Flat mode now has the full toolbar: search, sort (artist/title/year),
group-by (off/letter/artist) and a grid/list view toggle, driven by a
derive_folders() pass that mirrors favorites::derive_albums over the
directory-grouped album set (folders-visible / folders-grouped).
Tree mode is a new two-pane filesystem browser: a flattened FolderNode
list in the left rail (lazy one-level expand via list_folder_children,
collapse drops the descendant block, recursive track counts gate the
chevron) and a detail pane on the right showing the selected folder's
direct tracks plus immediate subfolders, with Play all (recursive) and
per-track play scoped to the folder's direct list. A flat/tree segmented
toggle switches modes; the tree loads its roots lazily on first switch.
Slint has no native TreeView, so the tree is a depth-indented ListView of
visible nodes spliced on expand/collapse. No pills (ADR-008): underline
tabs, small-radius rectangles and an accent selection bar.
cc
vicrodh
d676a2f5a4