fix: rework compact nav and centralized back routing

Use master-detail layout on skinny windows so server and channel lists share one screen, with back returning to the space list instead of redirect loops. Add useBackRoute for title-bar and page-header back buttons with view transitions.

src/app/components/BackRouteHandler.tsx

@@ -1,90 +1,11 @@
-import { ReactNode, useCallback } from 'react';
-import { matchPath, useLocation, useNavigate } from 'react-router-dom';
-import {
-  decodeRouteParam,
-  getDirectPath,
-  getExplorePath,
-  getHomePath,
-  getInboxPath,
-  getSpacePath,
-} from '../pages/pathUtils';
-import { DIRECT_PATH, EXPLORE_PATH, HOME_PATH, INBOX_PATH, SPACE_PATH } from '../pages/paths';
+import { ReactNode } from 'react';
+import { useBackRoute } from '../hooks/useBackRoute';
 
 type BackRouteHandlerProps = {
   children: (onBack: () => void) => ReactNode;
 };
 export function BackRouteHandler({ children }: BackRouteHandlerProps) {
-  const navigate = useNavigate();
-  const location = useLocation();
-
-  const goBack = useCallback(() => {
-    if (
-      matchPath(
-        {
-          path: HOME_PATH,
-          caseSensitive: true,
-          end: false,
-        },
-        location.pathname
-      )
-    ) {
-      navigate(getHomePath());
-      return;
-    }
-    if (
-      matchPath(
-        {
-          path: DIRECT_PATH,
-          caseSensitive: true,
-          end: false,
-        },
-        location.pathname
-      )
-    ) {
-      navigate(getDirectPath());
-      return;
-    }
-    const spaceMatch = matchPath(
-      {
-        path: SPACE_PATH,
-        caseSensitive: true,
-        end: false,
-      },
-      location.pathname
-    );
-    if (spaceMatch?.params.spaceIdOrAlias) {
-      const spaceIdOrAlias = decodeRouteParam(spaceMatch.params.spaceIdOrAlias);
-      if (spaceIdOrAlias) {
-        navigate(getSpacePath(spaceIdOrAlias));
-      }
-      return;
-    }
-    if (
-      matchPath(
-        {
-          path: EXPLORE_PATH,
-          caseSensitive: true,
-          end: false,
-        },
-        location.pathname
-      )
-    ) {
-      navigate(getExplorePath());
-      return;
-    }
-    if (
-      matchPath(
-        {
-          path: INBOX_PATH,
-          caseSensitive: true,
-          end: false,
-        },
-        location.pathname
-      )
-    ) {
-      navigate(getInboxPath());
-    }
-  }, [navigate, location]);
+  const { goBack } = useBackRoute();
 
   return children(goBack);
 }

src/app/components/page/Page.tsx

@@ -5,6 +5,7 @@ import { ContainerColor } from '../../styles/ContainerColor.css';
 import * as css from './style.css';
 import { ScreenSize, useScreenSizeContext } from '../../hooks/useScreenSize';
 import { SidebarDockedCallPanel } from '../../features/call/SidebarDockedCallPanel';
+import { useShowCompactMasterView } from '../../hooks/useCompactNav';
 
 type PageRootProps = {
   nav: ReactNode;
@@ -13,6 +14,7 @@ type PageRootProps = {
 
 export function PageRoot({ nav, children }: PageRootProps) {
   const screenSize = useScreenSizeContext();
+  const showCompactMaster = useShowCompactMasterView();
 
   return (
     <Box grow="Yes" className={ContainerColor({ variant: 'Background' })}>
@@ -20,7 +22,7 @@ export function PageRoot({ nav, children }: PageRootProps) {
       {screenSize !== ScreenSize.Mobile && (
         <Line variant="Background" size="300" direction="Vertical" />
       )}
-      {children}
+      {!showCompactMaster && children}
     </Box>
   );
 }

src/app/components/title-bar/TitleBar.css.ts

@@ -76,6 +76,11 @@ export const TitleBarDragRegion = style({
   color: color.Surface.OnContainer,
 });
 
+export const TitleBarBackButton = style({
+  WebkitAppRegion: 'no-drag',
+  flexShrink: 0,
+});
+
 export const SyncStatusBadge = style({
   position: 'absolute',
   left: '50%',

src/app/components/title-bar/TitleBar.tsx

@@ -1,5 +1,5 @@
 import React, { ReactNode, useMemo, useEffect, useState, useCallback, useRef } from 'react';
-import { Box, Text } from 'folds';
+import { Box, Text, IconButton } from 'folds';
 import { invoke } from '@tauri-apps/api/core';
 import { MatrixClient, RoomEvent, ClientEvent, MatrixEvent, Room, IPushRules, SyncState } from 'matrix-js-sdk';
 import { useAtomValue } from 'jotai';
@@ -18,6 +18,8 @@ import { AccountDataEvent } from '../../../types/matrix/accountData';
 import { getNotificationMode, NotificationMode } from '../../hooks/useNotificationMode';
 import { isRoomId } from '../../utils/matrix';
 import { useSyncState } from '../../hooks/useSyncState';
+import { useBackRoute } from '../../hooks/useBackRoute';
+import { Icon, Icons } from '../icons';
 
 type NewMessageNotification = {
   id: string;
@@ -42,6 +44,7 @@ export function TitleBar({ mx, children }: TitleBarProps) {
   const navigate = useNavigate();
   const roomToParents = useAtomValue(roomToParentsAtom);
   const mDirects = useAtomValue(mDirectAtom);
+  const { showInTitleBar, goBack } = useBackRoute(mx);
 
   // Sync status state
   const [syncStateData, setSyncStateData] = useState<{
@@ -652,6 +655,20 @@ export function TitleBar({ mx, children }: TitleBarProps) {
         grow="Yes"
         onMouseDown={handleDragStart}
       >
+        {showInTitleBar && (
+          <IconButton
+            className={css.TitleBarBackButton}
+            size="300"
+            variant="Surface"
+            fill="None"
+            radii="300"
+            onClick={goBack}
+            onMouseDown={(e) => e.stopPropagation()}
+            aria-label="Back"
+          >
+            <Icon src={Icons.ArrowLeft} size="200" />
+          </IconButton>
+        )}
         <Text size="T200" truncate style={{ color: 'inherit' }}>
           <span style={{ fontWeight: 700 }}>Paarrot</span>{titleParts.suffix}
         </Text>

src/app/features/lobby/LobbyHeader.tsx

@@ -16,7 +16,7 @@ import { UseStateProvider } from '../../components/UseStateProvider';
 import { LeaveSpacePrompt } from '../../components/leave-space-prompt';
 import { stopPropagation } from '../../utils/keyboard';
 import { ScreenSize, useScreenSizeContext } from '../../hooks/useScreenSize';
-import { BackRouteHandler } from '../../components/BackRouteHandler';
+import { useBackRoute } from '../../hooks/useBackRoute';
 import { mxcUrlToHttp } from '../../utils/matrix';
 import { useMediaAuthentication } from '../../hooks/useMediaAuthentication';
 import { useOpenSpaceSettings } from '../../state/hooks/spaceSettings';
@@ -165,6 +165,7 @@ export function LobbyHeader({ showProfile, showSpaceToolbar, powerLevels }: Lobb
   const [menuAnchor, setMenuAnchor] = useState<RectCords>();
   const [addExisting, setAddExisting] = useState<OpenAddExistingOptions | null>(null);
   const screenSize = useScreenSizeContext();
+  const { showInPageHeader, goBack } = useBackRoute();
 
   const name = useRoomName(space);
   const avatarMxc = useRoomAvatar(space);
@@ -270,6 +271,13 @@ export function LobbyHeader({ showProfile, showSpaceToolbar, powerLevels }: Lobb
       <>
       <PageHeader outlined>
         <Box grow="Yes" alignItems="Center" gap="300">
+          {showInPageHeader && (
+            <Box shrink="No">
+              <IconButton onClick={goBack} aria-label="Back">
+                <Icon src={Icons.ArrowLeft} />
+              </IconButton>
+            </Box>
+          )}
           <Avatar size="300" shrink="No">
             <RoomAvatar
               roomId={space.roomId}
@@ -361,16 +369,12 @@ export function LobbyHeader({ showProfile, showSpaceToolbar, powerLevels }: Lobb
   return (
     <PageHeader className={showProfile ? undefined : css.Header} balance>
       <Box grow="Yes" alignItems="Center" gap="200">
-        {screenSize === ScreenSize.Mobile ? (
+        {showInPageHeader ? (
           <>
             <Box shrink="No">
-              <BackRouteHandler>
-                {(onBack) => (
-                  <IconButton onClick={onBack}>
+              <IconButton onClick={goBack} aria-label="Back">
                 <Icon src={Icons.ArrowLeft} />
               </IconButton>
-                )}
-              </BackRouteHandler>
             </Box>
             <Box grow="Yes" justifyContent="Center">
               {showProfile && (

src/app/features/room/RoomViewHeader.tsx

@@ -36,7 +36,7 @@ import { stopPropagation } from '../../utils/keyboard';
 import { getMatrixToRoom } from '../../plugins/matrix-to';
 import { getViaServers } from '../../plugins/via-servers';
 import { PluginButtonSlot } from '../settings/plugins/PluginButtonSlot';
-import { BackRouteHandler } from '../../components/BackRouteHandler';
+import { useBackRoute } from '../../hooks/useBackRoute';
 import { useMediaAuthentication } from '../../hooks/useMediaAuthentication';
 import { useRoomPinnedEvents } from '../../hooks/useRoomPinnedEvents';
 import { RoomPinMenu } from './room-pin-menu';
@@ -463,6 +463,7 @@ export function RoomViewHeader({ forumLayout = false }: RoomViewHeaderProps) {
   const mx = useMatrixClient();
   const useAuthentication = useMediaAuthentication();
   const screenSize = useScreenSizeContext();
+  const { showInPageHeader, goBack } = useBackRoute();
   const room = useRoom();
   const space = useSpaceOptionally();
   const [menuAnchor, setMenuAnchor] = useState<RectCords>();
@@ -501,21 +502,17 @@ export function RoomViewHeader({ forumLayout = false }: RoomViewHeaderProps) {
   };
 
   return (
-    <PageHeader balance={screenSize === ScreenSize.Mobile}>
+    <PageHeader balance={showInPageHeader}>
       <Box grow="Yes" gap="300">
-        {screenSize === ScreenSize.Mobile && (
-          <BackRouteHandler>
-            {(onBack) => (
+        {showInPageHeader && (
           <Box shrink="No" alignItems="Center">
-                <IconButton onClick={onBack}>
+            <IconButton onClick={goBack} aria-label="Back">
               <Icon src={Icons.ArrowLeft} />
             </IconButton>
           </Box>
         )}
-          </BackRouteHandler>
-        )}
         <Box grow="Yes" alignItems="Center" gap="300">
-          {screenSize !== ScreenSize.Mobile && (
+          {!showInPageHeader && (
             <Avatar size="300">
               <RoomAvatar
                 roomId={room.roomId}

src/app/hooks/useBackRoute.ts

@@ -0,0 +1,151 @@
+import { useCallback, useMemo } from 'react';
+import { Location, matchPath, useLocation, useParams } from 'react-router-dom';
+import type { MatrixClient } from 'matrix-js-sdk';
+import {
+  decodeRouteParam,
+  getDirectPath,
+  getExplorePath,
+  getHomePath,
+  getInboxPath,
+  getSpacePath,
+} from '../pages/pathUtils';
+import {
+  DIRECT_PATH,
+  EXPLORE_PATH,
+  HOME_PATH,
+  INBOX_PATH,
+  SPACE_FEED_PATH,
+  SPACE_LOBBY_PATH,
+  SPACE_PATH,
+  SPACE_ROOM_PATH,
+  SPACE_SEARCH_PATH,
+} from '../pages/paths';
+import { ScreenSize } from './useScreenSize';
+import { useNavigateWithTransition } from './useViewTransitions';
+import { useMatrixClientOptionally } from './useMatrixClient';
+import { useScreenSizeContext } from './useScreenSize';
+import { getCanonicalAliasOrRoomId, getCanonicalAliasRoomId, isRoomAlias } from '../utils/matrix';
+
+type BackRouteContext = {
+  location: Location;
+  mx: MatrixClient;
+  selectedSpaceId?: string;
+};
+
+const spaceListPath = (mx: MatrixClient, spaceId: string, spaceIdOrAlias: string): string =>
+  getSpacePath(getCanonicalAliasOrRoomId(mx, spaceId) ?? spaceIdOrAlias);
+
+export const getBackRouteTarget = ({
+  location,
+  mx,
+  selectedSpaceId,
+}: BackRouteContext): string | null => {
+  const { pathname } = location;
+
+  const homeMatch = matchPath({ path: HOME_PATH, caseSensitive: true, end: false }, pathname);
+  if (homeMatch) {
+    const atRoot = matchPath({ path: HOME_PATH, caseSensitive: true, end: true }, pathname);
+    if (!atRoot) {
+      return getHomePath();
+    }
+    return null;
+  }
+
+  const directMatch = matchPath({ path: DIRECT_PATH, caseSensitive: true, end: false }, pathname);
+  if (directMatch) {
+    const atRoot = matchPath({ path: DIRECT_PATH, caseSensitive: true, end: true }, pathname);
+    if (!atRoot) {
+      return getDirectPath();
+    }
+    return null;
+  }
+
+  const spaceMatch = matchPath({ path: SPACE_PATH, caseSensitive: true, end: false }, pathname);
+  if (spaceMatch?.params.spaceIdOrAlias) {
+    const spaceIdOrAlias = decodeRouteParam(spaceMatch.params.spaceIdOrAlias);
+    if (!spaceIdOrAlias) return null;
+
+    const spaceId = selectedSpaceId ?? spaceIdOrAlias;
+    const listPath = spaceListPath(mx, spaceId, spaceIdOrAlias);
+
+    const inRoom = matchPath({ path: SPACE_ROOM_PATH, caseSensitive: true, end: false }, pathname);
+    if (inRoom) {
+      return listPath;
+    }
+
+    const atLobby = matchPath({ path: SPACE_LOBBY_PATH, caseSensitive: true, end: false }, pathname);
+    if (atLobby) {
+      return listPath;
+    }
+
+    const atFeed = matchPath({ path: SPACE_FEED_PATH, caseSensitive: true, end: false }, pathname);
+    if (atFeed) {
+      return listPath;
+    }
+
+    const atSearch = matchPath({ path: SPACE_SEARCH_PATH, caseSensitive: true, end: false }, pathname);
+    if (atSearch) {
+      return listPath;
+    }
+
+    return null;
+  }
+
+  const exploreMatch = matchPath({ path: EXPLORE_PATH, caseSensitive: true, end: false }, pathname);
+  if (exploreMatch) {
+    const atRoot = matchPath({ path: EXPLORE_PATH, caseSensitive: true, end: true }, pathname);
+    if (!atRoot) {
+      return getExplorePath();
+    }
+    return null;
+  }
+
+  const inboxMatch = matchPath({ path: INBOX_PATH, caseSensitive: true, end: false }, pathname);
+  if (inboxMatch) {
+    const atRoot = matchPath({ path: INBOX_PATH, caseSensitive: true, end: true }, pathname);
+    if (!atRoot) {
+      return getInboxPath();
+    }
+    return null;
+  }
+
+  return null;
+};
+
+export const showBackInPageHeader = (screenSize: ScreenSize): boolean =>
+  screenSize !== ScreenSize.Desktop;
+
+export const showBackInTitleBar = (screenSize: ScreenSize, canGoBack: boolean): boolean =>
+  screenSize === ScreenSize.Desktop && canGoBack;
+
+export const useBackRoute = (mxOverride?: MatrixClient | null) => {
+  const navigate = useNavigateWithTransition();
+  const location = useLocation();
+  const mxFromContext = useMatrixClientOptionally();
+  const mx = mxOverride ?? mxFromContext;
+  const screenSize = useScreenSizeContext();
+  const { spaceIdOrAlias: rawSpaceIdOrAlias } = useParams();
+  const spaceIdOrAlias = decodeRouteParam(rawSpaceIdOrAlias);
+  const selectedSpaceId =
+    mx && spaceIdOrAlias && isRoomAlias(spaceIdOrAlias)
+      ? getCanonicalAliasRoomId(mx, spaceIdOrAlias)
+      : spaceIdOrAlias;
+
+  const target = useMemo(() => {
+    if (!mx) return null;
+    return getBackRouteTarget({ location, mx, selectedSpaceId });
+  }, [location, mx, selectedSpaceId]);
+
+  const goBack = useCallback(() => {
+    if (target) {
+      navigate(target);
+    }
+  }, [navigate, target]);
+
+  return {
+    canGoBack: target !== null,
+    goBack,
+    showInPageHeader: showBackInPageHeader(screenSize) && target !== null,
+    showInTitleBar: showBackInTitleBar(screenSize, target !== null),
+  };
+};

src/app/hooks/useCompactNav.ts

@@ -0,0 +1,26 @@
+import { useMatch } from 'react-router-dom';
+import { DIRECT_PATH, EXPLORE_PATH, HOME_PATH, INBOX_PATH, SPACE_PATH } from '../pages/paths';
+import { ScreenSize, useScreenSizeContext } from './useScreenSize';
+
+/** Skinny window layout (≤750px): master-detail instead of 3-column desktop. */
+export const useCompactNav = (): boolean => {
+  const screenSize = useScreenSizeContext();
+  return screenSize === ScreenSize.Mobile;
+};
+
+/** Routes where sidebar + channel list are shown together (no room/content pane). */
+export const useIsCompactListRoute = (): boolean => {
+  const homeMatch = useMatch({ path: HOME_PATH, caseSensitive: true, end: true });
+  const directMatch = useMatch({ path: DIRECT_PATH, caseSensitive: true, end: true });
+  const spaceMatch = useMatch({ path: SPACE_PATH, caseSensitive: true, end: true });
+  const exploreMatch = useMatch({ path: EXPLORE_PATH, caseSensitive: true, end: true });
+  const inboxMatch = useMatch({ path: INBOX_PATH, caseSensitive: true, end: true });
+
+  return !!(homeMatch || directMatch || spaceMatch || exploreMatch || inboxMatch);
+};
+
+export const useShowCompactMasterView = (): boolean => {
+  const compact = useCompactNav();
+  const isListRoute = useIsCompactListRoute();
+  return compact && isListRoute;
+};

src/app/hooks/useMatrixClient.ts

@@ -10,3 +10,7 @@ export function useMatrixClient(): MatrixClient {
   if (!mx) throw new Error('MatrixClient not initialized!');
   return mx;
 }
+
+export function useMatrixClientOptionally(): MatrixClient | null {
+  return useContext(MatrixClientContext);
+}

src/app/pages/MobileFriendly.tsx

@@ -1,23 +1,20 @@
 import { ReactNode } from 'react';
 import { useMatch } from 'react-router-dom';
-import { ScreenSize, useScreenSizeContext } from '../hooks/useScreenSize';
 import { DIRECT_PATH, EXPLORE_PATH, HOME_PATH, INBOX_PATH, SPACE_PATH } from './paths';
+import { useCompactNav } from '../hooks/useCompactNav';
 
 type MobileFriendlyClientNavProps = {
   children: ReactNode;
 };
 export function MobileFriendlyClientNav({ children }: MobileFriendlyClientNavProps) {
-  const screenSize = useScreenSizeContext();
+  const compact = useCompactNav();
   const homeMatch = useMatch({ path: HOME_PATH, caseSensitive: true, end: true });
   const directMatch = useMatch({ path: DIRECT_PATH, caseSensitive: true, end: true });
   const spaceMatch = useMatch({ path: SPACE_PATH, caseSensitive: true, end: true });
   const exploreMatch = useMatch({ path: EXPLORE_PATH, caseSensitive: true, end: true });
   const inboxMatch = useMatch({ path: INBOX_PATH, caseSensitive: true, end: true });
 
-  if (
-    screenSize === ScreenSize.Mobile &&
-    !(homeMatch || directMatch || spaceMatch || exploreMatch || inboxMatch)
-  ) {
+  if (compact && !(homeMatch || directMatch || spaceMatch || exploreMatch || inboxMatch)) {
     return null;
   }
 
@@ -29,14 +26,14 @@ type MobileFriendlyPageNavProps = {
   children: ReactNode;
 };
 export function MobileFriendlyPageNav({ path, children }: MobileFriendlyPageNavProps) {
-  const screenSize = useScreenSizeContext();
+  const compact = useCompactNav();
   const exactPath = useMatch({
     path,
     caseSensitive: true,
     end: true,
   });
 
-  if (screenSize === ScreenSize.Mobile && !exactPath) {
+  if (compact && !exactPath) {
     return null;
   }
 

src/app/pages/client/space/SpaceIndexRedirect.tsx

@@ -5,17 +5,24 @@ import { useSpace } from '../../../hooks/useSpace';
 import { shouldShowForumLobby } from '../../../utils/room';
 import { getSpaceDefaultPath } from '../../pathUtils';
 import { ForumFeedPage } from '../../../features/forum/ForumFeedPage';
+import { useCompactNav } from '../../../hooks/useCompactNav';
 
-/** Sends /:spaceId/ to the forum feed or space lobby. */
+/** Sends /:spaceId/ to the forum feed or space lobby (desktop). On compact nav, stay on index for the channel list. */
 export function SpaceIndexRedirect() {
   const mx = useMatrixClient();
   const space = useSpace();
   const navigate = useNavigate();
+  const compact = useCompactNav();
   const isForum = shouldShowForumLobby(space);
 
   useEffect(() => {
+    if (compact) return;
     navigate(getSpaceDefaultPath(mx, space.roomId), { replace: true });
-  }, [mx, navigate, space.roomId]);
+  }, [compact, mx, navigate, space.roomId]);
+
+  if (compact) {
+    return null;
+  }
 
   // Avoid a blank main pane while redirecting forum spaces to /feed/.
   if (isForum) {