How to generate Authorization header JWT token for custom API endpoint?

action generateExtensionToken {
  fn: import { generateExtensionToken } from "@src/auth/extensionAuth",
  entities: [User]
}
...
api improve {
  fn: import { improve } from "@src/api/improve",
  httpRoute: (POST, "/spellxy/improve"),
  auth: true
}

import jwt from 'jsonwebtoken';
import { HttpError } from 'wasp/server';
import { config } from 'wasp/server';

export const generateExtensionToken = async (args, context) => {
  if (!context.user) {
    throw new HttpError(401, 'Not authorized');
  }

  const token = jwt.sign({ userId: context.user.id }, config.auth.jwtSecret, { expiresIn: '1y' });

  return { token };
};