snapshot of https://github.com/mountain-loop/yaak.git (main, 2026-09-23; blobs > 131072B omitted)

packages/theme/src/appearance.ts

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+import { platform } from "@yaakapp-internal/platform";
+
+export type Appearance = "light" | "dark";
+
+const SYSTEM_APPEARANCE_CHANGE_EVENT = "system_appearance_change";
+
+declare global {
+  interface Window {
+    __YAAK_INITIAL_APPEARANCE__?: Appearance;
+  }
+}
+
+// NOTE: On macOS and Linux the backend detects the appearance the OS prefers and injects
+//  it here, later emitting change events. This is required because applying a theme forces
+//  the window appearance, which poisons what the webview reports (CSS media queries and
+//  window theme events follow the override).
+export function getSystemAppearance(): Appearance | null {
+  const appearance = window.__YAAK_INITIAL_APPEARANCE__;
+  return appearance === "dark" || appearance === "light" ? appearance : null;
+}
+
+export function getCSSAppearance(): Appearance {
+  return window.matchMedia("(prefers-color-scheme: dark)").matches ? "dark" : "light";
+}
+
+export async function getWindowAppearance(): Promise<Appearance> {
+  const appearance = await platform.window.theme();
+  return appearance ?? getCSSAppearance();
+}
+
+export function subscribeToCSSAppearanceChange(cb: (appearance: Appearance) => void): () => void {
+  const media = window.matchMedia("(prefers-color-scheme: dark)");
+  const listener = () => cb(media.matches ? "dark" : "light");
+  media.addEventListener("change", listener);
+  return () => media.removeEventListener("change", listener);
+}
+
+export function subscribeToWindowAppearanceChange(
+  cb: (appearance: Appearance) => void,
+): () => void {
+  return platform.window.onThemeChanged(cb);
+}
+
+export function subscribeToSystemAppearanceChange(
+  cb: (appearance: Appearance) => void,
+): () => void {
+  return platform.listen<Appearance>(SYSTEM_APPEARANCE_CHANGE_EVENT, cb);
+}
+
+export function resolveAppearance(
+  preferredAppearance: Appearance,
+  appearanceSetting: string,
+): Appearance {
+  const appearance = appearanceSetting === "system" ? preferredAppearance : appearanceSetting;
+  return appearance === "dark" ? "dark" : "light";
+}
+
+export function subscribeToPreferredAppearance(cb: (appearance: Appearance) => void) {
+  const systemAppearance = getSystemAppearance();
+  if (systemAppearance != null) {
+    cb(systemAppearance);
+    return subscribeToSystemAppearanceChange(cb);
+  }
+
+  cb(getCSSAppearance());
+  void getWindowAppearance().then(cb);
+  return subscribeToPreferredAppearanceChange(cb);
+}
+
+export function subscribeToPreferredAppearanceChange(cb: (appearance: Appearance) => void) {
+  if (getSystemAppearance() != null) {
+    // The CSS and window sources are poisoned by forced window appearances, so only
+    // listen to the backend's system appearance detection when it's available
+    return subscribeToSystemAppearanceChange(cb);
+  }
+
+  const unsubscribeCSS = subscribeToCSSAppearanceChange(cb);
+  const unsubscribeWindow = subscribeToWindowAppearanceChange(cb);
+  const unsubscribeSystem = subscribeToSystemAppearanceChange(cb);
+  return () => {
+    unsubscribeCSS();
+    unsubscribeWindow();
+    unsubscribeSystem();
+  };
+}