The library's DNGs carry the photographer's earlier develop settings
in their embedded XMP — the house style their photographs were made
with. A photograph opened with no edit of DarkRoom's now starts from
that earlier edit, translated (HSL bands, highlights, blacks and the
rest), as one undoable step named "Earlier Edit"; from there it is an
ordinary edit, saved with the photograph. Export does the same, so a
photograph never opened exports as opening it would show.
Only on positive evidence that there is no DarkRoom edit: a local file
with no sidecar beside it, or a server that answered "no such file"
with nothing in the cache. The stored-edit fetch now says which
(FetchedSidecar::absent). Offline, unreachable or unreadable never
counts — the earlier edit would otherwise be saved over a real edit
that merely failed to arrive.