Replace scattered env reads with one startup check

Your Python service reads its settings from environment variables, through os.environ.get calls spread across 30 files. Last week a deploy set RETRY_LIMIT to five. Nothing complained until a request crashed 2 hours later. You want an agent to replace all of it with one config loader.

Write the spec you would hand the agent.

What you know:

• the settings: DATABASE_URL (required), PORT (int, default 8080), RETRY_LIMIT (int, default 3), REQUEST_TIMEOUT (float seconds, default 2.5) and ENABLE_BETA (bool, default false)
• Python 3.12, and no new dependencies
• the service runs in containers, and a container that exits is restarted and flagged

Then, in a few sentences: what does "parse my config from env" leave out?