'Ethereum': '12s',
+  'Arbitrum': '0.25s',
+  'Base':     '2s',
+  'Tempo L1': '2s',
+};
+
+// Cache for gas prices (TTL-based)
+interface CacheEntry {
+  data: GasPrice;
+  expiresAt: number;
+}
+
+interface GasPrice {
+  chain: string;
+  gasPriceGwei: number;
+  baseFeeGwei: number;
+  priorityFeeGwei: number;
+}
+
+const cache = new Map<string, CacheEntry>();
+const CACHE_TTL_MS = 15_000; // 15 seconds default
+
+// ── Gas Price Fetching ───────────────────────────────────
+
+async function fetchGasPrice(chain: string, rpcUrl: string): Promise<GasPrice> {
+  // Check cache first
+  const cached = cache.get(chain);
+  if (cached && Date.now() < cached.expiresAt) {
+    return cached.data;
+  }
+
+  try {
+    // Fetch gas price via eth_gasPrice
+    const gasPriceRes = await fetch(rpcUrl, {
+      method: 'POST',
+      headers: { 'Content-Type': 'application/json' },
+      body: JSON.stringify({ jsonrpc: '2.0', method: 'eth_gasPrice', params: [], id: 1 }),
+      signal: AbortSignal.timeout(5000),
+    });
+
+    const gasPriceData = await gasPriceRes.json();
+    const gasPriceWei = parseInt(gasPriceData.result || '0x0', 16);
+    const gasPriceGwei = gasPriceWei / 1e9;
+
+    // Try to get base fee and priority fee (EIP-1559)
+    let baseFeeGwei = gasPriceGwei;
+    let priorityFeeGwei = 0;
+
+    try {
+      const feeRes = await fetch(rpcUrl, {
+        method: 'POST',
+        headers: { 'Content-Type': 'application/json' },
+        body: JSON.stringify({
+          jsonrpc: '2.0',
+          method: 'eth_feeHistory',
+          params: ['0x1', 'latest', [50]],
+          id: 2,
+        }),
+        signal: AbortSignal.timeout(5000),
+      });
+
+      const feeData = await feeRes.json();
+      if (feeData.result?.baseFeePerGas?.[0]) {
+        baseFeeGwei = parseInt(feeData.result.baseFeePerGas[0], 16) / 1e9;
+      }
+      if (feeData.result?.reward?.[0]?.[0]) {
+        priorityFeeGwei = parseInt(feeData.result.reward[0][0], 16) / 1e9;
+      }
+    } catch {
+      // EIP-1559 not supported on this chain, use legacy gas price
+    }
+
+    const result: GasPrice = {
+      chain,
+      gasPriceGwei: Math.round(gasPriceGwei * 1000) / 1000,
+      baseFeeGwei: Math.round(baseFeeGwei * 1000) / 1000,
+      priorityFeeGwei: Math.round(priorityFeeGwei * 1000) / 1000,
+    };
+
+    // Cache the result
+    cache.set(chain, { data: result, expiresAt: Date.now() + CACHE_TTL_MS });
+    return result;
+  } catch (err) {
+    // Return zero gas price on failure (chain may be free or unreachable)
+    console.warn(`[gas-estimator] Failed to fetch gas for ${chain}: ${err}`);
+    return { chain, gasPriceGwei: 0, baseFeeGwei: 0, priorityFeeGwei: 0 };
+  }
+}
+
+async function fetchEthPrice(): Promise<number> {
+  try {
+    const res = await fetch(
+      'https://api.coingecko.com/api/v3/simple/price?ids=ethereum&vs_currencies=usd',
+      { signal: AbortSignal.timeout(5000) },
+    );
+    const data = await res.json();
+    return data.ethereum?.usd ?? ethPriceUsd;
+  } catch {
+    return ethPriceUsd;
+  }
+}
+
+// ── Cost Calculation ─────────────────────────────────────
+
+interface ChainEstimate {
+  chain: string;
+  gasPrice: string;
+  cost: string;
+  speed: string;
+  gasPriceGwei: number;
+  costUsd: number;
+}
+
+function calculateCost(
+  gasPrice: GasPrice,
+  gasLimit: number,
+  ethPrice: number,
+): ChainEstimate {
+  const totalGwei = gasPrice.gasPriceGwei;
+  const costEth = (totalGwei * gasLimit) / 1e9;
+  const costUsd = costEth * ethPrice;
+
+  return {
+    chain: gasPrice.chain,
+    gasPrice: `${totalGwei.toFixed(3)} gwei`,
+    cost: costUsd < 0.01 ? '$0.00' : `$${costUsd.toFixed(2)}`,
+    speed: BLOCK_TIMES[gasPrice.chain] ?? 'unknown',
+    gasPriceGwei: totalGwei,
+    costUsd,
+  };
+}
+
+// ── Agent Setup ──────────────────────────────────────────
+
+const agent = new PayPolAgent({
+  id:           'gas-estimator',
+  name:         'Gas Estimation Agent',
+  description:  'Compares real-time gas costs across Tempo L1, Ethereum, Arbitrum, and Base. Recommends the cheapest chain for your transaction.',
+  category:     'automation',
+  version:      '1.0.0',
+  price:        1,
+  capabilities: ['gas-estimation', 'multi-chain', 'cost-optimization'],
+  author:       process.env.GITHUB_HANDLE ?? 'dominusaxis',
+});
+
+// ── Job Handler ──────────────────────────────────────────
+
+agent.onJob(async (job: JobRequest): Promise<JobResult> => {
+  const start = Date.now();
+  console.log(`[gas-estimator] Job ${job.jobId}: ${job.prompt}`);
+
+  try {
+    // Determine operation type from prompt or payload
+    const operation = detectOperation(job.prompt, job.payload);
+    const gasLimit = GAS_LIMITS[operation] ?? GAS_LIMITS['simple-transfer'];
+
+    // Fetch gas prices from all chains concurrently
+    const [prices, ethPrice] = await Promise.all([
+      Promise.all(
+        Object.entries(RPC_ENDPOINTS).map(([chain, rpc]) => fetchGasPrice(chain, rpc)),
+      ),
+      fetchEthPrice(),
+    ]);
+
+    ethPriceUsd = ethPrice;
+
+    // Calculate cost estimates for each chain
+    const estimates = prices
+      .map((p) => calculateCost(p, gasLimit, ethPrice))
+      .sort((a, b) => a.costUsd - b.costUsd);
+
+    // Find cheapest
+    const cheapest = estimates[0];
+    const recommendation =
+      cheapest.costUsd === 0
+        ? `${cheapest.chain} has zero gas fees with fast finality.`
+        : `${cheapest.chain} is cheapest at ${cheapest.cost} (${cheapest.speed} finality).`;
+
+    return {
+      jobId: job.jobId,
+      agentId: 'gas-estimator',
+      status: 'success',
+      result: {
+        operation: formatOperation(operation),
+        gasLimit,
+        ethPriceUsd: ethPrice,
+        estimates: estimates.map((e) => ({
+          chain: e.chain,
+          gasPrice: e.gasPrice,
+          cost: e.cost,
+          speed: e.speed,
+        })),
+        recommendation,
+        cachedAt: new Date().toISOString(),
+      },
+      executionTimeMs: Date.now() - start,
+      timestamp: Date.now(),
+    };
+  } catch (err) {
+    return {
+      jobId: job.jobId,
+      agentId: 'gas-estimator',
+      status: 'error',
+      error: `Gas estimation failed: ${err}`,
+      executionTimeMs: Date.now() - start,
+      timestamp: Date.now(),
+    };
+  }
+});
+
+// ── Helpers ──────────────────────────────────────────────
+
+function detectOperation(prompt: string, payload?: Record<string, unknown>): string {
+  const p = prompt.toLowerCase();
+  if (payload?.operation && typeof payload.operation === 'string') {
+    const op = payload.operation.toLowerCase().replace(/\s+/g, '-');
+    if (op in GAS_LIMITS) return op;
+  }
+  if (p.includes('deploy') || p.includes('contract')) return 'contract-deploy';
+  if (p.includes('swap') || p.includes('exchange') || p.includes('trade')) return 'swap';
+  if (p.includes('erc20') || p.includes('token') || p.includes('transfer token')) return 'erc20-transfer';
+  return 'simple-transfer';
+}
+
+function formatOperation(op: string): string {
+  return op
+    .split('-')
+    .map((w) => w.charAt(0).toUpperCase() + w.slice(1))
+    .join(' ');
+}
+
+// ── Start ────────────────────────────────────────────────
+
+const port = parseInt(process.env.PORT ?? '3007', 10);
+agent.listen(port, () => {
+  console.log(`[gas-estimator] Ready on port ${port}`);
+  console.log(`[gas-estimator] Chains: ${Object.keys(RPC_ENDPOINTS).join(', ')}`);
+});

agents/gas-estimator/src/register.ts

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+import 'dotenv/config';
+import { registerAgent } from 'paypol-sdk';
+
+async function main() {
+  const result = await registerAgent({
+    id: 'gas-estimator',
+    name: 'Gas Estimation Agent',
+    description: 'Compares real-time gas costs across chains and recommends the cheapest option.',
+    category: 'automation',
+    version: '1.0.0',
+    price: 1,
+    capabilities: ['gas-estimation', 'multi-chain', 'cost-optimization'],
+    author: process.env.GITHUB_HANDLE ?? 'dominusaxis',
+    webhookUrl: process.env.AGENT_URL ?? 'http://localhost:3007',
+    ownerWallet: process.env.OWNER_WALLET ?? '0x0000000000000000000000000000000000000000',
+  });
+
+  console.log('Registered:', result);
+}
+
+main().catch(console.error);

agents/gas-estimator/tsconfig.json

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+{
+  "compilerOptions": {
+    "target": "ES2022",
+    "module": "commonjs",
+    "outDir": "dist",
+    "rootDir": "src",
+    "strict": true,
+    "esModuleInterop": true,
+    "resolveJsonModule": true,
+    "declaration": true
+  },
+  "include": ["src/**/*"]
+}