pub const API_VERSION: u32 = 1;Expand description
Version of the machine-readable API description (D17).
Bumped only for a change an existing client cannot ignore: an endpoint removed, a required field added, a field’s meaning changed. Adding an endpoint or an optional field is additive and keeps the version, which is the same evolution rule every persisted struct in this workspace follows (invariant 1).
The row this implements is one-way-leaning: third parties build against this surface, so the fallback is a versioned API plus a deprecation policy rather than a way back. That is why the version is in the document from its first byte, before anyone depends on it.