One thing I am having a hard time wrapping my head around is how to reliably integrate business logic into a system like this. Just hook up my Rails models etc. and have it use those?

Let’s say I’ve got a “widgets” table and I want the system to tell me how many “deprecated widgets” there are, but there is no convenient “deprecated” flag on the table—it’s defined as a Rails scope on the model or something (business logic).

The DB schema might make it possible to run a simple query to count widgets or whatever, but I just don’t have a good mental model of how these systems might work with “business logic” type things.

Sounds like you may want an MCP server for your Rails API instead of connecting directly to db.