Updated on 2026-08-14

features/send/impl/src/main/java/com/tangem/features/send/impl/presentation/state/fee/FeeStateFactory.kt

@@ -166,6 +166,31 @@ internal class FeeStateFactory(
         )
     }
 
+    fun tryAutoFixCustomFeeValue(): SendUiState {
+        val state = currentStateProvider()
+        val isEditState = stateRouterProvider().isEditState
+        val feeState = state.getFeeState(isEditState) ?: return state
+        val feeSelectorState = feeState.feeSelectorState as? FeeSelectorState.Content ?: return state
+        return when (feeSelectorState.selectedFee) {
+            FeeType.Slow,
+            FeeType.Market,
+            FeeType.Fast,
+            -> state
+            FeeType.Custom -> {
+                val updatedFeeSelectorState = customFeeFieldConverter.tryAutoFixValue(feeSelectorState)
+
+                val fee = feeConverter.convert(updatedFeeSelectorState)
+                return state.copyWrapped(
+                    isEditState = isEditState,
+                    feeState = feeState.copy(
+                        feeSelectorState = updatedFeeSelectorState,
+                        fee = fee,
+                    ),
+                )
+            }
+        }
+    }
+
     private fun isPrimaryButtonEnabled(
         feeState: SendStates.FeeState,
         notifications: ImmutableList<NotificationUM>,

features/send/impl/src/main/java/com/tangem/features/send/impl/presentation/state/fee/SendFeeCustomFieldConverter.kt

@@ -1,6 +1,7 @@
 package com.tangem.features.send.impl.presentation.state.fee
 
 import com.tangem.blockchain.common.transaction.Fee
+import com.tangem.blockchain.common.transaction.TransactionFee
 import com.tangem.domain.appcurrency.model.AppCurrency
 import com.tangem.domain.tokens.model.CryptoCurrencyStatus
 import com.tangem.features.send.impl.presentation.state.StateRouter
@@ -78,4 +79,19 @@ internal class SendFeeCustomFieldConverter(
             else -> feeSelectorState.customValues
         },
     )
+
+    fun tryAutoFixValue(feeSelectorState: FeeSelectorState.Content) = feeSelectorState.copy(
+        customValues = when (feeSelectorState.fees) {
+            is TransactionFee.Choosable -> feeSelectorState.fees.minimum
+            is TransactionFee.Single -> feeSelectorState.fees.normal
+        }.let {
+            when (it) {
+                is Fee.Kaspa -> kaspaCustomFeeConverter.tryAutoFixValue(
+                    minimumFee = it,
+                    customValues = feeSelectorState.customValues,
+                )
+                else -> feeSelectorState.customValues
+            }
+        },
+    )
 }

features/send/impl/src/main/java/com/tangem/features/send/impl/presentation/state/fee/custom/KaspaCustomFeeConverter.kt

@@ -95,6 +95,40 @@ internal class KaspaCustomFeeConverter(
         }.toImmutableList()
     }
 
+    fun tryAutoFixValue(
+        minimumFee: Fee.Kaspa,
+        customValues: ImmutableList<SendTextField.CustomFee>,
+    ): ImmutableList<SendTextField.CustomFee> {
+        val mutableCustomValues = customValues.toMutableList()
+        val minimumFeeAmountValue = minimumFee.amount.value
+
+        return mutableCustomValues.apply {
+            // check that there is reveal transaction info (= krc-20 token transfer)
+            // return without changes otherwise
+            if (minimumFee.revealTransactionFee != null && minimumFeeAmountValue != null) {
+                getOrNull(FEE_AMOUNT_INDEX)?.let {
+                    val valueDecimal = it.value.parseToBigDecimal(it.decimals)
+                    // krc-20 transaction will be failed if custom fee value is less than minimum,
+                    // so we set value to minimum in this case
+                    if (valueDecimal < minimumFee.amount.value) {
+                        val fixedValue = minimumFeeAmountValue.parseBigDecimal(it.decimals)
+                        set(
+                            FEE_AMOUNT_INDEX,
+                            it.copy(
+                                value = fixedValue,
+                                label = getFiatReference(
+                                    rate = feeCryptoCurrencyStatusProvider()?.value?.fiatRate,
+                                    value = valueDecimal,
+                                    appCurrency = appCurrencyProvider(),
+                                ),
+                            ),
+                        )
+                    }
+                }
+            }
+        }.toImmutableList()
+    }
+
     private companion object {
         private const val FEE_AMOUNT_INDEX = 0
     }

features/send/impl/src/main/java/com/tangem/features/send/impl/presentation/viewmodel/SendViewModel.kt

@@ -513,13 +513,12 @@ internal class SendViewModel @Inject constructor(
         when (currentState.type) {
             SendUiStateType.Fee,
             SendUiStateType.EditFee,
-            -> if (onFeeNext()) return
+            -> if (onFeeNextIntercept(isFromEdit)) return
             SendUiStateType.Amount,
             SendUiStateType.EditAmount,
             -> loadFee()
             else -> Unit
         }
-
         stateRouter.onNextClick()
     }
 
@@ -580,9 +579,23 @@ internal class SendViewModel @Inject constructor(
 
     override fun onTokenDetailsClick(currency: CryptoCurrency) = innerRouter.openTokenDetails(userWalletId, currency)
 
-    private fun onFeeNext(): Boolean {
+    private fun onFeeNextIntercept(isFromEdit: Boolean): Boolean {
         val feeState = uiState.value.getFeeState(stateRouter.isEditState)
         val feeSelectorState = feeState?.feeSelectorState as? FeeSelectorState.Content ?: return false
+
+        if (isFromEdit) {
+            // in some cases, if it's possible to fix incorrect fee automatically,
+            // do it, update current state and go let continue the flow
+            val fixedState = feeStateFactory.tryAutoFixCustomFeeValue()
+            if (fixedState.editFeeState != feeState) {
+                uiState.value = fixedState
+                val currentState = stateRouter.currentState.value
+                uiState.value = stateFactory.syncEditStates(isFromEdit = isFromEdit)
+                sendScreenAnalyticSender.send(currentState.type, uiState.value)
+                return false
+            }
+        }
+
         if (checkIfFeeTooLow(feeSelectorState)) {
             uiState.value = eventStateFactory.getFeeTooLowAlert(
                 onConsume = { uiState.value = eventStateFactory.onConsumeEventState() },