feat(service): Introduce fallback worker to ensure service stays alive (#4295)

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

app/src/main/java/com/geeksville/mesh/worker/ServiceKeepAliveWorker.kt

@@ -0,0 +1,94 @@
+/*
+ * Copyright (c) 2025-2026 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 com.geeksville.mesh.worker
+
+import android.app.Notification
+import android.content.Context
+import android.content.pm.ServiceInfo
+import android.os.Build
+import androidx.core.app.NotificationCompat
+import androidx.hilt.work.HiltWorker
+import androidx.work.CoroutineWorker
+import androidx.work.ForegroundInfo
+import androidx.work.WorkerParameters
+import co.touchlab.kermit.Logger
+import com.geeksville.mesh.R
+import com.geeksville.mesh.service.MeshService
+import com.geeksville.mesh.service.startService
+import dagger.assisted.Assisted
+import dagger.assisted.AssistedInject
+import org.meshtastic.core.service.MeshServiceNotifications
+import org.meshtastic.core.service.SERVICE_NOTIFY_ID
+
+/**
+ * A worker whose sole purpose is to start the MeshService from the background. This is used as a fallback when
+ * `startForegroundService` is blocked by Android 14+ restrictions. It runs as an Expedited worker to gain temporary
+ * foreground start privileges.
+ */
+@HiltWorker
+class ServiceKeepAliveWorker
+@AssistedInject
+constructor(
+    @Assisted appContext: Context,
+    @Assisted workerParams: WorkerParameters,
+    private val serviceNotifications: MeshServiceNotifications,
+) : CoroutineWorker(appContext, workerParams) {
+
+    override suspend fun getForegroundInfo(): ForegroundInfo {
+        // We use the same notification channel as the main service notification
+        // to minimize user disruption.
+        // On Android 12+, we need to provide a foreground info for expedited work.
+        val notification = createNotification()
+
+        return if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.Q) {
+            ForegroundInfo(
+                SERVICE_NOTIFY_ID,
+                notification,
+                ServiceInfo.FOREGROUND_SERVICE_TYPE_DATA_SYNC or ServiceInfo.FOREGROUND_SERVICE_TYPE_CONNECTED_DEVICE,
+            )
+        } else {
+            ForegroundInfo(SERVICE_NOTIFY_ID, notification)
+        }
+    }
+
+    @Suppress("TooGenericExceptionCaught")
+    override suspend fun doWork(): Result {
+        Logger.i { "ServiceKeepAliveWorker: Attempting to start MeshService" }
+        return try {
+            MeshService.startService(applicationContext)
+            Result.success()
+        } catch (e: Exception) {
+            Logger.e(e) { "ServiceKeepAliveWorker failed to start service" }
+            Result.failure()
+        }
+    }
+
+    private fun createNotification(): Notification {
+        // We ensure channels are created
+        serviceNotifications.initChannels()
+
+        // We create a generic "Resuming" notification.
+        // We use "my_service" which matches NotificationType.ServiceState.channelId in MeshServiceNotificationsImpl
+
+        return NotificationCompat.Builder(applicationContext, "my_service")
+            .setSmallIcon(R.drawable.ic_launcher_foreground)
+            .setContentTitle("Resuming Mesh Service")
+            .setPriority(NotificationCompat.PRIORITY_LOW)
+            .setOngoing(true)
+            .build()
+    }
+}