fix(desktop): render the Windows window opaquely

Windows composited the desktop wallpaper behind the window through backgroundMaterial: 'acrylic', so every non-opaque surface blended it into the theme colours and the app looked washed out next to macOS. Paint an opaque background instead.

Author: elkaix

.changeset/windows-opaque-window.md

@@ -0,0 +1,5 @@
+---
+'@pymodel/pythinker-desktop': patch
+---
+
+Render the Windows desktop window opaquely so the theme colours are not blended with the desktop wallpaper

apps/desktop/src/main.ts

@@ -201,8 +201,9 @@ async function createMainWindow(): Promise<BrowserWindow> {
       vibrancy: 'sidebar' as const,
       visualEffectState: 'followWindow' as const,
     } : {}),
+    // Windows uses an opaque window so theme colors do not blend with desktop wallpaper.
     ...(process.platform === 'win32' ? {
-      backgroundMaterial: 'acrylic' as const,
+      backgroundColor: '#0d1117',
       hasShadow: true,
       roundedCorners: true,
       thickFrame: true,

apps/desktop/tests/window-appearance.spec.ts

@@ -0,0 +1,43 @@
+// Static check: no Windows host exists in CI or locally, so this test guards the
+// window configuration rather than the rendered result.
+import { readFileSync } from 'node:fs'
+import { resolve } from 'node:path'
+import { describe, expect, it } from 'vitest'
+
+const desktopRoot = resolve(import.meta.dirname, '..')
+const mainSource = readFileSync(resolve(desktopRoot, 'src', 'main.ts'), 'utf8')
+
+describe('desktop window appearance configuration', () => {
+  it('keeps Windows opaque and non-Windows windows transparent', () => {
+    const backgroundMaterialMatches = [...mainSource.matchAll(/backgroundMaterial/g)]
+    const win32BranchMatches = [...mainSource.matchAll(
+      /\.\.\.\(process\.platform === 'win32' \? \{([\s\S]*?)\} : \{\s*transparent: true,/g,
+    )]
+    const nonWin32BranchMatches = [...mainSource.matchAll(
+      /\} : \{\s*transparent: true,[\s\S]*?\}\),\s*title:/g,
+    )]
+
+    expect(backgroundMaterialMatches).toHaveLength(0)
+    expect(win32BranchMatches).toHaveLength(1)
+    expect(nonWin32BranchMatches).toHaveLength(1)
+
+    const win32Branch = win32BranchMatches[0]![1]!
+    const opaqueColorMatches = [...win32Branch.matchAll(/backgroundColor:\s*'#[0-9a-fA-F]{6}'/g)]
+    const alphaColorMatches = [...win32Branch.matchAll(/#[0-9a-fA-F]{8}/g)]
+    const hasShadowMatches = [...win32Branch.matchAll(/hasShadow:\s*true/g)]
+    const roundedCornersMatches = [...win32Branch.matchAll(/roundedCorners:\s*true/g)]
+    const thickFrameMatches = [...win32Branch.matchAll(/thickFrame:\s*true/g)]
+
+    expect(opaqueColorMatches).toHaveLength(1)
+    expect(alphaColorMatches).toHaveLength(0)
+    expect(hasShadowMatches).toHaveLength(1)
+    expect(roundedCornersMatches).toHaveLength(1)
+    expect(thickFrameMatches).toHaveLength(1)
+
+    expect(win32Branch).toContain('backgroundColor')
+    expect(nonWin32BranchMatches[0]![0]).toContain('transparent: true')
+    expect(win32Branch).toContain('hasShadow')
+    expect(win32Branch).toContain('roundedCorners')
+    expect(win32Branch).toContain('thickFrame')
+  })
+})