AIP-21: a record that reaches `post-quantum` shows that the commit quorum of distinct validators sealed the block
post-quantum in some round; it does not by itself prove that the block was decided (follows the AIP-22 erratum of the same
day). AIP-23: dated note on what the finality level rests on; level names unchanged. Three formal models carry a dated note
where they treated certificate uniqueness as a property of the code rather than of the model.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
