feat(settings): Only show homoglyph setting for Cyrillic locales (#4559)

Signed-off-by: James Rich <2199651+jamesarich@users.noreply.github.com>

feature/settings/src/main/kotlin/org/meshtastic/feature/settings/SettingsScreen.kt

@@ -25,6 +25,7 @@ import android.provider.Settings
 import android.provider.Settings.ACTION_APP_LOCALE_SETTINGS
 import androidx.activity.compose.rememberLauncherForActivityResult
 import androidx.activity.result.contract.ActivityResultContracts
+import androidx.annotation.VisibleForTesting
 import androidx.appcompat.app.AppCompatActivity.RESULT_OK
 import androidx.appcompat.app.AppCompatDelegate
 import androidx.compose.foundation.layout.Column
@@ -53,9 +54,11 @@ import androidx.compose.runtime.remember
 import androidx.compose.runtime.rememberCoroutineScope
 import androidx.compose.runtime.setValue
 import androidx.compose.ui.Modifier
+import androidx.compose.ui.platform.LocalConfiguration
 import androidx.compose.ui.platform.LocalContext
 import androidx.compose.ui.unit.dp
 import androidx.core.net.toUri
+import androidx.core.os.ConfigurationCompat
 import androidx.hilt.lifecycle.viewmodel.compose.hiltViewModel
 import androidx.lifecycle.compose.collectAsStateWithLifecycle
 import com.google.accompanist.permissions.ExperimentalPermissionsApi
@@ -313,11 +316,10 @@ fun SettingsScreen(
 
                 val homoglyphEncodingEnabled by
                     viewModel.homoglyphEncodingEnabledFlow.collectAsStateWithLifecycle(false)
-                SwitchListItem(
-                    text = stringResource(Res.string.use_homoglyph_characters_encoding),
-                    checked = homoglyphEncodingEnabled,
-                    leadingIcon = Icons.Default.Abc,
-                    onClick = { viewModel.toggleHomoglyphCharactersEncodingEnabled() },
+
+                HomoglyphSetting(
+                    homoglyphEncodingEnabled = homoglyphEncodingEnabled,
+                    onToggle = { viewModel.toggleHomoglyphCharactersEncodingEnabled() },
                 )
 
                 val settingsLauncher =
@@ -535,3 +537,18 @@ private fun ThemePickerDialog(onClickTheme: (Int) -> Unit, onDismiss: () -> Unit
         },
     )
 }
+
+@VisibleForTesting
+@Composable
+fun HomoglyphSetting(homoglyphEncodingEnabled: Boolean, onToggle: () -> Unit) {
+    val currentLocale = ConfigurationCompat.getLocales(LocalConfiguration.current).get(0)
+    val supportedLanguages = listOf("ru", "uk", "be", "bg", "sr", "mk", "kk", "ky", "tg", "mn")
+    if (currentLocale?.language in supportedLanguages) {
+        SwitchListItem(
+            text = stringResource(Res.string.use_homoglyph_characters_encoding),
+            checked = homoglyphEncodingEnabled,
+            leadingIcon = Icons.Default.Abc,
+            onClick = onToggle,
+        )
+    }
+}

feature/settings/src/test/kotlin/org/meshtastic/feature/settings/HomoglyphSettingTest.kt

@@ -0,0 +1,68 @@
+/*
+ * Copyright (c) 2026 Meshtastic LLC
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+package org.meshtastic.feature.settings
+
+import android.content.res.Configuration
+import androidx.compose.runtime.CompositionLocalProvider
+import androidx.compose.ui.platform.LocalConfiguration
+import androidx.compose.ui.test.assertIsDisplayed
+import androidx.compose.ui.test.junit4.v2.createComposeRule
+import androidx.compose.ui.test.onNodeWithText
+import com.meshtastic.core.strings.getString
+import org.junit.Rule
+import org.junit.Test
+import org.junit.runner.RunWith
+import org.meshtastic.core.strings.Res
+import org.meshtastic.core.strings.use_homoglyph_characters_encoding
+import org.robolectric.RobolectricTestRunner
+import org.robolectric.annotation.Config
+import java.util.Locale
+
+@RunWith(RobolectricTestRunner::class)
+@Config(sdk = [34])
+class HomoglyphSettingTest {
+
+    @get:Rule val composeTestRule = createComposeRule()
+
+    @Test
+    fun homoglyphSetting_isVisible_forRussianLocale() {
+        val russianConfig = Configuration().apply { setLocale(Locale.forLanguageTag("ru")) }
+
+        composeTestRule.setContent {
+            CompositionLocalProvider(LocalConfiguration provides russianConfig) {
+                HomoglyphSetting(homoglyphEncodingEnabled = false, onToggle = {})
+            }
+        }
+
+        val expectedText = getString(Res.string.use_homoglyph_characters_encoding)
+        composeTestRule.onNodeWithText(expectedText).assertIsDisplayed()
+    }
+
+    @Test
+    fun homoglyphSetting_isNotVisible_forEnglishLocale() {
+        val englishConfig = Configuration().apply { setLocale(Locale.forLanguageTag("en")) }
+
+        composeTestRule.setContent {
+            CompositionLocalProvider(LocalConfiguration provides englishConfig) {
+                HomoglyphSetting(homoglyphEncodingEnabled = false, onToggle = {})
+            }
+        }
+
+        val expectedText = getString(Res.string.use_homoglyph_characters_encoding)
+        composeTestRule.onNodeWithText(expectedText).assertDoesNotExist()
+    }
+}