How to use Cursor to fix errors with Agentfix
The shared Cursor demonstration identifies u.nmee as a typo for u.name, edits server.js and restarts the development server; the terminal output reports the error fixed.
news.ycombinator.com
Prompt to try
Editorial adaptation, not the source author’s exact prompt. Replace bracketed inputs and review tool permissions first.
Use Agentfix with [Cursor provider configuration] to run [development command]. When [runtime error] appears, inspect the reported file, identify the cause and apply a focused correction. Reload the app and report the changed code and observed result.
Reach people exploring AI agents
See placements →What happened
The shared Cursor demonstration identifies u.nmee as a typo for u.name, edits server.js and restarts the development server; the terminal output reports the error fixed.
Reported by willgdjones on Hacker NewsHow the agent did it
- Started a development application under Agentfix with Cursor as provider.
- Detected a TypeError and passed its context to the agent.
- Read server.js and identified a misspelled user property.
Where a person stepped in
The demonstrated repair loop does not show a human approval or code-review step before the file edit and restart.
A person set the goal and reviewed the result.
Will Jones built Agentfix at the Build With Cursor London hackathon in December. The project wraps a child process running an application, watches its output for errors and passes detected error context to an AI through either the Cursor or Claude SDK. The agent attempts to patch files, after which the watcher reloads the application.
The supplied terminal demonstration uses Cursor as the provider. Agentfix starts a development server and detects a TypeError involving toUpperCase. The agent reads server.js to inspect the failing code and identifies a misspelled property: u.nmee was used where u.name was intended. Because that property did not exist, the code attempted to call toUpperCase on undefined.
The agent edits server.js, the server restarts and the demonstration reports the error fixed. This is evidence of the specific typo-repair demonstration, rather than a general guarantee that arbitrary runtime failures will be repaired successfully.
Jones frames the project as an experiment in trusting AI with real-time maintenance, aiming to reduce interruptions without requiring a pull request for each repair.
Who it's for: Developers exploring automated repair loops who can evaluate changes applied directly to a running application’s files.
Prompt
Suggested prompt (written by Agents In Use, not the author's)
Source: Hacker News · willgdjones
Frequently asked questions
What did the demonstrated fix change?
The agent replaced the incorrect property u.nmee with u.name in server.js after inspecting a TypeError caused by calling toUpperCase on undefined.
Does Agentfix require a pull request for a repair?
The author describes a system that patches files directly and reloads the application without requiring a pull request. The post does not describe human approval in the demonstrated loop.
More details
Remaining steps
- Edited server.js and restarted the application with the correction.
About this account
Agentfix detected the runtime error, invoked Cursor, applied a file edit and restarted the server in the shared demonstration.
Platform: Hacker News. Attribution: https://news.ycombinator.com/item?id=46469725. Prompt: Suggested (written by Agents In Use, not the author's). Sourced by the Agents In Use pipeline.
Credit: willgdjones on Hacker News
Source published 2 Jan 2026
Source checked 14 Oct 2026
Tools and topics
Agentfix · Cursor SDK · Claude SDK
AI coding
Editorial completeness: 100/100. Measures documented fields, not agent performance or verified outcomes.