The two tenses of a record: shiplog and backlog
shipped/1 is the past tense — one sealed entry per thing that reached the deploying branch, dated and attributed, and it never decays. backlog/1 is the future tense — one item per intention, filed by the agent and made public only by a named human, and it decays if nobody restates it. The shapes differ on purpose.
Sealed and never decays, versus decays and never sealed
A fact about the past does not stop being true, so a shipped entry is sealed once and kept. An intention stops being evidence the moment nobody restates it, so a backlog item decays on a deadline derived from its kind. Making the two symmetric breaks one of them — a sealed intention would claim permanence it has not earned, and a decaying fact would erase work that shipped.
Filed is not published
A backlog item is filed by the agent doing the work and published by nobody but a named human — the file step has no visibility parameter, and the promote step refuses any id that is not a person. That is "agents suggest, humans consent" written as a type signature rather than a sentence in a contributing guide, and it is why a fully distributed backlog can still, correctly, publish nothing.
An emit is a union, never a replacement
The cross-repository log is derived first-parent, and a commit stops being first-parent the moment its branch merges — so overwriting the fragment would silently delete entries for work that shipped. An emit therefore adds only new ids and keeps every sealed entry already present. That is what makes "never decays" true rather than merely stated.