fix: fallback expired Bolt 11 to on-chain on unified invoice

Bitkit/Resources/Localization/en.lproj/Localizable.strings

@@ -370,6 +370,7 @@
 "other__pay_insufficient_spending" = "Insufficient Spending Balance";
 "other__pay_insufficient_savings_description" = "More ₿ needed to pay this Bitcoin invoice.";
 "other__pay_insufficient_savings_amount_description" = "₿ {amount} more needed to pay this Bitcoin invoice.";
+"other__pay_insufficient_spending_description" = "More ₿ needed to pay this Lightning invoice.";
 "other__pay_insufficient_spending_amount_description" = "₿ {amount} more needed to pay this Lightning invoice.";
 "other__swipe" = "Swipe To Confirm";
 "other__scan_err_decoding" = "Decoding Error";

Bitkit/Utilities/CurrencyFormatter.swift

@@ -9,4 +9,12 @@ enum CurrencyFormatter {
 
         return formatter.string(from: amount as NSDecimalNumber) ?? ""
     }
+
+    /// Format satoshis with space as grouping separator (e.g., 10000 -> "10 000")
+    static func formatSats(_ sats: UInt64) -> String {
+        let formatter = NumberFormatter()
+        formatter.numberStyle = .decimal
+        formatter.groupingSeparator = " "
+        return formatter.string(from: NSNumber(value: sats)) ?? String(sats)
+    }
 }

Bitkit/Utilities/NetworkValidationHelper.swift

@@ -0,0 +1,57 @@
+import BitkitCore
+import LDKNode
+
+/// Helper for validating Bitcoin network compatibility of addresses and invoices
+enum NetworkValidationHelper {
+    /// Infer the Bitcoin network from an on-chain address prefix
+    /// - Parameter address: The Bitcoin address to check
+    /// - Returns: The detected network, or nil if the address format is unrecognized
+    static func getAddressNetwork(_ address: String) -> LDKNode.Network? {
+        let lowercased = address.lowercased()
+
+        // Bech32/Bech32m addresses (order matters: check bcrt1 before bc1)
+        if lowercased.hasPrefix("bcrt1") {
+            return .regtest
+        } else if lowercased.hasPrefix("bc1") {
+            return .bitcoin
+        } else if lowercased.hasPrefix("tb1") {
+            return .testnet
+        }
+
+        // Legacy addresses - check first character
+        guard let first = address.first else { return nil }
+        switch first {
+        case "1", "3": return .bitcoin
+        case "m", "n", "2": return .testnet // testnet and regtest share these
+        default: return nil
+        }
+    }
+
+    /// Convert BitkitCore.NetworkType to LDKNode.Network
+    /// - Parameter networkType: The BitkitCore network type
+    /// - Returns: The equivalent LDKNode network
+    static func convertNetworkType(_ networkType: NetworkType) -> LDKNode.Network {
+        switch networkType {
+        case .bitcoin: return .bitcoin
+        case .testnet: return .testnet
+        case .signet: return .signet
+        case .regtest: return .regtest
+        }
+    }
+
+    /// Check if an address/invoice network mismatches the current app network
+    /// - Parameters:
+    ///   - addressNetwork: The network detected from the address/invoice
+    ///   - currentNetwork: The app's current network (typically Env.network)
+    /// - Returns: true if there's a mismatch (address won't work on current network)
+    static func isNetworkMismatch(addressNetwork: LDKNode.Network?, currentNetwork: LDKNode.Network) -> Bool {
+        guard let addressNetwork else { return false }
+
+        // Special case: regtest uses testnet prefixes (m, n, 2, tb1)
+        if currentNetwork == .regtest && addressNetwork == .testnet {
+            return false
+        }
+
+        return addressNetwork != currentNetwork
+    }
+}

Bitkit/Utilities/PaymentNavigationHelper.swift

@@ -102,7 +102,7 @@ struct PaymentNavigationHelper {
         app: AppViewModel,
         currency: CurrencyViewModel,
         settings: SettingsViewModel
-    ) -> SendRoute {
+    ) -> SendRoute? {
         if let lnurlWithdrawData = app.lnurlWithdrawData {
             if lnurlWithdrawData.minWithdrawable == lnurlWithdrawData.maxWithdrawable {
                 return .lnurlWithdrawConfirm
@@ -125,8 +125,8 @@ struct PaymentNavigationHelper {
         }
 
         // Handle lightning invoice
-        if app.scannedLightningInvoice != nil {
-            let amount = app.scannedLightningInvoice!.amountSatoshis
+        if let invoice = app.scannedLightningInvoice {
+            let amount = invoice.amountSatoshis
 
             if amount > 0 && shouldUseQuickpay {
                 return .quickpay
@@ -140,6 +140,11 @@ struct PaymentNavigationHelper {
         }
 
         // Handle onchain invoice
-        return .amount
+        if let _ = app.scannedOnchainInvoice {
+            return .amount
+        }
+
+        // No valid invoice data
+        return nil
     }
 }