Fix white/inverted flash when windows open

Three layers: windows are created hidden and revealed on the webview's
first dom-ready (800ms fallback); the bun preload bakes the persisted
theme data-attributes so the first paint is already themed; and
index.html carries an inline background style covering the
pre-stylesheet paint (values mirrored from styles.css tokens).

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

src/bun/index.ts

@@ -14,7 +14,7 @@ import { migrateLegacyDataDir } from "./store/paths";
 import { SettingsStore } from "./store/settings";
 import { AppTray } from "./tray";
 import { TransferEngine } from "./transfers/engine";
-import { buildPreload } from "./windows";
+import { buildPreload, showWhenReady } from "./windows";
 
 const PROD_URL = "views://app/index.html";
 
@@ -56,6 +56,11 @@ const events = {
 const rpc = createAppRPC({ registry, engine, store, settings, edits, contextMenu, events });
 const url = await getMainViewUrl();
 
+// Loaded before any window exists: the persisted theme is baked into every
+// window's preload so the first paint is already themed (no flash). Kept
+// fresh via the saveSettings flow below.
+let currentSettings = await settings.load();
+
 const isMac = process.platform === "darwin";
 
 const win = new BrowserWindow({
@@ -73,16 +78,20 @@ const win = new BrowserWindow({
 	...(isMac
 		? { titleBarStyle: "hiddenInset" as const, trafficLightOffset: { x: 12, y: 13 } }
 		: {}),
-	// lets the UI pick the fused layout before first paint
-	preload: buildPreload("main"),
+	// lets the UI pick the fused layout + theme before first paint
+	preload: buildPreload("main", currentSettings),
 	rpc,
+	// revealed on first dom-ready — avoids the unthemed native flash
+	hidden: true,
 });
+showWhenReady(win);
 
 const editors = new EditorWindows({
 	registry,
 	settings,
 	edits,
 	url,
+	currentSettings: () => currentSettings,
 	mainFrame: () => win.getFrame(),
 	notifyMain: { pathRefresh: (info) => rpc.send.pathRefresh(info) },
 });
@@ -90,6 +99,7 @@ const manager = new ManagerWindow({
 	store,
 	settings,
 	url,
+	currentSettings: () => currentSettings,
 	mainFrame: () => win.getFrame(),
 	notifyMain: {
 		managerState: (info) => rpc.send.managerState(info),
@@ -101,6 +111,7 @@ const manager = new ManagerWindow({
 
 events.openEditor = (ctx) => editors.open(ctx);
 events.settingsChanged = (s) => {
+	currentSettings = s; // future windows' preloads bake the fresh theme
 	editors.broadcastSettings(s);
 	manager.broadcastSettings(s);
 };
@@ -199,7 +210,7 @@ events.sessionClosed = (info) => {
 	editors.notifySessionClosed(info);
 };
 events.connectionsChanged = () => void applyApplicationMenu(store);
-void settings.load().then((s) => engine.setConcurrency(effectiveConcurrency(s)));
+engine.setConcurrency(effectiveConcurrency(currentSettings));
 
 void applyApplicationMenu(store);
 ApplicationMenu.on("application-menu-clicked", (event) => {