diff --git a/src/app/plugins/react-custom-html-parser.tsx b/src/app/plugins/react-custom-html-parser.tsx
index 60aead019..17cbb84fb 100644
--- a/src/app/plugins/react-custom-html-parser.tsx
+++ b/src/app/plugins/react-custom-html-parser.tsx
@@ -125,7 +125,7 @@ function KatexRenderer({
 
   useEffect(() => {
     let mounted = true;
-    void Promise.all([import('katex'), import('katex/dist/katex.min.css')]).then(([katex]) => {
+    void import('katex').then((katex) => {
       if (mounted) {
         setHtml(katex.default.renderToString(math, { throwOnError: false, displayMode }));
       }
diff --git a/src/app/utils/mediaTransport.test.ts b/src/app/utils/mediaTransport.test.ts
index 9d599313c..de6caf937 100644
--- a/src/app/utils/mediaTransport.test.ts
+++ b/src/app/utils/mediaTransport.test.ts
@@ -114,6 +114,36 @@ describe('fetchMediaBlob', () => {
     TEST_TIMEOUT
   );
 
+  it('selects the JSON-encoded active session instead of falling back to the first account', async () => {
+    const { getActiveMediaSession, getCurrentMediaSessionScope } = await import('./mediaTransport');
+
+    localStorage.setItem(
+      'matrixSessions',
+      JSON.stringify([
+        {
+          baseUrl: 'https://matrix.example.org',
+          userId: '@alice:example.org',
+          deviceId: 'ALICE',
+          accessToken: 'alice-token',
+        },
+        {
+          baseUrl: 'https://other.example.org',
+          userId: '@bob:example.org',
+          deviceId: 'BOB',
+          accessToken: 'bob-token',
+        },
+      ])
+    );
+    localStorage.setItem('matrixActiveSession', JSON.stringify('@bob:example.org'));
+
+    expect(getActiveMediaSession()).toEqual({
+      baseUrl: 'https://other.example.org',
+      accessToken: 'bob-token',
+      userId: '@bob:example.org',
+    });
+    expect(getCurrentMediaSessionScope()).toBe('@bob:example.org');
+  });
+
   it(
     'uses caller-provided auth and cache scope when present',
     async () => {
diff --git a/src/app/utils/mediaTransport.ts b/src/app/utils/mediaTransport.ts
index e4a93b710..34083eb76 100644
--- a/src/app/utils/mediaTransport.ts
+++ b/src/app/utils/mediaTransport.ts
@@ -65,11 +65,24 @@ function parseStoredSessions(): StoredSession[] {
   }
 }
 
+function getStoredActiveSessionId(): string | undefined {
+  const raw = localStorage.getItem(ACTIVE_SESSION_KEY);
+  if (!raw) return undefined;
+
+  try {
+    const parsed = JSON.parse(raw);
+    return typeof parsed === 'string' ? parsed : undefined;
+  } catch {
+    // Keep reading pre-multi-account values written without JSON encoding.
+    return raw;
+  }
+}
+
 function getActiveStoredSession(): StoredSession | undefined {
   if (typeof localStorage === 'undefined') return undefined;
 
   const sessions = parseStoredSessions();
-  const activeSessionId = localStorage.getItem(ACTIVE_SESSION_KEY);
+  const activeSessionId = getStoredActiveSessionId();
   return (
     (activeSessionId
       ? sessions.find((session) => session.userId === activeSessionId)
diff --git a/src/app/utils/tauriMediaAuth.test.ts b/src/app/utils/tauriMediaAuth.test.ts
index db576446e..2c5713f71 100644
--- a/src/app/utils/tauriMediaAuth.test.ts
+++ b/src/app/utils/tauriMediaAuth.test.ts
@@ -112,4 +112,30 @@ describe('Tauri media session coordinator', () => {
     const scopes = commands.setMediaSession.mock.calls.map(([params]) => params.scope);
     expect(scopes).toEqual(['@a:matrix.example', '@a:matrix.example']);
   });
+
+  it('syncs the native session when the active account changes in this window', async () => {
+    mediaTransport.getActiveMediaSession
+      .mockReturnValueOnce({
+        baseUrl: 'https://one.example',
+        accessToken: 'one',
+        userId: '@a:one.example',
+      })
+      .mockReturnValue({
+        baseUrl: 'https://two.example',
+        accessToken: 'two',
+        userId: '@b:two.example',
+      });
+
+    await initTauriMediaSession();
+    commands.setMediaSession.mockClear();
+
+    window.dispatchEvent(new Event('sable-session-changed'));
+    await vi.waitFor(() => expect(commands.setMediaSession).toHaveBeenCalledTimes(1));
+
+    expect(commands.setMediaSession).toHaveBeenCalledWith({
+      baseUrl: 'https://two.example',
+      token: 'two',
+      scope: '@b:two.example',
+    });
+  });
 });
diff --git a/src/app/utils/tauriMediaAuth.ts b/src/app/utils/tauriMediaAuth.ts
index 40da92901..6ca4877d0 100644
--- a/src/app/utils/tauriMediaAuth.ts
+++ b/src/app/utils/tauriMediaAuth.ts
@@ -6,6 +6,7 @@ import { getActiveMediaSession } from './mediaTransport';
 const log = createLogger('tauri-media-auth');
 
 let pendingNativeWrite: Promise<void> = Promise.resolve();
+let tauriMediaSessionListenersInstalled = false;
 
 export const updateTauriMediaSession = (
   baseUrl?: string,
@@ -41,9 +42,14 @@ const syncTauriMediaSession = (): Promise<void> => {
 export const initTauriMediaSession = (): Promise<void> => {
   if (!isTauri()) return Promise.resolve();
 
-  const initialSync = syncTauriMediaSession();
-  window.addEventListener('storage', () => {
-    void syncTauriMediaSession();
-  });
-  return initialSync;
+  if (!tauriMediaSessionListenersInstalled) {
+    const sync = () => {
+      void syncTauriMediaSession();
+    };
+    window.addEventListener('storage', sync);
+    window.addEventListener('sable-session-changed', sync);
+    tauriMediaSessionListenersInstalled = true;
+  }
+
+  return syncTauriMediaSession();
 };
diff --git a/src/index.tsx b/src/index.tsx
index 1b67abe5b..ded943743 100644
--- a/src/index.tsx
+++ b/src/index.tsx
@@ -7,6 +7,7 @@ import '@fontsource/space-mono/400.css';
 import '@fontsource/space-mono/700.css';
 import '@fontsource/space-mono/400-italic.css';
 import '@fontsource/space-mono/700-italic.css';
+import 'katex/dist/katex.min.css';
 import 'folds/dist/style.css';
 import { configClass, varsClass } from 'folds';
 import App from './app/pages/App';
diff --git a/vite.config.ts b/vite.config.ts
index f980a90c8..e1dd090b7 100644
--- a/vite.config.ts
+++ b/vite.config.ts
@@ -143,7 +143,7 @@ export default defineConfig(({ command }) => {
     clearScreen: false,
     appType: 'spa',
     publicDir: false,
-    base: buildConfig.base,
+    base: command === 'build' && isTauriBuild ? './' : buildConfig.base,
     envPrefix: ['VITE_', 'TAURI_ENV_*'],
     define: {
       APP_VERSION: JSON.stringify(appVersion),