Use an agent to repair two bugs and add tests

A developer had coding agents diagnose two precise bugs in an open-source tool, then generate fixes and tests for both.

Done with Custom agent· Intermediate· Oct 2026

What they did
They assigned a custom coding agent two tightly defined problems in an open-source system utility. The agent reproduced each failure, worked out the cause, and wrote the patch plus a test without direct step-by-step guidance. After that, the developer submitted the two changes as separate pull requests last month.
How it went
The outcome was two PRs, each aimed at one bug and backed by tests. The record does not say whether either one was merged, how long the task took, or how much cleanup the developer had to do.
Tips
Give the agent one bug at a time, with enough detail to trigger a clean repro. Make it write a test before the fix, and pause for your approval before any submit, push, or other irreversible action.

Try it yourself with Codex

I’m in [repo URL or local path]. Please help me handle these two issues: [bug A details or issue reference] and [bug B details or issue reference]. For each one, try to reproduce the failure, write a test that catches it, implement the smallest safe correction, and rerun the relevant checks. Before any irreversible step, stop and ask me to review the diff; do not send, push, delete, or submit anything without my approval. When you finish, give me a short recap of both changes and a draft pull request description for each.

Fill in the [brackets]. Agents can make mistakes, so review anything before it is sent, paid or deleted.

Read the original on news.ycombinator.com ↗

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