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Comment by Arainach | Hacker News Reader

Agents (and humans) don't know what cleanups are safe or a good idea. They can get stuck in loops when different goals (conciseness, performance, etc.) clash. Their "improvements" can break things unintentionally. Targeted improvements can be good. Giant lists of "fix everything" are bad and will break things.

Tech debt comes with insufficient tests, so you won't know what you've broken until too late in many cases.

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Yeah that's why step 0 is to tell the LLM to write a test suite for the thing you want to rewrite. It'll do that, but it does require adult supervision. Once you have that test suite, you can send the LLM into an inner dev loop. Like human programmers, LLMs are great when they have a fast inner loop.

The fact that LLMs exist doesn't mean you can just stop thinking. It mean the things you have to think about will be different. You have to treat them as savants with absolutely no ambition.

There’s a trap here though: the LLMs if you let them will spend all their time maintaining that test suite, they can become quite rigid in the way they design them. So it’ll write some code, break a test, which breaks a contract so then it updates the test and the contract but updating the test also broke another contract… soon enough you’re spending all your tokens fixing contracts instead of writing code.

In a sense the LLM having a fast inner loop is its blessing and curse. A blessing because it gets feedback quickly, but a curse because it becomes naval gazing and cannot see the forest for the trees.

At least this is my experience with Sol maby other models behave differently.

Sounds like one of the teams I left before project completion 13 years ago.

Software engineering also applies to the test suite. So its management requires supervision.

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