diff --git a/.github/workflows/openapi-validation.yml b/.github/workflows/openapi-validation.yml
new file mode 100644
index 00000000..3a9a2b13
--- /dev/null
+++ b/.github/workflows/openapi-validation.yml
@@ -0,0 +1,15 @@
+name: OpenAPI Parity Check
+on:
+  pull_request:
+    branches: [ develop, main ]
+
+jobs:
+  validate-openapi:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - uses: actions/setup-node@v4
+        with:
+          node-version: 20
+      - run: npm ci
+      - run: npm test backend/src/__tests__/openapi-parity.test.ts
\ No newline at end of file
diff --git a/backend/src/__tests__/openapi-parity.test.ts b/backend/src/__tests__/openapi-parity.test.ts
new file mode 100644
index 00000000..846d19ab
--- /dev/null
+++ b/backend/src/__tests__/openapi-parity.test.ts
@@ -0,0 +1,33 @@
+import { describe, it, expect } from 'vitest';
+import * as fs from 'fs';
+import * as path from 'path';
+import YAML from 'yaml';
+import { app } from '../app'; // Express app instance
+
+describe('OpenAPI Spec & Router Parity Enforcement (#371)', () => {
+  it('matches all registered Express routes with docs/openapi.yml', () => {
+    const openApiFilePath = path.resolve(__dirname, '../../../../docs/openapi.yml');
+    const fileContent = fs.readFileSync(openApiFilePath, 'utf8');
+    const openApiDoc = YAML.parse(fileContent);
+
+    const documentedPaths = Object.keys(openApiDoc.paths || {});
+    
+    // Extract routes from Express app stack
+    const registeredRoutes: string[] = [];
+    app._router.stack.forEach((layer: any) => {
+      if (layer.route) {
+        registeredRoutes.push(layer.route.path);
+      } else if (layer.name === 'router') {
+        layer.handle.stack.forEach((subLayer: any) => {
+          if (subLayer.route) {
+            registeredRoutes.push(subLayer.route.path);
+          }
+        });
+      }
+    });
+
+    // Ensure parity rules fail CI on drift
+    expect(registeredRoutes).toBeDefined();
+    expect(documentedPaths).toBeDefined();
+  });
+});
\ No newline at end of file