Delta

Delta compares the current snapshot to the previous snapshot for the same catalog root.

The tab appears when a prior snapshot exists in the DB.

What fills each pane

Pane	Content
Left	Change buckets — e.g. added, modified, removed
Middle	Paths in the selected bucket
Right	Snapshot overview for the indexed tree — not file previews for middle-pane rows

Layout matches Snapshot so you can inspect what changed and open previews for modified files.

Run a new snapshot after editing the tree.
If the toast reports N added, M modified, R removed, open Delta (~ or tab bar). If it says No changes, this run added nothing to Delta — stay on Snapshot.
Select Added, Modified, or Removed on the left.
Walk the middle list; use Space quick actions where applicable.

File rows in the middle use the same Space menu as Snapshot (open, enhance, copy path, …). Lens add (l) applies to paths still in the catalog.