Guide

How I do is to, set up the project once to use it functionally.. then pick up one-by-one thing, specifically the entry point, like routes, main function, understanding basics... how things "might be working", I feel most of the tech-stack are kinda similar, you don't understand completely but gets the vibe.. and then you can google specific things which feel different from your understanding.

I usually pick one feature or something and try to understand it a bit to get the "feeling" of the project, and I think that's sufficient.. because anyway nobody knows or has to understand the complete codebase.. every time you just go with the flow.. you get something, you understand that specific part and a few bits here & there.. and do it.

For new tech stack, I usually just read 1-2 basic documentation pages, which summarise why they are doing - what they are doing and how they are doing.. that gives a basic analogy... after that slowly things start making sense, and ofc we do have AI for any specific help..

Also most of the time, there are people familiar with the codebase, debugging things with them helps a lot. One thing that our team use to do is to assign new joiners as shadow on-call, and then giving them time to debug on their own first, and later on the main on-call helps & debug together.. 100% recommended :))

Put everything in claude