Comment by CarVac

I want to be able to reason about my code without sitting in front of it, so I simply don't use those tools and this understanding of the codebase builds over time.

When you're working in one area of it, you read it and make additions in it repeatedly, and eventually your familiarity increases until you have mastery.

Then you can code anywhere, anytime, and merely type it in when you get back to the keyboard.

It's like learning a (human) language. As an analogy: "[foreign language] speakers who don't use a dictionary, how do you do it?" But the foreign language is your codebase. Learn it.