fix: USB/OTA update flow - version check, chunk size, UX improvements

- MainActivity: suppress toast when activity not resumed, auto-navigate to
  Settings on new firmware
- SettingsActivity: unified BLE/USB radio buttons + single update button,
  version check before OTA, show dialog before loadFirmware, spinner timeout
- BleRelayManager: expose getEspVersion()
- OtaManager: reduce chunk size 500→248 to fit BLE MTU 255
- ESP: WRITE→WRITE_NR on OTA characteristic (was silently dropping data)
- Layout/strings: remove intro text, add method radio buttons
- Bump all firmware versions to v5

android/app/src/main/java/nl/eddydevink/sylda/BleRelayManager.kt

@@ -217,6 +217,8 @@ class BleRelayManager(
         appVersion = version
     }
 
+    fun getEspVersion(): String? = espVersion
+
     @SuppressLint("MissingPermission")
     private fun connectToDevice(device: android.bluetooth.BluetoothDevice) {
         handler.post { callbacks.onStatusChanged(BleStatus.Connecting) }

android/app/src/main/java/nl/eddydevink/sylda/MainActivity.kt

@@ -22,7 +22,7 @@ class MainActivity : AppCompatActivity(), BleCallbacks {
         private const val REQUEST_SETTINGS = 1
         private const val POST_SETTINGS_RESCAN_MS = 500L
         private const val ON_RESUME_SCAN_DELAY_MS = 300L
-        private const val BUNDLED_FIRMWARE_VERSION = "2"
+        private const val BUNDLED_FIRMWARE_VERSION = "5"
     }
 
     private lateinit var manager: BleRelayManager
@@ -222,8 +222,10 @@ class MainActivity : AppCompatActivity(), BleCallbacks {
 
     override fun onFirmwareVersion(espVersion: String, appVersion: String) {
         runOnUiThread {
+            if (isFinishing || isDestroyed || !lifecycle.currentState.isAtLeast(androidx.lifecycle.Lifecycle.State.RESUMED)) return@runOnUiThread
             if (espVersion.isEmpty() || espVersion != appVersion) {
-                Toast.makeText(this, getString(R.string.ota_update_available), Toast.LENGTH_LONG).show()
+                Toast.makeText(this, getString(R.string.ota_update_available), Toast.LENGTH_SHORT).show()
+                startActivityForResult(Intent(this, SettingsActivity::class.java), REQUEST_SETTINGS)
             } else {
                 Toast.makeText(this, getString(R.string.ota_up_to_date), Toast.LENGTH_SHORT).show()
             }

android/app/src/main/java/nl/eddydevink/sylda/OtaManager.kt

@@ -23,7 +23,7 @@ class OtaManager(
 ) {
     companion object {
         private const val TAG = "OtaManager"
-        private const val OTA_CHUNK_DATA_SIZE = 500
+        private const val OTA_CHUNK_DATA_SIZE = 248
         private const val OTA_CMD_START: Byte = 0x10
         private const val OTA_CMD_END: Byte = 0x11
         private const val OTA_STATUS_ACK: Byte = 0x00

android/app/src/main/java/nl/eddydevink/sylda/SettingsActivity.kt

@@ -64,7 +64,7 @@ class SettingsActivity : AppCompatActivity() {
         private const val REBOOT_WAIT_MS = 5000L
         private const val REBOOT_POLL_MS = 500L
         private const val REBOOT_MAX_WAIT_MS = 15000L
-        private const val EXPECTED_FIRMWARE_VERSION = "1"
+        private const val EXPECTED_FIRMWARE_VERSION = "5"
     }
 
     private enum class UsbAction { NONE, EXCHANGE_KEY, FLASH }
@@ -77,6 +77,8 @@ class SettingsActivity : AppCompatActivity() {
     private var otaManager: OtaManager? = null
     private var otaJob: Job? = null
     private var lastTheme: String? = null
+    private val rebootTimeoutHandler = Handler(Looper.getMainLooper())
+    private var rebootTimeoutRunnable: Runnable? = null
 
     private val usbAttachedReceiver = object : BroadcastReceiver() {
         override fun onReceive(context: Context, intent: Intent) {
@@ -138,14 +140,13 @@ class SettingsActivity : AppCompatActivity() {
         supportActionBar?.setDisplayHomeAsUpEnabled(true)
         supportActionBar?.title = getString(R.string.title_settings)
 
-        findViewById<Button>(R.id.flashFirmwareButton).setOnClickListener {
+        findViewById<Button>(R.id.updateModuleButton).setOnClickListener {
+            if (findViewById<RadioGroup>(R.id.flashMethodGroup).checkedRadioButtonId == R.id.methodUsb) {
                 startFlashing()
-        }
-
-        val otaButton = findViewById<Button>(R.id.otaUpdateButton)
-        otaButton.setOnClickListener {
+            } else {
                 startOtaUpdate()
             }
+        }
 
         registerReceiver(usbAttachedReceiver, IntentFilter(UsbManager.ACTION_USB_DEVICE_ATTACHED), Context.RECEIVER_EXPORTED)
         registerReceiver(usbPermissionReceiver, IntentFilter(ACTION_USB_PERMISSION), Context.RECEIVER_NOT_EXPORTED)
@@ -219,15 +220,26 @@ class SettingsActivity : AppCompatActivity() {
             Toast.makeText(this, getString(R.string.ota_needs_usb_first), Toast.LENGTH_LONG).show()
             return
         }
-        otaManager = OtaManager(this, manager)
 
-        if (otaManager?.loadFirmware() != true) {
-            Toast.makeText(this, getString(R.string.ota_load_failed), Toast.LENGTH_SHORT).show()
+        val espVersion = manager.getEspVersion()
+        if (espVersion != null && espVersion == EXPECTED_FIRMWARE_VERSION) {
+            Toast.makeText(this, getString(R.string.ota_up_to_date), Toast.LENGTH_SHORT).show()
             return
         }
 
         showOtaProgressDialog()
 
+        otaManager = OtaManager(this, manager)
+
+        if (otaManager?.loadFirmware() != true) {
+            progressDialog?.dismiss()
+            progressDialog = null
+            Toast.makeText(this, getString(R.string.ota_load_failed), Toast.LENGTH_SHORT).show()
+            return
+        }
+
+        manager.enableOtaNotifications()
+
         otaJob = lifecycleScope.launch {
             val result = otaManager!!.performOta(object : OtaManager.OtaCallback {
                 override fun onProgress(percent: Int, message: String) {
@@ -267,6 +279,8 @@ class SettingsActivity : AppCompatActivity() {
 
     override fun onDestroy() {
         super.onDestroy()
+        rebootTimeoutRunnable?.let { rebootTimeoutHandler.removeCallbacks(it) }
+        rebootTimeoutRunnable = null
         currentAction = UsbAction.NONE
         flasherJob?.cancel()
         flasherJob = null
@@ -396,9 +410,10 @@ class SettingsActivity : AppCompatActivity() {
         lifecycleScope.launch {
             val version = readEspVersion(usbManager, device)
             if (version == EXPECTED_FIRMWARE_VERSION && !expectingReboot) {
-                Log.d(TAG, "Firmware version $version matches, skipping flash")
+                Log.d(TAG, "Firmware version $version matches, up to date")
                 progressDialog?.dismiss()
                 progressDialog = null
+                Toast.makeText(this@SettingsActivity, getString(R.string.ota_up_to_date), Toast.LENGTH_SHORT).show()
                 currentAction = UsbAction.EXCHANGE_KEY
                 doKeyExchange(usbManager, device)
                 return@launch
@@ -437,6 +452,8 @@ class SettingsActivity : AppCompatActivity() {
                     getString(R.string.title_firmware_flash),
                     getString(R.string.msg_env_waiting_reboot)
                 )
+                rebootTimeoutRunnable = Runnable { cleanupAction() }
+                rebootTimeoutHandler.postDelayed(rebootTimeoutRunnable!!, REBOOT_MAX_WAIT_MS)
             } catch (e: kotlinx.coroutines.CancellationException) {
                 cleanupAction()
                 throw e
@@ -453,6 +470,8 @@ class SettingsActivity : AppCompatActivity() {
     // === USB dispatch ===
 
     private fun onDeviceReady(usbManager: UsbManager, device: UsbDevice) {
+        rebootTimeoutRunnable?.let { rebootTimeoutHandler.removeCallbacks(it) }
+        rebootTimeoutRunnable = null
         when (currentAction) {
             UsbAction.EXCHANGE_KEY -> doKeyExchange(usbManager, device)
             UsbAction.FLASH -> doFlashing(usbManager, device)
@@ -501,6 +520,8 @@ class SettingsActivity : AppCompatActivity() {
     private fun cleanupAction() {
         currentAction = UsbAction.NONE
         expectingReboot = false
+        rebootTimeoutRunnable?.let { rebootTimeoutHandler.removeCallbacks(it) }
+        rebootTimeoutRunnable = null
         dialog?.dismiss()
         dialog = null
         progressDialog?.dismiss()

android/app/src/main/res/layout/activity_settings.xml

@@ -5,25 +5,36 @@
     android:orientation="vertical"
     android:padding="24dp">
 
-    <TextView
+    <RadioGroup
+        android:id="@+id/flashMethodGroup"
         android:layout_width="match_parent"
         android:layout_height="wrap_content"
-        android:text="@string/msg_flash_mode_help"
-        android:textSize="14sp"
-        android:layout_marginBottom="16dp" />
+        android:orientation="horizontal"
+        android:layout_marginBottom="8dp"
+        android:checkedButton="@id/methodBluetooth">
+
+        <RadioButton
+            android:id="@+id/methodBluetooth"
+            android:layout_width="0dp"
+            android:layout_height="wrap_content"
+            android:layout_weight="1"
+            android:gravity="center"
+            android:text="@string/method_bluetooth" />
+
+        <RadioButton
+            android:id="@+id/methodUsb"
+            android:layout_width="0dp"
+            android:layout_height="wrap_content"
+            android:layout_weight="1"
+            android:gravity="center"
+            android:text="@string/method_usb" />
+    </RadioGroup>
 
     <Button
-        android:id="@+id/flashFirmwareButton"
+        android:id="@+id/updateModuleButton"
         android:layout_width="match_parent"
         android:layout_height="wrap_content"
-        android:text="@string/button_firmware_flash" />
-
-    <Button
-        android:id="@+id/otaUpdateButton"
-        android:layout_width="match_parent"
-        android:layout_height="wrap_content"
-        android:text="@string/button_ota_update"
-        android:layout_marginTop="8dp" />
+        android:text="@string/button_update_module" />
 
     <TextView
         android:id="@+id/otaStatusText"

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

@@ -27,9 +27,9 @@
 
     <!-- SettingsActivity -->
     <string name="title_settings">Instellingen</string>
-    <string name="msg_settings_intro">Sluit de ESP aan op USB en kies een actie.</string>
-    <string name="msg_flash_mode_help">Sluit de module aan op de USB-poort.</string>
-    <string name="button_firmware_flash">Firmware bijwerken</string>
+    <string name="method_bluetooth">Bluetooth</string>
+    <string name="method_usb">USB</string>
+    <string name="button_update_module">Module bijwerken</string>
     <string name="usb_access_denied">USB-toegang geweigerd</string>
     <string name="key_read_success">Beveiligingssleutel gelezen</string>
     <string name="key_exchange_failed">Sleutel uitwisselen mislukt - probeer opnieuw</string>
@@ -104,8 +104,7 @@
     <string name="theme_applied">Thema: %s</string>
 
     <!-- OTA Updates -->
-    <string name="button_ota_update">Firmware bijwerken via Bluetooth</string>
-    <string name="title_ota_update">OTA Firmware Update</string>
+    <string name="title_ota_update">Module bijwerken</string>
     <string name="msg_ota_starting">OTA update starten...</string>
     <string name="ota_update_available">Nieuwe firmware beschikbaar</string>
     <string name="ota_up_to_date">Firmware is up‑to‑date</string>

src/main.cpp

@@ -34,7 +34,7 @@
 #define NVS_NAMESPACE "hmac"
 #define NVS_KEY_NAME  "key"
 #define NVS_UUID_NAME "uuid"
-#define FIRMWARE_VERSION "2"
+#define FIRMWARE_VERSION "5"
 
 NimBLECharacteristic *pCharacteristic;
 bool deviceConnected = false;
@@ -343,7 +343,7 @@ void setup() {
 
     NimBLECharacteristic *pOtaChar = pService->createCharacteristic(
         OTA_UUID,
-        NIMBLE_PROPERTY::WRITE | NIMBLE_PROPERTY::NOTIFY
+        NIMBLE_PROPERTY::WRITE_NR | NIMBLE_PROPERTY::NOTIFY
     );
     pOtaChar->setCallbacks(new OtaCharacteristicCallbacks());