I don't even like having secrets on disk for my personal projects that only I will touch. Why was there a plaintext production database credential available to the agent anywhere on the disk in the first place? How did the agent gain access to the file system outside of the code base?
The Railway stuff isn't great, don't get me wrong, but plaintext production secrets on disk is one of the reddest possible flags to me, and he just kind of breezes over it in the post mortem. It's all I needed to read to know he doesn't have the experience required to run a production application that businesses rely on for their day-to-day.