refactor(service): harden KMP service layer — database init, connection reliability, handler decomposition (#4992)

desktop/src/main/kotlin/org/meshtastic/desktop/Main.kt

@@ -61,6 +61,7 @@ import okio.Path.Companion.toPath
 import org.jetbrains.skia.Image
 import org.koin.core.context.startKoin
 import org.meshtastic.core.common.util.MeshtasticUri
+import org.meshtastic.core.database.desktopDataDir
 import org.meshtastic.core.navigation.SettingsRoutes
 import org.meshtastic.core.navigation.TopLevelDestination
 import org.meshtastic.core.navigation.rememberMultiBackstack
@@ -248,7 +249,7 @@ fun main(args: Array<String>) = application(exitProcessOnExit = false) {
             },
         ) {
             setSingletonImageLoaderFactory { context ->
-                val cacheDir = System.getProperty("user.home") + "/.meshtastic/image_cache_v3"
+                val cacheDir = desktopDataDir() + "/image_cache_v3"
                 ImageLoader.Builder(context)
                     .components {
                         add(KtorNetworkFetcherFactory(httpClient = httpClient))

desktop/src/main/kotlin/org/meshtastic/desktop/di/DesktopPlatformModule.kt

@@ -34,6 +34,7 @@ import okio.Path.Companion.toPath
 import org.koin.core.qualifier.named
 import org.koin.dsl.module
 import org.meshtastic.core.common.BuildConfigProvider
+import org.meshtastic.core.database.desktopDataDir
 import org.meshtastic.core.datastore.serializer.ChannelSetSerializer
 import org.meshtastic.core.datastore.serializer.LocalConfigSerializer
 import org.meshtastic.core.datastore.serializer.LocalStatsSerializer
@@ -43,16 +44,6 @@ import org.meshtastic.proto.LocalConfig
 import org.meshtastic.proto.LocalModuleConfig
 import org.meshtastic.proto.LocalStats
 
-/**
- * Resolves the desktop data directory for persistent storage (DataStore files, Room database). Defaults to
- * `~/.meshtastic/`. Override via `MESHTASTIC_DATA_DIR` environment variable.
- */
-private fun desktopDataDir(): String {
-    val override = System.getenv("MESHTASTIC_DATA_DIR")
-    if (!override.isNullOrBlank()) return override
-    return System.getProperty("user.home") + "/.meshtastic"
-}
-
 /** Creates a file-backed [DataStore]<[Preferences]> at the given path under the data directory. */
 private fun createPreferencesDataStore(name: String, scope: CoroutineScope): DataStore<Preferences> {
     val dir = desktopDataDir() + "/datastore"
@@ -90,7 +81,14 @@ private class DesktopProcessLifecycleOwner : LifecycleOwner {
  */
 @Suppress("InjectDispatcher")
 fun desktopPlatformModule() = module {
-    includes(desktopPreferencesDataStoreModule(), desktopProtoDataStoreModule())
+    // Application-lifetime scope shared by all DataStore instances. Per the DataStore docs:
+    // "The Job within this context dictates the lifecycle of the DataStore's internal operations.
+    // Ensure it is an application-scoped context that is not canceled by UI lifecycle events."
+    // DataStore has no close() API — the in-memory cache is released only when this Job is cancelled
+    // (at process exit). Using SupervisorJob so a single store's failure doesn't cascade.
+    val dataStoreScope = CoroutineScope(Dispatchers.IO + SupervisorJob())
+
+    includes(desktopPreferencesDataStoreModule(dataStoreScope), desktopProtoDataStoreModule(dataStoreScope))
 
     // -- Build config --
     single<BuildConfigProvider> {
@@ -109,10 +107,7 @@ fun desktopPlatformModule() = module {
 }
 
 /** Named [DataStore]<[Preferences]> instances for all preference domains. */
-@Suppress("InjectDispatcher")
-private fun desktopPreferencesDataStoreModule() = module {
-    val scope = CoroutineScope(Dispatchers.IO + SupervisorJob())
-
+private fun desktopPreferencesDataStoreModule(scope: CoroutineScope) = module {
     single<DataStore<Preferences>>(named("AnalyticsDataStore")) { createPreferencesDataStore("analytics", scope) }
     single<DataStore<Preferences>>(named("HomoglyphEncodingDataStore")) {
         createPreferencesDataStore("homoglyph_encoding", scope)
@@ -135,9 +130,7 @@ private fun desktopPreferencesDataStoreModule() = module {
 }
 
 /** Proto [DataStore] instances (OkioStorage-backed). */
-@Suppress("InjectDispatcher")
-private fun desktopProtoDataStoreModule() = module {
-    val scope = CoroutineScope(Dispatchers.IO + SupervisorJob())
+private fun desktopProtoDataStoreModule(scope: CoroutineScope) = module {
     val protoDir = desktopDataDir() + "/datastore"
 
     single<DataStore<LocalConfig>>(named("CoreLocalConfigDataStore")) {

desktop/src/main/kotlin/org/meshtastic/desktop/radio/DesktopRadioTransportFactory.kt

@@ -51,7 +51,10 @@ class DesktopRadioTransportFactory(
             TCPInterface(service, dispatchers, address.removePrefix(InterfaceId.TCP.id.toString()))
         }
         address.startsWith(InterfaceId.SERIAL.id) -> {
-            SerialTransport(portName = address.removePrefix(InterfaceId.SERIAL.id.toString()), service = service)
+            SerialTransport.open(
+                portName = address.removePrefix(InterfaceId.SERIAL.id.toString()),
+                service = service,
+            )
         }
         else -> error("Unsupported transport for address: $address")
     }

desktop/src/main/kotlin/org/meshtastic/desktop/stub/NoopStubs.kt

@@ -75,6 +75,7 @@ class NoopRadioInterfaceService : RadioInterfaceService {
 
     override val receivedData = MutableSharedFlow<ByteArray>()
     override val meshActivity = MutableSharedFlow<MeshActivity>()
+    override val connectionError = MutableSharedFlow<String>()
 
     override fun sendToRadio(bytes: ByteArray) {
         logWarn("NoopRadioInterfaceService.sendToRadio(${bytes.size} bytes)")