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Short musings on "cognitive debt" - I'm seeing this in my own work, where excessive unreviewed AI-generated code leads me to lose a firm mental model of what I've built, which then makes it harder to confidently make future decisions simonwillison.net/2026/Feb/15/...

So is the conclusion that we can't vibe code large projects because we can't maintain them? Has anyone managed to keep vibe coding at scale?

My conclusion is that you can only go so far not understanding how the project you're building works - you may not need to look at every line of code, but you gotta slow down and make sure your mental model is accurate enough to stay productive

I just love thinking about this stuff so much, because no matter what path the discourse takes, you'll always land on "a good engineer will get good results from this". While it feels like everything is changing, things aren't really changing all *that* much.

I’ve been working with it a lot and I’ve got two habits that seem to help. One it atomic commits per feature with a good commit message and the other is getting the agent to add/update a mental model doc which is kept intensionally brief. This then allows me to both load up my brain and the AI’s