auto(agent): enhance auth tests with duplicate email handling

backend/src/__tests__/auth.test.js

@@ -107,5 +107,43 @@ test('login should reject invalid credentials', async () => {
   assert.strictEqual(res.statusCode, 401);
 });
 
+test('register should handle duplicate email', async () => {
+  const mockPoolWithDup = {
+    query: (sql, params) => {
+      if (sql.includes('INSERT INTO users')) {
+        const err = new Error('Duplicate entry');
+        err.code = 'ER_DUP_ENTRY';
+        throw err;
+      }
+      return [];
+    }
+  };
+
+  pool.query = mockPoolWithDup.query;
+
+  const req = {
+    body: {
+      email: 'test@example.com',
+      password: 'password123',
+      displayName: 'Test User'
+    }
+  };
+  const res = {
+    status: (code) => {
+      res.statusCode = code;
+      return res;
+    },
+    json: (data) => {
+      res.data = data;
+    }
+  };
+
+  await require('../routes/auth').default.post('/register', req, res);
+  assert.strictEqual(res.statusCode, 409);
+
+  // Restore the original pool
+  pool.query = originalPool.query;
+});
+
 // Restore the original pool
 pool.query = originalPool;

docs/runtime/pick_next_task_state.env

@@ -1,2 +1,2 @@
-LAST_ROUTE=offers.js
-UPDATED_AT=2026-03-06T19:56:59Z
+LAST_ROUTE=auth.js
+UPDATED_AT=2026-03-06T20:10:38Z