The three filter rails — feed Sidebar, PlexSidebar, PlaylistsRail — each rendered
the same SidePanel chrome (title bar, customize `editing` state, edit-toggle,
reset-to-layout-default, edit hint) around a PanelGroups body, differing only in
identity + filter content. Extracted that shell into components/FilterRail.tsx:
each rail now supplies only what differs (title/icon, active-filter count +
Clear-all action, its `items`, and optional content above/below the groups —
`top` for the feed's scope toggle, `children` for its tag manager). FilterRail
owns the `editing` state, so all three drop their duplicated useState + SidePanel
wiring.
MediaSource facade (lib/mediaSource.ts): a thin `MediaSourceKind = "feed" | "plex"`
naming the two browsable, filterable sources (a PanelId minus "playlists", which
is a rail but not a source). Already unified in practice — one SortControl, the
source-agnostic ActiveFilter[] chips, PanelId layouts, now the shared shell — so
this is formalization, not new capability: a single named seam for a future third
source or a cross-source feature. The two media-source rails annotate their `kind`
with it; PlaylistsRail passes the plain PanelId. Per the recon, the playlist-dialog
merge was deliberately NOT forced (it proved forced + low value). UX-3 control-vocab
sweep deliberately deferred — the rails already use the canonical primitives.
Behaviour-preserving. Gate green (tsc, knip, lint 0-err, 247 vitest). Self-E2E
(localdev): all three rails render via FilterRail — feed (scope toggle + panel
groups + Customize→editing with reset + 56 reorder affordances, exits clean), Plex
(filter groups + customize), Playlists (sections + customize); 0 JS console errors.
peter
4fe6f38f1b