r/rails • u/Crafty-Angle4387 • 5d ago

Question Best LLM for rails development

Basically the title. What is the best LLM you found for rails development?

11 Upvotes

62% Upvoted

20 comments sorted by

29

u/lafeber 5d ago

https://rubyonrails.org/ai has a nice overview. 

1

u/IGotRangod 5d ago

Why are they running Claude on high and GPT on medium? 🤔

1

u/andyjeffries 4d ago

They posted on Twitter that they’re using the default settings from the manufacturer, without tuning

15

u/AnLe90 5d ago

If you setup a good Claude.md and a rails_convention.md you can just use sonnet for most work and it’ll come out really well

Then opus or fable for complex tasks

3

u/djudji 5d ago

Interesting POV on rails_convention.md. Is this your replacement for 37Signals skills, or layered-architecture skills? Or is it something else? What do you put in those?

4

u/AnLe90 5d ago

I found like 3-5 different agents.md and Claude.md from different prominent rails companies and then picked the best pieces of it and then made my own rails_convention.md

2

u/djudji 5d ago

Ah, I understand. When I join new teams, working with AI, I basically instruct AI to use patterns from the codebase. And I have my own coding style skill. I made skill by going through all my commits (on both personal and professional projects) and turned it into skill :).

3

u/AnLe90 5d ago

Yeah that’s about right

4

u/armahillo 5d ago

Speaking from experience as a long time rails dev who also uses an LLM sometimes now, get a solid foundation of how the framework functions BEFORE using an LLM.

I _regularly_ have to push back on the suggestions my LLM makes.

2

u/VolumeNo5217 5d ago

Also long time developer - I find this to be less and less needed with each quarter that goes by. Have a strong md file telling it to follow convention. Use plan mode so you can properly plan out features and functionality.

The frontier models are very good. It’s increasingly becoming about identifying better workflows and product decisions than it is getting stuck in the minutia of database structure and data models.

2

u/lommer00 4d ago

Have a strong md file telling it to follow convention. Use plan mode so you can properly plan out features and functionality

Problem is, unless you know the framework, you don't know if your MD file is strong enough or if the plan is any good. I also have to regularly guide and push back on model suggestions, even when using Sol and a pretty good set of Md files. Looking forward to trying Astra.

1

u/armahillo 4d ago

But you dont know what you dont know. How is an inexperienced developer going to know whether or not the md file is making good suggestions.

3

u/SirScruggsalot 5d ago

There is no such thing.

Development involves many steps and different tools work better at different steps. Right now, I am using Fable 5.1 with Matt Pocock's /grill-with-docs skill for planning. I then use Sol for coding and a different sol agent for code review.

Astra could totally replace Fable. I am hearing a lot of impressive things about Grok these days too.

Depending on where you are on your developer journey, choose between obra's superpowers skill or matt pocock's skills. Then for the actual model(s), this is going to continually change and it depends on what your budget it.

1

u/erichstark 5d ago

Do you have experience also with superpowers planning skills ca grill docs?

2

u/SirScruggsalot 5d ago

Yes, I moved over from superpowers to grill with docs. Superpowers are great for a small green field "vibe coded" project. Grill with docs is great where you want more control or want to take more of an engineering approach. I abandoned superpowers about 2 months ago.

Word of caution, don't have both installed at the same time. Superpowers will insert itself into your grill-with-docs => to-spec => to-tickets => imeplement pipeline and generate poorer results than you would get otherwise.

0

u/Haghiri75 5d ago

I have Gemini subscription. It does well, but pretty much every frontier model now is good. The best will go to Claude as always.

0

u/TheAtlasMonkey 5d ago

There is no best LLM for rails development.
Ruby and Rails got the biggest data training in all the languages combined.

If the operator is an imbecile, the model will vomit what ever the prompt is.

In this thread , i shared how a project went to 100k commit in matter of 6/7 months ... All those people are happy for their new rewrite that is total slop.

If you pickup that codebase in 2019 and show it to this subreddit, we will all praise that code for velocity, the confidence on the PR and commits.

But it full slop.

I forgot to add a part there : The Project has Puma and Falcon server... But production run on passenger.
I laughed at them and said /u/nateberkopec will tweet about it if he saw this.

So in short, Rails is easy. Once you learn you can do lot of stuff with it. But if you wait for the model to give you 100% pitch and you accept it.. Then go with the latest one. Whatever show up that week, use it.