Combine Map Local and Breakpoint with Scripting feature - Proxyman (https://proxyman.io)

script.js

// /Users/nghiatran/Library/Application Support/com.proxyman.NSProxy/users/D6B9C80C.default_message_683CE65F.json
const file = require("@users/D6B9C80C.default_message_683CE65F.json");

function onRequest(context, url, request) {
  // Done
  return request;
}

function onResponse(context, url, request, response) {
  
  // Change name of the local file
  file.name = "Proxyman"
  
  // Add custom header
  response.headers["x-key"] = "Proxyman"
  
  // Map again
  response.body = file
  
  // Done
  return response;
}