Binance UX: fiat precision, lot size info & network error handling

accbot-android/app/src/main/java/com/accbot/dca/domain/model/Models.kt

@@ -82,7 +82,19 @@ enum class Exchange(
         supportedCryptos = listOf("BTC", "ETH", "SOL", "ADA"),
         minOrderSize = mapOf("EUR" to BigDecimal("1"), "USD" to BigDecimal("1")),
         sandboxSupport = SandboxSupport.FULL
-    )
+    );
+
+    companion object {
+        /** Binance LOT_SIZE step sizes per crypto (from /api/v3/exchangeInfo). */
+        val binanceLotStepSize = mapOf(
+            "BTC" to "0.00001",
+            "ETH" to "0.0001",
+            "BNB" to "0.001",
+            "SOL" to "0.001",
+            "ADA" to "0.1",
+            "DOT" to "0.01"
+        )
+    }
 }
 
 /**

accbot-android/app/src/main/java/com/accbot/dca/domain/usecase/ValidateAndSaveCredentialsUseCase.kt

@@ -5,6 +5,7 @@ import com.accbot.dca.data.local.UserPreferences
 import com.accbot.dca.domain.model.Exchange
 import com.accbot.dca.domain.model.ExchangeCredentials
 import com.accbot.dca.exchange.ExchangeApiFactory
+import java.net.UnknownHostException
 import javax.inject.Inject
 
 /**
@@ -13,6 +14,7 @@ import javax.inject.Inject
 sealed class CredentialValidationResult {
     data object Success : CredentialValidationResult()
     data class Error(val message: String) : CredentialValidationResult()
+    data object NetworkError : CredentialValidationResult()
 }
 
 /**
@@ -82,6 +84,10 @@ class ValidateAndSaveCredentialsUseCase @Inject constructor(
                 } else ""
                 CredentialValidationResult.Error("Invalid API credentials.$hint")
             }
+        } catch (e: UnknownHostException) {
+            CredentialValidationResult.NetworkError
+        } catch (e: java.io.IOException) {
+            CredentialValidationResult.NetworkError
         } catch (e: Exception) {
             val isSandbox = userPreferences.isSandboxMode()
             val hint = if (isSandbox) {

accbot-android/app/src/main/java/com/accbot/dca/presentation/credentials/CredentialFormDelegate.kt

@@ -1,6 +1,10 @@
 package com.accbot.dca.presentation.credentials
 
+import androidx.annotation.StringRes
+import androidx.compose.runtime.Composable
 import androidx.compose.runtime.Immutable
+import androidx.compose.ui.res.stringResource
+import com.accbot.dca.R
 import com.accbot.dca.data.local.CredentialsStore
 import com.accbot.dca.data.local.UserPreferences
 import com.accbot.dca.domain.model.Exchange
@@ -29,10 +33,21 @@ data class CredentialFormState(
     val isValidatingCredentials: Boolean = false,
     val credentialsValid: Boolean = false,
     val credentialsError: String? = null,
+    @StringRes val credentialsErrorRes: Int = 0,
     val isSandboxMode: Boolean = false,
     val availableExchanges: List<Exchange> = emptyList(),
     val showExperimental: Boolean = false
-)
+) {
+    val hasCredentialsError: Boolean
+        get() = credentialsError != null || credentialsErrorRes != 0
+}
+
+/** Resolve the credentials error to a localized string. */
+val CredentialFormState.resolvedCredentialsError: String?
+    @Composable get() = when {
+        credentialsErrorRes != 0 -> stringResource(credentialsErrorRes)
+        else -> credentialsError
+    }
 
 /**
  * Shared delegate for credential form state and logic.
@@ -76,7 +91,7 @@ class CredentialFormDelegate(
                 apiSecret = credentials?.apiSecret ?: "",
                 passphrase = credentials?.passphrase ?: "",
                 clientId = credentials?.clientId ?: "",
-                credentialsError = null
+                credentialsError = null, credentialsErrorRes = 0
             )
         }
     }
@@ -95,25 +110,25 @@ class CredentialFormDelegate(
                 apiKey = "",
                 apiSecret = "",
                 passphrase = "",
-                credentialsError = null
+                credentialsError = null, credentialsErrorRes = 0
             )
         }
     }
 
     fun setClientId(value: String) {
-        _state.update { it.copy(clientId = value, credentialsError = null) }
+        _state.update { it.copy(clientId = value, credentialsError = null, credentialsErrorRes = 0) }
     }
 
     fun setApiKey(value: String) {
-        _state.update { it.copy(apiKey = value, credentialsError = null) }
+        _state.update { it.copy(apiKey = value, credentialsError = null, credentialsErrorRes = 0) }
     }
 
     fun setApiSecret(value: String) {
-        _state.update { it.copy(apiSecret = value, credentialsError = null) }
+        _state.update { it.copy(apiSecret = value, credentialsError = null, credentialsErrorRes = 0) }
     }
 
     fun setPassphrase(value: String) {
-        _state.update { it.copy(passphrase = value, credentialsError = null) }
+        _state.update { it.copy(passphrase = value, credentialsError = null, credentialsErrorRes = 0) }
     }
 
     fun validateAndSaveCredentials(onSuccess: () -> Unit) {
@@ -123,7 +138,7 @@ class CredentialFormDelegate(
         val exchange = state.selectedExchange ?: return
 
         coroutineScope.launch {
-            _state.update { it.copy(isValidatingCredentials = true, credentialsError = null) }
+            _state.update { it.copy(isValidatingCredentials = true, credentialsError = null, credentialsErrorRes = 0) }
 
             val result = validateAndSaveCredentialsUseCase.execute(
                 exchange = exchange,
@@ -152,10 +167,27 @@ class CredentialFormDelegate(
                         )
                     }
                 }
+                is CredentialValidationResult.NetworkError -> {
+                    _state.update {
+                        it.copy(
+                            isValidatingCredentials = false,
+                            credentialsErrorRes = R.string.error_no_internet
+                        )
+                    }
+                }
             }
         }
     }
 
+    fun notifyNetworkError() {
+        _state.update {
+            it.copy(
+                isValidatingCredentials = false,
+                credentialsErrorRes = R.string.error_no_internet
+            )
+        }
+    }
+
     fun setExperimentalExchangesEnabled(enabled: Boolean) {
         userPreferences.setExperimentalExchangesEnabled(enabled)
         val isSandbox = _state.value.isSandboxMode

accbot-android/app/src/main/java/com/accbot/dca/presentation/plan/PlanFormContent.kt

@@ -3,6 +3,8 @@ package com.accbot.dca.presentation.plan
 import androidx.compose.foundation.clickable
 import androidx.compose.foundation.layout.*
 import androidx.compose.foundation.text.KeyboardOptions
+import androidx.compose.material.icons.Icons
+import androidx.compose.material.icons.filled.Info
 import androidx.compose.material3.*
 import androidx.compose.runtime.Composable
 import androidx.compose.ui.Alignment
@@ -18,6 +20,7 @@ import androidx.compose.ui.unit.dp
 import com.accbot.dca.R
 import com.accbot.dca.domain.model.DcaFrequency
 import com.accbot.dca.domain.model.DcaStrategy
+import com.accbot.dca.domain.model.Exchange
 import com.accbot.dca.presentation.components.AmountInputWithPresets
 import com.accbot.dca.presentation.components.ChipGroup
 import com.accbot.dca.presentation.components.FrequencyDropdown
@@ -52,6 +55,7 @@ fun PlanFormContent(
     onWithdrawalAddressChanged: (String) -> Unit,
     onTargetAmountChanged: (String) -> Unit,
     modifier: Modifier = Modifier,
+    exchange: Exchange? = null,
     showCryptoFiatSelection: Boolean = true,
     errorMessage: String? = null
 ) {
@@ -93,6 +97,28 @@ fun PlanFormContent(
                 minOrderSize = state.minOrderSize,
                 amountBelowMinimum = state.amountBelowMinimum
             )
+            if (exchange == Exchange.BINANCE) {
+                val stepSize = Exchange.binanceLotStepSize[state.selectedCrypto]
+                if (stepSize != null) {
+                    Spacer(modifier = Modifier.height(8.dp))
+                    Row(
+                        verticalAlignment = Alignment.Top,
+                        horizontalArrangement = Arrangement.spacedBy(6.dp)
+                    ) {
+                        Icon(
+                            imageVector = Icons.Default.Info,
+                            contentDescription = null,
+                            tint = MaterialTheme.colorScheme.onSurfaceVariant,
+                            modifier = Modifier.size(16.dp)
+                        )
+                        Text(
+                            text = stringResource(R.string.binance_lot_size_note, state.selectedCrypto, stepSize),
+                            style = MaterialTheme.typography.bodySmall,
+                            color = MaterialTheme.colorScheme.onSurfaceVariant
+                        )
+                    }
+                }
+            }
         }
 
         // Frequency selection

accbot-android/app/src/main/java/com/accbot/dca/presentation/screens/AddPlanScreen.kt

@@ -213,6 +213,7 @@ fun AddPlanScreen(
                     onWithdrawalEnabledChanged = viewModel.planForm::setWithdrawalEnabled,
                     onWithdrawalAddressChanged = viewModel.planForm::setWithdrawalAddress,
                     onTargetAmountChanged = viewModel.planForm::setTargetAmount,
+                    exchange = cred.selectedExchange,
                     errorMessage = uiState.errorMessage
                 )
 

accbot-android/app/src/main/java/com/accbot/dca/presentation/screens/AddPlanViewModel.kt

@@ -111,6 +111,11 @@ class AddPlanViewModel @Inject constructor(
                             }
                             return@launch
                         }
+                        is CredentialValidationResult.NetworkError -> {
+                            credentialForm.notifyNetworkError()
+                            _localState.update { it.copy(isLoading = false) }
+                            return@launch
+                        }
                         is CredentialValidationResult.Success -> {
                             // Credentials validated and saved, continue with plan creation
                         }

accbot-android/app/src/main/java/com/accbot/dca/presentation/screens/exchanges/AddExchangeScreen.kt

@@ -40,6 +40,7 @@ import com.accbot.dca.domain.usecase.ApiImportResultState
 import com.accbot.dca.presentation.components.AccBotTopAppBar
 import com.accbot.dca.presentation.components.ApiImportResultDialog
 import com.accbot.dca.presentation.components.CredentialsInputCard
+import com.accbot.dca.presentation.credentials.resolvedCredentialsError
 import com.accbot.dca.presentation.components.ExchangeSelectionTile
 import com.accbot.dca.presentation.components.ExperimentalExchangeDisclaimer
 import com.accbot.dca.presentation.components.RequestExchangeTile
@@ -135,7 +136,7 @@ fun AddExchangeScreen(
                 apiSecret = uiState.credentialForm.apiSecret,
                 passphrase = uiState.credentialForm.passphrase,
                 isValidating = uiState.credentialForm.isValidatingCredentials,
-                error = uiState.credentialForm.credentialsError,
+                error = uiState.credentialForm.resolvedCredentialsError,
                 onClientIdChange = viewModel.credentialForm::setClientId,
                 onApiKeyChange = viewModel.credentialForm::setApiKey,
                 onApiSecretChange = viewModel.credentialForm::setApiSecret,

accbot-android/app/src/main/java/com/accbot/dca/presentation/screens/exchanges/ExchangeDetailScreen.kt

@@ -29,6 +29,7 @@ import com.accbot.dca.domain.model.supportsApiImport
 import com.accbot.dca.presentation.components.AccBotTopAppBar
 import com.accbot.dca.presentation.components.ApiImportResultDialog
 import com.accbot.dca.presentation.components.CredentialsInputCard
+import com.accbot.dca.presentation.credentials.resolvedCredentialsError
 import com.accbot.dca.presentation.components.ExchangeAvatar
 import com.accbot.dca.presentation.components.ImportConfigDialog
 import com.accbot.dca.presentation.ui.theme.Error
@@ -251,7 +252,7 @@ fun ExchangeDetailScreen(
                                 onApiKeyChange = viewModel.credentialForm::setApiKey,
                                 onApiSecretChange = viewModel.credentialForm::setApiSecret,
                                 onPassphraseChange = viewModel.credentialForm::setPassphrase,
-                                errorMessage = uiState.credentialForm.credentialsError,
+                                errorMessage = uiState.credentialForm.resolvedCredentialsError,
                                 isValidating = uiState.credentialForm.isValidatingCredentials
                             )
 

accbot-android/app/src/main/java/com/accbot/dca/presentation/screens/onboarding/ExchangeSetupScreen.kt

@@ -26,6 +26,7 @@ import com.accbot.dca.domain.model.Exchange
 import com.accbot.dca.domain.model.isStable
 import com.accbot.dca.presentation.components.AccBotTopAppBar
 import com.accbot.dca.presentation.components.CredentialsInputCard
+import com.accbot.dca.presentation.credentials.resolvedCredentialsError
 import com.accbot.dca.presentation.components.ExchangeSelectionGrid
 import com.accbot.dca.presentation.components.ExchangeInstructionsCard
 import com.accbot.dca.presentation.components.ExperimentalExchangeDisclaimer
@@ -191,7 +192,7 @@ fun ExchangeSetupScreen(
                     onApiKeyChange = viewModel.credentialForm::setApiKey,
                     onApiSecretChange = viewModel.credentialForm::setApiSecret,
                     onPassphraseChange = viewModel.credentialForm::setPassphrase,
-                    errorMessage = cred.credentialsError,
+                    errorMessage = cred.resolvedCredentialsError,
                     isValidating = cred.isValidatingCredentials
                 )
             }

accbot-android/app/src/main/java/com/accbot/dca/presentation/screens/onboarding/FirstPlanScreen.kt

@@ -102,6 +102,7 @@ fun FirstPlanScreen(
                     onWithdrawalEnabledChanged = viewModel.planForm::setWithdrawalEnabled,
                     onWithdrawalAddressChanged = viewModel.planForm::setWithdrawalAddress,
                     onTargetAmountChanged = viewModel.planForm::setTargetAmount,
+                    exchange = uiState.credentialForm.selectedExchange,
                     errorMessage = uiState.error
                 )
 

accbot-android/app/src/main/java/com/accbot/dca/presentation/screens/plans/EditPlanScreen.kt

@@ -127,6 +127,7 @@ fun EditPlanScreen(
                             onWithdrawalEnabledChanged = viewModel.planForm::setWithdrawalEnabled,
                             onWithdrawalAddressChanged = viewModel.planForm::setWithdrawalAddress,
                             onTargetAmountChanged = viewModel.planForm::setTargetAmount,
+                            exchange = uiState.exchange,
                             errorMessage = if (uiState.isSaving) uiState.error else null
                         )
                     }

accbot-android/app/src/main/java/com/accbot/dca/presentation/screens/plans/EditPlanViewModel.kt

@@ -6,6 +6,7 @@ import com.accbot.dca.data.local.DcaPlanDao
 import com.accbot.dca.data.local.DcaPlanEntity
 import com.accbot.dca.domain.model.DcaFrequency
 import com.accbot.dca.domain.model.DcaStrategy
+import com.accbot.dca.domain.model.Exchange
 import com.accbot.dca.domain.usecase.CalculateMonthlyCostUseCase
 import com.accbot.dca.domain.util.CronUtils
 import com.accbot.dca.data.local.UserPreferences
@@ -26,6 +27,7 @@ data class EditPlanUiState(
     val planId: Long = 0,
     val crypto: String = "",
     val fiat: String = "",
+    val exchange: Exchange? = null,
     val exchangeName: String = "",
 
     // Plan form (from delegate)
@@ -79,6 +81,7 @@ class EditPlanViewModel @Inject constructor(
                         planId = plan.id,
                         crypto = plan.crypto,
                         fiat = plan.fiat,
+                        exchange = plan.exchange,
                         exchangeName = plan.exchange.displayName,
                         isLoading = false
                     )