Retire DOT-HEZ bridge from the Bridge screen

The DOT<->HEZ bridge backend (the legacy single-key bot) is being
permanently decommissioned - it had zero multisig protection and no
liquidity gate at all on that leg (unconditionally "active" regardless
of pool state, the single least-safe path in the whole bridge). Once
USDT bridging is solid, HEZ is reachable indirectly (bridge USDT, swap
for HEZ within Pezkuwi's own ecosystem) without a dedicated native
bridge that would need its own from-scratch security work (native
currency has no Assets.approve_transfer-style delegation to reuse).

- BridgePair/BridgeDirection collapsed to USDT-only (USDT_TO_WUSDT/
  WUSDT_TO_USDT) - kept the pair/pairOptions/picker structure itself
  since it costs nothing and is the natural seam for a future pair,
  rather than hardcoding a single value inline.
- Removed the now-dead DOT/HEZ exchange-rate fetching (CoinGecko
  polling, fallback rate) and liquidity-gate logic entirely, not just
  the unreachable enum branches.
- Removed the separate "Bridge DOT ↔ HEZ" entry from the asset
  selector bottom sheet (BuySellSelectorMixin) - both it and "Bridge
  USDT" opened the exact same screen with no preset, so keeping a
  DOT-HEZ-labeled entry pointing at a USDT-only screen would have been
  actively misleading, not just redundant.
- bridge_title was the generic toolbar/picker-sheet title but hardcoded
  "DOT ↔ HEZ Bridge" regardless of pair - fixed to "USDT Bridge".
- Removed now-unreferenced strings (wallet_asset_bridge,
  bridge_pair_dot_hez, bridge_rate_format(_reverse),
  bridge_hez_to_dot_note/warning/blocked) from the base strings.xml.

Confirmed via research: feature-bridge-api/feature-bridge-impl modules
exist but are unrelated orphaned scaffolding, not depended on by :app,
zero code overlap with this screen - correctly out of scope here.

common/src/main/res/values/strings.xml

@@ -350,27 +350,20 @@
 
     <string name="wallet_asset_sell_tokens">Sell tokens</string>
     <string name="wallet_asset_buy_tokens">Buy tokens</string>
-    <string name="wallet_asset_bridge">Bridge DOT ↔ HEZ</string>
     <string name="wallet_asset_bridge_usdt">Bridge USDT(DOT) ↔ USDT(HEZ)</string>
 
     <!-- Bridge Screen -->
-    <string name="bridge_title">DOT ↔ HEZ Bridge</string>
+    <string name="bridge_title">USDT Bridge</string>
-    <string name="bridge_pair_dot_hez">HEZ ⇄ DOT</string>
     <string name="bridge_pair_usdt">USDT ⇄ USDT.p</string>
     <string name="bridge_you_send">You send</string>
     <string name="bridge_you_receive">You receive (estimated)</string>
     <string name="bridge_exchange_rate">Exchange rate</string>
     <string name="bridge_fee">Bridge fee</string>
     <string name="bridge_minimum">Minimum</string>
-    <string name="bridge_rate_format">1 DOT = %s HEZ</string>
-    <string name="bridge_rate_format_reverse">1 HEZ = %s DOT</string>
     <string name="bridge_swap_button">Swap</string>
-    <string name="bridge_hez_to_dot_note">HEZ→DOT swaps are processed when sufficient DOT liquidity is available.</string>
     <string name="bridge_insufficient_balance">Insufficient balance</string>
     <string name="bridge_below_minimum">Amount below minimum</string>
     <string name="bridge_enter_amount">Enter amount</string>
-    <string name="bridge_hez_to_dot_warning">HEZ→DOT swaps may have limited availability based on current liquidity.</string>
-    <string name="bridge_hez_to_dot_blocked">HEZ→DOT swaps are temporarily unavailable. Please try again when DOT liquidity is sufficient.</string>
     <string name="bridge_wusdt_to_usdt_blocked">USDT(Pez)→USDT(Pol) swaps are temporarily unavailable. Waiting for 1:1 liquidity to be established.</string>
 
     <string name="bridge_sign_status_ok">Bridge allowance OK (%s)</string>

feature-assets/src/main/java/io/novafoundation/nova/feature_assets/presentation/balance/common/buySell/BuySellSelectorMixin.kt

@@ -75,7 +75,6 @@ class RealBuySellSelectorMixin(
     private suspend fun openAllAssetsSelector() = BuySellSelectorMixin.SelectorPayload(
         buyItem(enabled = true) { router.openBuyFlow() },
         sellItem(enabled = buySellRestrictionCheckMixin.isAllowed()) { router.openSellFlow() },
-        bridgeItem(enabled = true) { router.openBridgeFlow() },
         bridgeUsdtItem(enabled = true) { router.openBridgeFlow() }
     )
 
@@ -116,16 +115,6 @@ class RealBuySellSelectorMixin(
         )
     }
 
-    private fun bridgeItem(enabled: Boolean, action: () -> Unit): ListSelectorMixin.Item {
-        return ListSelectorMixin.Item(
-            R.drawable.ic_bridge,
-            if (enabled) R.color.icon_primary else R.color.icon_inactive,
-            R.string.wallet_asset_bridge,
-            if (enabled) R.color.text_primary else R.color.button_text_inactive,
-            action
-        )
-    }
-
     private fun bridgeUsdtItem(enabled: Boolean, action: () -> Unit): ListSelectorMixin.Item {
         return ListSelectorMixin.Item(
             R.drawable.ic_bridge,

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

@@ -36,8 +36,8 @@ class BridgeFragment : BaseFragment<BridgeViewModel, FragmentBridgeBinding>() {
         // One-tap direction flip - replaces the old segmented direction buttons
         binder.bridgeFlipButton.setOnClickListener {
             when (viewModel.direction.value) {
-                BridgeDirection.DOT_TO_HEZ, BridgeDirection.USDT_TO_WUSDT -> viewModel.setDirectionRight()
+                BridgeDirection.USDT_TO_WUSDT -> viewModel.setDirectionRight()
-                BridgeDirection.HEZ_TO_DOT, BridgeDirection.WUSDT_TO_USDT -> viewModel.setDirectionLeft()
+                BridgeDirection.WUSDT_TO_USDT -> viewModel.setDirectionLeft()
                 null -> Unit
             }
         }
@@ -160,13 +160,10 @@ class BridgeFragment : BaseFragment<BridgeViewModel, FragmentBridgeBinding>() {
 }
 
 enum class BridgePair {
-    DOT_HEZ,
     USDT
 }
 
 enum class BridgeDirection {
-    DOT_TO_HEZ,
-    HEZ_TO_DOT,
     USDT_TO_WUSDT,
     WUSDT_TO_USDT
 }

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

@@ -30,6 +30,14 @@ import java.math.BigDecimal
 import java.math.RoundingMode
 import java.net.URL
 
+/**
+ * DOT<->HEZ used to be a second pair here, retired 2026-07 in favor of the multisig-custodied
+ * USDT<->wUSDT pair only - the legacy single-key bot that executed it (and every other swap on
+ * this screen) was replaced by the detect-only Rust listener + pwap-web multisig approval flow
+ * (see /home/myhez/res/validators-tiki.md). Kept the BridgePair/pairOptions/picker structure
+ * (rather than collapsing to a single hardcoded pair) since it costs nothing and is exactly the
+ * seam a future new pair would reuse.
+ */
 class BridgeViewModel(
     private val router: AssetsRouter,
     private val resourceManager: ResourceManager,
@@ -45,26 +53,20 @@ class BridgeViewModel(
         val POLKADOT_ASSET_HUB_ID = ChainGeneses.POLKADOT_ASSET_HUB
         val PEZKUWI_ASSET_HUB_ID = ChainGeneses.PEZKUWI_ASSET_HUB
 
-        const val UTILITY_ASSET_ID = 0
-
         // USDT asset IDs in chain config
         const val POLKADOT_USDT_ASSET_ID = 1 // assetId in chains.json for Polkadot AH
         const val PEZKUWI_USDT_ASSET_ID = 1000 // assetId in chains.json for Pezkuwi AH
 
-        const val FALLBACK_RATE = 3.0
         const val FEE_PERCENT = 0.001
-        const val MIN_DOT = 0.1
-        const val MIN_HEZ = 0.3
         const val MIN_USDT = 1.0
 
-        const val COINGECKO_API = "https://api.coingecko.com/api/v3/simple/price?ids=polkadot,hezkurd&vs_currencies=usd"
         const val BRIDGE_STATUS_API = "http://217.77.6.126:3030/status"
     }
 
-    private val _pair = MutableLiveData(BridgePair.DOT_HEZ)
+    private val _pair = MutableLiveData(BridgePair.USDT)
     val pair: LiveData<BridgePair> = _pair
 
-    private val _direction = MutableLiveData(BridgeDirection.DOT_TO_HEZ)
+    private val _direction = MutableLiveData(BridgeDirection.USDT_TO_WUSDT)
     val direction: LiveData<BridgeDirection> = _direction
 
     private val _outputAmount = MutableLiveData("0.0")
@@ -119,28 +121,23 @@ class BridgeViewModel(
     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()
         fetchBridgeStatus()
         refreshSignerState()
         updateCards()
         loadPairOptions()
+        updateUI()
     }
 
     fun setPair(newPair: BridgePair) {
         if (_pair.value != newPair) {
             _pair.value = newPair
             // Reset direction to left (forward) when switching pair
-            _direction.value = when (newPair) {
+            _direction.value = BridgeDirection.USDT_TO_WUSDT
-                BridgePair.DOT_HEZ -> BridgeDirection.DOT_TO_HEZ
-                BridgePair.USDT -> BridgeDirection.USDT_TO_WUSDT
-            }
             updateUI()
             calculateOutput()
             updateWarningState()
@@ -149,11 +146,7 @@ class BridgeViewModel(
     }
 
     fun setDirectionLeft() {
-        val newDir = when (_pair.value) {
+        val newDir = BridgeDirection.USDT_TO_WUSDT
-            BridgePair.DOT_HEZ -> BridgeDirection.DOT_TO_HEZ
-            BridgePair.USDT -> BridgeDirection.USDT_TO_WUSDT
-            null -> BridgeDirection.DOT_TO_HEZ
-        }
         if (_direction.value != newDir) {
             _direction.value = newDir
             updateUI()
@@ -164,11 +157,7 @@ class BridgeViewModel(
     }
 
     fun setDirectionRight() {
-        val newDir = when (_pair.value) {
+        val newDir = BridgeDirection.WUSDT_TO_USDT
-            BridgePair.DOT_HEZ -> BridgeDirection.HEZ_TO_DOT
-            BridgePair.USDT -> BridgeDirection.WUSDT_TO_USDT
-            null -> BridgeDirection.HEZ_TO_DOT
-        }
         if (_direction.value != newDir) {
             _direction.value = newDir
             updateUI()
@@ -195,15 +184,11 @@ class BridgeViewModel(
 
         launch {
             val chainId = when (dir) {
-                BridgeDirection.DOT_TO_HEZ -> POLKADOT_ASSET_HUB_ID
-                BridgeDirection.HEZ_TO_DOT -> PEZKUWI_ASSET_HUB_ID
                 BridgeDirection.USDT_TO_WUSDT -> POLKADOT_ASSET_HUB_ID
                 BridgeDirection.WUSDT_TO_USDT -> PEZKUWI_ASSET_HUB_ID
             }
 
             val assetId = when (dir) {
-                BridgeDirection.DOT_TO_HEZ -> UTILITY_ASSET_ID
-                BridgeDirection.HEZ_TO_DOT -> UTILITY_ASSET_ID
                 BridgeDirection.USDT_TO_WUSDT -> POLKADOT_USDT_ASSET_ID
                 BridgeDirection.WUSDT_TO_USDT -> PEZKUWI_USDT_ASSET_ID
             }
@@ -223,63 +208,27 @@ class BridgeViewModel(
         router.back()
     }
 
-    private fun fetchExchangeRate() {
-        launch {
-            try {
-                val (rate, _) = withContext(Dispatchers.IO) {
-                    fetchRateFromCoinGecko()
-                }
-                dotToHezRate = rate
-                updateUI()
-                calculateOutput()
-            } catch (e: Exception) {
-                dotToHezRate = FALLBACK_RATE
-                updateUI()
-            }
-        }
-    }
-
-    private fun fetchRateFromCoinGecko(): Pair<Double, String> {
-        return try {
-            val response = URL(COINGECKO_API).readText()
-            val json = JSONObject(response)
-            val dotPrice = json.optJSONObject("polkadot")?.optDouble("usd", 0.0) ?: 0.0
-            val hezPrice = json.optJSONObject("hezkurd")?.optDouble("usd", 0.0) ?: 0.0
-            when {
-                dotPrice > 0 && hezPrice > 0 -> Pair(dotPrice / hezPrice, "coingecko")
-                else -> Pair(FALLBACK_RATE, "fallback")
-            }
-        } catch (e: Exception) {
-            Pair(FALLBACK_RATE, "fallback")
-        }
-    }
-
     private fun fetchBridgeStatus() {
         launch {
             try {
-                val (hezToDot, wusdtToUsdt) = withContext(Dispatchers.IO) {
+                isWusdtToUsdtActive = withContext(Dispatchers.IO) {
                     fetchStatusFromApi()
                 }
-                isHezToDotActive = hezToDot
-                isWusdtToUsdtActive = wusdtToUsdt
                 updateWarningState()
             } catch (e: Exception) {
-                isHezToDotActive = false
                 isWusdtToUsdtActive = false
                 updateWarningState()
             }
         }
     }
 
-    private fun fetchStatusFromApi(): Pair<Boolean, Boolean> {
+    private fun fetchStatusFromApi(): Boolean {
         return try {
             val response = URL(BRIDGE_STATUS_API).readText()
             val json = JSONObject(response)
-            val hezToDot = json.optBoolean("hezToDotActive", false)
+            json.optBoolean("wusdtToUsdtActive", false)
-            val wusdtToUsdt = json.optBoolean("wusdtToUsdtActive", false)
-            Pair(hezToDot, wusdtToUsdt)
         } catch (e: Exception) {
-            Pair(false, false)
+            false
         }
     }
 
@@ -287,16 +236,6 @@ class BridgeViewModel(
         val dir = _direction.value ?: return
 
         when (dir) {
-            BridgeDirection.HEZ_TO_DOT -> {
-                _showWarning.postValue(true)
-                if (!isHezToDotActive) {
-                    _warningBlocked.postValue(true)
-                    _warningText.postValue(resourceManager.getString(R.string.bridge_hez_to_dot_blocked))
-                } else {
-                    _warningBlocked.postValue(false)
-                    _warningText.postValue(resourceManager.getString(R.string.bridge_hez_to_dot_warning))
-                }
-            }
             BridgeDirection.WUSDT_TO_USDT -> {
                 _showWarning.postValue(true)
                 if (!isWusdtToUsdtActive) {
@@ -316,16 +255,7 @@ class BridgeViewModel(
     }
 
     private fun calculateOutput() {
-        val dir = _direction.value ?: return
+        val netOutput = currentAmount * (1 - FEE_PERCENT) // 1:1, fee-adjusted
-
-        val grossOutput = when (dir) {
-            BridgeDirection.DOT_TO_HEZ -> currentAmount * dotToHezRate
-            BridgeDirection.HEZ_TO_DOT -> currentAmount / dotToHezRate
-            BridgeDirection.USDT_TO_WUSDT -> currentAmount // 1:1
-            BridgeDirection.WUSDT_TO_USDT -> currentAmount // 1:1
-        }
-
-        val netOutput = grossOutput * (1 - FEE_PERCENT)
 
         _outputAmount.value = if (netOutput > 0) {
             BigDecimal(netOutput).setScale(6, RoundingMode.DOWN).stripTrailingZeros().toPlainString()
@@ -335,41 +265,19 @@ class BridgeViewModel(
     }
 
     private fun updateUI() {
-        val dir = _direction.value ?: return
+        _exchangeRateText.value = "1:1 (fee 0.1%)"
-
+        _minimumText.value = "$MIN_USDT USDT"
-        when (dir) {
-            BridgeDirection.DOT_TO_HEZ -> {
-                val rateFormatted = BigDecimal(dotToHezRate).setScale(4, RoundingMode.HALF_UP).stripTrailingZeros().toPlainString()
-                _exchangeRateText.value = "1 DOT = $rateFormatted HEZ"
-                _minimumText.value = "$MIN_DOT DOT"
-            }
-            BridgeDirection.HEZ_TO_DOT -> {
-                val reverseRate = BigDecimal(1.0 / dotToHezRate).setScale(6, RoundingMode.HALF_UP).stripTrailingZeros().toPlainString()
-                _exchangeRateText.value = "1 HEZ = $reverseRate DOT"
-                _minimumText.value = "$MIN_HEZ HEZ"
-            }
-            BridgeDirection.USDT_TO_WUSDT, BridgeDirection.WUSDT_TO_USDT -> {
-                _exchangeRateText.value = "1:1 (fee 0.1%)"
-                _minimumText.value = "$MIN_USDT USDT"
-            }
-        }
 
         updateButtonState()
     }
 
     private fun updateButtonState() {
         val dir = _direction.value ?: return
-        val minimum = when (dir) {
-            BridgeDirection.DOT_TO_HEZ -> MIN_DOT
-            BridgeDirection.HEZ_TO_DOT -> MIN_HEZ
-            BridgeDirection.USDT_TO_WUSDT, BridgeDirection.WUSDT_TO_USDT -> MIN_USDT
-        }
 
         _buttonState.value = when {
             currentAmount <= 0 -> ButtonState.DISABLED
-            currentAmount < minimum -> ButtonState.DISABLED
+            currentAmount < MIN_USDT -> 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
         }
@@ -443,20 +351,18 @@ class BridgeViewModel(
         // Same chainId/assetId mapping already used by swapClicked() to resolve the origin side -
         // mirrored here (plus its destination counterpart) purely to display logos/names, no new business rule.
         val originChainId = when (dir) {
-            BridgeDirection.DOT_TO_HEZ, BridgeDirection.USDT_TO_WUSDT -> POLKADOT_ASSET_HUB_ID
+            BridgeDirection.USDT_TO_WUSDT -> POLKADOT_ASSET_HUB_ID
-            BridgeDirection.HEZ_TO_DOT, BridgeDirection.WUSDT_TO_USDT -> PEZKUWI_ASSET_HUB_ID
+            BridgeDirection.WUSDT_TO_USDT -> PEZKUWI_ASSET_HUB_ID
         }
         val destChainId = when (dir) {
-            BridgeDirection.DOT_TO_HEZ, BridgeDirection.USDT_TO_WUSDT -> PEZKUWI_ASSET_HUB_ID
+            BridgeDirection.USDT_TO_WUSDT -> PEZKUWI_ASSET_HUB_ID
-            BridgeDirection.HEZ_TO_DOT, BridgeDirection.WUSDT_TO_USDT -> POLKADOT_ASSET_HUB_ID
+            BridgeDirection.WUSDT_TO_USDT -> POLKADOT_ASSET_HUB_ID
         }
         val originAssetId = when (dir) {
-            BridgeDirection.DOT_TO_HEZ, BridgeDirection.HEZ_TO_DOT -> UTILITY_ASSET_ID
             BridgeDirection.USDT_TO_WUSDT -> POLKADOT_USDT_ASSET_ID
             BridgeDirection.WUSDT_TO_USDT -> PEZKUWI_USDT_ASSET_ID
         }
         val destAssetId = when (dir) {
-            BridgeDirection.DOT_TO_HEZ, BridgeDirection.HEZ_TO_DOT -> UTILITY_ASSET_ID
             BridgeDirection.USDT_TO_WUSDT -> PEZKUWI_USDT_ASSET_ID
             BridgeDirection.WUSDT_TO_USDT -> POLKADOT_USDT_ASSET_ID
         }
@@ -485,11 +391,9 @@ class BridgeViewModel(
 
     private fun loadPairOptions() {
         launch {
-            val dotHezIcon = cardUiFor(POLKADOT_ASSET_HUB_ID, UTILITY_ASSET_ID).assetIcon
             val usdtIcon = cardUiFor(POLKADOT_ASSET_HUB_ID, POLKADOT_USDT_ASSET_ID).assetIcon
 
             _pairOptions.value = listOf(
-                BridgePairUi(BridgePair.DOT_HEZ, dotHezIcon, resourceManager.getString(R.string.bridge_pair_dot_hez)),
                 BridgePairUi(BridgePair.USDT, usdtIcon, resourceManager.getString(R.string.bridge_pair_usdt))
             )
         }

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

@@ -113,7 +113,7 @@
                             android:layout_height="wrap_content"
                             android:textColor="@color/text_primary"
                             android:textSize="14sp"
-                            tools:text="1 DOT = 3.00 HEZ" />
+                            tools:text="1:1 (fee 0.1%)" />
 
                     </LinearLayout>
 
@@ -162,7 +162,7 @@
                             android:layout_height="wrap_content"
                             android:textColor="@color/text_primary"
                             android:textSize="14sp"
-                            tools:text="0.1 DOT" />
+                            tools:text="1.0 USDT" />
 
                     </LinearLayout>
 
@@ -170,7 +170,7 @@
 
             </com.google.android.material.card.MaterialCardView>
 
-            <!-- Warning for HEZ to DOT / USDT liquidity -->
+            <!-- Warning for USDT liquidity -->
             <io.novafoundation.nova.common.view.AlertView
                 android:id="@+id/bridgeWarningAlert"
                 android:layout_width="match_parent"