A manifest under the 768 KiB validation cap can still overflow the host's 1 MiB inbound
frame once sealed (base64 adds a third), more so when a commit carries its blob list. The
host answers such a frame by closing the socket, so the move failed with a lost answer.
The catalog client now measures the request against REMOTE_RUNTIME_MAX_INBOUND_REQUEST_JSON_BYTES
and refuses it with the existing 'too large' guidance, unsent.