mint
Put a file in Bitcoin.
A counter is a Counterparty asset whose description is a file, carried in a v11 taproot envelope. The indexer numbers it gap-free from zero, in the order it reached the chain. Nothing here is uploaded anywhere — the bytes go into a Bitcoin block, and that is the only place they will ever live.
Leave it empty and a free numeric name is drawn for you at mint time.
Both wallets speak Counterparty. Minting needs a taproot account in either.
Two transactions: a commit that funds the envelope, then a reveal that spends it and puts the file in Bitcoin. The commit is broadcast before the reveal is signed — a browser wallet cannot sign an input whose parent it cannot find. If the reveal signature fails, nothing is lost: the envelope names your key, so it can be signed again.