fix(channels): back active-workspace persistence with a jotai atom so the native pager sees switcher picks instead of a stale memoized localStorage read

src/app/pages/client/channels/Channels.tsx

@@ -1,5 +1,6 @@
 import React, { useEffect, useMemo, useRef } from 'react';
 import { useTranslation } from 'react-i18next';
+import { useSetAtom } from 'jotai';
 import { Icons } from 'folds';
 import { useSpace } from '../../../hooks/useSpace';
 import { PageNav, PageNavContent } from '../../../components/page';
@@ -8,12 +9,12 @@ import { useMobilePagerPane } from '../../../components/mobile-tabs-pager/Mobile
 import { StreamHeaderPrimaryAction } from '../../../state/mobilePagerHeader';
 import { useOpenCreateRoomModal } from '../../../state/hooks/createRoomModal';
 import { useOpenCreateSpaceModal } from '../../../state/hooks/createSpaceModal';
+import { activeChannelsSpaceAtom } from '../../../state/activeChannelsSpace';
 import { CreateRoomType } from '../../../components/create-room/types';
 import { ChannelsList } from './ChannelsList';
 import { ChannelsLanding } from './ChannelsLanding';
 import { ChannelsWorkspaceHorseshoe } from './ChannelsWorkspaceHorseshoe';
 import { WorkspaceFooter } from './WorkspaceFooter';
-import { ACTIVE_SPACE_KEY } from './useActiveSpace';
 
 // Index route at /channels/ (no space selected). Renders the shared
 // StreamHeader (segment switcher) plus the resolve-active-space-or-
@@ -79,18 +80,17 @@ export function Channels() {
   const scrollRef = useRef<HTMLDivElement>(null);
   const inPagerMode = useMobilePagerPane() !== null;
   const openCreateRoomModal = useOpenCreateRoomModal();
+  const setActiveSpace = useSetAtom(activeChannelsSpaceAtom);
 
   // Persist URL-driven active space so cold-starts at /channels/ resume on
-  // the same workspace. `useActiveSpace` (in ChannelsLanding) reads the
-  // value but never writes it because the index route has no
-  // :spaceIdOrAlias param — the write happens here.
+  // the same workspace. `useActiveSpace` (in ChannelsLanding and
+  // MobileTabsPager) subscribes to the same atom, so this write
+  // immediately invalidates their cached reads — without that, the pager
+  // would serve a stale `destinationFor('channels')` after a switcher
+  // pick + tab swap on native.
   useEffect(() => {
-    try {
-      localStorage.setItem(ACTIVE_SPACE_KEY, space.roomId);
-    } catch {
-      /* private mode / quota — non-fatal */
-    }
-  }, [space.roomId]);
+    setActiveSpace(space.roomId);
+  }, [setActiveSpace, space.roomId]);
 
   // Plus on the tabs row creates a channel inside the active workspace.
   // Single entry point for «create» on the Channels tab.

src/app/pages/client/channels/useActiveSpace.ts

@@ -1,18 +1,10 @@
 import { useMemo } from 'react';
 import { useParams } from 'react-router-dom';
+import { useAtomValue } from 'jotai';
 import { useMatrixClient } from '../../../hooks/useMatrixClient';
+import { activeChannelsSpaceAtom } from '../../../state/activeChannelsSpace';
 import { getCanonicalAliasRoomId, isRoomAlias } from '../../../utils/matrix';
 
-export const ACTIVE_SPACE_KEY = 'vojo.activeSpaceId';
-
-const readPersisted = (): string | null => {
-  try {
-    return localStorage.getItem(ACTIVE_SPACE_KEY);
-  } catch {
-    return null;
-  }
-};
-
 const safeDecode = (raw: string): string | undefined => {
   try {
     return decodeURIComponent(raw);
@@ -23,16 +15,22 @@ const safeDecode = (raw: string): string | undefined => {
 
 // Resolves the active Space for the channels segment. Priority:
 //   1. URL `:spaceIdOrAlias` param (if joined-orphan)
-//   2. localStorage['vojo.activeSpaceId'] (if joined-orphan)
+//   2. `activeChannelsSpaceAtom` (= localStorage, reactive) (if joined-orphan)
 //   3. first joined-orphan Space
 // Returns undefined when the user has 0 joined orphan spaces. Persistence
-// (writing to localStorage) lives in `Channels.tsx`, where the inner
-// route already has the resolved space context — at the index `/channels/`
+// (writing the atom) lives in `Channels.tsx`, where the inner route
+// already has the resolved space context — at the index `/channels/`
 // route, useParams().spaceIdOrAlias is always undefined.
+//
+// The persisted value is read via Jotai so writes from `Channels.tsx`
+// immediately invalidate every consumer (notably `MobileTabsPager`,
+// which stays mounted across tab swipes and would otherwise serve a
+// stale cached value to its `destinationFor('channels')`).
 export const useActiveSpace = (orphanSpaceIds: string[]): string | undefined => {
   const mx = useMatrixClient();
   const { spaceIdOrAlias } = useParams();
   const orphanSet = useMemo(() => new Set(orphanSpaceIds), [orphanSpaceIds]);
+  const persisted = useAtomValue(activeChannelsSpaceAtom);
 
   const urlSpaceId = useMemo(() => {
     if (!spaceIdOrAlias) return undefined;
@@ -42,10 +40,10 @@ export const useActiveSpace = (orphanSpaceIds: string[]): string | undefined =>
     return resolved && orphanSet.has(resolved) ? resolved : undefined;
   }, [mx, spaceIdOrAlias, orphanSet]);
 
-  const persistedSpaceId = useMemo(() => {
-    const stored = readPersisted();
-    return stored && orphanSet.has(stored) ? stored : undefined;
-  }, [orphanSet]);
+  const persistedSpaceId = useMemo(
+    () => (persisted && orphanSet.has(persisted) ? persisted : undefined),
+    [persisted, orphanSet]
+  );
 
   return urlSpaceId ?? persistedSpaceId ?? orphanSpaceIds[0];
 };

src/app/state/activeChannelsSpace.ts

@@ -0,0 +1,37 @@
+import { atomWithLocalStorage } from './utils/atomWithLocalStorage';
+
+// Persisted across reloads and tabs as a plain string (not JSON-encoded)
+// to stay backwards-compatible with the legacy `localStorage.setItem(key, roomId)`
+// writes that shipped before this atom existed.
+export const ACTIVE_CHANNELS_SPACE_KEY = 'vojo.activeSpaceId';
+
+const getRawString = (key: string): string | undefined => {
+  try {
+    return localStorage.getItem(key) ?? undefined;
+  } catch {
+    return undefined;
+  }
+};
+
+const setRawString = (key: string, value: string | undefined) => {
+  try {
+    if (value === undefined) {
+      localStorage.removeItem(key);
+    } else {
+      localStorage.setItem(key, value);
+    }
+  } catch {
+    /* private mode / quota — non-fatal */
+  }
+};
+
+// Single source of truth for the channels-tab «active workspace» selection.
+// Subscribed reads (via `useAtomValue`) re-render when the atom is written
+// in the same tab and when another tab updates localStorage — fixes the
+// stale-memo bug where `MobileTabsPager` cached the persisted value at
+// first render and never refreshed after the user picked a new workspace.
+export const activeChannelsSpaceAtom = atomWithLocalStorage<string | undefined>(
+  ACTIVE_CHANNELS_SPACE_KEY,
+  getRawString,
+  setRawString
+);