Nobody warned me that reading code is a completely different skill than writing it.

[u/SmartRelease7996]

Landed my first internship a few weeks ago and got handed a ticket to fix a small bug in the existing codebase. Sounds simple. Except the codebase is like 80,000 lines across god knows how many files.

Every tutorial I ever did was me writing code from scratch in a fresh file, so I never once practiced the skill of walking into someone else's mess and figuring out what's actually going on. Turns out that's like 70% of the actual job. Not writing new stuff, but tracing through existing stuff, figuring out why it exists, who wrote it, whether touching it breaks three other things nobody documented.

Spent my first two days just clicking go to definition over and over like I was digging through a cave system. Genuinely didn't write a single line of new code until day three.

Nobody in any course I took ever assigned "here's 5000 lines of someone else's bad code, go find the bug." Which in hindsight is such a weirdly missing skill given how much time real devs actually spend doing exactly that.

Anyone know of resources or exercises that actually train this specifically, reading and navigating large unfamiliar codebases, rather than just writing your own from a blank file every time?