I have a "llm-shared" git submodule I add to all my projects.

In there I have generic advice on project management (use `gh` and Github issues for todo lists) and language-specific guidance in separate files, like which libraries to use etc.

Then I have a common prompt template for different agents that tells them to look there for specific technology choices and create/update their own WHATEVER.md file in the repo.

Gemini-cli is pretty efficient for creating specs and doesn't run out of context. With Context7 it can pull up API specs into the documentation it creates and with Brave API it can search for other stuff.

After it's done, I can just tell Claude to make a step by step plan based on the specs and create Github issues for them with the appropriate labels.

Clear context, and get Claude working on the issues one by one.