1@README.md
2
3## Notes for agents
4
5**Never add a field that carries what a visitor sent.** Not a path, a query, a
6header, an address or a user agent; the closed types are the guarantee. A new
7thing worth logging becomes a new variant of a closed type, not a `String`.
8
9**A route's note is for what only the site's own build can cause**, such as a
10file that was never generated. Never a request's content.
11
12**A 5xx is `Error` whatever the route says.** The override is for lowering
13noise (a probe's 404), not for hiding the site's own failures.