D221 - Environment variables are declared in one crate

Status: decided Date: 2026-09-26

orbistoun-env declares every environment variable with a summary, an example, its reader, and whether it is a setting or a diagnostic; orbistoun-cli env prints the registry and an undeclared ORBISTOUN_ variable is reported. Diagnostics - fills, plants, pokes, dumps, forced returns - are environment variables for one run, share one parser and one conditions entry, and never come from a file.

Why: without a list a misspelled variable runs an ordinary experiment and reports an ordinary result. A diagnostic is a question asked once; one left in a file becomes an undocumented workaround. Shared plumbing keeps one matching rule, including matching an unnamed import by hash.

Rejected:

• Variables read ad hoc per crate: no list, typos pass silently.
• Diagnostics as persistent settings: experiments outlive their question.
• A crate named for configuration: config.toml belongs to the service near the top of the spine.