refactor: move biometric prompt trigger to UI

app/src/main/java/com/bitcointxoko/gudariwallet/ui/WalletViewModel.kt

@@ -10,7 +10,6 @@ import com.bitcointxoko.gudariwallet.data.WalletRepository
 import kotlinx.coroutines.flow.SharedFlow
 import kotlinx.coroutines.flow.StateFlow
 import kotlinx.coroutines.launch
-import androidx.fragment.app.FragmentActivity
 import com.bitcointxoko.gudariwallet.data.BalancePrefsStore
 import com.bitcointxoko.gudariwallet.data.LightningAddressStore
 import com.bitcointxoko.gudariwallet.ui.balance.BalanceViewModel
@@ -103,12 +102,9 @@ class WalletViewModel(
     fun payLnurlInvoice(state: SendState.LnurlInvoiceReady, strings: SendStrings) =
         sendVm.payLnurlInvoice(state, strings)
 
-    fun requestPayment(
-        activity : FragmentActivity,
-        subtitle : String,
-        strings  : SendStrings,
-        pay      : () -> Unit,
-    ) = sendVm.requestPayment(activity, subtitle, strings, pay)
+    fun onAuthFailed(message: String, strings: SendStrings) {
+        sendVm.onAuthFailed(message, strings)
+    }
     fun resetSendState() = sendVm.resetSendState()
 
     val sendEvents: SharedFlow<SendEvent> = sendVm.events

app/src/main/java/com/bitcointxoko/gudariwallet/ui/send/ConfirmCard.kt

@@ -30,6 +30,7 @@ import com.bitcointxoko.gudariwallet.ui.SendState
 import com.bitcointxoko.gudariwallet.ui.WalletViewModel
 import com.bitcointxoko.gudariwallet.ui.components.CopyIconButton
 import com.bitcointxoko.gudariwallet.ui.components.DetailRow
+import com.bitcointxoko.gudariwallet.util.BiometricHelper
 import com.bitcointxoko.gudariwallet.util.fiatLabel
 import com.bitcointxoko.gudariwallet.util.payingToLabel
 import kotlinx.coroutines.delay
@@ -52,13 +53,13 @@ internal fun Bolt11ConfirmCard(
         title     = strings.invoiceDetails,                                // ← "Invoice Details"
         invoice   = state,
         fiatLabel = fiatLbl,
-        onPay     = {
-            vm.requestPayment(
-                activity,
-                strings.sendBiometricPrompt(state.amountSats),
-                strings   = sendStrings,       // ← "Send X sats"
-            ) { vm.payBolt11(state.bolt11, sendStrings) }
-        },
+        onPay = rememberBiometricPay(
+            activity = activity,
+            subtitle = strings.sendBiometricPrompt(state.amountSats),
+            strings  = sendStrings,
+            vm       = vm,
+            pay      = { vm.payBolt11(state.bolt11, sendStrings) }
+        ),
         onCancel  = { vm.resetSendState() }
     )
 }
@@ -79,13 +80,13 @@ internal fun LnurlInvoiceConfirmCard(
         title     = strings.payingTo(label),                              // ← "Paying to X"
         invoice   = state,
         fiatLabel = fiatLbl,
-        onPay     = {
-            vm.requestPayment(
-                activity,
-                strings.sendBiometricPromptTo(state.amountSats, label),
-                strings   = sendStrings,   // ← "Send X sats to Y"
-            ) { vm.payLnurlInvoice(state, sendStrings) }
-        },
+        onPay = rememberBiometricPay(
+            activity = activity,
+            subtitle = strings.sendBiometricPromptTo(state.amountSats, label),
+            strings  = sendStrings,
+            vm       = vm,
+            pay      = { vm.payLnurlInvoice(state, sendStrings) }
+        ),
         onCancel  = { vm.resetSendState() }
     )
 }
@@ -270,3 +271,25 @@ private fun PayCancelButton(onCancel: () -> Unit) {
         Text(strings.cancel)                                               // ← "Cancel"
     }
 }
+
+@Composable
+private fun rememberBiometricPay(
+    activity : FragmentActivity,
+    subtitle : String,
+    strings  : SendStrings,
+    vm       : WalletViewModel,
+    pay      : () -> Unit,
+): () -> Unit = remember(subtitle) {
+    {
+        if (BiometricHelper.canAuthenticate(activity)) {
+            BiometricHelper.prompt(
+                activity  = activity,
+                subtitle  = subtitle,
+                onSuccess = pay,
+                onError   = { _, msg -> vm.onAuthFailed(msg.toString(), strings) }
+            )
+        } else {
+            pay()
+        }
+    }
+}

app/src/main/java/com/bitcointxoko/gudariwallet/ui/send/SendViewModel.kt

@@ -71,6 +71,10 @@ class SendViewModel(
     private val _sendState = MutableStateFlow<SendState>(SendState.Idle)
     val sendState: StateFlow<SendState> = _sendState
 
+    fun onAuthFailed(message: String, strings: SendStrings) {
+        _sendState.value = SendState.Error(strings.authFailed(message))
+    }
+
     // ── Entry point ──────────────────────────────────────────────────────────
 
     fun scan(rawInput: String, strings: SendStrings) {
@@ -321,31 +325,6 @@ class SendViewModel(
         }
     }
 
-    /**
-     * Biometric gate. Shows prompt if device supports it; calls [pay] directly if not.
-     */
-    fun requestPayment(
-        activity : FragmentActivity,
-        subtitle : String,
-        strings  : SendStrings,
-        pay      : () -> Unit
-    ) {
-        if (!BiometricHelper.canAuthenticate(activity)) {
-            pay()
-            return
-        }
-        BiometricHelper.prompt(
-            activity  = activity,
-            subtitle  = subtitle,
-            onSuccess = pay,
-            onError   = { _, msg ->
-                _sendState.value = SendState.Error(
-                    strings.authFailed(msg.toString())                                    // ← "Authentication failed: $msg"
-                )
-            }
-        )
-    }
-
     fun resetSendState() { _sendState.value = SendState.Idle }
 
     // ── Scan handlers ────────────────────────────────────────────────────────