Environment
Also called Deployment environment
One complete place your software can run, with its own address, its own data and its own settings. Development on your machine, staging and production are the usual three.
The more two environments differ, the less a pass in one tells you about the other. And an agent that can't tell which one it is in will sooner or later run the right command in the wrong place.
Say it to your agent
“Add a dev:fresh script so you can boot your own copy of this app on a free port, with a throwaway SQLite database and seed data. Test against that. Print which environment you are in on the first log line.”