refactor(playlists): scope module state in PlaylistsProvider

Lift the Playlists module's shared local state (rail name filter + selected
playlist) out of App into a split-context PlaylistsProvider, mirroring
FeedFiltersProvider. Header, PlaylistsRail, and the Playlists detail pane read
it via usePlaylists()/usePlaylistsActions() instead of props drilled through
App; the modules take only a uniform `me` prop now. App loses two useStates and
the selected-playlist persistence helper. (Platform S6b.2)

frontend/src/components/Header.tsx

@@ -8,6 +8,7 @@ import SearchBar from "./SearchBar";
 import SyncStatus from "./SyncStatus";
 import { useNavigation, useNavigationActions } from "./NavigationProvider";
 import { useFeedFilters, useFeedFiltersActions } from "./FeedFiltersProvider";
+import { usePlaylists, usePlaylistsActions } from "./PlaylistsProvider";
 
 // The floating top header: a row of glass pills over the content — a ModuleName pill (label +
 // accent dot + back/forward arrows), the module's SearchBar where it has one, and the per-user
@@ -18,8 +19,6 @@ export default function Header({
   setPlexQ,
   channelsSearch,
   setChannelsSearch,
-  playlistsSearch,
-  setPlaylistsSearch,
   onYtSearch,
   onGoToFullHistory,
 }: {
@@ -29,8 +28,6 @@ export default function Header({
   setPlexQ: (q: string) => void;
   channelsSearch: string;
   setChannelsSearch: (q: string) => void;
-  playlistsSearch: string;
-  setPlaylistsSearch: (q: string) => void;
   // Trigger a live YouTube search for the current term (feed only; hidden for the demo account,
   // which can't spend the shared quota).
   onYtSearch: (q: string) => void;
@@ -42,6 +39,9 @@ export default function Header({
   const { setPage } = useNavigationActions();
   const filters = useFeedFilters();
   const { setFilters } = useFeedFiltersActions();
+  // The playlists name filter lives in PlaylistsProvider (shared with its rail + detail pane).
+  const { search: playlistsSearch } = usePlaylists();
+  const { setSearch: setPlaylistsSearch } = usePlaylistsActions();
   // The ◀/▶ arrows step cyclically through the user's available modules (derived from `me`, so
   // it stays correct as modules are added/gated). Labels of every active module feed ModuleName's
   // dynamic width so the pill is sized to the widest reachable title in the current language.

frontend/src/components/Playlists.tsx

@@ -31,7 +31,7 @@ import {
   X,
   Youtube,
 } from "lucide-react";
-import { api, type Video } from "../lib/api";
+import { api, type Me, type Video } from "../lib/api";
 import { formatDuration } from "../lib/format";
 import { notify } from "../lib/notifications";
 import { notifyYouTubeActionError } from "../lib/youtubeErrors";
@@ -40,6 +40,7 @@ const PlayerModal = lazy(() => import("./PlayerModal"));
 import UndoToolbar from "./UndoToolbar";
 import { PageToolbar } from "./PageShell";
 import { useConfirm } from "./ConfirmProvider";
+import { usePlaylists, usePlaylistsActions } from "./PlaylistsProvider";
 
 type SortKey = "manual" | "title" | "duration" | "channel";
 type SortDir = "asc" | "desc";
@@ -178,17 +179,12 @@ function Row({
   );
 }
 
-export default function Playlists({
-  canWrite,
-  selectedId,
-  setSelectedId,
-}: {
-  canWrite: boolean;
-  // The selected playlist is App state, shared with the App-level PlaylistsRail (which owns the
+export default function Playlists({ me }: { me: Me }) {
+  const canWrite = me.can_write;
+  // The selected playlist lives in PlaylistsProvider, shared with the PlaylistsRail (which owns the
   // list + its rail controls). This detail pane reacts to the selection.
-  selectedId: number | null;
-  setSelectedId: (id: number | null) => void;
-}) {
+  const { selectedId } = usePlaylists();
+  const { setSelectedId } = usePlaylistsActions();
   const { t } = useTranslation();
   const qc = useQueryClient();
   const confirm = useConfirm();

frontend/src/components/PlaylistsProvider.tsx

@@ -0,0 +1,69 @@
+import {
+  createContext,
+  useCallback,
+  useContext,
+  useMemo,
+  useState,
+  type ReactNode,
+} from "react";
+import { getAccountRaw, LS, setAccountRaw } from "../lib/storage";
+
+// Owns the Playlists module's shared local state — the rail's name filter and the selected playlist
+// — lifted out of the App god component so the header search box, the PlaylistsRail, and the
+// Playlists detail pane read it via hooks instead of prop-drilling through App. Mirrors
+// FeedFiltersProvider / NavigationProvider (split State + Actions contexts, one-line hooks; composed
+// in main.tsx around <App/>).
+//
+// The `search` term is ephemeral (resets on reload, like the other list filters); the selected
+// playlist is per-account persisted (LS.playlist) so a reload returns you to it. Neither is
+// server-synced, and an account switch does a full reload, so init-from-storage is all the
+// hydration these need — no per-account load effect (unlike the server-backed feed filters).
+
+type PlaylistsState = {
+  search: string;
+  selectedId: number | null;
+};
+
+interface PlaylistsActions {
+  setSearch: (q: string) => void;
+  setSelectedId: (id: number | null) => void;
+}
+
+const StateContext = createContext<PlaylistsState>({ search: "", selectedId: null });
+const ActionsContext = createContext<PlaylistsActions>({
+  setSearch: () => {},
+  setSelectedId: () => {},
+});
+
+export function usePlaylists(): PlaylistsState {
+  return useContext(StateContext);
+}
+export function usePlaylistsActions(): PlaylistsActions {
+  return useContext(ActionsContext);
+}
+
+export function PlaylistsProvider({ children }: { children: ReactNode }) {
+  const [search, setSearchState] = useState("");
+  const [selectedId, setSelectedIdState] = useState<number | null>(() => {
+    const s = getAccountRaw(LS.playlist);
+    return s ? Number(s) : null;
+  });
+
+  const setSearch = useCallback((q: string) => setSearchState(q), []);
+  const setSelectedId = useCallback((id: number | null) => {
+    setSelectedIdState(id);
+    if (id != null) setAccountRaw(LS.playlist, String(id));
+  }, []);
+
+  const state = useMemo<PlaylistsState>(() => ({ search, selectedId }), [search, selectedId]);
+  const actions = useMemo<PlaylistsActions>(
+    () => ({ setSearch, setSelectedId }),
+    [setSearch, setSelectedId],
+  );
+
+  return (
+    <ActionsContext.Provider value={actions}>
+      <StateContext.Provider value={state}>{children}</StateContext.Provider>
+    </ActionsContext.Provider>
+  );
+}

frontend/src/components/PlaylistsRail.tsx

@@ -2,7 +2,7 @@ import { useEffect, useMemo, useRef, useState } from "react";
 import { useTranslation } from "react-i18next";
 import { useMutation, useQuery, useQueryClient } from "@tanstack/react-query";
 import { ArrowDown, ArrowUp, ListVideo, Pin, Plus, RefreshCw, Youtube } from "lucide-react";
-import { api, type Playlist } from "../lib/api";
+import { api, type Me, type Playlist } from "../lib/api";
 import { formatDuration } from "../lib/format";
 import { notify } from "../lib/notifications";
 import { notifyYouTubeActionError } from "../lib/youtubeErrors";
@@ -10,6 +10,7 @@ import { LS, readAccountMerged, writeAccount } from "../lib/storage";
 import { defaultLayout, type PanelLayout } from "../lib/panelLayout";
 import SidePanel from "./SidePanel";
 import PanelGroups, { type PanelItem } from "./PanelGroups";
+import { usePlaylists, usePlaylistsActions } from "./PlaylistsProvider";
 
 type PlSort = { key: "custom" | "name" | "count" | "duration"; dir: "asc" | "desc"; dirtyFirst: boolean };
 const PL_SORT_DEFAULT: PlSort = { key: "custom", dir: "asc", dirtyFirst: false };
@@ -19,24 +20,23 @@ const PL_SORT_DEFAULT: PlSort = { key: "custom", dir: "asc", dirtyFirst: false }
 // controls (sort / new / sync); the selected playlist is App state so the module's detail pane
 // (Playlists.tsx) reacts to it. Grouped into two islands: "manage" and the playlist list.
 export default function PlaylistsRail({
-  canWrite,
-  search,
-  selectedId,
-  setSelectedId,
+  me,
   layout,
   setLayout,
   collapsed,
   onToggleCollapse,
 }: {
-  canWrite: boolean;
-  search: string;
-  selectedId: number | null;
-  setSelectedId: (id: number | null) => void;
+  me: Me;
   layout: PanelLayout;
   setLayout: (l: PanelLayout) => void;
   collapsed: boolean;
   onToggleCollapse: () => void;
 }) {
+  const canWrite = me.can_write;
+  // The name filter + the selected playlist live in PlaylistsProvider (shared with the header search
+  // box and the Playlists detail pane); this rail owns the list query + its own controls.
+  const { search, selectedId } = usePlaylists();
+  const { setSelectedId } = usePlaylistsActions();
   const { t } = useTranslation();
   const qc = useQueryClient();
   const [plSort, setPlSort] = useState<PlSort>(() => readAccountMerged(LS.plSort, PL_SORT_DEFAULT));