Isn’t that easy to add with some rules and guidelines documents? I usually ask Claude code to research modern best practices for SwiftUI apps and to summarize the learnings in a rules file that will be part of the SwiftUI project.

Yes and no. Proper Agentic coding tools like Claude Code are a bit more than just a bunch of markdown rulesets.

For example: it uses Haiku as a model to run tools and most likely has automatic translations for when the model signals it wants to search or find something -> either use the built-in search or run find/fd/grep/rg

All that _can_ be done by prompting, but - as always with LLMS - prompts are more like suggestions.