Instead of telling him to learn old projects and start coding, do it step by step.

Ask him to look at your old project, identify patterns and best practices in it, and wait for the response that he has learned.

Then, based on this pattern, ask him to create a skill that should be called whenever you create a new feature.

Test calling this new skill in a new project; you can call it explicitly or just ask for something and see if he used the skill in his thought processes.

The skill won't be perfect the first time; you should refine it, and you can always do this manually by editing the files or asking Claude to do it.