Improve the notebook by making it easier to browse a large collection of notes, both in the note book and on the right pane next to a manuscript. The proposed UI returns a folder-like structure to the UI while still supporting tags.
Three-pane notebook view
Persistent left sidebar with categories and tags replaces the filter pop-over; one click filters, counts show at a glance, and active filters appear as removable chips.
"Hide planning" becomes a greyed-out Planning entry rather than a checkbox in a menu.
Cards become compact rows (title, meta, tags), roughly tripling notes per screen.
Notes group under collapsible category headers, mirroring the old folder tree.
A reading pane shows the selected note in full; arrow keys move selection, so browsing needs no clicks.
Density toggle keeps the card view available as an option.
Right pane (manuscript view)
Filter pop-over removed; the pane top shrinks to a tab bar, a slim toolbar (search, sort, tag filter, collapse-all) and a status row that appears only when a filter is active.
Collapsible category headers with coloured dots and counts handle category filtering and browsing; collapse-all reduces 100 notes to seven lines.
Single-line rows (title, optional preview, tag, age) replace multi-line cards; word count drops to hover.
Tags chosen via a small picker show as removable chips, so active filters are always visible.
Full-width "Create Note" button becomes a plus icon in the tab bar, freeing height for more rows.
Planning-hidden shown as a quiet toggle in the status row.