fix(overlay): correct Hyprland fullscreen overlay alignment on Linux (#107)

src/core/services/overlay-window-bounds.ts

@@ -7,11 +7,56 @@ type ScreenDipConverter = {
   ) => Electron.Rectangle;
 };
 
+type ContentBoundsWindow = {
+  isDestroyed: () => boolean;
+  getBounds: () => Electron.Rectangle;
+  getContentBounds: () => Electron.Rectangle;
+};
+
+function resolveContentAlignedBounds(
+  geometry: WindowGeometry,
+  window?: ContentBoundsWindow | null,
+): WindowGeometry {
+  if (!window || window.isDestroyed()) {
+    return geometry;
+  }
+
+  let outer: Electron.Rectangle;
+  let content: Electron.Rectangle;
+  try {
+    outer = window.getBounds();
+    content = window.getContentBounds();
+  } catch {
+    return geometry;
+  }
+
+  const leftInset = content.x - outer.x;
+  const topInset = content.y - outer.y;
+  const rightInset = outer.x + outer.width - (content.x + content.width);
+  const bottomInset = outer.y + outer.height - (content.y + content.height);
+  const insets = [leftInset, topInset, rightInset, bottomInset];
+  if (insets.some((inset) => !Number.isFinite(inset) || inset < 0)) {
+    return geometry;
+  }
+
+  return {
+    x: geometry.x - leftInset,
+    y: geometry.y - topInset,
+    width: geometry.width + leftInset + rightInset,
+    height: geometry.height + topInset + bottomInset,
+  };
+}
+
 export function normalizeOverlayWindowBoundsForPlatform(
   geometry: WindowGeometry,
   platform: NodeJS.Platform,
   screen: ScreenDipConverter | null,
+  window?: ContentBoundsWindow | null,
 ): WindowGeometry {
+  if (platform === 'linux') {
+    return resolveContentAlignedBounds(geometry, window);
+  }
+
   if (platform !== 'win32' || !screen) {
     return geometry;
   }