.env.example says DATABASE_URL=postgres://localhost:5432/app. The compose file the team uses for local work mounts a volume and sets DATABASE_URL=sqlite:///data/app.db. The CI workflow exports DB_URL, a name the code stopped reading two refactors ago. Production has a secret called DATABASE_URL that nobody has looked at since the last rotation. Each of those files is valid, and every linter you could point at them passes them. The app still behaves differently on three machines, and the first person to find out is whoever is on call.