Looks like you've put a heap of work into it!

I've been building minimal open source versions of those features for JSON Resume -> https://registry.jsonresume.org/thomasdavis/letter

I removed the interview feature because it didn't seem to have much value but I will be sure to give your implementation a spin.

I haven't released it yet, but it feels amazing when I play with the prototype is a feature where you essentially talk to a job counsellor and it writes your resume as you go. It feels very natural and using 4o etc gives fantastic results.