Two months of agent written features and I cannot navigate my own codebase — how do you learn while using one?

I did eight months of accepting diffs I mostly understood, and it was fine right up until a production incident at 2am where the failing path was code I had shipped and never read. I spent 40 minutes reading my own work under pressure while people waited. Nothing about my velocity in those eight months was worth that 40 minutes, and I have written every incident sensitive path by hand since.

The rule that fixed this for the two juniors on my team: you write the test, the agent writes the implementation. Writing the test forces you to know where the code lives, what it is called, what it takes and what it returns, and what a correct answer looks like, which is exactly the knowledge you are missing. The implementation is the part where the tool is genuinely faster and the part you learn least from watching. It slows you down maybe 20 percent and after six weeks both of them could navigate without help.

Harder line than the others: at two months in, turn the completions off entirely for a month. Not the chat, the inline suggestions, because those are the ones that stop you from ever sitting in the discomfort where learning happens. You will be slower and your tickets will take longer and your team will survive it. Every junior I have watched do this came out the other side able to work with the tool rather than through it, and the ones who did not are still asking it where things are eight months later.

I timed myself for a fortnight because I suspected I was in the same hole. Hand writing the first 30 minutes of any task, then handing off, cost me about 15 percent on total task time and eliminated the situation where I could not answer a question in review. The 30 minutes is not enough to finish anything, which is the point: it is enough to force me to find the files, read the surrounding code, and form an opinion about the shape before anything is generated. The opinion is the thing you are currently not forming.

Read the diff out loud before you accept it. If you cannot say what a line does, delete it and ask why it was there. That is the whole method.