A field guide to the moment before you understand a codebase, when everything looks like a mistake.
Every codebase you inherit looks wrong for the first week. The abstractions feel off by one, the naming conventions seem hostile, and someone clearly shipped a Saturday afternoon experiment into production. You are almost certainly wrong about all of it.
I’ve onboarded onto six different production systems in the last four years. Each time, I spent the first three days convinced I was looking at a codebase that had been built by people who didn’t know what they were doing. Each time, by the end of the second week, I understood most of the decisions and would have made maybe two of them differently.
The difference between a senior engineer and a junior one isn’t that the senior writes better code on day one. It’s that the senior knows their first impression is wrong, doesn’t say it out loud, and gives the codebase the courtesy of assuming competence until proven otherwise.
Here’s my field guide to that uncomfortable first week: Read the commit history before you read the code. Find the oldest file in the repository and trace it forward. Look for the comment that says “this is temporary” — it’s still there, and it tells you more about the team than any architecture document. And when you finally understand something that looked wrong, write down what you thought it was and what it actually is. That note will be the most useful thing you produce all month.