From e2271c11da7f31e9f5df46a187baf167c488d2ea Mon Sep 17 00:00:00 2001
From: huymobile <kingonwork@gmail.com>
Date: Sat, 3 Oct 2026 01:59:32 +0700
Subject: [PATCH] fix: keep navigation theme type when adapting a single theme

The light-only and dark-only overloads of adaptNavigationTheme returned the
narrow NavigationTheme type, dropping `fonts` and custom colors from the
input theme even though they are preserved at runtime. This made the result
unassignable to React Navigation's Theme. Return the input theme type, as
the overload for both themes already does.

Fixes #4751

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
---
 src/core/__tests__/theming.test.tsx | 20 ++++++++++++++++++++
 src/theme/provider.tsx              |  4 ++--
 2 files changed, 22 insertions(+), 2 deletions(-)

diff --git a/src/core/__tests__/theming.test.tsx b/src/core/__tests__/theming.test.tsx
index cb61aef20d..3ae5d44691 100644
--- a/src/core/__tests__/theming.test.tsx
+++ b/src/core/__tests__/theming.test.tsx
@@ -264,6 +264,26 @@ describe('adaptNavigationTheme', () => {
     });
   });
 
+  it('should keep fonts and custom colors when adapting a single theme', () => {
+    const { LightTheme: navLight } = adaptNavigationTheme({
+      reactNavigationLight: {
+        ...NavigationThemeWithFonts,
+        colors: NavigationCustomLightTheme.colors,
+      },
+    });
+    const { DarkTheme: navDark } = adaptNavigationTheme({
+      reactNavigationDark: { ...NavigationThemeWithFonts, dark: true },
+    });
+
+    expect(navLight.colors.secondary).toBe('rgb(150,45,85)');
+    expect(navLight.fonts.regular.fontFamily).toBe(
+      LightTheme.fonts.bodyMedium.fontFamily
+    );
+    expect(navDark.fonts.regular.fontFamily).toBe(
+      DarkTheme.fonts.bodyMedium.fontFamily
+    );
+  });
+
   it('should not expect fonts on theme without fonts', () => {
     const { LightTheme: navLight, DarkTheme: navDark } = adaptNavigationTheme({
       reactNavigationLight: NavigationLightTheme,
diff --git a/src/theme/provider.tsx b/src/theme/provider.tsx
index 8f7e77681e..2c1f8ca9f9 100644
--- a/src/theme/provider.tsx
+++ b/src/theme/provider.tsx
@@ -75,14 +75,14 @@ export function adaptNavigationTheme<T extends NavigationTheme>(themes: {
   reactNavigationLight: T;
   materialLight?: Theme;
 }): {
-  LightTheme: NavigationTheme;
+  LightTheme: T;
 };
 // eslint-disable-next-line no-redeclare
 export function adaptNavigationTheme<T extends NavigationTheme>(themes: {
   reactNavigationDark: T;
   materialDark?: Theme;
 }): {
-  DarkTheme: NavigationTheme;
+  DarkTheme: T;
 };
 // eslint-disable-next-line no-redeclare
 export function adaptNavigationTheme<