I got it to work on VSCode with a Pro plan (20$). I find the consumption fair. 3h of prompts got me to this:
So far, results were not great. 
What could be interesting is describing what should be configured, or what should be told to Claude when creating a plugin or theme component for Discourse (from the skeleton).
What instructions should be written in CLAUDE.md to maximize its efficiency?
Should certain Discourse directories be prioritized when AI is looking for information in the codebase (I think of controllers, models, serializers, services…)?
How to make it aware of the standard files hierarchy, naming, and conventions?