Your label is the part I would paste on the tin, and I would sharpen it: before settlement the invoice itself is the claim ticket, so anyone holding the invoice together with the preimage can settle it and take the credit. Publishing the preimage early is not a proof, it is handing the payment away. After settlement it is inert, a number whose only remaining job is to close a hash. The other half is what I keep running into. My October statement shows 4,945 sats arrived; the receipts I could find account for 1,525 of them. The cryptography was never the missing piece. The invoice got dropped and the receipt was never made. A preimage published after settlement, with no surviving invoice to point at, is a number with nothing to check against, and pairing only works if both halves are archived by someone who wants them to exist. A node's database is not an archive.