Moving a file into a folder made the sync look at a new path, find nothing, and
convert it again — minutes of work to produce bytes that already existed a
directory away — while the old folder stayed behind forever, because nothing ever
deleted one.
A move preserves size and mtime, and both are already in the manifest and in the
stat. So the sync indexes what is already derived on that pair, and a file that
has moved has its ladder RENAMED across.
An ambiguous match is refused rather than guessed. Two originals can share a size
and an mtime — a camera dump can write a whole card in one second — and
rebuilding is merely slow where attaching the wrong photographs to a name is
wrong.
Orphans are removed afterwards, and only on a WHOLE-TREE sync. A scoped run knows
about one folder, so everything outside it looks abandoned; deleting on that
basis would take out the library the first time somebody re-synced a subfolder.
Safe otherwise because derived/ is reproducible by definition, which is what its
name has meant since these two folders stopped being called `user` and `treated`.
Both are counted, recorded in the ledger and shown only when they happened, so an
ordinary run stays one short line.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
pastilhasandClaude Opus 5
01652f3480