Integration: port push-token registration to new FcmService (P4 follow-up)

Move the legacy MyFirebaseMessagingService.onNewToken() device-registration
path onto the new iOS-parity FcmService. The legacy service is already
unwired from the manifest MESSAGING_EVENT filter; this removes its last
functional responsibility. Behaviour preserved: auth-token guard,
DeviceRegistrationRequest with ANDROID_ID + Build.MODEL, log-only on error.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

composeApp/src/androidMain/kotlin/com/tt/honeyDue/notifications/FcmService.kt

@@ -1,6 +1,7 @@
 package com.tt.honeyDue.notifications
 
 import android.app.PendingIntent
+import android.content.Context
 import android.content.Intent
 import android.net.Uri
 import android.os.Build
@@ -11,6 +12,13 @@ import com.google.firebase.messaging.FirebaseMessagingService
 import com.google.firebase.messaging.RemoteMessage
 import com.tt.honeyDue.MainActivity
 import com.tt.honeyDue.R
+import com.tt.honeyDue.models.DeviceRegistrationRequest
+import com.tt.honeyDue.network.ApiResult
+import com.tt.honeyDue.network.NotificationApi
+import com.tt.honeyDue.storage.TokenStorage
+import kotlinx.coroutines.CoroutineScope
+import kotlinx.coroutines.Dispatchers
+import kotlinx.coroutines.launch
 
 /**
  * New-generation FirebaseMessagingService built for iOS parity. Routes each
@@ -19,21 +27,52 @@ import com.tt.honeyDue.R
  * messageId as the notification id so duplicate redeliveries replace (not
  * stack).
  *
- * This lives alongside the legacy `MyFirebaseMessagingService`. The manifest
- * currently wires FCM to this service; the legacy class is retained until
- * its call sites (widget + notification-action flows) are migrated.
+ * This is the sole MESSAGING_EVENT handler after the deferred-cleanup pass:
+ * the manifest no longer wires the legacy `MyFirebaseMessagingService`, and
+ * [onNewToken] now carries the token-registration path that used to live
+ * there (auth-token guard + device-id + platform="android").
  */
 class FcmService : FirebaseMessagingService() {
 
     override fun onNewToken(token: String) {
         super.onNewToken(token)
         Log.d(TAG, "FCM token refreshed (len=${token.length})")
-        // TODO: wire token registration to APILayer.registerDevice.
-        // Registration is already performed by MyFirebaseMessagingService.onNewToken
-        // at composeApp/src/androidMain/kotlin/com/tt/honeyDue/MyFirebaseMessagingService.kt:20-65
-        // using NotificationApi().registerDevice(...). When that legacy service is
-        // removed, port the same call path here (auth-token guard + device-id +
-        // platform="android"). P4 Stream N scope is receive-side only.
+
+        // Store token locally so the rest of the app can find it on demand.
+        getSharedPreferences(PREFS_NAME, Context.MODE_PRIVATE)
+            .edit()
+            .putString(KEY_FCM_TOKEN, token)
+            .apply()
+
+        // Register with backend only if the user is logged in. Log-only on
+        // failure — FCM will re-invoke onNewToken on next rotation.
+        CoroutineScope(Dispatchers.IO).launch {
+            try {
+                val authToken = TokenStorage.getToken() ?: return@launch
+                val deviceId = android.provider.Settings.Secure.getString(
+                    applicationContext.contentResolver,
+                    android.provider.Settings.Secure.ANDROID_ID
+                )
+                val request = DeviceRegistrationRequest(
+                    deviceId = deviceId,
+                    registrationId = token,
+                    platform = "android",
+                    name = android.os.Build.MODEL
+                )
+                when (val result = NotificationApi().registerDevice(authToken, request)) {
+                    is ApiResult.Success ->
+                        Log.d(TAG, "Device registered successfully with new token")
+                    is ApiResult.Error ->
+                        Log.e(TAG, "Failed to register device with new token: ${result.message}")
+                    is ApiResult.Loading,
+                    is ApiResult.Idle -> {
+                        // These states shouldn't occur for direct API calls.
+                    }
+                }
+            } catch (e: Exception) {
+                Log.e(TAG, "Error registering device with new token", e)
+            }
+        }
     }
 
     override fun onMessageReceived(message: RemoteMessage) {
@@ -205,5 +244,13 @@ class FcmService : FirebaseMessagingService() {
         const val EXTRA_TASK_ID = "fcm_task_id"
         const val EXTRA_RESIDENCE_ID = "fcm_residence_id"
         const val EXTRA_TYPE = "fcm_type"
+
+        private const val PREFS_NAME = "honeydue_prefs"
+        private const val KEY_FCM_TOKEN = "fcm_token"
+
+        /** Compatibility helper — mirrors the old MyFirebaseMessagingService API. */
+        fun getStoredToken(context: Context): String? =
+            context.getSharedPreferences(PREFS_NAME, Context.MODE_PRIVATE)
+                .getString(KEY_FCM_TOKEN, null)
     }
 }