diff --git a/examples/ecommerce/shopify-guardrail/README.md b/examples/ecommerce/shopify-guardrail/README.md
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+++ b/examples/ecommerce/shopify-guardrail/README.md
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+# APort Shopify Refund Guardrail
+
+This example is a deployable Shopify webhook app that checks refund events against the APort `payments.refund.v1` policy before a team treats the refund as approved.
+
+## What It Does
+
+- Verifies Shopify refund webhook signatures with the `X-Shopify-Hmac-Sha256` header.
+- Fetches the related Shopify order when an Admin API token is configured.
+- Sends refund amount, order context, and agent passport details to APort `/v1/verify`.
+- Allows policy-approved refunds.
+- Tags denied refunds with `aport-refund-review` so operators can review them manually.
+- Returns clear JSON outcomes for approved, held, invalid, and verification-failed requests.
+
+## Setup
+
+```bash
+cd examples/ecommerce/shopify-guardrail
+cp env.example .env
+npm install
+npm start
+```
+
+Register the webhook URL in Shopify:
+
+```text
+POST https://your-domain.example/webhooks/refunds/create
+Topic: refunds/create
+Format: JSON
+```
+
+## Environment
+
+| Variable | Required | Description |
+| --- | --- | --- |
+| `SHOPIFY_WEBHOOK_SECRET` | yes | Shopify webhook signing secret. |
+| `SHOPIFY_SHOP_DOMAIN` | yes | Store domain, for example `your-store.myshopify.com`. |
+| `SHOPIFY_ADMIN_ACCESS_TOKEN` | no | Admin API token used to fetch and tag orders. |
+| `APORT_API_BASE_URL` | no | Defaults to `https://api.aport.io`. |
+| `APORT_API_KEY` | yes | APort API key. |
+| `APORT_POLICY_ID` | no | Defaults to `payments.refund.v1`. |
+| `APORT_AGENT_PASSPORT_ID` | no | Passport ID used for the refund automation agent. |
+| `REFUND_HOLD_TAG` | no | Tag applied when APort denies a refund. |
+
+## Verification Flow
+
+1. Shopify sends a `refunds/create` webhook.
+2. The app rejects the request unless the HMAC signature is valid.
+3. The app builds an APort verification payload with the refund amount, currency, order ID, refund ID, shop, and policy ID.
+4. If APort returns `allowed: true` or `decision: "allow"`, the webhook returns `approved`.
+5. Otherwise the app tags the order for manual review and returns `held_for_review`.
+
+## Tests
+
+```bash
+npm test
+```
+
+The test suite covers invalid webhook signatures, approved refunds, denied refunds with Shopify order tagging, and the APort payload builder.
diff --git a/examples/ecommerce/shopify-guardrail/env.example b/examples/ecommerce/shopify-guardrail/env.example
new file mode 100644
index 0000000..19ab24a
--- /dev/null
+++ b/examples/ecommerce/shopify-guardrail/env.example
@@ -0,0 +1,9 @@
+PORT=3000
+SHOPIFY_WEBHOOK_SECRET=replace-with-shopify-webhook-secret
+SHOPIFY_SHOP_DOMAIN=your-store.myshopify.com
+SHOPIFY_ADMIN_ACCESS_TOKEN=shpat_replace_with_admin_token
+APORT_API_BASE_URL=https://api.aport.io
+APORT_API_KEY=aport_live_replace_with_api_key
+APORT_POLICY_ID=payments.refund.v1
+APORT_AGENT_PASSPORT_ID=shopify-refund-agent
+REFUND_HOLD_TAG=aport-refund-review
diff --git a/examples/ecommerce/shopify-guardrail/package.json b/examples/ecommerce/shopify-guardrail/package.json
new file mode 100644
index 0000000..4952325
--- /dev/null
+++ b/examples/ecommerce/shopify-guardrail/package.json
@@ -0,0 +1,15 @@
+{
+  "name": "aport-shopify-refund-guardrail",
+  "version": "0.1.0",
+  "description": "Shopify refund webhook guardrail using APort policy verification",
+  "private": true,
+  "type": "module",
+  "scripts": {
+    "start": "node src/server.js",
+    "test": "node --test tests/*.test.js"
+  },
+  "dependencies": {
+    "express": "^4.19.2"
+  },
+  "devDependencies": {}
+}
diff --git a/examples/ecommerce/shopify-guardrail/src/aport.js b/examples/ecommerce/shopify-guardrail/src/aport.js
new file mode 100644
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--- /dev/null
+++ b/examples/ecommerce/shopify-guardrail/src/aport.js
@@ -0,0 +1,85 @@
+export class APortVerificationError extends Error {
+  constructor(message, details = undefined) {
+    super(message);
+    this.name = 'APortVerificationError';
+    this.details = details;
+  }
+}
+
+export function buildRefundVerificationPayload(refund, order, config) {
+  const refundTotal = calculateRefundTotal(refund);
+
+  return {
+    policyId: config.aportPolicyId,
+    passportId: config.aportAgentPassportId,
+    action: 'payments.refund.v1',
+    resource: {
+      type: 'shopify_refund',
+      shop: config.shopifyShopDomain,
+      orderId: String(refund.order_id || order?.id || ''),
+      refundId: String(refund.id || ''),
+    },
+    context: {
+      refund,
+      order,
+      amount: refundTotal.amount,
+      currency: refundTotal.currency,
+      createdAt: refund.created_at,
+    },
+  };
+}
+
+export async function verifyRefundWithAPort(refund, order, config, fetchImpl = globalThis.fetch) {
+  if (!fetchImpl) {
+    throw new APortVerificationError('No fetch implementation is available');
+  }
+
+  const response = await fetchImpl(`${config.aportApiBaseUrl}/v1/verify`, {
+    method: 'POST',
+    headers: {
+      Authorization: `Bearer ${config.aportApiKey}`,
+      'Content-Type': 'application/json',
+    },
+    body: JSON.stringify(buildRefundVerificationPayload(refund, order, config)),
+  });
+
+  let body;
+  try {
+    body = await response.json();
+  } catch {
+    body = {};
+  }
+
+  if (!response.ok) {
+    throw new APortVerificationError('APort verification request failed', {
+      status: response.status,
+      body,
+    });
+  }
+
+  return {
+    allowed: body.allowed === true || body.decision === 'allow',
+    decision: body.decision || (body.allowed ? 'allow' : 'deny'),
+    reason: body.reason || body.message || 'No reason provided',
+    raw: body,
+  };
+}
+
+function calculateRefundTotal(refund) {
+  const transactions = Array.isArray(refund.transactions) ? refund.transactions : [];
+  const refundLineItems = Array.isArray(refund.refund_line_items) ? refund.refund_line_items : [];
+
+  const transactionTotal = transactions
+    .filter((transaction) => ['refund', 'suggested_refund'].includes(transaction.kind))
+    .reduce((sum, transaction) => sum + Number(transaction.amount || 0), 0);
+
+  const lineItemTotal = refundLineItems
+    .reduce((sum, item) => sum + Number(item.subtotal || item.total_tax || 0), 0);
+
+  const amount = transactionTotal || lineItemTotal;
+  const currency = transactions.find((transaction) => transaction.currency)?.currency
+    || refund.currency
+    || 'USD';
+
+  return { amount, currency };
+}
diff --git a/examples/ecommerce/shopify-guardrail/src/app.js b/examples/ecommerce/shopify-guardrail/src/app.js
new file mode 100644
index 0000000..f11416d
--- /dev/null
+++ b/examples/ecommerce/shopify-guardrail/src/app.js
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+import express from 'express';
+import { verifyRefundWithAPort } from './aport.js';
+import { fetchShopifyOrder, tagOrderForReview, verifyShopifyWebhook } from './shopify.js';
+
+export function createApp(config, dependencies = {}) {
+  const app = express();
+  const fetchImpl = dependencies.fetch || globalThis.fetch;
+  const logger = dependencies.logger || console;
+
+  app.get('/health', (_req, res) => {
+    res.json({ ok: true });
+  });
+
+  app.post('/webhooks/refunds/create', express.raw({ type: 'application/json' }), async (req, res) => {
+    const hmac = req.header('x-shopify-hmac-sha256');
+
+    if (!verifyShopifyWebhook(req.body, hmac, config.shopifyWebhookSecret)) {
+      return res.status(401).json({ error: 'Invalid Shopify webhook signature' });
+    }
+
+    let refund;
+    try {
+      refund = JSON.parse(req.body.toString('utf8'));
+    } catch {
+      return res.status(400).json({ error: 'Invalid JSON webhook payload' });
+    }
+
+    try {
+      const order = await fetchShopifyOrder(refund.order_id, config, fetchImpl);
+      const decision = await verifyRefundWithAPort(refund, order, config, fetchImpl);
+
+      if (!decision.allowed) {
+        await tagOrderForReview(refund.order_id, config, fetchImpl);
+        logger.warn('Refund held for review by APort policy', {
+          orderId: refund.order_id,
+          refundId: refund.id,
+          reason: decision.reason,
+        });
+
+        return res.status(202).json({
+          status: 'held_for_review',
+          decision: decision.decision,
+          reason: decision.reason,
+        });
+      }
+
+      logger.info('Refund approved by APort policy', {
+        orderId: refund.order_id,
+        refundId: refund.id,
+      });
+
+      return res.json({
+        status: 'approved',
+        decision: decision.decision,
+        reason: decision.reason,
+      });
+    } catch (error) {
+      logger.error('Refund guardrail failed', {
+        orderId: refund.order_id,
+        refundId: refund.id,
+        error: error.message,
+      });
+
+      return res.status(502).json({
+        status: 'verification_failed',
+        error: 'Refund verification is temporarily unavailable',
+      });
+    }
+  });
+
+  return app;
+}
diff --git a/examples/ecommerce/shopify-guardrail/src/config.js b/examples/ecommerce/shopify-guardrail/src/config.js
new file mode 100644
index 0000000..49d71a5
--- /dev/null
+++ b/examples/ecommerce/shopify-guardrail/src/config.js
@@ -0,0 +1,25 @@
+export function loadConfig(env = process.env) {
+  return {
+    port: Number(env.PORT || 3000),
+    shopifyWebhookSecret: env.SHOPIFY_WEBHOOK_SECRET,
+    shopifyShopDomain: env.SHOPIFY_SHOP_DOMAIN,
+    shopifyAdminAccessToken: env.SHOPIFY_ADMIN_ACCESS_TOKEN,
+    aportApiBaseUrl: env.APORT_API_BASE_URL || 'https://api.aport.io',
+    aportApiKey: env.APORT_API_KEY,
+    aportPolicyId: env.APORT_POLICY_ID || 'payments.refund.v1',
+    aportAgentPassportId: env.APORT_AGENT_PASSPORT_ID || 'shopify-refund-agent',
+    refundHoldTag: env.REFUND_HOLD_TAG || 'aport-refund-review',
+  };
+}
+
+export function assertRequiredConfig(config) {
+  const missing = [
+    ['SHOPIFY_WEBHOOK_SECRET', config.shopifyWebhookSecret],
+    ['SHOPIFY_SHOP_DOMAIN', config.shopifyShopDomain],
+    ['APORT_API_KEY', config.aportApiKey],
+  ].filter(([, value]) => !value);
+
+  if (missing.length > 0) {
+    throw new Error(`Missing required environment variables: ${missing.map(([key]) => key).join(', ')}`);
+  }
+}
diff --git a/examples/ecommerce/shopify-guardrail/src/server.js b/examples/ecommerce/shopify-guardrail/src/server.js
new file mode 100644
index 0000000..e3ad5c2
--- /dev/null
+++ b/examples/ecommerce/shopify-guardrail/src/server.js
@@ -0,0 +1,11 @@
+import { createApp } from './app.js';
+import { assertRequiredConfig, loadConfig } from './config.js';
+
+const config = loadConfig();
+assertRequiredConfig(config);
+
+const app = createApp(config);
+
+app.listen(config.port, () => {
+  console.log(`APort Shopify refund guardrail listening on port ${config.port}`);
+});
diff --git a/examples/ecommerce/shopify-guardrail/src/shopify.js b/examples/ecommerce/shopify-guardrail/src/shopify.js
new file mode 100644
index 0000000..7a7c00f
--- /dev/null
+++ b/examples/ecommerce/shopify-guardrail/src/shopify.js
@@ -0,0 +1,84 @@
+import crypto from 'node:crypto';
+
+export class ShopifyWebhookError extends Error {
+  constructor(message) {
+    super(message);
+    this.name = 'ShopifyWebhookError';
+  }
+}
+
+export function verifyShopifyWebhook(rawBody, hmacHeader, secret) {
+  if (!secret) {
+    throw new ShopifyWebhookError('SHOPIFY_WEBHOOK_SECRET is required');
+  }
+
+  if (!hmacHeader) {
+    return false;
+  }
+
+  const digest = crypto
+    .createHmac('sha256', secret)
+    .update(rawBody)
+    .digest('base64');
+
+  const expected = Buffer.from(digest, 'utf8');
+  const received = Buffer.from(hmacHeader, 'utf8');
+
+  return expected.length === received.length && crypto.timingSafeEqual(expected, received);
+}
+
+export async function fetchShopifyOrder(orderId, config, fetchImpl = globalThis.fetch) {
+  if (!orderId || !config.shopifyAdminAccessToken) {
+    return null;
+  }
+
+  const response = await fetchImpl(
+    `https://${config.shopifyShopDomain}/admin/api/2024-10/orders/${orderId}.json`,
+    {
+      headers: {
+        'X-Shopify-Access-Token': config.shopifyAdminAccessToken,
+        'Content-Type': 'application/json',
+      },
+    },
+  );
+
+  if (!response.ok) {
+    throw new ShopifyWebhookError(`Failed to fetch Shopify order ${orderId}`);
+  }
+
+  const body = await response.json();
+  return body.order || null;
+}
+
+export async function tagOrderForReview(orderId, config, fetchImpl = globalThis.fetch) {
+  if (!orderId || !config.shopifyAdminAccessToken || !config.refundHoldTag) {
+    return;
+  }
+
+  const order = await fetchShopifyOrder(orderId, config, fetchImpl);
+  const existingTags = order?.tags
+    ? order.tags.split(',').map((tag) => tag.trim()).filter(Boolean)
+    : [];
+
+  if (existingTags.includes(config.refundHoldTag)) {
+    return;
+  }
+
+  const tags = [...existingTags, config.refundHoldTag].join(', ');
+
+  const response = await fetchImpl(
+    `https://${config.shopifyShopDomain}/admin/api/2024-10/orders/${orderId}.json`,
+    {
+      method: 'PUT',
+      headers: {
+        'X-Shopify-Access-Token': config.shopifyAdminAccessToken,
+        'Content-Type': 'application/json',
+      },
+      body: JSON.stringify({ order: { id: orderId, tags } }),
+    },
+  );
+
+  if (!response.ok) {
+    throw new ShopifyWebhookError(`Failed to tag Shopify order ${orderId}`);
+  }
+}
diff --git a/examples/ecommerce/shopify-guardrail/tests/app.test.js b/examples/ecommerce/shopify-guardrail/tests/app.test.js
new file mode 100644
index 0000000..1bb1145
--- /dev/null
+++ b/examples/ecommerce/shopify-guardrail/tests/app.test.js
@@ -0,0 +1,134 @@
+import assert from 'node:assert/strict';
+import crypto from 'node:crypto';
+import { test } from 'node:test';
+import { createApp } from '../src/app.js';
+import { buildRefundVerificationPayload } from '../src/aport.js';
+
+const config = {
+  shopifyWebhookSecret: 'top-secret',
+  shopifyShopDomain: 'demo.myshopify.com',
+  shopifyAdminAccessToken: 'shpat_test',
+  aportApiBaseUrl: 'https://aport.example',
+  aportApiKey: 'aport_test',
+  aportPolicyId: 'payments.refund.v1',
+  aportAgentPassportId: 'shopify-refund-agent',
+  refundHoldTag: 'aport-refund-review',
+};
+
+test('rejects webhooks with invalid Shopify HMAC', async () => {
+  const app = createApp(config, { fetch: async () => assert.fail('fetch should not be called') });
+  const server = app.listen(0);
+
+  try {
+    const response = await fetch(url(server), {
+      method: 'POST',
+      headers: {
+        'Content-Type': 'application/json',
+        'x-shopify-hmac-sha256': 'bad-signature',
+      },
+      body: JSON.stringify({ id: 1, order_id: 2 }),
+    });
+
+    assert.equal(response.status, 401);
+  } finally {
+    server.close();
+  }
+});
+
+test('approves refund when APort allows the payments.refund.v1 action', async () => {
+  const calls = [];
+  const refund = { id: 1001, order_id: 2002, transactions: [{ kind: 'refund', amount: '42.50', currency: 'USD' }] };
+  const app = createApp(config, { fetch: mockFetch(calls, { allowed: true, reason: 'within policy' }) });
+  const server = app.listen(0);
+
+  try {
+    const response = await fetch(url(server), signedRequest(refund));
+    const body = await response.json();
+
+    assert.equal(response.status, 200);
+    assert.equal(body.status, 'approved');
+    assert.equal(calls.length, 2);
+    assert.equal(JSON.parse(calls[1].body).action, 'payments.refund.v1');
+  } finally {
+    server.close();
+  }
+});
+
+test('holds refund and tags order when APort denies the request', async () => {
+  const calls = [];
+  const refund = { id: 1001, order_id: 2002, transactions: [{ kind: 'refund', amount: '125.00', currency: 'USD' }] };
+  const app = createApp(config, { fetch: mockFetch(calls, { allowed: false, reason: 'amount above limit' }) });
+  const server = app.listen(0);
+
+  try {
+    const response = await fetch(url(server), signedRequest(refund));
+    const body = await response.json();
+
+    assert.equal(response.status, 202);
+    assert.equal(body.status, 'held_for_review');
+    assert.equal(calls.length, 4);
+    assert.equal(JSON.parse(calls[3].body).order.tags, 'existing, aport-refund-review');
+  } finally {
+    server.close();
+  }
+});
+
+test('buildRefundVerificationPayload includes refund amount and policy metadata', () => {
+  const payload = buildRefundVerificationPayload(
+    { id: 10, order_id: 20, transactions: [{ kind: 'refund', amount: '12.34', currency: 'USD' }] },
+    { id: 20 },
+    config,
+  );
+
+  assert.equal(payload.policyId, 'payments.refund.v1');
+  assert.equal(payload.passportId, 'shopify-refund-agent');
+  assert.equal(payload.context.amount, 12.34);
+  assert.equal(payload.resource.type, 'shopify_refund');
+});
+
+function signedRequest(payload) {
+  const body = JSON.stringify(payload);
+  const hmac = crypto
+    .createHmac('sha256', config.shopifyWebhookSecret)
+    .update(Buffer.from(body))
+    .digest('base64');
+
+  return {
+    method: 'POST',
+    headers: {
+      'Content-Type': 'application/json',
+      'x-shopify-hmac-sha256': hmac,
+    },
+    body,
+  };
+}
+
+function mockFetch(calls, aportDecision) {
+  return async (requestUrl, options = {}) => {
+    calls.push({ requestUrl: String(requestUrl), ...options });
+
+    if (String(requestUrl).includes('/admin/api/')) {
+      if (options.method === 'PUT') {
+        return jsonResponse({ order: { id: 2002 } });
+      }
+      return jsonResponse({ order: { id: 2002, tags: 'existing' } });
+    }
+
+    return jsonResponse(aportDecision);
+  };
+}
+
+function jsonResponse(body, status = 200) {
+  return {
+    ok: status >= 200 && status < 300,
+    status,
+    async json() {
+      return body;
+    },
+  };
+}
+
+function url(server) {
+  const { port } = server.address();
+  return `http://127.0.0.1:${port}/webhooks/refunds/create`;
+}