refactor(nav): read navigation from context, drop the prop-drilling

VideoCard/PlayerModal read openChannel from useNavigationActions (the memo'd
VideoCard subscribes to the STABLE actions context, so a page/channel change
no longer re-renders it); NavSidebar/Header read page/setPage; ChannelPage
reads closeChannel; NotificationsPanel reads setPage. App sheds the matching
props, and Feed/VirtualFeed no longer thread onOpenChannel at all.

frontend/src/App.tsx

@@ -148,7 +148,7 @@ function loadInitialFilters(): FeedFilters {
 export default function App() {
   const { t, i18n } = useTranslation();
   const { page, channelView, ytSearch } = useNavigation();
-  const { setPage, openChannel, closeChannel, enterYtSearch, exitYtSearch } = useNavigationActions();
+  const { setPage, openChannel, enterYtSearch, exitYtSearch } = useNavigationActions();
   const [theme, setThemeState] = useState<ThemePrefs>(() => loadLocalTheme());
   const [filters, setFiltersState] = useState<FeedFilters>(loadInitialFilters);
   // Whether this load arrived via a "Share view" link (captured once, before the URL is stripped)
@@ -636,8 +636,6 @@ export default function App() {
     <div className="h-screen flex text-fg">
       <NavSidebar
         me={meQuery.data!}
-        page={page}
-        setPage={setPage}
         onOpenAbout={() => setAboutOpen(true)}
         onChangeLanguage={changeLanguage}
         language={i18n.language as LangCode}
@@ -699,8 +697,6 @@ export default function App() {
               me={meQuery.data!}
               view={view}
               setView={setView}
-              onBack={closeChannel}
-              onOpenChannel={openChannel}
               onShowInFeed={() => {
                 // Keep the rest of the feed's filters — the point is "this channel, the way I
                 // normally read": unwatched, my tags, my date window.
@@ -730,8 +726,6 @@ export default function App() {
           setChannelsSearch={setChannelsSearch}
           playlistsSearch={playlistsSearch}
           setPlaylistsSearch={setPlaylistsSearch}
-          page={page}
-          setPage={setPage}
           onYtSearch={enterYtSearch}
           onGoToFullHistory={() => {
             setChannelFilter("needs_full");
@@ -789,7 +783,7 @@ export default function App() {
               setSelectedId={setSelectedPlaylistId}
             />
           ) : page === "notifications" ? (
-            <NotificationsPanel filters={filters} setFilters={setFilters} setPage={setPage} onFocusChannel={focusChannel} />
+            <NotificationsPanel filters={filters} setFilters={setFilters} onFocusChannel={focusChannel} />
           ) : page === "messages" && !meQuery.data!.is_demo ? (
             <div className="p-4 max-w-3xl w-full mx-auto">
               <Messages meId={meQuery.data!.id} />
@@ -826,7 +820,6 @@ export default function App() {
               ytSearch={ytSearch}
               onYtSearch={enterYtSearch}
               onExitYtSearch={exitYtSearch}
-              onOpenChannel={openChannel}
             />
           )}
           </Suspense>

frontend/src/components/ChannelPage.tsx

@@ -1,6 +1,7 @@
 import { useCallback, useEffect, useRef, useState } from "react";
 import { useTranslation } from "react-i18next";
 import { useMutation, useQuery, useQueryClient } from "@tanstack/react-query";
+import { useNavigationActions } from "./NavigationProvider";
 import { ArrowLeft, Ban, Check, ExternalLink, Loader2, Plus, RefreshCw, SlidersHorizontal } from "lucide-react";
 import Avatar from "./Avatar";
 import Feed from "./Feed";
@@ -57,8 +58,6 @@ export default function ChannelPage({
   me,
   view,
   setView,
-  onBack,
-  onOpenChannel,
   onShowInFeed,
 }: {
   channelId: string;
@@ -68,14 +67,13 @@ export default function ChannelPage({
   // toolbar carries the same switcher and a change here is the same account-wide choice.
   view: FeedView;
   setView: (v: FeedView) => void;
-  onBack: () => void;
   // Narrow the real feed to this channel and go there. Offered only for a channel you're
   // subscribed to: the feed defaults to scope "my", so filtering it to a channel you don't
   // follow would just land you on an empty page.
   onShowInFeed: () => void;
-  onOpenChannel: (id: string, name?: string) => void;
 }) {
   const { t, i18n } = useTranslation();
+  const { closeChannel } = useNavigationActions();
   const qc = useQueryClient();
   const confirm = useConfirm();
   const [tab, setTab] = useState<"videos" | "about">("videos");
@@ -245,7 +243,7 @@ export default function ChannelPage({
         )}
         <button
           data-testid="channel-back"
-          onClick={onBack}
+          onClick={closeChannel}
           className="absolute top-5 left-7 sm:left-9 z-10 inline-flex items-center gap-1.5 px-3 py-1.5 rounded-lg text-sm bg-black/45 text-white hover:bg-black/65 backdrop-blur-sm"
         >
           <ArrowLeft className="w-4 h-4" />
@@ -382,7 +380,6 @@ export default function ChannelPage({
             ytSearch={null}
             onYtSearch={() => {}}
             onExitYtSearch={() => {}}
-            onOpenChannel={onOpenChannel}
             channelScoped
           />
           {!ch?.subscribed && nextToken && (

frontend/src/components/Feed.tsx

@@ -88,7 +88,6 @@ export default function Feed({
   ytSearch,
   onYtSearch,
   onExitYtSearch,
-  onOpenChannel,
   channelScoped,
 }: {
   filters: FeedFilters;
@@ -107,9 +106,6 @@ export default function Feed({
   ytSearch: string | null;
   onYtSearch: (q: string) => void;
   onExitYtSearch: () => void;
-  // Open a channel's dedicated page (from a card's channel name / avatar). Threaded down to
-  // the cards via VirtualFeed.
-  onOpenChannel?: (channelId: string, channelName?: string) => void;
   // True when this feed is scoped to a single channel (the channel page). Drops sort options
   // that are constant within one channel (subscribers, priority) — they'd be meaningless.
   channelScoped?: boolean;
@@ -308,13 +304,6 @@ export default function Feed({
     [qc]
   );
 
-  const handleOpenChannel = useCallback(
-    (channelId: string, channelName: string) => {
-      onOpenChannel?.(channelId, channelName);
-    },
-    [onOpenChannel]
-  );
-
   const onToggleSave = useCallback(
     (id: string, saved: boolean) => {
       setSavedOverrides((o) => ({ ...o, [id]: saved }));
@@ -447,7 +436,6 @@ export default function Feed({
               view={view}
               onState={onState}
               onToggleSave={onToggleSave}
-              onOpenChannel={handleOpenChannel}
               onResetState={onResetState}
               onOpen={openVideo}
               hasNextPage={false}
@@ -480,7 +468,6 @@ export default function Feed({
               queue={ytPlayerQueue}
               onClose={() => setActiveVideo(null)}
               onState={onState}
-              onOpenChannel={onOpenChannel}
             />
           </Suspense>
         )}
@@ -698,7 +685,6 @@ export default function Feed({
           view={view}
           onState={onState}
           onToggleSave={onToggleSave}
-          onOpenChannel={handleOpenChannel}
           onResetState={onResetState}
           onOpen={openVideo}
           hasNextPage={!!hasNextPage}
@@ -714,7 +700,6 @@ export default function Feed({
             queue={playerQueue}
             onClose={() => setActiveVideo(null)}
             onState={onState}
-            onOpenChannel={onOpenChannel}
           />
         </Suspense>
       )}

frontend/src/components/Header.tsx

@@ -2,11 +2,11 @@ import { type ReactNode } from "react";
 import { useTranslation } from "react-i18next";
 import { Youtube } from "lucide-react";
 import type { FeedFilters, Me } from "../lib/api";
-import type { Page } from "../lib/urlState";
 import { moduleLabelKey, moduleOrder, stepModule } from "../lib/modules";
 import ModuleName from "./ModuleName";
 import SearchBar from "./SearchBar";
 import SyncStatus from "./SyncStatus";
+import { useNavigation, useNavigationActions } from "./NavigationProvider";
 
 // 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
@@ -21,8 +21,6 @@ export default function Header({
   setChannelsSearch,
   playlistsSearch,
   setPlaylistsSearch,
-  page,
-  setPage,
   onYtSearch,
   onGoToFullHistory,
 }: {
@@ -36,8 +34,6 @@ export default function Header({
   setChannelsSearch: (q: string) => void;
   playlistsSearch: string;
   setPlaylistsSearch: (q: string) => void;
-  page: Page;
-  setPage: (p: Page) => 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;
@@ -45,6 +41,8 @@ export default function Header({
   onGoToFullHistory: () => void;
 }) {
   const { t } = useTranslation();
+  const { page } = useNavigation();
+  const { setPage } = useNavigationActions();
   // 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/NavSidebar.tsx

@@ -2,6 +2,7 @@ import { useEffect, useRef, useState, useSyncExternalStore } from "react";
 import { createPortal } from "react-dom";
 import { useTranslation } from "react-i18next";
 import { useQuery } from "@tanstack/react-query";
+import { useNavigation, useNavigationActions } from "./NavigationProvider";
 import {
   Activity,
   BarChart3,
@@ -40,8 +41,6 @@ import LanguageSwitcher from "./LanguageSwitcher";
 // a thin icon-only rail. Account actions sit at the bottom in a popover.
 export default function NavSidebar({
   me,
-  page,
-  setPage,
   onOpenAbout,
   onChangeLanguage,
   language,
@@ -49,8 +48,6 @@ export default function NavSidebar({
   onToggleCollapse,
 }: {
   me: Me;
-  page: Page;
-  setPage: (p: Page) => void;
   onOpenAbout: () => void;
   onChangeLanguage: (code: LangCode) => void;
   language: LangCode;
@@ -60,6 +57,8 @@ export default function NavSidebar({
   onToggleCollapse: () => void;
 }) {
   const { t } = useTranslation();
+  const { page } = useNavigation();
+  const { setPage } = useNavigationActions();
   // When unpinned, the rail sits slim (icons only) and peeks open into a labelled overlay on hover
   // or keyboard focus WITHOUT pushing content. Pinned keeps it expanded in-flow like before.
   // `collapsed` (persisted per-account) now means "unpinned".

frontend/src/components/NotificationsPanel.tsx

@@ -20,8 +20,8 @@ import {
   type VideoWatchedMeta,
 } from "../lib/notifications";
 import { channelYouTubeUrl, relativeFromMs, relativeTime } from "../lib/format";
-import type { Page } from "../lib/urlState";
 import { LEVEL_STYLE } from "./Toaster";
+import { useNavigationActions } from "./NavigationProvider";
 
 // The single notification center. "System" = durable, server-backed notifications (inbox
 // phase 1). "Activity" = the client-side transient events (action confirmations, errors, with
@@ -32,15 +32,14 @@ const POLL_MS = 8000;
 export default function NotificationsPanel({
   filters,
   setFilters,
-  setPage,
   onFocusChannel,
 }: {
   filters: FeedFilters;
   setFilters: (f: FeedFilters) => void;
-  setPage: (p: Page) => void;
   onFocusChannel: (name: string) => void;
 }) {
   const { t } = useTranslation();
+  const { setPage } = useNavigationActions();
   const qc = useQueryClient();
   const q = useLiveQuery<{ items: AppNotification[]; total: number }>(
     ["notifications"],

frontend/src/components/PlayerModal.tsx

@@ -1,6 +1,7 @@
 import { useEffect, useMemo, useRef, useState } from "react";
 import { useTranslation } from "react-i18next";
 import { createPortal } from "react-dom";
+import { useNavigationActions } from "./NavigationProvider";
 import { useQuery, useQueryClient } from "@tanstack/react-query";
 import { AlertTriangle, ArrowLeft, Check, CheckCheck, ChevronLeft, ChevronRight, ExternalLink, Repeat, Repeat1, Settings, Shuffle, SkipBack, SkipForward, Volume2, VolumeX, X } from "lucide-react";
 import Avatar from "./Avatar";
@@ -55,7 +56,6 @@ export default function PlayerModal({
   startIndex,
   onClose,
   onState,
-  onOpenChannel,
 }: {
   video: Video;
   // Where to start the opened video: a number of seconds (0 = Restart), or null/undefined
@@ -70,9 +70,9 @@ export default function PlayerModal({
   onState: (id: string, status: string) => void;
   // Open the active video's channel page in-app (closes the player first). The small external
   // icon next to the name keeps the open-on-YouTube behaviour.
-  onOpenChannel?: (channelId: string, channelName?: string) => void;
 }) {
   const { t, i18n } = useTranslation();
+  const { openChannel } = useNavigationActions();
   const qc = useQueryClient();
   const descFade = useScrollFade();
   // Browser/mouse Back closes the player instead of leaving the page.
@@ -840,16 +840,15 @@ export default function PlayerModal({
               <div className="flex items-center gap-1.5 shrink-0 min-w-0">
                 <button
                   onClick={() => {
-                    if (!onOpenChannel) return onClose();
                     const cid = active.channel_id;
                     const cname = active.channel_title ?? undefined;
                     // Closing the player pops its own history entry (useBackToClose → history.back()).
                     // Open the channel only AFTER that pop's popstate — pushing the channel entry
                     // before it would let the back remove it again (the bug: clicking the name only
-                    // closed the player). One-shot listener fires after App's popstate handler.
+                    // closed the player). One-shot listener fires after the popstate handler.
                     const open = () => {
                       window.removeEventListener("popstate", open);
-                      onOpenChannel(cid, cname);
+                      openChannel(cid, cname);
                     };
                     window.addEventListener("popstate", open);
                     onClose();

frontend/src/components/VideoCard.tsx

@@ -1,5 +1,6 @@
 import { memo, useEffect, useRef, useState } from "react";
 import { useTranslation } from "react-i18next";
+import { useNavigationActions } from "./NavigationProvider";
 import {
   Bookmark,
   Check,
@@ -368,7 +369,6 @@ function VideoCard({
   onState,
   onResetState,
   onToggleSave,
-  onOpenChannel,
   onOpen,
 }: {
   video: Video;
@@ -378,10 +378,10 @@ function VideoCard({
   onState: (id: string, status: string) => void;
   onResetState?: (id: string) => void;
   onToggleSave: (id: string, saved: boolean) => void;
-  onOpenChannel?: (channelId: string, channelName: string) => void;
   onOpen?: (v: Video, startAt?: number | null) => void;
 }) {
   const { t, i18n } = useTranslation();
+  const { openChannel } = useNavigationActions();
   const spec = FEED_VIEW_SPEC[view];
   const watched = video.status === "watched";
   // The thumbnail-less row drops Thumb, and with it the duration / live state / saved marker that
@@ -451,7 +451,7 @@ function VideoCard({
       data-testid="video-card-channel"
       onClick={(e) => {
         e.stopPropagation();
-        onOpenChannel?.(video.channel_id, video.channel_title ?? t("card.thisChannel"));
+        openChannel(video.channel_id, video.channel_title ?? t("card.thisChannel"));
       }}
       title={channelClamped ? video.channel_title ?? undefined : undefined}
       className="text-sm text-muted truncate block w-fit max-w-full text-left hover:text-fg"

frontend/src/components/VirtualFeed.tsx

@@ -58,7 +58,6 @@ export interface VirtualFeedProps {
   view: FeedView;
   onState: (id: string, status: string) => void;
   onToggleSave: (id: string, saved: boolean) => void;
-  onOpenChannel: (channelId: string, channelName: string) => void;
   onResetState: (id: string) => void;
   onOpen: (v: Video, startAt?: number | null) => void;
   hasNextPage: boolean;
@@ -71,7 +70,6 @@ export default function VirtualFeed({
   view,
   onState,
   onToggleSave,
-  onOpenChannel,
   onResetState,
   onOpen,
   hasNextPage,
@@ -187,7 +185,6 @@ export default function VirtualFeed({
                   width={FEED_VIEW_SPEC[view].thumb ? 0 : itemWidth}
                   onState={onState}
                   onToggleSave={onToggleSave}
-                  onOpenChannel={onOpenChannel}
                   onResetState={onResetState}
                   onOpen={onOpen}
                 />