fix: use saved fees after gateway errors

app/build.gradle.kts

@@ -363,7 +363,7 @@ androidComponents {
         buildConfigFields.put("E2E_HOMEGATE_URL", e2eHomegateUrlEnv.stringField())
         buildConfigFields.put("E2E_HOMESERVER_PUBKY", e2eHomeserverPubkyEnv.stringField())
         buildConfigFields.put("E2E_HOMEGATE_OVERRIDE", e2eHomegateOverrideEnv.stringField())
-        for (key in listOf("E2E_VSS_SERVER_URL", "E2E_LNURL_AUTH_SERVER_URL")) {
+        for (key in listOf("E2E_VSS_SERVER_URL", "E2E_LNURL_AUTH_SERVER_URL", "E2E_BLOCKTANK_API_URL")) {
             val value = if (variant.buildType == "debug") localProp(key).orElse("") else provider { "" }
             buildConfigFields.put(key, value.stringField())
         }

app/src/main/java/to/bitkit/data/WalletConnectionRecovery.kt

@@ -62,6 +62,13 @@ class WalletConnectionRecovery @Inject constructor(
         }
     }
 
+    /** A queued UI intent remains bound to its original wallet, including same-seed replacement. */
+    internal fun currentGeneration(): Long? = synchronized(stateLock) { generation.takeUnless { wiping } }
+
+    internal fun isCurrentGeneration(expected: Long?): Boolean = synchronized(stateLock) {
+        expected != null && !wiping && generation == expected
+    }
+
     private fun admittedGeneration(): Long = synchronized(stateLock) {
         checkAdmission()
         generation

app/src/main/java/to/bitkit/env/BlocktankTestEndpoint.kt

@@ -0,0 +1,17 @@
+package to.bitkit.env
+
+import java.net.URI
+
+internal object BlocktankTestEndpoint {
+    fun resolve(enabled: Boolean, value: String?): String? {
+        if (!enabled) return null
+        val endpoint = value.orEmpty().trim().takeIf { it.isNotEmpty() } ?: return null
+        val valid = runCatching {
+            val url = URI(endpoint)
+            url.scheme in listOf("http", "https") && url.host == "localhost" && url.port in 1..65535 &&
+                url.userInfo == null && url.query == null && url.fragment == null && !url.path.isNullOrEmpty()
+        }.getOrDefault(false)
+        require(valid) { "E2E Blocktank endpoint must be a localhost URL with an explicit port and path" }
+        return endpoint
+    }
+}

app/src/main/java/to/bitkit/env/Env.kt

@@ -141,10 +141,13 @@ internal object Env {
             Network.BITCOIN -> "https://api1.blocktank.to"
             else -> "https://api.stag0.blocktank.to"
         }
-    val blocktankApiUrl
-        get() = when (network) {
-            Network.BITCOIN -> "$blocktankBaseUrl/api"
-            else -> "$blocktankBaseUrl/blocktank/api/v2"
+    val blocktankApiUrl: String
+        get() {
+            val fixture = BlocktankTestEndpoint.resolve(isDebug && isE2eTest, BuildConfig.E2E_BLOCKTANK_API_URL)
+            return fixture ?: when (network) {
+                Network.BITCOIN -> "$blocktankBaseUrl/api"
+                else -> "$blocktankBaseUrl/blocktank/api/v2"
+            }
         }
     val blocktankNotificationApiUrl
         get() = when (network) {

app/src/main/java/to/bitkit/services/CoreService.kt

@@ -5,6 +5,7 @@ import com.synonym.bitkitcore.Activity
 import com.synonym.bitkitcore.ActivityFilter
 import com.synonym.bitkitcore.ActivityTags
 import com.synonym.bitkitcore.AddressType
+import com.synonym.bitkitcore.BlocktankException
 import com.synonym.bitkitcore.BtOrderState2
 import com.synonym.bitkitcore.CJitStateEnum
 import com.synonym.bitkitcore.ClosedChannelDetails
@@ -70,6 +71,8 @@ import io.ktor.client.request.get
 import io.ktor.http.HttpStatusCode
 import kotlinx.coroutines.async
 import kotlinx.coroutines.awaitAll
+import kotlinx.coroutines.currentCoroutineContext
+import kotlinx.coroutines.ensureActive
 import kotlinx.coroutines.flow.first
 import org.lightningdevkit.ldknode.ChannelDetails
 import org.lightningdevkit.ldknode.ConfirmationStatus
@@ -2170,18 +2173,40 @@ class BlocktankService(
     }
 
     suspend fun getFees(): Result<FeeRates> {
-        var fees = fees(refresh = true)
+        val fresh = runSuspendCatching { fees(refresh = true) }
+        val error = fresh.exceptionOrNull()
+        if (error != null && !isInfoBadGateway(error)) throw error
+        var fees = fresh.getOrNull()
         if (fees == null) {
+            currentCoroutineContext().ensureActive()
             Logger.warn("Failed to fetch fresh fee rate, using cached rate.")
             fees = fees(refresh = false)
+            currentCoroutineContext().ensureActive()
         }
         if (fees == null) {
-            return Result.failure(AppError("Fees unavailable from bitkit-core"))
+            return Result.failure(error ?: AppError("Fees unavailable from bitkit-core"))
         }
 
         return Result.success(fees)
     }
 
+    private fun isInfoBadGateway(error: Throwable): Boolean {
+        var cause = error
+        repeat(8) {
+            when (val current = cause) {
+                is BlocktankException.DataException -> {
+                    val prefix = "Failed to fetch info from Blocktank: Blocktank error: " +
+                        "Failed to get info: Client error: "
+                    return current.errorDetails.startsWith(prefix + "Request failed with status 502 Bad Gateway:") ||
+                        current.errorDetails.startsWith(prefix + "Request failed (502 Bad Gateway):")
+                }
+                is AppError -> cause = current.cause ?: return false
+                else -> return false
+            }
+        }
+        return false
+    }
+
     suspend fun createCjit(
         channelSizeSat: ULong,
         invoiceSat: ULong,

app/src/main/java/to/bitkit/ui/sheets/SendSheet.kt

@@ -171,7 +171,10 @@ fun SendSheet(
     LaunchedEffect(startDestination) {
         // always reset state on new user-initiated send
         if (startDestination == SendRoute.Recipient) {
-            appViewModel.resetSendState(hardwareWalletId = hardwareWalletId)
+            if (!appViewModel.resetSendState(hardwareWalletId = hardwareWalletId)) {
+                appViewModel.hideSheet()
+                return@LaunchedEffect
+            }
             appViewModel.resetQuickPay()
             routingCacheResetAttempted = false
         }