QuantumBadger · jacob-sinex · Jul 3, 2026
diff --git a/src/main/java/org/quantumbadger/redreader/activities/OptionsMenuUtility.java b/src/main/java/org/quantumbadger/redreader/activities/OptionsMenuUtility.java
@@ -19,6 +19,7 @@
 
 import android.app.Activity;
 import android.content.Intent;
+import android.content.res.Configuration;
 import android.graphics.Rect;
 import android.view.Menu;
 import android.view.MenuItem;
@@ -670,11 +671,50 @@ private static void add(
 							final AppearanceTheme currentTheme
 									= PrefsUtility.appearance_theme();
 
-							final String[] themeNames = activity.getResources()
-									.getStringArray(R.array.pref_appearance_theme);
+							// When following the system theme, the single theme
+							// key is ignored - the active theme is the light or
+							// dark selection for the current mode. Offer only the
+							// themes for that mode and write to its key, so every
+							// choice changes the theme currently on screen instead
+							// of silently doing nothing.
+							final String[] themeNames;
+							final String[] themeValues;
+							final String themeKey;
+							final int titleRes;
+
+							if(PrefsUtility.appearance_theme_use_system()) {
+
+								final int uiMode = activity.getResources()
+										.getConfiguration().uiMode
+										& Configuration.UI_MODE_NIGHT_MASK;
+
+								if(uiMode == Configuration.UI_MODE_NIGHT_YES) {
+									themeNames = activity.getResources().getStringArray(
+											R.array.pref_appearance_theme_dark);
+									themeValues = activity.getResources().getStringArray(
+											R.array.pref_appearance_theme_dark_return);
+									themeKey = activity.getString(
+											R.string.pref_appearance_theme_dark_key);
+									titleRes = R.string.pref_appearance_theme_dark_title;
+								} else {
+									themeNames = activity.getResources().getStringArray(
+											R.array.pref_appearance_theme_light);
+									themeValues = activity.getResources().getStringArray(
+											R.array.pref_appearance_theme_light_return);
+									themeKey = activity.getString(
+											R.string.pref_appearance_theme_light_key);
+									titleRes = R.string.pref_appearance_theme_light_title;
+								}
 
-							final String[] themeValues = activity.getResources()
-									.getStringArray(R.array.pref_appearance_theme_return);
+							} else {
+								themeNames = activity.getResources().getStringArray(
+										R.array.pref_appearance_theme);
+								themeValues = activity.getResources().getStringArray(
+										R.array.pref_appearance_theme_return);
+								themeKey = activity.getString(
+										R.string.pref_appearance_theme_key);
+								titleRes = R.string.pref_appearance_theme_title;
+							}
 
 							int selectedPos = -1;
 							for(int i = 0; i < themeValues.length; i++) {
@@ -688,17 +728,14 @@ private static void add(
 
 							final MaterialAlertDialogBuilder dialog
 									= new MaterialAlertDialogBuilder(activity);
-							dialog.setTitle(R.string.pref_appearance_theme_title);
+							dialog.setTitle(titleRes);
 
 							dialog.setSingleChoiceItems(
 									themeNames,
 									selectedPos,
 									(dialog1, item1) -> {
 										prefs.edit()
-												.putString(
-														activity.getString(
-														R.string.pref_appearance_theme_key),
-														themeValues[item1])
+												.putString(themeKey, themeValues[item1])
 												.apply();
 										dialog1.dismiss();
 									});

diff --git a/src/main/java/org/quantumbadger/redreader/common/PrefsUtility.java b/src/main/java/org/quantumbadger/redreader/common/PrefsUtility.java
@@ -156,6 +156,9 @@ public static boolean isRefreshRequired(final Context context, final String key)
 	public static boolean isRestartRequired(final Context context, final String key) {
 		return context.getString(R.string.pref_appearance_twopane_key).equals(key)
 				|| context.getString(R.string.pref_appearance_theme_key).equals(key)
+				|| context.getString(R.string.pref_appearance_theme_use_system_key).equals(key)
+				|| context.getString(R.string.pref_appearance_theme_light_key).equals(key)
+				|| context.getString(R.string.pref_appearance_theme_dark_key).equals(key)
 				|| context.getString(R.string.pref_appearance_navbar_color_key).equals(key)
 				|| context.getString(R.string.pref_appearance_langforce_key).equals(key)
 				|| context.getString(R.string.pref_behaviour_bezel_toolbar_swipezone_key)
@@ -206,15 +209,42 @@ public static AppearanceTwopane appearance_twopane() {
 	}
 
 	public static boolean isNightMode() {
-
-		final AppearanceTheme theme = appearance_theme();
-
+		final AppearanceTheme theme = appearance_theme(mRes);
 		return theme == AppearanceTheme.NIGHT
 				|| theme == AppearanceTheme.NIGHT_LOWCONTRAST
 				|| theme == AppearanceTheme.ULTRABLACK;
 	}
 
+	public static boolean appearance_theme_use_system() {
+		return getBoolean(R.string.pref_appearance_theme_use_system_key, false);
+	}
+
+	public static AppearanceTheme appearance_theme_light() {
+		return AppearanceTheme.valueOf(StringUtils.asciiUppercase(getString(
+				R.string.pref_appearance_theme_light_key,
+				"red")));
+	}
+
+	public static AppearanceTheme appearance_theme_dark() {
+		return AppearanceTheme.valueOf(StringUtils.asciiUppercase(getString(
+				R.string.pref_appearance_theme_dark_key,
+				"night")));
+	}
+
 	public static AppearanceTheme appearance_theme() {
+		return appearance_theme(mRes);
+	}
+
+	public static AppearanceTheme appearance_theme(@Nullable final Resources resources) {
+		if(resources != null && appearance_theme_use_system()) {
+			final int uiMode = resources.getConfiguration().uiMode
+					& android.content.res.Configuration.UI_MODE_NIGHT_MASK;
+			if(uiMode == android.content.res.Configuration.UI_MODE_NIGHT_YES) {
+				return appearance_theme_dark();
+			} else {
+				return appearance_theme_light();
+			}
+		}
 		return AppearanceTheme.valueOf(StringUtils.asciiUppercase(getString(
 				R.string.pref_appearance_theme_key,
 				"red")));
@@ -232,7 +262,7 @@ public static AppearanceNavbarColour appearance_navbar_colour() {
 
 	public static void applyTheme(@NonNull final Activity activity) {
 
-		final AppearanceTheme theme = appearance_theme();
+		final AppearanceTheme theme = appearance_theme(activity.getResources());
 
 		switch(theme) {
 			case RED:

diff --git a/src/main/java/org/quantumbadger/redreader/settings/SettingsFragment.java b/src/main/java/org/quantumbadger/redreader/settings/SettingsFragment.java
@@ -22,6 +22,7 @@
 import android.content.ContentResolver;
 import android.content.Context;
 import android.content.Intent;
+import android.content.res.Configuration;
 import android.os.Bundle;
 import android.text.Html;
 import android.util.Log;
@@ -64,6 +65,7 @@
 
 import java.io.File;
 import java.util.ArrayList;
+import java.util.Arrays;
 import java.util.EnumMap;
 import java.util.HashMap;
 import java.util.List;
@@ -119,6 +121,8 @@ public void onCreatePreferences(
 				R.string.pref_behaviour_fling_comment_left_key,
 				R.string.pref_behaviour_fling_comment_right_key,
 				R.string.pref_appearance_theme_key,
+				R.string.pref_appearance_theme_light_key,
+				R.string.pref_appearance_theme_dark_key,
 				R.string.pref_appearance_navbar_color_key,
 				R.string.pref_cache_maxage_listing_key,
 				R.string.pref_cache_maxage_thumb_key,
@@ -235,6 +239,50 @@ public void onCreatePreferences(
 			});
 		}
 
+		{
+			final CheckBoxPreference useSystemThemePref =
+					findPreference(getString(R.string.pref_appearance_theme_use_system_key));
+			final ListPreference themePref =
+					findPreference(getString(R.string.pref_appearance_theme_key));
+			final ListPreference themeLightPref =
+					findPreference(getString(R.string.pref_appearance_theme_light_key));
+			final ListPreference themeDarkPref =
+					findPreference(getString(R.string.pref_appearance_theme_dark_key));
+
+			if(useSystemThemePref != null && themePref != null
+					&& themeLightPref != null && themeDarkPref != null) {
+
+				final boolean useSystem = useSystemThemePref.isChecked();
+				themePref.setVisible(!useSystem);
+				themeLightPref.setVisible(useSystem);
+				themeDarkPref.setVisible(useSystem);
+
+				useSystemThemePref.setOnPreferenceChangeListener((preference, newValue) -> {
+					final boolean nowUseSystem = Boolean.TRUE.equals(newValue);
+					themePref.setVisible(!nowUseSystem);
+					themeLightPref.setVisible(nowUseSystem);
+					themeDarkPref.setVisible(nowUseSystem);
+
+					// Carry the currently-active theme across the toggle so it
+					// isn't replaced by a stale value the user never chose.
+					if(nowUseSystem) {
+						// Turning on: route the single theme into its natural
+						// light or dark slot (themes are inherently one or the
+						// other). The active theme then still shows if it matches
+						// the current system mode; otherwise the mode-appropriate
+						// theme is shown, which is the point of following system.
+						carryThemeToSystemSlot(themePref, themeLightPref, themeDarkPref);
+					} else {
+						// Turning off: adopt whichever of light/dark is currently
+						// active for the system mode, so the single theme matches
+						// what is already on screen.
+						carryActiveThemeToSingle(themePref, themeLightPref, themeDarkPref);
+					}
+					return true;
+				});
+			}
+		}
+
 		{
 			final CheckBoxPreference notifPref =
 					findPreference(getString(R.string.pref_behaviour_notifications_key));
@@ -580,6 +628,64 @@ public void onCreatePreferences(
 		}
 	}
 
+	// When Follow system theme is turned on, move the single theme selection
+	// into its natural light or dark slot so the active theme carries over.
+	private void carryThemeToSystemSlot(
+			final ListPreference themePref,
+			final ListPreference themeLightPref,
+			final ListPreference themeDarkPref) {
+
+		final String value = themePref.getValue();
+		if(value == null) {
+			return;
+		}
+
+		if(isDarkThemeValue(value)) {
+			themeDarkPref.setValue(value);
+			updateListPreferenceSummary(themeDarkPref);
+		} else {
+			themeLightPref.setValue(value);
+			updateListPreferenceSummary(themeLightPref);
+		}
+	}
+
+	// When Follow system theme is turned off, adopt whichever of the light/dark
+	// selections is currently active for the system's mode, so the single theme
+	// matches what is already displayed.
+	private void carryActiveThemeToSingle(
+			final ListPreference themePref,
+			final ListPreference themeLightPref,
+			final ListPreference themeDarkPref) {
+
+		final int uiMode = getResources().getConfiguration().uiMode
+				& Configuration.UI_MODE_NIGHT_MASK;
+
+		final String value = uiMode == Configuration.UI_MODE_NIGHT_YES
+				? themeDarkPref.getValue()
+				: themeLightPref.getValue();
+
+		if(value != null) {
+			themePref.setValue(value);
+			updateListPreferenceSummary(themePref);
+		}
+	}
+
+	private boolean isDarkThemeValue(final String value) {
+		return Arrays.asList(getResources().getStringArray(
+				R.array.pref_appearance_theme_dark_return)).contains(value);
+	}
+
+	// setValue() persists and re-applies the theme, but the row summary is set
+	// manually elsewhere (and only via the change listener, which programmatic
+	// setValue does not trigger), so refresh it here to keep the displayed
+	// selection in sync without a settings reload.
+	private void updateListPreferenceSummary(final ListPreference pref) {
+		final int index = pref.findIndexOfValue(pref.getValue());
+		if(index >= 0) {
+			pref.setSummary(pref.getEntries()[index]);
+		}
+	}
+
 	//Based on https://stackoverflow.com/a/55724743
 	@Override
 	public void setPreferenceScreen(final PreferenceScreen preferenceScreen) {

diff --git a/src/main/res/values/arrays.xml b/src/main/res/values/arrays.xml
@@ -266,6 +266,38 @@
 		<item>ultrablack</item>
 	</string-array>
 
+	<string-array name="pref_appearance_theme_light">
+		<item>@string/theme_name_red</item>
+		<item>@string/theme_name_green</item>
+		<item>@string/theme_name_blue</item>
+		<item>@string/theme_name_ltblue</item>
+		<item>@string/theme_name_orange</item>
+		<item>@string/theme_name_gray</item>
+	</string-array>
+
+	<!-- Constants. Do not change. -->
+	<string-array name="pref_appearance_theme_light_return">
+		<item>red</item>
+		<item>green</item>
+		<item>blue</item>
+		<item>ltblue</item>
+		<item>orange</item>
+		<item>gray</item>
+	</string-array>
+
+	<string-array name="pref_appearance_theme_dark">
+		<item>@string/theme_name_night</item>
+		<item>@string/theme_name_night_lowcontrast</item>
+		<item>@string/theme_name_ultrablack</item>
+	</string-array>
+
+	<!-- Constants. Do not change. -->
+	<string-array name="pref_appearance_theme_dark_return">
+		<item>night</item>
+		<item>night_lowcontrast</item>
+		<item>ultrablack</item>
+	</string-array>
+
     <string-array name="pref_appearance_langforce">
 		<item>@string/lang_auto</item>
 		<item>@string/lang_en</item>

diff --git a/src/main/res/values/strings.xml b/src/main/res/values/strings.xml
@@ -46,6 +46,13 @@
     <string name="pref_appearance_theme_key" translatable="false">pref_appearance_theme</string>
     <string name="pref_appearance_theme_title">Theme</string>
 
+    <string name="pref_appearance_theme_use_system_key" translatable="false">pref_appearance_theme_use_system</string>
+    <string name="pref_appearance_theme_use_system_title">Follow system theme</string>
+    <string name="pref_appearance_theme_light_key" translatable="false">pref_appearance_theme_light</string>
+    <string name="pref_appearance_theme_light_title">Light theme</string>
+    <string name="pref_appearance_theme_dark_key" translatable="false">pref_appearance_theme_dark</string>
+    <string name="pref_appearance_theme_dark_title">Dark theme</string>
+
     <string name="pref_appearance_fontscale_posts_key" translatable="false">pref_appearance_fontscale_posts</string>
     <string name="pref_appearance_fontscale_posts_title">Post titles</string>
 

diff --git a/src/main/res/xml/prefs_appearance.xml b/src/main/res/xml/prefs_appearance.xml
@@ -31,12 +31,28 @@
 
     <PreferenceCategory android:title="@string/pref_appearance_theme_header">
 
+        <CheckBoxPreference android:title="@string/pref_appearance_theme_use_system_title"
+                            android:key="@string/pref_appearance_theme_use_system_key"
+                            android:defaultValue="false"/>
+
         <ListPreference android:title="@string/pref_appearance_theme_title"
                         android:key="@string/pref_appearance_theme_key"
                         android:entries="@array/pref_appearance_theme"
                         android:entryValues="@array/pref_appearance_theme_return"
                         android:defaultValue="red"/>
 
+        <ListPreference android:title="@string/pref_appearance_theme_light_title"
+                        android:key="@string/pref_appearance_theme_light_key"
+                        android:entries="@array/pref_appearance_theme_light"
+                        android:entryValues="@array/pref_appearance_theme_light_return"
+                        android:defaultValue="red"/>
+
+        <ListPreference android:title="@string/pref_appearance_theme_dark_title"
+                        android:key="@string/pref_appearance_theme_dark_key"
+                        android:entries="@array/pref_appearance_theme_dark"
+                        android:entryValues="@array/pref_appearance_theme_dark_return"
+                        android:defaultValue="night"/>
+
 		<ListPreference android:title="@string/pref_appearance_navbar_color_title"
 						android:key="@string/pref_appearance_navbar_color_key"
 						android:entries="@array/pref_appearance_navbar_color_options"