DecodedMutation
class DecodedMutation<B : Any>(val endpoint: NetworkEndpoint, val body: B?, val bodyType: TypeInfo?)
The endpoint + body pair a MutationCodec reconstructs from a persisted payload. Distinct from QueuedMutation because it carries no MutationRecord.id/MutationRecord.key — those live on the record itself and are reattached by MutationQueue after decoding.
bodyType must describe body whenever body is non-null: it is what the client serializes the body with, and a client refuses to send a typed body without it. Prefer the reified DecodedMutation(endpoint, body) factory, which fills it in for you.