diff --git a/app/src/main/java/com/electricdreams/numo/BalanceCheckActivity.kt b/app/src/main/java/com/electricdreams/numo/BalanceCheckActivity.kt
index 91f40597..61e4356e 100644
--- a/app/src/main/java/com/electricdreams/numo/BalanceCheckActivity.kt
+++ b/app/src/main/java/com/electricdreams/numo/BalanceCheckActivity.kt
@@ -149,17 +149,23 @@ class BalanceCheckActivity : AppCompatActivity() {
             try {
                 Log.d(TAG, "1. Creating Satocash client...")
                 satocashClient = SatocashNfcClient(tag)
+                val client = satocashClient
+                if (client == null) {
+                    Log.e(TAG, "❌ Failed to create Satocash client")
+                    handleBalanceCheckError(getString(R.string.balance_check_error_invalid_nfc_tag))
+                    return@Thread
+                }
 
                 Log.d(TAG, "2. Connecting to NFC card...")
-                satocashClient!!.connect()
+                client.connect()
                 Log.d(TAG, "✅ Successfully connected to NFC card")
 
                 Log.d(TAG, "3. Selecting Satocash applet...")
-                satocashClient!!.selectApplet(SatocashNfcClient.SATOCASH_AID)
+                client.selectApplet(SatocashNfcClient.SATOCASH_AID)
                 Log.d(TAG, "✅ Satocash Applet found and selected!")
 
                 Log.d(TAG, "4. Initializing secure channel...")
-                satocashClient!!.initSecureChannel()
+                client.initSecureChannel()
                 Log.d(TAG, "✅ Secure Channel Initialized!")
 
                 Log.d(TAG, "5. Getting accurate card balance (no PIN authentication)...")
@@ -191,8 +197,15 @@ class BalanceCheckActivity : AppCompatActivity() {
     private val cardBalance: Long
         get() {
             Log.d(TAG, "Getting card balance using getProofInfo (no PIN required)...")
+            val client = satocashClient
+            if (client == null) {
+                Log.e(TAG, "Satocash client is null when reading balance")
+                updateCardInfoDisplay(getString(R.string.balance_check_info_no_state_data))
+                return 0
+            }
+
             return try {
-                val status = satocashClient!!.status
+                val status = client.status
                 Log.d(TAG, "Card status: $status")
 
                 val nbProofsUnspent = status.getOrDefault("nb_proofs_unspent", 0) as Int
@@ -207,7 +220,7 @@ class BalanceCheckActivity : AppCompatActivity() {
 
                 Log.d(TAG, "Total proofs in card: $totalProofs ($nbProofsUnspent unspent, $nbProofsSpent spent)")
 
-                val proofStates = satocashClient!!.getProofInfo(
+                val proofStates = client.getProofInfo(
                     SatocashNfcClient.Unit.SAT,
                     SatocashNfcClient.ProofInfoType.METADATA_STATE,
                     0,
@@ -222,7 +235,7 @@ class BalanceCheckActivity : AppCompatActivity() {
                     return 0
                 }
 
-                val amounts = satocashClient!!.getProofInfo(
+                val amounts = client.getProofInfo(
                     SatocashNfcClient.Unit.SAT,
                     SatocashNfcClient.ProofInfoType.METADATA_AMOUNT_EXPONENT,
                     0,
diff --git a/app/src/main/java/com/electricdreams/numo/PaymentReceivedActivity.kt b/app/src/main/java/com/electricdreams/numo/PaymentReceivedActivity.kt
index 7d2c91f8..c1b3d70a 100644
--- a/app/src/main/java/com/electricdreams/numo/PaymentReceivedActivity.kt
+++ b/app/src/main/java/com/electricdreams/numo/PaymentReceivedActivity.kt
@@ -78,8 +78,9 @@ class PaymentReceivedActivity : AppCompatActivity() {
         amount = intent.getLongExtra(EXTRA_AMOUNT, 0)
         
         // Parse token to extract amount and unit if not provided
-        if (amount == 0L && tokenString != null) {
-            parseToken(tokenString!!)
+        val token = tokenString
+        if (amount == 0L && token != null) {
+            parseToken(token)
         }
         
         // Set up UI
@@ -196,13 +197,14 @@ class PaymentReceivedActivity : AppCompatActivity() {
     }
     
     private fun shareToken() {
-        if (tokenString.isNullOrEmpty()) {
+        val token = tokenString
+        if (token.isNullOrEmpty()) {
             Toast.makeText(this, R.string.payment_received_error_no_token, Toast.LENGTH_SHORT).show()
             return
         }
         
         // Create intent to share/export the token
-        val cashuUri = "cashu:$tokenString"
+        val cashuUri = "cashu:$token"
         
         // Create intent for viewing the URI
         val uriIntent = Intent(Intent.ACTION_VIEW, android.net.Uri.parse(cashuUri)).apply {
diff --git a/app/src/main/java/com/electricdreams/numo/PaymentRequestActivity.kt b/app/src/main/java/com/electricdreams/numo/PaymentRequestActivity.kt
index f7bacb71..30a915ff 100644
--- a/app/src/main/java/com/electricdreams/numo/PaymentRequestActivity.kt
+++ b/app/src/main/java/com/electricdreams/numo/PaymentRequestActivity.kt
@@ -471,9 +471,12 @@ class PaymentRequestActivity : AppCompatActivity() {
             }
         }
 
-        if (isResumingPayment && resumeNostrSecretHex != null && resumeNostrNprofile != null) {
+        val secretHex = resumeNostrSecretHex
+        val nprofile = resumeNostrNprofile
+
+        if (isResumingPayment && secretHex != null && nprofile != null) {
             // Resume with stored keys
-            handler.resume(paymentAmount, resumeNostrSecretHex!!, resumeNostrNprofile!!, callback)
+            handler.resume(paymentAmount, secretHex, nprofile, callback)
         } else {
             // Start fresh
             handler.start(paymentAmount, pendingPaymentId, callback)
@@ -484,13 +487,17 @@ class PaymentRequestActivity : AppCompatActivity() {
         lightningStarted = true
 
         // Check if we're resuming with existing Lightning quote
-        if (resumeLightningQuoteId != null && resumeLightningMintUrl != null && resumeLightningInvoice != null) {
-            Log.d(TAG, "Resuming Lightning quote: id=$resumeLightningQuoteId")
+        val quoteId = resumeLightningQuoteId
+        val mintUrl = resumeLightningMintUrl
+        val invoice = resumeLightningInvoice
+
+        if (quoteId != null && mintUrl != null && invoice != null) {
+            Log.d(TAG, "Resuming Lightning quote: id=$quoteId")
             
             lightningHandler?.resume(
-                quoteId = resumeLightningQuoteId!!,
-                mintUrlStr = resumeLightningMintUrl!!,
-                invoice = resumeLightningInvoice!!,
+                quoteId = quoteId,
+                mintUrlStr = mintUrl,
+                invoice = invoice,
                 callback = createLightningCallback()
             )
         } else {
diff --git a/app/src/main/java/com/electricdreams/numo/TopUpActivity.kt b/app/src/main/java/com/electricdreams/numo/TopUpActivity.kt
index 8e09fd5c..b0d349c2 100644
--- a/app/src/main/java/com/electricdreams/numo/TopUpActivity.kt
+++ b/app/src/main/java/com/electricdreams/numo/TopUpActivity.kt
@@ -352,16 +352,35 @@ class TopUpActivity : AppCompatActivity() {
                 Log.d(TAG, "Connected to NFC card")
 
                 satocashClient = tempClient
-                satocashWallet = SatocashWallet(satocashClient!!)
+                val client = satocashClient
+                if (client == null) {
+                    Log.e(TAG, "Satocash client is null after connection")
+                    showStatusMessage(
+                        getString(R.string.top_up_status_nfc_error, "Client init failed"),
+                        success = false
+                    )
+                    return@Thread
+                }
+
+                satocashWallet = SatocashWallet(client)
 
-                satocashClient!!.selectApplet(SatocashNfcClient.SATOCASH_AID)
+                client.selectApplet(SatocashNfcClient.SATOCASH_AID)
                 Log.d(TAG, "Satocash Applet found and selected!")
 
-                satocashClient!!.initSecureChannel()
+                client.initSecureChannel()
                 Log.d(TAG, "Secure Channel Initialized!")
 
                 try {
-                    val importedCount = satocashWallet!!.importProofsFromToken(token).join()
+                    val wallet = satocashWallet
+                    if (wallet == null) {
+                        showStatusMessage(
+                            getString(R.string.top_up_status_generic_error, "Wallet not initialized"),
+                            success = false
+                        )
+                        return@Thread
+                    }
+
+                    val importedCount = wallet.importProofsFromToken(token).join()
                     showStatusMessage(
                         getString(R.string.top_up_status_success_imported, importedCount),
                         success = true
@@ -383,8 +402,8 @@ class TopUpActivity : AppCompatActivity() {
                             Log.d(TAG, "PIN authentication needed")
 
                             try {
-                                satocashClient?.let { client ->
-                                    client.close()
+                                satocashClient?.let { clientToClose ->
+                                    clientToClose.close()
                                     Log.d(TAG, "NFC connection closed before PIN entry")
                                     satocashClient = null
                                 }
@@ -478,22 +497,41 @@ class TopUpActivity : AppCompatActivity() {
                 Log.d(TAG, "Connected to NFC card for PIN import")
 
                 satocashClient = tempClient
-                satocashWallet = SatocashWallet(satocashClient!!)
+                val client = satocashClient
+                if (client == null) {
+                    Log.e(TAG, "Satocash client is null for PIN import")
+                    showStatusMessage(
+                        getString(R.string.top_up_status_nfc_error, "Client init failed"),
+                        success = false
+                    )
+                    return@Thread
+                }
 
-                satocashClient!!.selectApplet(SatocashNfcClient.SATOCASH_AID)
+                satocashWallet = SatocashWallet(client)
+
+                client.selectApplet(SatocashNfcClient.SATOCASH_AID)
                 Log.d(TAG, "Satocash Applet found and selected!")
 
-                satocashClient!!.initSecureChannel()
+                client.initSecureChannel()
                 Log.d(TAG, "Secure Channel Initialized!")
 
                 Log.d(TAG, "Authenticating with saved PIN...")
-                val authenticated = satocashWallet!!.authenticatePIN(pin).join()
+                val wallet = satocashWallet
+                if (wallet == null) {
+                    showStatusMessage(
+                        getString(R.string.top_up_status_generic_error, "Wallet not initialized"),
+                        success = false
+                    )
+                    return@Thread
+                }
+
+                val authenticated = wallet.authenticatePIN(pin).join()
 
                 if (authenticated) {
                     Log.d(TAG, "PIN Verified! Card Ready.")
 
                     val token = pendingProofToken ?: ""
-                    val importedCount = satocashWallet!!.importProofsFromToken(token).join()
+                    val importedCount = wallet.importProofsFromToken(token).join()
 
                     waitingForRescan = false
                     savedPin = null
@@ -540,8 +578,8 @@ class TopUpActivity : AppCompatActivity() {
                 showStatusMessage(message, success = false)
             } finally {
                 try {
-                    satocashClient?.let { client ->
-                        client.close()
+                    satocashClient?.let { clientToClose ->
+                        clientToClose.close()
                         Log.d(TAG, "NFC connection closed.")
                         satocashClient = null
                     }
diff --git a/app/src/main/java/com/electricdreams/numo/core/worker/BitcoinPriceWorker.kt b/app/src/main/java/com/electricdreams/numo/core/worker/BitcoinPriceWorker.kt
index 76315751..2f5b2c88 100644
--- a/app/src/main/java/com/electricdreams/numo/core/worker/BitcoinPriceWorker.kt
+++ b/app/src/main/java/com/electricdreams/numo/core/worker/BitcoinPriceWorker.kt
@@ -122,7 +122,8 @@ class BitcoinPriceWorker private constructor(context: Context) {
     }
 
     fun start() {
-        if (scheduler != null && !scheduler!!.isShutdown) return
+        val currentScheduler = scheduler
+        if (currentScheduler != null && !currentScheduler.isShutdown) return
 
         scheduler = Executors.newSingleThreadScheduledExecutor().also { exec ->
             exec.scheduleAtFixedRate(
@@ -210,7 +211,9 @@ class BitcoinPriceWorker private constructor(context: Context) {
                     reader = BufferedReader(InputStreamReader(connection.inputStream))
                     val response = buildString {
                         var line: String?
-                        while (reader!!.readLine().also { line = it } != null) {
+                        while (true) {
+                            line = reader?.readLine()
+                            if (line == null) break
                             append(line)
                         }
                     }
diff --git a/app/src/main/java/com/electricdreams/numo/feature/history/TransactionDetailActivity.kt b/app/src/main/java/com/electricdreams/numo/feature/history/TransactionDetailActivity.kt
index 6270dd36..1d788324 100644
--- a/app/src/main/java/com/electricdreams/numo/feature/history/TransactionDetailActivity.kt
+++ b/app/src/main/java/com/electricdreams/numo/feature/history/TransactionDetailActivity.kt
@@ -368,11 +368,9 @@ class TransactionDetailActivity : AppCompatActivity() {
 
     private fun openBasketReceipt() {
         // Use saved basket data if available, otherwise fall back to checkoutBasketJson
-        val basketJsonToUse = if (savedBasket != null) {
-            convertSavedBasketToCheckoutBasket(savedBasket!!).toJson()
-        } else {
-            checkoutBasketJson
-        }
+        val basketJsonToUse = savedBasket?.let { basket ->
+            convertSavedBasketToCheckoutBasket(basket).toJson()
+        } ?: checkoutBasketJson
         
         val intent = Intent(this, BasketReceiptActivity::class.java).apply {
             putExtra(BasketReceiptActivity.EXTRA_CHECKOUT_BASKET_JSON, basketJsonToUse)
diff --git a/app/src/main/java/com/electricdreams/numo/feature/items/CheckoutScannerActivity.kt b/app/src/main/java/com/electricdreams/numo/feature/items/CheckoutScannerActivity.kt
index 1b1eb265..6e7d15bc 100644
--- a/app/src/main/java/com/electricdreams/numo/feature/items/CheckoutScannerActivity.kt
+++ b/app/src/main/java/com/electricdreams/numo/feature/items/CheckoutScannerActivity.kt
@@ -194,11 +194,16 @@ class CheckoutScannerActivity : AppCompatActivity() {
 
     private fun updateBasketForCurrentItem() {
         val item = currentItem ?: return
+        val itemId = item.id
+        if (itemId == null) {
+            Toast.makeText(this, "Item ID missing", Toast.LENGTH_SHORT).show()
+            return
+        }
 
         if (currentQuantity <= 0) {
-            basketManager.removeItem(item.id!!)
+            basketManager.removeItem(itemId)
         } else {
-            val updated = basketManager.updateItemQuantity(item.id!!, currentQuantity)
+            val updated = basketManager.updateItemQuantity(itemId, currentQuantity)
             if (!updated) {
                 basketManager.addItem(item, currentQuantity)
             }
@@ -380,8 +385,9 @@ class CheckoutScannerActivity : AppCompatActivity() {
         updateQuantityDisplay()
 
         // Load image
-        if (!item.imagePath.isNullOrEmpty()) {
-            val imageFile = File(item.imagePath!!)
+        val path = item.imagePath
+        if (!path.isNullOrEmpty()) {
+            val imageFile = File(path)
             if (imageFile.exists()) {
                 val bitmap: Bitmap? = BitmapFactory.decodeFile(imageFile.absolutePath)
                 if (bitmap != null) {
diff --git a/app/src/main/java/com/electricdreams/numo/feature/items/ItemEntryActivity.kt b/app/src/main/java/com/electricdreams/numo/feature/items/ItemEntryActivity.kt
index db30a6a4..fc6d29e6 100644
--- a/app/src/main/java/com/electricdreams/numo/feature/items/ItemEntryActivity.kt
+++ b/app/src/main/java/com/electricdreams/numo/feature/items/ItemEntryActivity.kt
@@ -298,12 +298,16 @@ class ItemEntryActivity : AppCompatActivity() {
             dialog.dismiss() 
         }
         dialogView.findViewById<Button>(R.id.dialog_confirm_button).setOnClickListener {
-            currentItem?.let { item ->
-                itemManager.removeItem(item.id!!)
+            val item = currentItem
+            val itemId = item?.id
+            if (item != null && itemId != null) {
+                itemManager.removeItem(itemId)
                 setResult(RESULT_OK)
-                dialog.dismiss()
-                finish()
+            } else {
+                Toast.makeText(this, "Unable to delete item: missing ID", Toast.LENGTH_SHORT).show()
             }
+            dialog.dismiss()
+            finish()
         }
         dialog.show()
     }
diff --git a/app/src/main/java/com/electricdreams/numo/feature/items/adapters/SelectionBasketAdapter.kt b/app/src/main/java/com/electricdreams/numo/feature/items/adapters/SelectionBasketAdapter.kt
index 7305bef4..7c5a0340 100644
--- a/app/src/main/java/com/electricdreams/numo/feature/items/adapters/SelectionBasketAdapter.kt
+++ b/app/src/main/java/com/electricdreams/numo/feature/items/adapters/SelectionBasketAdapter.kt
@@ -78,8 +78,10 @@ class SelectionBasketAdapter(
             }
 
             removeButton.setOnClickListener {
-                val itemId = item.id!!
-                onItemRemoved(itemId)
+                val itemId = item.id
+                if (itemId != null) {
+                    onItemRemoved(itemId)
+                }
             }
         }
     }
diff --git a/app/src/main/java/com/electricdreams/numo/feature/items/adapters/SelectionItemsAdapter.kt b/app/src/main/java/com/electricdreams/numo/feature/items/adapters/SelectionItemsAdapter.kt
index 09db7a77..f30df1ae 100644
--- a/app/src/main/java/com/electricdreams/numo/feature/items/adapters/SelectionItemsAdapter.kt
+++ b/app/src/main/java/com/electricdreams/numo/feature/items/adapters/SelectionItemsAdapter.kt
@@ -92,8 +92,9 @@ class SelectionItemsAdapter(
      */
     fun addCustomVariation(baseItem: Item, variationName: String) {
         // Create a new item with custom variation and unique ID
+        val customItemId = baseItem.id ?: UUID.randomUUID().toString()
         val customItem = baseItem.copy(
-            id = "custom_${baseItem.id}_${UUID.randomUUID().toString().take(8)}",
+            id = "custom_${customItemId}_${UUID.randomUUID().toString().take(8)}",
             uuid = UUID.randomUUID().toString(),
             variationName = variationName
         )
@@ -113,7 +114,9 @@ class SelectionItemsAdapter(
         
         // Add to basket with quantity 1
         basketManager.addItem(customItem, 1)
-        basketQuantities[customItem.id!!] = 1
+        customItem.id?.let { id ->
+            basketQuantities[id] = 1
+        }
         
         // Refresh basket UI
         onQuantityChanged()
@@ -164,7 +167,9 @@ class SelectionItemsAdapter(
     private fun refreshBasketQuantities() {
         basketQuantities.clear()
         for (basketItem in basketManager.getBasketItems()) {
-            basketQuantities[basketItem.item.id!!] = basketItem.quantity
+            basketItem.item.id?.let { id ->
+                basketQuantities[id] = basketItem.quantity
+            }
         }
     }
 
@@ -178,7 +183,7 @@ class SelectionItemsAdapter(
 
     override fun onBindViewHolder(holder: ItemViewHolder, position: Int) {
         val item = items[position]
-        val quantity = basketQuantities[item.id] ?: 0
+        val quantity = item.id?.let { basketQuantities[it] } ?: 0
         val isExpanded = position == expandedPosition
         val isCustomVariation = item.id?.startsWith("custom_") == true
         holder.bind(item, quantity, position == items.lastIndex, isExpanded, isCustomVariation, position)
@@ -406,8 +411,9 @@ class SelectionItemsAdapter(
         }
 
         private fun loadItemImage(item: Item) {
-            if (!item.imagePath.isNullOrEmpty()) {
-                val imageFile = File(item.imagePath!!)
+            val path = item.imagePath
+            if (!path.isNullOrEmpty()) {
+                val imageFile = File(path)
                 if (imageFile.exists()) {
                     val bitmap = BitmapFactory.decodeFile(imageFile.absolutePath)
                     if (bitmap != null) {
@@ -422,14 +428,20 @@ class SelectionItemsAdapter(
         }
 
         private fun updateBasketItem(item: Item, newQuantity: Int, isCustomVariation: Boolean) {
+            val itemId = item.id
+            if (itemId == null) {
+                Toast.makeText(itemView.context, "Item ID missing", Toast.LENGTH_SHORT).show()
+                return
+            }
+
             if (newQuantity <= 0) {
-                basketManager.removeItem(item.id!!)
-                basketQuantities.remove(item.id!!)
+                basketManager.removeItem(itemId)
+                basketQuantities.remove(itemId)
                 
                 // Remove custom variation items from the list when quantity reaches 0
                 if (isCustomVariation) {
-                    customVariationItems.removeAll { it.id == item.id }
-                    val index = items.indexOfFirst { it.id == item.id }
+                    customVariationItems.removeAll { it.id == itemId }
+                    val index = items.indexOfFirst { it.id == itemId }
                     if (index >= 0) {
                         items.removeAt(index)
                         // Adjust expanded position if needed
@@ -444,11 +456,11 @@ class SelectionItemsAdapter(
                     }
                 }
             } else {
-                val updated = basketManager.updateItemQuantity(item.id!!, newQuantity)
+                val updated = basketManager.updateItemQuantity(itemId, newQuantity)
                 if (!updated) {
                     basketManager.addItem(item, newQuantity)
                 }
-                basketQuantities[item.id!!] = newQuantity
+                basketQuantities[itemId] = newQuantity
             }
 
             // Animate quantity change
diff --git a/app/src/main/java/com/electricdreams/numo/feature/pin/PinEntryActivity.kt b/app/src/main/java/com/electricdreams/numo/feature/pin/PinEntryActivity.kt
index 07994d65..db041328 100644
--- a/app/src/main/java/com/electricdreams/numo/feature/pin/PinEntryActivity.kt
+++ b/app/src/main/java/com/electricdreams/numo/feature/pin/PinEntryActivity.kt
@@ -229,7 +229,7 @@ class PinEntryActivity : AppCompatActivity() {
                 }
             }
         }
-        handler.post(lockoutUpdateRunnable!!)
+        lockoutUpdateRunnable?.let { handler.post(it) }
     }
 
     private fun openPinReset() {
diff --git a/app/src/main/java/com/electricdreams/numo/feature/settings/MintDetailsActivity.kt b/app/src/main/java/com/electricdreams/numo/feature/settings/MintDetailsActivity.kt
index 517a75b1..27b132d7 100644
--- a/app/src/main/java/com/electricdreams/numo/feature/settings/MintDetailsActivity.kt
+++ b/app/src/main/java/com/electricdreams/numo/feature/settings/MintDetailsActivity.kt
@@ -98,7 +98,7 @@ class MintDetailsActivity : AppCompatActivity() {
     private var hasFetchError: Boolean = false
     
     // Balance refresh broadcast receiver
-    private val balanceRefreshReceiver: BroadcastReceiver = BalanceRefreshBroadcast.createReceiver { reason ->
+    private val balanceRefreshReceiver: BroadcastReceiver = BalanceRefreshBroadcast.createReceiver { _ ->
         // Refresh balance when we receive a broadcast (e.g., from withdrawal success)
         loadBalance()
     }
@@ -294,7 +294,7 @@ class MintDetailsActivity : AppCompatActivity() {
                     displayCachedMintInfo(info)
                 }
             } catch (e: Exception) {
-                Log.w(TAG, "Failed to parse cached mint info: ${'$'}{e.message}")
+                Log.w(TAG, "Failed to parse cached mint info: ${e.message}")
             }
         }
     }
@@ -313,23 +313,27 @@ class MintDetailsActivity : AppCompatActivity() {
 
         // Version from cached structured data - show as separate rows
         val versionInfo = info.versionInfo
-        val hasSoftware = !versionInfo?.name.isNullOrBlank()
-        val hasVersion = !versionInfo?.version.isNullOrBlank()
+        val softwareName = versionInfo?.name
+        val versionNumber = versionInfo?.version
+        val hasSoftware = !softwareName.isNullOrBlank()
+        val hasVersion = !versionNumber.isNullOrBlank()
         
         if (hasSoftware) {
-            softwareRow.visibility = View.VISIBLE
-            softwareDivider.visibility = View.VISIBLE
-            softwareValue.text = versionInfo?.name
+            if (!softwareRow.isVisible || softwareValue.text.toString() != softwareName) {
+                softwareRow.visibility = View.VISIBLE
+                softwareDivider.visibility = View.VISIBLE
+                softwareValue.text = softwareName
+            }
         } else {
             softwareRow.visibility = View.GONE
             softwareDivider.visibility = View.GONE
         }
         
         if (hasVersion) {
-            versionRow.visibility = View.VISIBLE
-            versionValue.text = versionInfo?.version
-            // Only show URL divider if no software row above
-            urlDivider.visibility = if (hasSoftware) View.VISIBLE else View.VISIBLE
+            if (!versionRow.isVisible || versionValue.text.toString() != versionNumber) {
+                versionRow.visibility = View.VISIBLE
+                versionValue.text = versionNumber
+            }
         } else {
             versionRow.visibility = View.GONE
         }
@@ -464,7 +468,7 @@ class MintDetailsActivity : AppCompatActivity() {
         val hasVersion = !versionNumberVal.isNullOrBlank()
         
         if (hasSoftware) {
-            val newSoftwareValue = versionName!!
+            val newSoftwareValue = versionName
             if (!softwareRow.isVisible || softwareValue.text.toString() != newSoftwareValue) {
                 softwareRow.visibility = View.VISIBLE
                 softwareDivider.visibility = View.VISIBLE
@@ -476,7 +480,7 @@ class MintDetailsActivity : AppCompatActivity() {
         }
         
         if (hasVersion) {
-            val newVersionValue = versionNumberVal!!
+            val newVersionValue = versionNumberVal
             if (!versionRow.isVisible || versionValue.text.toString() != newVersionValue) {
                 versionRow.visibility = View.VISIBLE
                 versionValue.text = newVersionValue
diff --git a/app/src/main/java/com/electricdreams/numo/feature/settings/SeedPhraseActivity.kt b/app/src/main/java/com/electricdreams/numo/feature/settings/SeedPhraseActivity.kt
index ea2d7b75..868f1f2a 100644
--- a/app/src/main/java/com/electricdreams/numo/feature/settings/SeedPhraseActivity.kt
+++ b/app/src/main/java/com/electricdreams/numo/feature/settings/SeedPhraseActivity.kt
@@ -66,13 +66,14 @@ class SeedPhraseActivity : AppCompatActivity() {
     private fun loadMnemonic() {
         mnemonic = CashuWalletManager.getMnemonic()
 
-        if (mnemonic.isNullOrBlank()) {
+        val phrase = mnemonic
+        if (phrase.isNullOrBlank()) {
             Toast.makeText(this, "Wallet not initialized", Toast.LENGTH_SHORT).show()
             finish()
             return
         }
 
-        words = mnemonic!!.split(" ")
+        words = phrase.split(" ")
     }
 
     private fun displaySeedWords(blur: Boolean) {
@@ -115,7 +116,8 @@ class SeedPhraseActivity : AppCompatActivity() {
     }
 
     private fun copyToClipboard() {
-        mnemonic?.let { phrase ->
+        val phrase = mnemonic
+        if (phrase != null) {
             val clipboard = getSystemService(Context.CLIPBOARD_SERVICE) as ClipboardManager
             val clip = ClipData.newPlainText("Seed Phrase", phrase)
             clipboard.setPrimaryClip(clip)
diff --git a/app/src/main/java/com/electricdreams/numo/feature/settings/WithdrawMeltQuoteActivity.kt b/app/src/main/java/com/electricdreams/numo/feature/settings/WithdrawMeltQuoteActivity.kt
index 4d58e667..69ea7c38 100644
--- a/app/src/main/java/com/electricdreams/numo/feature/settings/WithdrawMeltQuoteActivity.kt
+++ b/app/src/main/java/com/electricdreams/numo/feature/settings/WithdrawMeltQuoteActivity.kt
@@ -108,12 +108,13 @@ class WithdrawMeltQuoteActivity : AppCompatActivity() {
 
     private fun displayQuoteInfo() {
         val destination = when {
-            !lightningAddress.isNullOrBlank() -> lightningAddress!!
+            !lightningAddress.isNullOrBlank() -> lightningAddress
             !invoice.isNullOrBlank() -> {
-                if (invoice!!.length > 24) {
-                    "${invoice!!.take(12)}...${invoice!!.takeLast(12)}"
+                val inv = invoice
+                if (inv != null && inv.length > 24) {
+                    "${inv.take(12)}...${inv.takeLast(12)}"
                 } else {
-                    invoice!!
+                    inv ?: getString(R.string.withdraw_melt_destination_unknown)
                 }
             }
             else -> getString(R.string.withdraw_melt_destination_unknown)
@@ -159,7 +160,7 @@ class WithdrawMeltQuoteActivity : AppCompatActivity() {
                 val destinationLabel = lightningAddress ?: request
                 val destinationType = when {
                     !lightningAddress.isNullOrBlank() -> "manual_address"
-                    !request.isBlank() -> "manual_invoice"
+                    request.isNotBlank() -> "manual_invoice"
                     else -> "manual_unknown"
                 }
 
diff --git a/app/src/main/java/com/electricdreams/numo/ndef/CashuPaymentHelper.kt b/app/src/main/java/com/electricdreams/numo/ndef/CashuPaymentHelper.kt
index 5300e9dc..de9971c1 100644
--- a/app/src/main/java/com/electricdreams/numo/ndef/CashuPaymentHelper.kt
+++ b/app/src/main/java/com/electricdreams/numo/ndef/CashuPaymentHelper.kt
@@ -110,7 +110,7 @@ object CashuPaymentHelper {
         }
     }
 
-    // === Token helpers ======================================================
+    // === Token helpers =====================================================
 
     @JvmStatic
     fun isCashuToken(text: String?): Boolean =
@@ -316,22 +316,25 @@ object CashuPaymentHelper {
             )
                 ?: throw RedemptionException("Failed to parse PaymentRequestPayload")
 
-            if (payload.mint.isNullOrEmpty()) {
+            val mintUrl = payload.mint
+            val unit = payload.unit
+            val proofs = payload.proofs
+
+            if (mintUrl.isNullOrEmpty()) {
                 throw RedemptionException("PaymentRequestPayload is missing mint")
             }
-            if (payload.unit == null || payload.unit != "sat") {
-                throw RedemptionException("Unsupported unit in PaymentRequestPayload: ${payload.unit}")
+            if (unit == null || unit != "sat") {
+                throw RedemptionException("Unsupported unit in PaymentRequestPayload: $unit")
             }
-            if (payload.proofs.isNullOrEmpty()) {
+            if (proofs.isNullOrEmpty()) {
                 throw RedemptionException("PaymentRequestPayload contains no proofs")
             }
 
-            val mintUrl = payload.mint!!
             if (!allowedMints.isNullOrEmpty() && !allowedMints.contains(mintUrl)) {
                 throw RedemptionException("Mint $mintUrl not in allowed list")
             }
 
-            val totalAmount = payload.proofs!!.sumOf { it.amount }
+            val totalAmount = proofs.sumOf { it.amount }
             if (totalAmount < expectedAmount) {
                 throw RedemptionException(
                     "Insufficient amount in payload proofs: $totalAmount < expected $expectedAmount",
@@ -340,7 +343,7 @@ object CashuPaymentHelper {
 
             // Build a legacy cashu-jdk Token from proofs, then let CDK wallet
             // handle the redemption via redeemToken(encoded).
-            val tempToken = com.cashujdk.nut00.Token(payload.proofs!!, payload.unit!!, mintUrl)
+            val tempToken = com.cashujdk.nut00.Token(proofs, unit, mintUrl)
             val encoded = tempToken.encode()
             return redeemToken(encoded)
         } catch (e: JsonSyntaxException) {
diff --git a/app/src/main/java/com/electricdreams/numo/nostr/NostrMintBackup.kt b/app/src/main/java/com/electricdreams/numo/nostr/NostrMintBackup.kt
index 0290a92a..1e713cb8 100644
--- a/app/src/main/java/com/electricdreams/numo/nostr/NostrMintBackup.kt
+++ b/app/src/main/java/com/electricdreams/numo/nostr/NostrMintBackup.kt
@@ -272,9 +272,10 @@ object NostrMintBackup {
                         relayUrl = relayUrl,
                         publicKeyHex = publicKeyHex,
                         onEvent = { event ->
-                            if (event.id != null) {
-                                receivedEvents[event.id!!] = Pair(relayUrl, event)
-                                Log.d(TAG, "Received backup event ${event.id} from $relayUrl")
+                            val id = event.id
+                            if (id != null) {
+                                receivedEvents[id] = Pair(relayUrl, event)
+                                Log.d(TAG, "Received backup event $id from $relayUrl")
                             }
                         },
                         onComplete = {
diff --git a/app/src/main/java/com/electricdreams/numo/payment/NfcPaymentProcessor.kt b/app/src/main/java/com/electricdreams/numo/payment/NfcPaymentProcessor.kt
index 662793f7..c7ec271c 100644
--- a/app/src/main/java/com/electricdreams/numo/payment/NfcPaymentProcessor.kt
+++ b/app/src/main/java/com/electricdreams/numo/payment/NfcPaymentProcessor.kt
@@ -58,12 +58,24 @@ class NfcPaymentProcessor(
             try {
                 val tempClient = SatocashNfcClient(tag).also { it.connect() }
                 satocashClient = tempClient
-                satocashWallet = SatocashWallet(satocashClient)
-                satocashClient?.selectApplet(SatocashNfcClient.SATOCASH_AID)
-                satocashClient?.initSecureChannel()
+                val client = satocashClient
+                if (client == null) {
+                    onPaymentError(activity.getString(R.string.nfc_payment_error_nfc_comm, "Client init failed"))
+                    return@Thread
+                }
+
+                satocashWallet = SatocashWallet(client)
+                val wallet = satocashWallet
+                if (wallet == null) {
+                    onPaymentError(activity.getString(R.string.nfc_payment_error_generic, "Wallet not initialized"))
+                    return@Thread
+                }
+
+                client.selectApplet(SatocashNfcClient.SATOCASH_AID)
+                client.initSecureChannel()
                 
                 try {
-                    val token = satocashWallet!!.getPayment(requestedAmount, "SAT").join()
+                    val token = wallet.getPayment(requestedAmount, "SAT").join()
                     onPaymentSuccess(token)
                     return@Thread
                 } catch (e: RuntimeException) {