fix(android): follow system theme so WebView sees correct prefers-color-scheme

mobile/src/main/AndroidManifest.xml

@@ -21,6 +21,7 @@
     <meta-data android:name="com.samsung.android.vr.application.mode" android:value="dual" />
 
     <application
+        android:name=".AWApplication"
         android:allowBackup="true"
         android:label="@string/app_name"
         android:roundIcon="@mipmap/aw_launcher_round"

mobile/src/main/java/net/activitywatch/android/AWApplication.kt

@@ -0,0 +1,16 @@
+package net.activitywatch.android
+
+import android.app.Application
+import androidx.appcompat.app.AppCompatDelegate
+
+class AWApplication : Application() {
+    override fun onCreate() {
+        super.onCreate()
+        // Follow the OS dark/light setting from process start so that:
+        // - WebView correctly reports prefers-color-scheme: dark when system is dark
+        // - The initial chrome (applyWebUiChrome in MainActivity) matches the system
+        // Without this, Theme.AppCompat.Light keeps the Activity in light mode and
+        // WebView always sees prefers-color-scheme: light (aw-android#300).
+        AppCompatDelegate.setDefaultNightMode(AppCompatDelegate.MODE_NIGHT_FOLLOW_SYSTEM)
+    }
+}

mobile/src/main/res/values-night/colors.xml

@@ -1,5 +1,9 @@
 <?xml version="1.0" encoding="utf-8"?>
 <resources>
+    <!-- Do not override default_text_color here. Native Auth/Sync/Onboarding
+         keep light chrome via applySafeWindowInsets(); a night white text
+         color would be unreadable on that background (aw-android#301 P1). -->
+
     <!-- Widget theme colors (dark mode overrides) -->
     <color name="widget_background">#2A2A2A</color>
     <color name="widget_text_primary">#FFFFFF</color>

mobile/src/main/res/values/styles.xml

@@ -1,7 +1,10 @@
 <resources>
 
-    <!-- Base application theme. -->
-    <style name="AppTheme" parent="Theme.AppCompat.Light.NoActionBar">
+    <!-- Base application theme. DayNight lets Android WebView see the correct
+         prefers-color-scheme value when the user chooses "System" in aw-webui.
+         The AppCompatDelegate.MODE_NIGHT_FOLLOW_SYSTEM call in AWApplication
+         ensures the mode is set before any Activity starts. -->
+    <style name="AppTheme" parent="Theme.AppCompat.DayNight.NoActionBar">
         <!-- Customize your theme here. -->
         <item name="colorPrimary">@color/colorPrimary</item>
         <item name="colorPrimaryDark">@color/colorPrimaryDark</item>

mobile/src/test/java/net/activitywatch/android/AWApplicationTest.kt

@@ -0,0 +1,33 @@
+package net.activitywatch.android
+
+import androidx.appcompat.app.AppCompatDelegate
+import org.junit.Assert.assertEquals
+import org.junit.Assert.assertFalse
+import org.junit.Test
+import java.io.File
+
+class AWApplicationTest {
+    @Test
+    fun applicationClassExists() {
+        // AWApplication must exist; Application.onCreate sets MODE_NIGHT_FOLLOW_SYSTEM
+        // so that WebView reports the correct prefers-color-scheme from the very first
+        // frame (aw-android#300).
+        val clazz = AWApplication::class.java
+        val superClass = clazz.superclass
+        assertEquals("android.app.Application", superClass?.name)
+    }
+
+    @Test
+    fun modeNightFollowSystemConstantValue() {
+        // Sanity-check that the constant we rely on is stable across AppCompat versions.
+        assertEquals(-1, AppCompatDelegate.MODE_NIGHT_FOLLOW_SYSTEM)
+    }
+
+    @Test
+    fun nightColorsDoNotOverrideDefaultTextColor() {
+        // Native screens stay on light chrome. White night text would be
+        // unreadable there (Greptile P1 on aw-android#301).
+        val night = File("src/main/res/values-night/colors.xml").readText()
+        assertFalse(night.contains("name=\"default_text_color\""))
+    }
+}