重新找回花三小時修好的 bug

Last week an AI agent fixed a bug for me in about five seconds. Clean fix, nice explanation, even a little summary at the end. And my first thought wasn't "wow." It was: "Huh. That one would've taken me three hours."

Three hours of reading logs, adding console.log everywhere, questioning my career choices, and finally finding that one missing line. Those three hours were painful. They were also where I learned almost everything I know.

So this isn't an "AI is bad" article. I use AI every day, and I like it. This is about what we gain, what we quietly lose, and why I sometimes catch myself missing the three-hour bug.

1. I'm glad I started coding before AI showed up

I started coding back when there was no AI to ask. Back then, if something broke, you had three options: read the docs, dig through Stack Overflow, or stare at the screen until the bug got embarrassed and confessed.

It made me think. It made me grow. It made me investigate things on my own. And yes, sometimes it made me struggle (and, okay, maybe cry a little). But it was worth every minute.

You know how studying works: reading something feels like learning, but doing it with your own hands is what actually sticks. And it turns out there's science behind that feeling. Psychologist Robert Bjork calls it "desirable difficulties": when learning is a bit harder and slower, you remember it much better. There's also the "generation effect": you remember things you came up with yourself far better than things you just read.

In other words, all that struggling wasn't wasted time. It was the actual learning. Every bug I tracked down myself is still somewhere in my head, and it still pays off today.

2. We have to be careful, or we'll end up with brain rot

"Brain rot" sounds like a joke, but it's starting to show up in research too.

An early study from MIT Media Lab, "Your Brain on ChatGPT" (Kosmyna et al., 2025), suggests that people who wrote essays with ChatGPT showed the weakest brain connectivity on EEG, compared to people who used a search engine or wrote entirely on their own. Most of them also struggled to quote a single sentence from the essay they had just written. It's a small study (54 people, still a preprint), so it's not the final word, but... you know. Ouch.

Another one, from Microsoft Research and Carnegie Mellon (Lee et al., CHI 2025), surveyed 319 knowledge workers and found that the more confident people were in AI, the less critical thinking they reported doing. Which makes sense: why double-check something you already believe is right?

Don't get me wrong: AI helps me get things done. A lot of things. But the real win isn't "I did my work faster." The real win is what I do with the time it saves me.

For me, that time should go into learning the deeper stuff: how the garbage collector actually works, what V8 does with my code, architecture problems that were solved decades ago and still apply to the code we write today, in any language and any framework.

Tools change every year. Fundamentals don't. If AI writes the code and we stop learning the fundamentals, we're not engineers anymore. We're very expensive copy-paste buttons.

3. Sometimes I miss the days before AI

Here's something nobody puts in the release notes: the cognitive load is insane.

Business requirements keep growing. Expectations keep growing. People want more, faster, and we, as developers, deliver. Often to our own detriment.

Coding eight hours a day was already hard. Now add making architecture decisions, juggling five or more tasks at once, and managing a team of AI agents on top of that. That's a different kind of tired.

It used to be that you'd spend hours writing and debugging a single function. Now AI writes it in seconds, and it's working on five tasks at the same time. Sounds like a vacation, right?

Yep, that would be great. But not in this universe.

Because now you have to read all of it, verify all of it, and manage all of it. Your brain has to hold the context of every task, all loaded at once, all day long. No wonder that by the end of the day all we want is to lie down and not think about anything at all.

I wish we could just let the agents handle the tired part too. (Jokes aside, nobody is shipping a "rest for you" feature anytime soon.)

How I try to keep my brain from rotting

"Be careful" is easy to say, so here's what I actually do:

• I write the first version myself before asking AI. Even if it's ugly. Even if it takes longer. Then I let AI improve it. That way I'm still the one solving the problem, and AI is the reviewer, not the other way around.
• I keep a "no-AI hour" for learning. One hour, just me, the docs and my own confusion. You know, like the good old days, just with better coffee.
• I pick one deep topic per month. The garbage collector, V8, the event loop. One month, one topic, no rushing. By the end of the year that's twelve things I actually understand instead of twelve things I've "heard about."

So, do I hate AI?

Not at all. I love it. It lets me do things in an afternoon that would otherwise take me a week.

But we should be careful with it. Not because of some far-fetched sci-fi scenario that doesn't concern the average person, but for something much closer to home: our own brains and our ability to think.

Use AI. Just don't let it do all the thinking for you.