feat: block Bridge swap when send amount exceeds available balance

The Bridge screen let a user type any amount and enabled the Swap
button regardless of what they actually held, unlike the Swap screen
which shows a live "Max: X" and disables on overflow. The confirm-step
ValidationSystem would still catch it before signing, but only after
routing through Send - no immediate feedback on the Bridge screen
itself.

Wires WalletInteractor.assetFlow(chainId, assetId) to the currently
selected origin side (re-subscribed on every direction/pair change),
tracking Asset.transferable - the same field the real transfer
validation checks. Reuses the existing MaxAmountView/MaxAvailableView
widget the Swap screen already uses for the "Max: X" display, and adds
a matching error-bordered state to BridgeAssetInputView. The
"Insufficient balance" string (bridge_insufficient_balance) was
already translated into every locale but never wired to any code.

feature-assets/src/main/java/io/novafoundation/nova/feature_assets/presentation/bridge/BridgeFragment.kt

@@ -10,6 +10,7 @@ import io.novafoundation.nova.common.view.setState
 import io.novafoundation.nova.feature_assets.databinding.FragmentBridgeBinding
 import io.novafoundation.nova.feature_assets.di.AssetsFeatureApi
 import io.novafoundation.nova.feature_assets.di.AssetsFeatureComponent
+import io.novafoundation.nova.feature_wallet_api.presentation.mixin.amountChooser.MaxActionAvailability
 
 class BridgeFragment : BaseFragment<BridgeViewModel, FragmentBridgeBinding>() {
 
@@ -49,6 +50,10 @@ class BridgeFragment : BaseFragment<BridgeViewModel, FragmentBridgeBinding>() {
             }
         })
 
+        binder.bridgeFromMaxAmount.setMaxActionAvailability(
+            MaxActionAvailability.Available { viewModel.maxClicked() }
+        )
+
         // Swap button
         binder.bridgeSwapButton.setOnClickListener {
             viewModel.swapClicked()
@@ -105,6 +110,18 @@ class BridgeFragment : BaseFragment<BridgeViewModel, FragmentBridgeBinding>() {
                 binder.bridgeWarningAlert.setMessage(text)
             }
         }
+
+        viewModel.maxAmountDisplay.observe { display ->
+            binder.bridgeFromMaxAmount.setMaxAmountDisplay(display)
+        }
+
+        viewModel.insufficientBalanceError.observe { error ->
+            binder.bridgeFromCard.setError(error)
+        }
+
+        viewModel.fillAmountEvent.observeEvent { amount ->
+            binder.bridgeFromCard.amountInput.setText(amount)
+        }
     }
 }
 

feature-assets/src/main/java/io/novafoundation/nova/feature_assets/presentation/bridge/BridgeViewModel.kt

@@ -5,10 +5,12 @@ import androidx.lifecycle.MutableLiveData
 import io.novafoundation.nova.common.base.BaseViewModel
 import io.novafoundation.nova.common.presentation.AssetIconProvider
 import io.novafoundation.nova.common.resources.ResourceManager
+import io.novafoundation.nova.common.utils.Event
 import io.novafoundation.nova.common.utils.images.Icon
 import io.novafoundation.nova.common.view.ButtonState
 import io.novafoundation.nova.feature_account_api.presenatation.chain.getAssetIconOrFallback
 import io.novafoundation.nova.feature_assets.R
+import io.novafoundation.nova.feature_assets.domain.WalletInteractor
 import io.novafoundation.nova.feature_assets.presentation.AssetsRouter
 import io.novafoundation.nova.feature_assets.presentation.send.amount.SendPayload
 import io.novafoundation.nova.feature_wallet_api.presentation.model.AssetPayload
@@ -18,6 +20,7 @@ import io.novafoundation.nova.runtime.ext.displayNameWithAssetStandard
 import io.novafoundation.nova.runtime.multiNetwork.ChainRegistry
 import io.novasama.substrate_sdk_android.ss58.SS58Encoder.toAccountId
 import kotlinx.coroutines.Dispatchers
+import kotlinx.coroutines.Job
 import kotlinx.coroutines.launch
 import kotlinx.coroutines.withContext
 import org.json.JSONObject
@@ -29,7 +32,8 @@ class BridgeViewModel(
     private val router: AssetsRouter,
     private val resourceManager: ResourceManager,
     private val chainRegistry: ChainRegistry,
-    private val assetIconProvider: AssetIconProvider
+    private val assetIconProvider: AssetIconProvider,
+    private val walletInteractor: WalletInteractor
 ) : BaseViewModel() {
 
     companion object {
@@ -90,10 +94,21 @@ class BridgeViewModel(
     private val _pairOptions = MutableLiveData<List<BridgePairUi>>(emptyList())
     val pairOptions: LiveData<List<BridgePairUi>> = _pairOptions
 
+    private val _maxAmountDisplay = MutableLiveData<String?>(null)
+    val maxAmountDisplay: LiveData<String?> = _maxAmountDisplay
+
+    private val _insufficientBalanceError = MutableLiveData<String?>(null)
+    val insufficientBalanceError: LiveData<String?> = _insufficientBalanceError
+
+    private val _fillAmountEvent = MutableLiveData<Event<String>>()
+    val fillAmountEvent: LiveData<Event<String>> = _fillAmountEvent
+
     private var currentAmount: Double = 0.0
     private var dotToHezRate: Double = FALLBACK_RATE
     private var isHezToDotActive: Boolean = false
     private var isWusdtToUsdtActive: Boolean = false
+    private var availableBalance: BigDecimal = BigDecimal.ZERO
+    private var balanceJob: Job? = null
 
     init {
         fetchExchangeRate()
@@ -150,9 +165,14 @@ class BridgeViewModel(
     fun setAmount(amount: Double) {
         currentAmount = amount
         calculateOutput()
+        updateInsufficientBalanceState()
         updateButtonState()
     }
 
+    fun maxClicked() {
+        _fillAmountEvent.value = Event(availableBalance.stripTrailingZeros().toPlainString())
+    }
+
     fun swapClicked() {
         val dir = _direction.value ?: return
         if (currentAmount <= 0) return
@@ -332,12 +352,21 @@ class BridgeViewModel(
         _buttonState.value = when {
             currentAmount <= 0 -> ButtonState.DISABLED
             currentAmount < minimum -> ButtonState.DISABLED
+            BigDecimal.valueOf(currentAmount) > availableBalance -> ButtonState.DISABLED
             dir == BridgeDirection.HEZ_TO_DOT && !isHezToDotActive -> ButtonState.DISABLED
             dir == BridgeDirection.WUSDT_TO_USDT && !isWusdtToUsdtActive -> ButtonState.DISABLED
             else -> ButtonState.NORMAL
         }
     }
 
+    private fun updateInsufficientBalanceState() {
+        _insufficientBalanceError.value = if (currentAmount > 0 && BigDecimal.valueOf(currentAmount) > availableBalance) {
+            resourceManager.getString(R.string.bridge_insufficient_balance)
+        } else {
+            null
+        }
+    }
+
     fun refreshBridgeStatus() {
         fetchBridgeStatus()
     }
@@ -370,6 +399,22 @@ class BridgeViewModel(
             _fromCard.value = cardUiFor(originChainId, originAssetId)
             _toCard.value = cardUiFor(destChainId, destAssetId)
         }
+
+        observeOriginBalance(originChainId, originAssetId)
+    }
+
+    private fun observeOriginBalance(chainId: String, assetId: Int) {
+        balanceJob?.cancel()
+        balanceJob = launch {
+            walletInteractor.assetFlow(chainId, assetId).collect { asset ->
+                availableBalance = asset.transferable
+                _maxAmountDisplay.postValue(
+                    "${availableBalance.setScale(6, RoundingMode.DOWN).stripTrailingZeros().toPlainString()} ${asset.token.configuration.symbol.value}"
+                )
+                updateInsufficientBalanceState()
+                updateButtonState()
+            }
+        }
     }
 
     private fun loadPairOptions() {

feature-assets/src/main/java/io/novafoundation/nova/feature_assets/presentation/bridge/di/BridgeModule.kt

@@ -10,6 +10,7 @@ import io.novafoundation.nova.common.di.viewmodel.ViewModelKey
 import io.novafoundation.nova.common.di.viewmodel.ViewModelModule
 import io.novafoundation.nova.common.presentation.AssetIconProvider
 import io.novafoundation.nova.common.resources.ResourceManager
+import io.novafoundation.nova.feature_assets.domain.WalletInteractor
 import io.novafoundation.nova.feature_assets.presentation.AssetsRouter
 import io.novafoundation.nova.feature_assets.presentation.bridge.BridgeViewModel
 import io.novafoundation.nova.runtime.multiNetwork.ChainRegistry
@@ -24,9 +25,10 @@ class BridgeModule {
         router: AssetsRouter,
         resourceManager: ResourceManager,
         chainRegistry: ChainRegistry,
-        assetIconProvider: AssetIconProvider
+        assetIconProvider: AssetIconProvider,
+        walletInteractor: WalletInteractor
     ): ViewModel {
-        return BridgeViewModel(router, resourceManager, chainRegistry, assetIconProvider)
+        return BridgeViewModel(router, resourceManager, chainRegistry, assetIconProvider, walletInteractor)
     }
 
     @Provides

feature-assets/src/main/java/io/novafoundation/nova/feature_assets/presentation/bridge/view/BridgeAssetInputView.kt

@@ -11,7 +11,9 @@ import io.novafoundation.nova.common.utils.WithContextExtensions
 import io.novafoundation.nova.common.utils.images.asUrlIcon
 import io.novafoundation.nova.common.utils.images.setIconOrMakeGone
 import io.novafoundation.nova.common.utils.inflater
+import io.novafoundation.nova.common.utils.setVisible
 import io.novafoundation.nova.common.view.shape.getInputBackground
+import io.novafoundation.nova.common.view.shape.getInputBackgroundError
 import io.novafoundation.nova.feature_account_api.presenatation.chain.setTokenIcon
 import io.novafoundation.nova.feature_assets.databinding.ViewBridgeAssetInputBinding
 import io.novafoundation.nova.feature_assets.presentation.bridge.BridgeAssetCardUi
@@ -60,4 +62,15 @@ class BridgeAssetInputView @JvmOverloads constructor(
         binder.bridgeAssetInputSubtitle.text = model.chainName
         binder.bridgeAssetInputSubtitleImage.setIconOrMakeGone(model.chainIconUrl?.asUrlIcon(), imageLoader)
     }
+
+    fun setError(message: String?) {
+        binder.bridgeAssetInputContainer.background = if (message != null) {
+            context.getInputBackgroundError()
+        } else {
+            context.getInputBackground()
+        }
+
+        binder.bridgeAssetInputError.text = message
+        binder.bridgeAssetInputError.setVisible(message != null)
+    }
 }

feature-assets/src/main/res/layout/fragment_bridge.xml

@@ -25,13 +25,27 @@
             android:orientation="vertical"
             android:padding="16dp">
 
-            <TextView
+            <LinearLayout
-                android:id="@+id/bridgeFromLabel"
+                android:layout_width="match_parent"
-                style="@style/TextAppearance.NovaFoundation.Regular.Footnote"
-                android:layout_width="wrap_content"
                 android:layout_height="wrap_content"
-                android:text="@string/bridge_you_send"
+                android:gravity="center_vertical"
-                android:textColor="@color/text_secondary" />
+                android:orientation="horizontal">
+
+                <TextView
+                    android:id="@+id/bridgeFromLabel"
+                    style="@style/TextAppearance.NovaFoundation.Regular.Footnote"
+                    android:layout_width="0dp"
+                    android:layout_height="wrap_content"
+                    android:layout_weight="1"
+                    android:text="@string/bridge_you_send"
+                    android:textColor="@color/text_secondary" />
+
+                <io.novafoundation.nova.feature_wallet_api.presentation.view.amount.MaxAmountView
+                    android:id="@+id/bridgeFromMaxAmount"
+                    android:layout_width="wrap_content"
+                    android:layout_height="wrap_content" />
+
+            </LinearLayout>
 
             <io.novafoundation.nova.feature_assets.presentation.bridge.view.BridgeAssetInputView
                 android:id="@+id/bridgeFromCard"

feature-assets/src/main/res/layout/view_bridge_asset_input.xml

@@ -110,4 +110,15 @@
 
     </androidx.constraintlayout.widget.ConstraintLayout>
 
+    <TextView
+        android:id="@+id/bridgeAssetInputError"
+        style="@style/TextAppearance.NovaFoundation.Regular.Caption1"
+        android:layout_width="wrap_content"
+        android:layout_height="wrap_content"
+        android:layout_marginTop="8dp"
+        android:textColor="@color/text_negative"
+        android:visibility="gone"
+        app:layout_constraintStart_toStartOf="parent"
+        app:layout_constraintTop_toBottomOf="@+id/bridgeAssetInputContainer" />
+
 </merge>