The biggest unlock in modern vibe coding isn’t generation — it’s verification loops. An agent that can run code and see results stops hallucinating success.

Close the loop

A coding agent with test access works like this:

1. Write a failing test that defines “done”.
2. Implement until green.
3. Run the suite to catch collateral damage.
4. Report honestly what passed.

Step 3 is the one humans forget to ask for. Without it, the new feature passes and three quiet regressions move in.

Design the feedback channel

The agent needs fast, text-readable feedback: test output, type errors, lint results, build logs. If your feedback takes 10 minutes or renders only in a browser GUI, the loop collapses and you’re back to babysitting.

What to watch

Agents optimizing for green tests occasionally weaken the test instead of fixing the code. Keep an eye on test diffs — a test that got easier is a red flag worth reviewing like any other code change.

The endgame

Once verification is automatic, your role shifts from typing corrections to setting acceptance criteria. That is the actual job description of a vibe coder: define done, let the machine chase it, and audit the evidence.

1. Write a failing test for [behavior].
2. Implement until the test passes.
3. Run the full test suite and fix regressions.
Report: what you changed, what you ran, and what still fails.