Quite mixed on this one given that the author has experience with Rust before coding agents and this is just his toy project.

There is going to be a time where these vibe coded projects have silent bugs, vulnerabilities or unnecessary performance issues and the AI coding agent just lies to the user that it has none.

The AI agent will be the one to introduce new issues in the codebase regardless of "tests". The new issue is now the non-technical human vibe-coding is none the wiser.

We have already seen this in Codex itself. Imagine this propagated in many other code-bases.

Having created and debugged human-written code with silent bugs, vulnerabilities, or unnecessary performance issues since my first day on the job, and pointing you to myriad companies with bugs and vulnerabilities that existed pre-AI, all I can say is "plus ça change, plus c'est la même chose."