Interface: ArtifactStreamPutInput

What a STREAMED put declares. Everything on PutArtifactInput the caller owns, minus the two things a store cannot honor without holding the payload whole:

• bytes is REQUIRED here (it is stamped, not measured). Retention has to plan an eviction BEFORE the bytes arrive, and an object store has to declare a content length before it opens the upload — neither can wait for a stream to end. A store that can see the true count verifies it and refuses a mismatch by name rather than storing a meta that lies about its own payload. • there is no digest. A digest is computed over the whole canonical payload with the same primitive every adapter shares; a store that never holds the payload cannot produce one, and an incremental hash computed a second way would be a different promise wearing the same field name. Digest the source yourself, or use put.