fix(android): repair bluetooth bond on startup

android/app/src/main/java/com/labfytools/trainlog/MainActivity.kt

@@ -14,6 +14,9 @@ import com.labfytools.trainlog.data.TrainlogRepository
 import com.labfytools.trainlog.data.SyncExporter
 import com.labfytools.trainlog.data.SyncCatalogInbox
 import com.labfytools.trainlog.data.SyncRequestOutbox
+import com.labfytools.trainlog.data.BackgroundSyncSettings
+import com.labfytools.trainlog.data.SyncBackgroundService
+import com.labfytools.trainlog.data.hasBluetoothConnectPermission
 import com.labfytools.trainlog.ui.TrainlogApp
 import com.labfytools.trainlog.ui.TrainlogAppState
 import com.labfytools.trainlog.ui.LanguagePresentation
@@ -30,6 +33,13 @@ class MainActivity : ComponentActivity() {
         super.onCreate(savedInstanceState)
         languageSettings = LanguageSettingsOwner(applicationContext)
 
+        if (
+            BackgroundSyncSettings(applicationContext).enabled &&
+            hasBluetoothConnectPermission(applicationContext)
+        ) {
+            SyncBackgroundService.start(applicationContext)
+        }
+
         val repository =
             TrainlogRepository(
                 applicationContext

android/app/src/main/java/com/labfytools/trainlog/data/BluetoothSyncTransport.kt

@@ -3,11 +3,13 @@ package com.labfytools.trainlog.data
 import android.Manifest
 import android.annotation.SuppressLint
 import android.bluetooth.BluetoothClass
+import android.bluetooth.BluetoothDevice
 import android.bluetooth.BluetoothManager
 import android.bluetooth.BluetoothSocket
 import android.content.Context
 import android.content.pm.PackageManager
 import android.os.Build
+import android.util.Log
 import androidx.core.content.ContextCompat
 import java.io.BufferedInputStream
 import java.io.BufferedOutputStream
@@ -355,6 +357,9 @@ internal class BluetoothSyncClient(
     private val context: Context,
     private val repository: TrainlogRepository,
 ) {
+    companion object {
+        private const val TAG = "TrainlogBluetoothSync"
+    }
     @Volatile private var activeSocket: BluetoothSocket? = null
     private val settings = BluetoothSyncSettings(context)
     private val codec = BluetoothFrameCodec(context.cacheDir)
@@ -374,12 +379,22 @@ internal class BluetoothSyncClient(
                 continue
             }
             val address = settings.desktopAddress ?: continue
+            val device =
+                runCatching { adapter.getRemoteDevice(address) }
+                    .onFailure { Log.w(TAG, "Configured Bluetooth desktop is invalid", it) }
+                    .getOrNull()
+            if (device == null || !ensureBond(device, stopped)) {
+                sleep(stopped, Duration.ofSeconds(5))
+                continue
+            }
             val socket =
                 runCatching {
-                    adapter
+                    device.createRfcommSocketToServiceRecord(
-                        .getRemoteDevice(address)
+                        UUID.fromString(TRAINLOG_BLUETOOTH_SERVICE_UUID)
-                        .createRfcommSocketToServiceRecord(UUID.fromString(TRAINLOG_BLUETOOTH_SERVICE_UUID))
+                    )
-                }.getOrNull()
+                }
+                    .onFailure { Log.w(TAG, "Unable to create RFCOMM socket", it) }
+                    .getOrNull()
             if (socket == null) {
                 sleep(stopped, Duration.ofSeconds(10))
                 continue
@@ -387,10 +402,10 @@ internal class BluetoothSyncClient(
             activeSocket = socket
             try {
                 socket.connect()
+                Log.i(TAG, "RFCOMM connected to selected Trainlog desktop")
                 serve(socket, stopped)
-            } catch (_: Exception) {
+            } catch (error: Exception) {
-                // Arrival polling is intentionally silent. A foreground manual
+                Log.w(TAG, "RFCOMM connection ended: ${error.message}", error)
-                // synchronization still exposes its own correlated diagnostic.
             } finally {
                 activeSocket = null
                 runCatching { socket.close() }
@@ -404,6 +419,33 @@ internal class BluetoothSyncClient(
         activeSocket = null
     }
 
+    @SuppressLint("MissingPermission")
+    private fun ensureBond(device: BluetoothDevice, stopped: AtomicBoolean): Boolean {
+        if (device.bondState == BluetoothDevice.BOND_BONDED) return true
+        if (device.bondState == BluetoothDevice.BOND_NONE) {
+            Log.i(TAG, "Bluetooth bond missing; requesting one-time repair")
+            if (!runCatching { device.createBond() }.getOrDefault(false)) {
+                Log.w(TAG, "Bluetooth bond request was rejected by Android")
+                return false
+            }
+        }
+        val deadline = System.nanoTime() + Duration.ofSeconds(30).toNanos()
+        while (!stopped.get() && System.nanoTime() < deadline) {
+            when (device.bondState) {
+                BluetoothDevice.BOND_BONDED -> {
+                    Log.i(TAG, "Bluetooth bond ready")
+                    return true
+                }
+                BluetoothDevice.BOND_NONE -> {
+                    Log.w(TAG, "Bluetooth bond repair failed")
+                    return false
+                }
+            }
+            sleep(stopped, Duration.ofMillis(250))
+        }
+        return device.bondState == BluetoothDevice.BOND_BONDED
+    }
+
     private fun sleep(stopped: AtomicBoolean, duration: Duration) {
         val deadline = System.nanoTime() + duration.toNanos()
         while (!stopped.get() && System.nanoTime() < deadline) {

docs/design/sync_bluetooth_transport_v1.md

@@ -2,7 +2,7 @@
 
 ## Status
 
-`TRAINLOG_SYNC_BLUETOOTH_TRANSPORT_V1=SOFTWARE_VALIDATED_DEVICE_TEST_PENDING`
+`TRAINLOG_SYNC_BLUETOOTH_TRANSPORT_V1=LIVE_DEVICE_PASS_DRIVE_SETUP_PENDING`
 
 This transport is additive. It does not change generation manifests, artifact
 formats, causal deletion, revision ancestry, acknowledgement semantics, SQLite
@@ -30,6 +30,35 @@ desktop are within Bluetooth range.
 The manual Web and Android Synchroniser actions remain as recovery/forced-sync
 controls.
 
+## Private live-device evidence — 2026-09-22
+
+The authorized Samsung Android peer and ArchASP completed a physical Bluetooth
+Classic/RFCOMM synchronization without MTP or Drive as a sync transport.
+
+- request: `sr_86ccc07f-cc5b-4506-86c1-06c00bd8b06a`;
+- run: `sy_df8f87fb-e4c1-44f5-b3f7-8fe87942d19e`;
+- inbound Android generation:
+  `gen_9609d163-4a3a-4187-a806-84379a1bcf4c`;
+- outbound desktop generation:
+  `gen_bc1d5e4b-4b16-49bc-b228-c3ff1f1a1705`;
+- final transport: `bt`;
+- final Bluetooth state: `success`;
+- final phase/result: `completed/completed`;
+- desktop SQLite integrity: `ok`;
+- post-sync AI export: `delivered_to_android`;
+- Android copy:
+  `Documents/Trainlog/trainlog_ai_export_v1.json`, 66,971 bytes,
+  SHA-256 `49f7f02fdeebd15699655e43fdb475bb20d9dd2d1bc59d2bdb4cd099ae50ecda`.
+
+The initial legacy bond contained mismatched link-key state. The private device
+was explicitly re-paired; Android then reported the bond ready and established
+the Trainlog RFCOMM service. Android now also repairs a missing bond through the
+normal platform pairing flow before attempting RFCOMM.
+
+The one remaining manual setup step is selecting the Android SAF destination
+`Trainlog/AI`. This is intentionally user-authorized provider access and is
+not bypassed by ADB or Trainlog.
+
 ## Trust and pairing
 
 Bluetooth device names are presentation only and are never authority.