Notify on foreground service start failure

app/src/main/java/protect/card_locker/NotificationInfo.kt

@@ -5,5 +5,7 @@ object NotificationInfo {
         const val NOTIFICATION_ID = 1001
         const val CHANNEL_ID = "catima_wear_bt"
         const val PAIRING_CHANNEL_ID = "catima_wear_bt_pairing"
+        const val CRITICAL_ERROR_NOTIFICATION_ID = 1002
+        const val CRITICAL_ERROR_CHANNEL_ID = "catima_wear_bt_critical_error"
     }
 }

app/src/main/java/protect/card_locker/wearos/WearSyncServiceManager.kt

@@ -1,13 +1,23 @@
 package protect.card_locker.wearos
 
 import android.Manifest
+import android.app.ForegroundServiceStartNotAllowedException
+import android.app.NotificationChannel
+import android.app.NotificationManager
 import android.content.Context
 import android.content.Intent
-import androidx.core.content.ContextCompat
+import android.content.pm.PackageManager
+import android.os.Build
+import android.util.Log
 import androidx.activity.result.ActivityResultCaller
 import androidx.activity.result.contract.ActivityResultContracts
+import androidx.core.app.ActivityCompat
+import androidx.core.app.NotificationCompat
+import androidx.core.app.NotificationManagerCompat
+import androidx.core.content.ContextCompat
 import androidx.core.content.edit
 import androidx.preference.PreferenceManager
+import protect.card_locker.NotificationInfo
 import protect.card_locker.R
 import protect.card_locker.preferences.Settings
 import protect.card_locker.shared.BluetoothPermissionHelper
@@ -55,6 +65,8 @@ class WearSyncPermissionRequester(
 }
 
 object WearSyncServiceManager {
+    private const val TAG = "CatimaWearSyncServiceManager"
+
     fun synchronize(context: Context, requestPermission: (() -> Unit)? = null) {
         if (!Settings(context).wearSyncEnabled) {
             stop(context)
@@ -105,7 +117,48 @@ object WearSyncServiceManager {
     }
 
     private fun start(context: Context) {
-        ContextCompat.startForegroundService(context, Intent(context, BluetoothServerService::class.java))
+        // Exception can only throw on API level 31 and up
+        if (Build.VERSION.SDK_INT >= 31) {
+            try {
+                ContextCompat.startForegroundService(
+                    context,
+                    Intent(context, BluetoothServerService::class.java)
+                )
+            } catch (e: ForegroundServiceStartNotAllowedException) {
+                // We naively assume we have enough permissions to show a notification as the service should never try to start
+                // before the user gave notification access anyway
+                Log.d(TAG, "Foreground service failed to launch: $e")
+                val channel = NotificationChannel(
+                    NotificationInfo.WearBluetooth.CRITICAL_ERROR_CHANNEL_ID,
+                    context.getString(R.string.wear_bt_critical_error_channel_name),
+                    NotificationManager.IMPORTANCE_HIGH
+                ).apply { setShowBadge(false) }
+                context.getSystemService(NotificationManager::class.java).createNotificationChannel(channel)
+                val notification = NotificationCompat.Builder(context, NotificationInfo.WearBluetooth.CRITICAL_ERROR_CHANNEL_ID)
+                    .setSmallIcon(R.drawable.ic_notification_error)
+                    .setContentTitle(context.getString(R.string.wear_bt_failed_foreground_notification_title))
+                    .setContentText(e.message)
+                    .build()
+                with(NotificationManagerCompat.from(context)) {
+                    if (ActivityCompat.checkSelfPermission(
+                            context,
+                            Manifest.permission.POST_NOTIFICATIONS
+                        ) != PackageManager.PERMISSION_GRANTED
+                    ) {
+                        return@with
+                    }
+                    notify(
+                        NotificationInfo.WearBluetooth.CRITICAL_ERROR_NOTIFICATION_ID,
+                        notification
+                    )
+                }
+            }
+        } else {
+            ContextCompat.startForegroundService(
+                context,
+                Intent(context, BluetoothServerService::class.java)
+            )
+        }
     }
 
     private fun stop(context: Context) {

app/src/main/res/drawable-anydpi-v24/ic_notification_error.xml

@@ -0,0 +1,30 @@
+<!--
+  ~ Copyright (C) 2026 The Android Open Source Project
+  ~
+  ~ Licensed under the Apache License, Version 2.0 (the "License");
+  ~ you may not use this file except in compliance with the License.
+  ~ You may obtain a copy of the License at
+  ~
+  ~      http://www.apache.org/licenses/LICENSE-2.0
+  ~
+  ~ Unless required by applicable law or agreed to in writing, software
+  ~ distributed under the License is distributed on an "AS IS" BASIS,
+  ~ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  ~ See the License for the specific language governing permissions and
+  ~ limitations under the License.
+  -->
+<vector xmlns:android="http://schemas.android.com/apk/res/android"
+    android:width="24dp"
+    android:height="24dp"
+    android:viewportWidth="960"
+    android:viewportHeight="960"
+    android:tint="#FFFFFF">
+  <group android:scaleX="1.104"
+      android:scaleY="1.104"
+      android:translateX="-49.92"
+      android:translateY="-49.92">
+    <path
+        android:fillColor="@android:color/white"
+        android:pathData="M508.5,668.5Q520,657 520,640Q520,623 508.5,611.5Q497,600 480,600Q463,600 451.5,611.5Q440,623 440,640Q440,657 451.5,668.5Q463,680 480,680Q497,680 508.5,668.5ZM440,520L520,520L520,280L440,280L440,520ZM480,880Q397,880 324,848.5Q251,817 197,763Q143,709 111.5,636Q80,563 80,480Q80,397 111.5,324Q143,251 197,197Q251,143 324,111.5Q397,80 480,80Q563,80 636,111.5Q709,143 763,197Q817,251 848.5,324Q880,397 880,480Q880,563 848.5,636Q817,709 763,763Q709,817 636,848.5Q563,880 480,880ZM480,800Q614,800 707,707Q800,614 800,480Q800,346 707,253Q614,160 480,160Q346,160 253,253Q160,346 160,480Q160,614 253,707Q346,800 480,800ZM480,480Q480,480 480,480Q480,480 480,480Q480,480 480,480Q480,480 480,480Q480,480 480,480Q480,480 480,480Q480,480 480,480Q480,480 480,480Z"/>
+  </group>
+</vector>

app/src/main/res/values/strings.xml

@@ -393,4 +393,6 @@
     <string name="wear_bt_channel_name">Wear OS companion</string>
     <string name="wear_bt_notification_title">Catima Wear OS sync active</string>
     <string name="settings_category_title_smartwatch">Smartwatch support</string>
+    <string name="wear_bt_failed_foreground_notification_title">Failed to start Wear OS sync service</string>
+    <string name="wear_bt_critical_error_channel_name">Wear OS sync critical error</string>
 </resources>