I'm currently working on a large project that was started by a 3rd-party vendor, then dumped onto the in-house team's lap due to an unforeseen financial pinch.

The vendor was basically right at the end of the "fun" part of cranking out features, and just about to hit the "rubber meets the road" part where you start fixing bugs, finding new edge cases, discovering new hidden requirements, and realizing X% of your design assumptions were completely wrong. Oh yeah, and minor little mop-up tasks that don't wow the client, like integrating with a payment processor, integrating with our internal scheduling system, exporting invitee lists from our CRM into our app, etc.

It's possible we're in a similar cognitive debt situation to having to maintain a large, swiftly-AI-coded app. After about 6 months of stressful development, which started with what I call throwing dye in the water and eventually progressed to understanding one small feature or flow at a time, we have maybe 50% of the mental model we'd have if we'd built the app ourselves. Whole chunks of the app are still a black box to us.

It doesn't help that requirements have evolved so much since the original documentation that it's worse than useless because we can't trust it. So the code, which we don't understand, is the only documentation of the current requirements.

Of course, our internal clients are pissed because the final product is taking so much longer than expected, when they could see all these awesome shiny, happy-path, 80%-done features 6 months ago. We're in a constant fire drill. Everyone on the project is miserable. It's the least fun kind of development.