Validate Address

Standardise an address against USPS, and say whether it is deliverable.

Frederick, 2026-08-19: "Let's do the USPS."

A READ-GATED WRITE-SHAPED CALL. It is a POST because an address does not belong in a URL -- a street address in a query string ends up in access logs and browser history -- but it changes nothing, so it takes the read grant.

UNCHECKED IS AN ANSWER. Without a USPS key this reports that nobody checked rather than failing the request; a transcriber can still key what the envelope says, which is the whole fallback the stub posture exists for.

ISS-1912: USPS is asked for a token and then the address (30 s timeout each) after two secret reads, so the route holds no pool connection: each read takes a slot and gives it back before the call goes out.