Dark theme loading screen

ts/background.ts

@@ -29,6 +29,7 @@ import type { Receipt } from './types/Receipt';
 import { getTitleBarVisibility, TitleBarVisibility } from './types/Settings';
 import { SocketStatus } from './types/SocketStatus';
 import { DEFAULT_CONVERSATION_COLOR } from './types/Colors';
+import { ThemeType } from './types/Util';
 import { ChallengeHandler } from './challenge';
 import * as durations from './util/durations';
 import { explodePromise } from './util/explodePromise';
@@ -166,6 +167,13 @@ export async function cleanupSessionResets(): Promise<void> {
 }
 
 export async function startApp(): Promise<void> {
+  if (window.initialTheme === ThemeType.light) {
+    document.body.classList.add('light-theme');
+  }
+  if (window.initialTheme === ThemeType.dark) {
+    document.body.classList.add('dark-theme');
+  }
+
   const idleDetector = new IdleDetector();
 
   await KeyboardLayout.initialize();

ts/main/settingsChannel.ts

@@ -17,6 +17,7 @@ import type {
 const EPHEMERAL_NAME_MAP = new Map([
   ['spellCheck', 'spell-check'],
   ['systemTraySetting', 'system-tray-setting'],
+  ['themeSetting', 'theme-setting'],
 ]);
 
 type ResponseQueueEntry = Readonly<{
@@ -68,7 +69,9 @@ export class SettingsChannel {
     this.installSetting('readReceiptSetting', { setter: false });
     this.installSetting('typingIndicatorSetting', { setter: false });
 
-    this.installSetting('themeSetting');
+    this.installSetting('themeSetting', {
+      isEphemeral: true,
+    });
     this.installSetting('hideMenuBar');
     this.installSetting('systemTraySetting', {
       isEphemeral: true,

ts/window.d.ts

@@ -29,7 +29,7 @@ import * as Curve from './Curve';
 import * as RemoteConfig from './RemoteConfig';
 import * as OS from './OS';
 import { getEnvironment } from './environment';
-import { LocalizerType } from './types/Util';
+import { LocalizerType, ThemeType } from './types/Util';
 import type { Receipt } from './types/Receipt';
 import { ConversationController } from './ConversationController';
 import { ReduxActions } from './state/types';
@@ -212,6 +212,7 @@ declare global {
     isAfterVersion: (version: string, anotherVersion: string) => boolean;
     isBeforeVersion: (version: string, anotherVersion: string) => boolean;
     isFullScreen: () => boolean;
+    initialTheme?: ThemeType;
     libphonenumber: {
       util: {
         getRegionCodeForNumber: (number: string) => string;