Tell it to use red/green TDD and start things off with an already configured test suite, maybe with a single test that asserts 1+1==2.

Make sure it know how to run the tests before it starts writing any additional code.

Then set it a clear goal.

I’ve found some success is small projects, with limited scope, in a greenfield.

I’m terrified to attempt agentic anything in the repo my job actually cares about. I triggered it once by accident, when the agent was first rolled out and enabled by default… it broke everything. Now I just use ask mode, and even that is wrong half the time, and once it goes wrong it just keeps getting worse.

I saw a post from Dave Plumber who vibe coded up a new cross platform task manager. He said his spec document for the AI was 107 pages long. So maybe what I’m doing wrong is not giving the AI a literal novel of spec.

There are two 'camps' with respect to AI.

One camp already knows that Neural Nets don't work and are a dead end.

The other camp hasn't yet figured out that Neural Nets don't work, but are convinced that they do (or eventually will), because they think everything always improves over time in a linear fashion.

I'd be happy to screenshare with you if you like, we can work on something trivial or open source. Half an hour should be more than enough to see whether you're doing anything obviously self-sabotaging.

You're appealing to ambiguity. All you've said is you have failed—how is anyone supposed to know what went wrong?

What is “it” specifically and what languages are you using?