diff --git a/.env.example b/.env.example
index 377cd6b..28dae5b 100644
--- a/.env.example
+++ b/.env.example
@@ -8,3 +8,5 @@ TREASURY_WALLET=0x0000000000000000000000000000000000000000
 MINT_CURRENCY_ADDRESS=0x0000000000000000000000000000000000000000
 MINT_AMOUNT_ATOMIC=5000000000000000
 
+# Optional: write deployment metadata JSON (address, tx hash, params).
+# DEPLOY_OUTPUT_PATH=./deploy/membership-deploy.sepolia.json
diff --git a/.nvmrc b/.nvmrc
new file mode 100644
index 0000000..209e3ef
--- /dev/null
+++ b/.nvmrc
@@ -0,0 +1 @@
+20
diff --git a/README.md b/README.md
index 2694c6e..e1e0c0e 100644
--- a/README.md
+++ b/README.md
@@ -23,6 +23,8 @@ Features:
 
 ## Local Commands
 
+Use a Hardhat-supported Node runtime (`20.x` recommended).
+
 1. `npm install`
 2. `npm run build`
 3. `npm run test`
@@ -40,6 +42,7 @@ Copy `.env.example` values into your shell/session before deploy:
 3. `TREASURY_WALLET`
 4. `MINT_CURRENCY_ADDRESS` (`0x000...000` for ETH)
 5. `MINT_AMOUNT_ATOMIC`
+6. `DEPLOY_OUTPUT_PATH` (optional)
 
 Example (Sepolia):
 
diff --git a/scripts/deploy-membership.cjs b/scripts/deploy-membership.cjs
index 8fa2d06..c02cc4f 100644
--- a/scripts/deploy-membership.cjs
+++ b/scripts/deploy-membership.cjs
@@ -1,4 +1,6 @@
 const hre = require("hardhat");
+const fs = require("fs");
+const path = require("path");
 
 function requiredEnv(name) {
   const value = process.env[name];
@@ -8,10 +10,36 @@ function requiredEnv(name) {
   return value.trim();
 }
 
+function requireAddress(name, value, { allowZero = false } = {}) {
+  if (!hre.ethers.utils.isAddress(value)) {
+    throw new Error(`Invalid address for ${name}: ${value}`);
+  }
+  if (!allowZero && value === hre.ethers.constants.AddressZero) {
+    throw new Error(`${name} cannot be zero address`);
+  }
+  return value;
+}
+
+function parseUint(name, value) {
+  try {
+    const parsed = hre.ethers.BigNumber.from(value);
+    if (parsed.lt(0)) {
+      throw new Error("must be >= 0");
+    }
+    return parsed;
+  } catch (err) {
+    throw new Error(`Invalid uint for ${name}: ${value} (${err.message})`);
+  }
+}
+
 async function main() {
-  const treasury = requiredEnv("TREASURY_WALLET");
-  const mintCurrency = (process.env.MINT_CURRENCY_ADDRESS || hre.ethers.constants.AddressZero).trim();
-  const mintAmountAtomic = requiredEnv("MINT_AMOUNT_ATOMIC");
+  const treasury = requireAddress("TREASURY_WALLET", requiredEnv("TREASURY_WALLET"));
+  const mintCurrency = requireAddress(
+    "MINT_CURRENCY_ADDRESS",
+    (process.env.MINT_CURRENCY_ADDRESS || hre.ethers.constants.AddressZero).trim(),
+    { allowZero: true },
+  );
+  const mintAmountAtomic = parseUint("MINT_AMOUNT_ATOMIC", requiredEnv("MINT_AMOUNT_ATOMIC"));
 
   const [deployer] = await hre.ethers.getSigners();
   console.log("deployer:", deployer.address);
@@ -25,10 +53,27 @@ async function main() {
   await contract.deployed();
 
   console.log("membership_contract:", contract.address);
+
+  const output = {
+    network: hre.network.name,
+    chainId: hre.network.config.chainId || null,
+    deployer: deployer.address,
+    treasury,
+    mintCurrency,
+    mintAmountAtomic: mintAmountAtomic.toString(),
+    membershipContract: contract.address,
+    txHash: contract.deployTransaction.hash,
+  };
+  const outputPath = (process.env.DEPLOY_OUTPUT_PATH || "").trim();
+  if (outputPath) {
+    const absolute = path.resolve(outputPath);
+    fs.mkdirSync(path.dirname(absolute), { recursive: true });
+    fs.writeFileSync(absolute, JSON.stringify(output, null, 2));
+    console.log("deployment_output:", absolute);
+  }
 }
 
 main().catch((err) => {
   console.error(err);
   process.exitCode = 1;
 });
-