diff --git a/packages/app/src/context/SettingsContext.js b/packages/app/src/context/SettingsContext.js
index f95d07e..df609e4 100644
--- a/packages/app/src/context/SettingsContext.js
+++ b/packages/app/src/context/SettingsContext.js
@@ -113,6 +113,11 @@ const VALUE_CONVERSIONS = {
 		toServer: v => v ? 'always' : 'never',
 		fromServer: v => v !== 'never'
 	},
+	// The other clients offer off, logo or library, where this app keeps a separate toggle for
+	// turning it off. There is nothing to draw for "off", so leave the mode we already have.
+	screensaverMode: {
+		fromServer: v => (v === 'off' ? undefined : v)
+	},
 	// Three states here against a boolean elsewhere. "Per Library" has no equivalent, so it
 	// declines to push and leaves whatever the server holds.
 	folderViewMode: {
@@ -137,7 +142,7 @@ const VALUE_CONVERSIONS = {
 	// move together, so it gets resolved whole rather than a key at a time.
 };
 
-const SYNCABLE_KEYS = [
+export const SYNCABLE_KEYS = [
 	'showShuffleButton', 'shuffleContentType', 'showGenresButton',
 	'showFavoritesButton', 'showLibrariesInToolbar', 'mergeContinueWatchingNextUp',
 	'nextUpMaxDays',
@@ -177,18 +182,24 @@ const SYNCABLE_KEYS = [
 	'diagnosticLoggingEnabled',
 	'uiLanguage',
 	'blockedRatings',
-	'customHomeRows',
 	'mergeRadarrSonarrCalendars',
 	'radarrCalendarShowCinema', 'radarrCalendarShowDigital', 'radarrCalendarShowPhysical',
 	'radarrCalendarShowDate', 'sonarrCalendarShowDate', 'sonarrCalendarShowEpisodeInfo',
 	'showSeerrButton',
+	'screensaverMode',
+	// Settings this app has no screen for. They ride along so a value set on another client
+	// survives the profile the TV writes back.
+	'showCastButton', 'themeMusicLoop',
+	'classicHomeRowsPadding', 'modernHomeRowsPadding',
+	'detailShowTechnicalDetails',
+	'recommendationSystemSource', 'recommendationsApplyParentalRatingCap',
 	'detailButtonOrderTv', 'hiddenDetailButtonsTv', 'osdButtonOrderTv', 'hiddenOsdButtonsTv',
 	'focusBorderColor',
 	'navbarOpacity',
 	'navbarColor',
 ];
 
-const profileToLocal = (serverProfile) => {
+export const profileToLocal = (serverProfile) => {
 	if (!serverProfile) return {};
 	const local = {};
 	for (const [key, value] of Object.entries(serverProfile)) {
@@ -211,7 +222,7 @@ const profileToLocal = (serverProfile) => {
 	return local;
 };
 
-const localToProfile = (localSettings) => {
+export const localToProfile = (localSettings) => {
 	const profile = {};
 	for (const key of SYNCABLE_KEYS) {
 		if (key === 'homeRows') continue;
diff --git a/packages/app/src/context/defaultSettings.js b/packages/app/src/context/defaultSettings.js
index 4ed312a..3239528 100644
--- a/packages/app/src/context/defaultSettings.js
+++ b/packages/app/src/context/defaultSettings.js
@@ -188,6 +188,15 @@ export const defaultSettings = {
 	truehdPassthrough: true,
 	blockedRatings: [],
 	showSeerrButton: true,
+	// Synced but not shown anywhere in this app, so null keeps the TV from stamping a default
+	// of its own over what another client set. The padding pair is a pixel count on the server.
+	themeMusicLoop: null,
+	showCastButton: null,
+	classicHomeRowsPadding: null,
+	modernHomeRowsPadding: null,
+	detailShowTechnicalDetails: null,
+	recommendationSystemSource: null,
+	recommendationsApplyParentalRatingCap: null,
 	performanceMode: 'auto',
 	focusBorderColor: '',
 	navbarOpacity: 100,
diff --git a/packages/app/src/context/settingsSync.test.js b/packages/app/src/context/settingsSync.test.js
new file mode 100644
index 0000000..119c86d
--- /dev/null
+++ b/packages/app/src/context/settingsSync.test.js
@@ -0,0 +1,84 @@
+// The server profile is typed, so a key this app spells differently isn't refused, it's
+// quietly dropped. Nothing on this side can prove a field name is right, but these lock down
+// what gets sent and what gets taken.
+
+// Nothing renders here. The provider only needs React to exist while the module loads, and
+// the real one can't be pulled in because the CLI ships a second copy that disagrees with it.
+jest.mock('react/jsx-dev-runtime', () => ({}));
+jest.mock('react', () => ({createContext: () => ({})}));
+// Storage picks its platform module through a dynamic import that jest can't transform.
+jest.mock('../services/storage', () => ({}));
+
+import {SYNCABLE_KEYS, defaultSettings, profileToLocal, localToProfile} from './SettingsContext';
+
+describe('profileToLocal', () => {
+	test('takes the TV button fields under their own names', () => {
+		const local = profileToLocal({
+			detailButtonOrderTv: ['play', 'trailer'],
+			hiddenDetailButtonsTv: ['shuffle'],
+			osdButtonOrderTv: ['subtitles'],
+			hiddenOsdButtonsTv: ['audio']
+		});
+
+		expect(local.detailButtonOrderTv).toEqual(['play', 'trailer']);
+		expect(local.hiddenDetailButtonsTv).toEqual(['shuffle']);
+		expect(local.osdButtonOrderTv).toEqual(['subtitles']);
+		expect(local.hiddenOsdButtonsTv).toEqual(['audio']);
+	});
+
+	test('leaves the desktop and mobile button fields alone', () => {
+		const local = profileToLocal({
+			osdButtonOrderDesktop: ['desktop-order'],
+			hiddenDetailButtonsMobile: ['mobile-hidden']
+		});
+
+		expect(local).toEqual({});
+	});
+
+	test('ignores a screensaver mode this app has no way to draw', () => {
+		expect(profileToLocal({screensaverMode: 'off'}).screensaverMode).toBeUndefined();
+		expect(profileToLocal({screensaverMode: 'logo'}).screensaverMode).toBe('logo');
+	});
+});
+
+describe('localToProfile', () => {
+	test('says nothing about settings this app has no screen for', () => {
+		const profile = localToProfile(defaultSettings);
+
+		for (const key of ['showCastButton', 'themeMusicLoop', 'classicHomeRowsPadding',
+			'modernHomeRowsPadding', 'detailShowTechnicalDetails', 'recommendationSystemSource',
+			'recommendationsApplyParentalRatingCap']) {
+			expect(profile).not.toHaveProperty(key);
+		}
+	});
+
+	test('writes those settings back once the server has supplied one', () => {
+		const profile = localToProfile({...defaultSettings, ...profileToLocal({
+			showCastButton: false,
+			classicHomeRowsPadding: 12
+		})});
+
+		expect(profile.showCastButton).toBe(false);
+		expect(profile.classicHomeRowsPadding).toBe(12);
+	});
+
+	test('keeps the local only home row list out of the profile', () => {
+		const profile = localToProfile({...defaultSettings, customHomeRows: [{id: 'row'}]});
+
+		expect(profile).not.toHaveProperty('customHomeRows');
+	});
+
+	// Some synced keys have no default at all, which is how a screen asks for its built in
+	// order rather than a stored one.
+	test('invents nothing when there is no local value to send', () => {
+		expect(localToProfile({})).toEqual({});
+	});
+});
+
+describe('SYNCABLE_KEYS', () => {
+	test('no key is listed twice', () => {
+		const repeated = SYNCABLE_KEYS.filter((key, i) => SYNCABLE_KEYS.indexOf(key) !== i);
+
+		expect(repeated).toEqual([]);
+	});
+});