attempt to fix QR scanner

app/src/main/java/sh/sar/basedbank/ui/home/TransferFragment.kt

@@ -32,7 +32,10 @@ import androidx.fragment.app.activityViewModels
 import androidx.lifecycle.lifecycleScope
 import android.app.Activity
 import android.content.Intent
+import androidx.activity.result.ActivityResult
+import androidx.activity.result.ActivityResultLauncher
 import androidx.activity.result.contract.ActivityResultContracts
+import java.util.UUID
 import kotlinx.coroutines.Dispatchers
 import kotlinx.coroutines.launch
 import kotlinx.coroutines.withContext
@@ -162,9 +165,21 @@ class TransferFragment : Fragment() {
             }
         ).also { mfaisaHandler = it }
 
-    private val qrLauncher = registerForActivityResult(ActivityResultContracts.StartActivityForResult()) { result ->
-        if (result.resultCode != Activity.RESULT_OK) return@registerForActivityResult
-        val raw = result.data?.getStringExtra(QrScannerActivity.EXTRA_QR_CONTENT) ?: return@registerForActivityResult
+    // Registered manually against the activity registry in onViewCreated rather than with a
+    // registerForActivityResult() field initializer: HomeActivity caches one TransferFragment
+    // instance (cachedTransferFragment) and re-shows it after a replace(). A field initializer
+    // runs only once, so once that instance was destroyed the launcher stayed unregistered and
+    // launching it threw. Keying off viewLifecycleOwner re-registers on every view creation.
+    private val qrLauncherKey = "transfer_qr_" + UUID.randomUUID()
+    private var qrLauncher: ActivityResultLauncher<Intent>? = null
+
+    private fun launchQrScanner() {
+        qrLauncher?.launch(Intent(requireContext(), QrScannerActivity::class.java))
+    }
+
+    private fun onQrScanned(result: ActivityResult) {
+        if (result.resultCode != Activity.RESULT_OK) return
+        val raw = result.data?.getStringExtra(QrScannerActivity.EXTRA_QR_CONTENT) ?: return
 
         // BML card/gateway QR — hand off to dedicated payment screen
         val bmlUrl = PaymvQrParser.extractBmlGatewayUrl(raw)
@@ -173,7 +188,7 @@ class TransferFragment : Fragment() {
                 it.profileType == "BML_PREPAID" || it.profileType == "BML_CREDIT" || it.profileType == "BML_DEBIT"
             }
             (requireActivity() as HomeActivity).navigateTo(R.id.nav_transfer, TransferFragment.newInstanceFromBmlQr(bmlUrl ?: raw, fromCard?.accountNumber))
-            return@registerForActivityResult
+            return
         }
 
         // M-Faisa merchant QR — content is just the numeric qrCodeId. Only attempt the lookup
@@ -184,13 +199,13 @@ class TransferFragment : Fragment() {
         if (trimmedRaw.length in 8..16 && trimmedRaw.all { it.isDigit() } &&
             app.mfaisaSessions.isNotEmpty()) {
             lookupMfaisaQrMerchant(trimmedRaw)
-            return@registerForActivityResult
+            return
         }
 
         val qr = PaymvQrParser.parse(raw)
         if (qr == null || qr.accountNumber == null) {
             Toast.makeText(requireContext(), R.string.transfer_qr_invalid, Toast.LENGTH_SHORT).show()
-            return@registerForActivityResult
+            return
         }
 
         // Cards can't pay PayMV QR — fall back to default account or clear selection
@@ -287,6 +302,10 @@ class TransferFragment : Fragment() {
     }
 
     override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
+        qrLauncher = requireActivity().activityResultRegistry.register(
+            qrLauncherKey, viewLifecycleOwner, ActivityResultContracts.StartActivityForResult()
+        ) { onQrScanned(it) }
+
         setupFromDropdown()
         setupAccountLookup()
 
@@ -340,7 +359,7 @@ class TransferFragment : Fragment() {
         }
 
         binding.btnScanQr.setOnClickListener {
-            qrLauncher.launch(Intent(requireContext(), QrScannerActivity::class.java))
+            launchQrScanner()
         }
 
         viewModel.connectivityErrors.observe(viewLifecycleOwner) { updateTransferButton() }
@@ -369,7 +388,7 @@ class TransferFragment : Fragment() {
         arguments?.getString(ARG_BML_QR_URL)?.let { bmlHandler().lookupQrMerchant(it) }
 
         if (arguments?.getBoolean(ARG_AUTO_SCAN, false) == true) {
-            qrLauncher.launch(Intent(requireContext(), QrScannerActivity::class.java))
+            launchQrScanner()
         }
 
         // Restore form state when view is recreated on the cached no-args instance
@@ -2002,6 +2021,8 @@ class TransferFragment : Fragment() {
         bmlHandler = null
         mfaisaHandler?.clearState()
         mfaisaHandler = null
+        // Unregistered automatically with viewLifecycleOwner; drop the stale handle.
+        qrLauncher = null
         _binding = null
     }