How to refactor old Node.js code with Cursor

1---
2description: Async/await conversion rules for Node.js
3globs: "*.js,*.ts"
4alwaysApply: false
5---
6
7## Async Refactoring Rules
8- Convert callback patterns to async/await, NEVER to raw Promises with .then()
9- Wrap awaited calls in try/catch blocks
10- Preserve original error messages and error codes
11- Use util.promisify() for Node.js core APIs (fs, child_process)
12- Keep function signatures backward-compatible where possible
13- Add JSDoc @returns {Promise<T>} annotations to converted functions
14- Do NOT change the function name during conversion

1git add -A && git commit -m "checkpoint: before async/await migration"

1// Original callback code:
2function getUser(id, callback) {
3  db.query('SELECT * FROM users WHERE id = ?', [id], (err, rows) => {
4    if (err) return callback(err);
5    if (!rows.length) return callback(new Error('User not found'));
6    callback(null, rows[0]);
7  });
8}
9
10// Cursor Cmd+K prompt:
11// "Convert this callback function to async/await. Use try/catch
12// for error handling. Keep the same function name."
13
14// Expected Cursor output:
15async function getUser(id) {
16  try {
17    const rows = await db.query('SELECT * FROM users WHERE id = ?', [id]);
18    if (!rows.length) {
19      throw new Error('User not found');
20    }
21    return rows[0];
22  } catch (err) {
23    throw err;
24  }
25}

1// Composer Agent prompt (Cmd+I):
2// @src/services Refactor all callback-based functions in this
3// folder to async/await. Follow these rules:
4// 1. Convert one file at a time
5// 2. Use try/catch for all error handling
6// 3. Use util.promisify for fs and child_process calls
7// 4. Update the callers in the same file
8// 5. Do NOT modify test files
9// 6. Wait for my approval between each file

1// Cursor Chat prompt (Cmd+L):
2// @codebase Find all files that call getUser(), getOrder(),
3// or getProduct() with a callback argument. Show me each
4// call site and generate the updated code using await instead
5// of callbacks. Include the necessary async keyword on the
6// parent function.

1// Terminal command:
2npm test
3
4// If tests fail, paste the error into Cursor Chat:
5// @src/services/userService.js The test for getUser is failing
6// with 'TypeError: callback is not a function'. The function
7// was converted from callback to async/await but some callers
8// still pass a callback. Fix the callers.