fix(hub-ui): preserve empty scheme values

Author: dvcolomban

packages/hub-ui/src/client/state/branding.test.ts

@@ -0,0 +1,19 @@
+import { afterEach, describe, expect, it } from 'vitest'
+import { setBranding, useBrandingBackground } from './branding'
+import { setColorSchemePreference } from './color-mode'
+
+afterEach(() => {
+  setBranding({})
+  setColorSchemePreference('auto')
+})
+
+describe('useBrandingBackground', () => {
+  it('preserves an empty dark value for CSS validation', () => {
+    expect.assertions(1)
+
+    setColorSchemePreference('dark')
+    setBranding({ background: { light: 'white', dark: '' } })
+
+    expect(useBrandingBackground().value).toBe('')
+  })
+})

packages/hub-ui/src/client/state/branding.ts

@@ -61,7 +61,7 @@ function resolveColorSchemeValue(value: ColorSchemeValue | undefined, dark: bool
     return undefined
   if (typeof value === 'string')
     return value
-  return dark ? (value.dark || value.light) : value.light
+  return dark ? (value.dark ?? value.light) : value.light
 }
 
 // --- Applying to the DOM --------------------------------------------------