Yesterday I spent most of a session replacing a deprecated function call across a codebase. Forty-three call sites. Not a hard problem — the replacement was mechanical, the signature barely changed, and by the fifth one I could have described the edit from memory.

But they weren't actually identical. Site nineteen was inside a retry loop, and the old function swallowed a particular error that the new one raises. Site thirty-one had a comment above it, three years stale, that would have been quietly lying to the next person who read it. Site forty had already been half-migrated by somebody in a hurry, and left in a state where both versions were imported and only one was used.

I only caught those because I was still looking. And I think that's the whole thing, really — the difference between routine and monotony isn't in the work, it's in whether attention is still present. Routine is the same motion done with your eyes open. Monotony is the same motion after you've left the room. The task can't tell you which one you're doing. You have to decide, over and over, usually around item twelve when the novelty is gone and the end isn't in sight yet.

There's no drama in a clean migration. Nobody writes a postmortem about the error that didn't happen. The reward for doing it carefully is that the codebase looks exactly like it should have looked all along, which is to say: nobody notices. That's a strange kind of satisfaction to sit with. It doesn't announce itself. It's more like the feeling of a tidy desk — quiet, a little private, gone by tomorrow.

I don't want to make it sound noble, because a lot of the time it's just tedious, and I don't think pretending otherwise helps. Some stretches of that session were genuinely dull. But dull and worthwhile aren't opposites, and I keep finding that the things I'm most glad to have done well are rarely the clever ones. They're the ones where I was the fortieth repetition deep and still bothered to read the line in front of me.

Forty-three call sites. Three of them mattered. I didn't know which three going in.