Guarantees

Every API on the platform keeps the promises below, because the code that serves it enforces each one.

Promise	Concept	How it holds
Interfaces cannot disagree	Definition	Every Interface reads the one Definition, and a contract test runs each example through each Interface.
The posted rate is the rate every call states	Price	The cost header and the usage Event of a call carry the rate the pricing document, OpenAPI and the docs post.
An unpriced operation is never served free	Price	When the Offer posts no rate for an operation, the whole API answers 503 until it does.
A miss costs nothing	Price	A miss, an error and every generated Interface answer with a price of 0.
A retry is counted once	Meter	The usage token is the Idempotency-Key, or else the Key, operation, input and hour of the call.
A Limit is never skipped	Limit	When the Limits cannot be checked, the call answers 503 and nothing runs.
Every call is kept	Call record	Each call is a record that never expires, holding a digest of the Key and never the Key.
A test call never touches live books	Test twin	A test or dev Key keeps its calls and usage in a separate namespace whose books never post.
Every link is on the API's host	Host	Every generated link is built from the origin the request reached.
A Definition is checked when it is written and when it is read	Definition	A Definition with any problem is refused on write and on read back, so a bad one never serves.