Something i read in the earlier paragraphs about llms being easier to work with in greenfield projects…
My experience has been the opposite. They work well on existing projects but are not so great at new ones (unless you are just vibe coding something simple).
I think it has something to do with it being able to rely on years of established structure/conventions on existing projects that makes them better IME
Agreed! I hate the start of a project with an LLM. The code it writes is always expletive, and wrangling it with rules, hooks, and what have you is just a series of half measures. I'm basically in a fistfight with a cheerful drunk keyboard.
Once there's enough code, tests, and docs to dominate the prefill and give it an understanding of what I expect in terms of code quality, style, and TDD etiquette, I can expect consistent performance.
That said, I've never been comfortable enough with it to let it write more than a few of functions at a time without diff/checking in.
I've seen folks with 500K LOC branches written by an LLM and my heart just sinks...
My experience with greenfield is that when you're just starting out, you have to be really strict and careful about overall architecture, establish a framework, provide structure, separate concerns well.
If the project is not throwaway, this first set of iterations is critical, without guidance LLMs will just bolt on things and produce special-cased spaghetti, even the very-frontier models.
Once the framework is established, it's smooth sailing.
But I haven't gotten to "very large" size yet, I expect it produces another kind of coherence problems.
I’ve had a good experience with a greenfield project.
The single thing that seems to have helped is that we all agreed to use OpenSpec early on, and to commit the specs alongside the code.
I have no affiliation with OpenSpec and I don’t suspect it’s doing anything unique here, but having the intent develop alongside the code in the repository seems to have ensured that agents have a more holistic view of the project.
It’s a night/day difference when I use an agent against this codebase that integrates its changes using OpenSpec and those that ignore it.
My experience has been the opposite. They work well on existing projects but are not so great at new ones (unless you are just vibe coding something simple).
I think it has something to do with it being able to rely on years of established structure/conventions on existing projects that makes them better IME
Once there's enough code, tests, and docs to dominate the prefill and give it an understanding of what I expect in terms of code quality, style, and TDD etiquette, I can expect consistent performance.
That said, I've never been comfortable enough with it to let it write more than a few of functions at a time without diff/checking in.
I've seen folks with 500K LOC branches written by an LLM and my heart just sinks...
If the project is not throwaway, this first set of iterations is critical, without guidance LLMs will just bolt on things and produce special-cased spaghetti, even the very-frontier models.
Once the framework is established, it's smooth sailing.
But I haven't gotten to "very large" size yet, I expect it produces another kind of coherence problems.
The single thing that seems to have helped is that we all agreed to use OpenSpec early on, and to commit the specs alongside the code.
I have no affiliation with OpenSpec and I don’t suspect it’s doing anything unique here, but having the intent develop alongside the code in the repository seems to have ensured that agents have a more holistic view of the project.
It’s a night/day difference when I use an agent against this codebase that integrates its changes using OpenSpec and those that ignore it.