I mostly vibe coded a queuing system to replace something we’re using at work (last week. Spent about $1500). Then I meticulously went through the code.
It was much harder to review because it was ultra defensive and included guards for tons of edge cases that weren’t possible.
Unnecessary abstractions for possible extension later. Useless indirection. Probably 3x as much code as there would have been if I’d written it by hand.
I didn’t one shot this. I kept a pretty tight leash on the AI. I had probably a dozen markdown files with of plans that I created over hours of back and forth with the AI and reviewed before each implementation round. I had automated reviews and quality gates etc…
What I found in review was that it was full of very subtle bugs that would have bitten hard in prod. Committing offsets asynchronously that would lead to dropped messages. Clock drift bugs that would lead to dropped messages or write amplification storms. Lack of back pressure in some stages of the pipeline that would cause notes to get silently OOM killed. Weird over-insistence on never crashing in most places that would mask systemic errors.
If I’d just shipped it without review, it would have mostly worked. But at the scale it’s going to be used (tens of thousands of messages per second) it would have caused production issues for months while we tracked down each of these issues.