Put the pieces together — the no-Redis Solid stack, Kamal, pgvector, and the hard-won disciplines of building with LLMs — and a coherent picture emerges: Rails is an outstanding host for AI-native applications, precisely because it lets a small team build and run both the app and its AI features. A synthesis of where the stack stands.
SOLID can feel like abstract acronym soup until a system grows complex enough to punish you for ignoring it. A war story applying the five principles to an algorithmic trading system — where each one earned its keep, and where dogmatic application would have hurt.
Rails is a great delivery mechanism and a poor place to keep your business logic. A deep-dive on hexagonal architecture in Rails — ports and adapters, isolating the domain from the framework, and how far to take it before it becomes over-engineering.
Skinny controllers pushed all the logic into fat models, and now they're unmanageable. Service objects are the most popular fix — here is how to use them well, when they help, and how they turn into a worse mess if you overdo it.