feat: add trezor onchain event watcher

app/src/main/java/to/bitkit/repositories/TrezorRepo.kt

@@ -9,6 +9,7 @@ import com.synonym.bitkitcore.CoinSelection
 import com.synonym.bitkitcore.ComposeOutput
 import com.synonym.bitkitcore.ComposeParams
 import com.synonym.bitkitcore.ComposeResult
+import com.synonym.bitkitcore.EventListener
 import com.synonym.bitkitcore.SingleAddressInfoResult
 import com.synonym.bitkitcore.TransactionHistoryResult
 import com.synonym.bitkitcore.TrezorAddressResponse
@@ -22,14 +23,19 @@ import com.synonym.bitkitcore.TrezorSignedTx
 import com.synonym.bitkitcore.TrezorTransportType
 import com.synonym.bitkitcore.WalletParams
 import com.synonym.bitkitcore.WalletSelection
+import com.synonym.bitkitcore.WatcherEvent
+import com.synonym.bitkitcore.WatcherParams
 import dagger.hilt.android.qualifiers.ApplicationContext
 import kotlinx.collections.immutable.ImmutableList
 import kotlinx.collections.immutable.persistentListOf
 import kotlinx.collections.immutable.toImmutableList
 import kotlinx.coroutines.CoroutineDispatcher
 import kotlinx.coroutines.CoroutineScope
 import kotlinx.coroutines.delay
+import kotlinx.coroutines.flow.MutableSharedFlow
 import kotlinx.coroutines.flow.MutableStateFlow
+import kotlinx.coroutines.flow.SharedFlow
+import kotlinx.coroutines.flow.asSharedFlow
 import kotlinx.coroutines.flow.asStateFlow
 import kotlinx.coroutines.flow.launchIn
 import kotlinx.coroutines.flow.onEach
@@ -73,6 +79,16 @@ class TrezorRepo @Inject constructor(
     private val _state = MutableStateFlow(TrezorState())
     val state = _state.asStateFlow()
 
+    private val _watcherEvents = MutableSharedFlow<Pair<String, WatcherEvent>>(extraBufferCapacity = 64)
+    val watcherEvents: SharedFlow<Pair<String, WatcherEvent>> = _watcherEvents.asSharedFlow()
+
+    private val eventBridge: EventListener = object : EventListener {
+        override fun onEvent(watcherId: String, event: WatcherEvent) {
+            TrezorDebugLog.log("WATCHER", "[$watcherId] ${event::class.simpleName}")
+            _watcherEvents.tryEmit(watcherId to event)
+        }
+    }
+
     /**
      * Flow indicating when a pairing code needs to be entered.
      * UI should show a dialog when this emits true.
@@ -551,6 +567,47 @@ class TrezorRepo @Inject constructor(
         }
     }
 
+    suspend fun startWatcher(
+        watcherId: String,
+        extendedKey: String,
+        network: BitkitCoreNetwork,
+        gapLimit: UInt = 20u,
+    ): Result<Unit> = withContext(ioDispatcher) {
+        runCatching {
+            val params = WatcherParams(
+                watcherId = watcherId,
+                extendedKey = extendedKey,
+                electrumUrl = electrumUrlForNetwork(network),
+                network = network,
+                accountType = null,
+                gapLimit = gapLimit,
+            )
+            trezorService.startWatcher(params, eventBridge)
+            TrezorDebugLog.log("WATCHER", "Started watcher '$watcherId' for '${extendedKey.take(12)}...'")
+            Logger.info("Started watcher '$watcherId'", context = TAG)
+        }.onFailure {
+            Logger.error("Start watcher failed", it, context = TAG)
+            _state.update { s -> s.copy(error = it.message) }
+        }
+    }
+
+    fun stopWatcher(watcherId: String): Result<Unit> = runCatching {
+        trezorService.stopWatcher(watcherId)
+        TrezorDebugLog.log("WATCHER", "Stopped watcher '$watcherId'")
+        Logger.info("Stopped watcher '$watcherId'", context = TAG)
+    }.onFailure {
+        Logger.error("Stop watcher failed", it, context = TAG)
+        _state.update { s -> s.copy(error = it.message) }
+    }
+
+    fun stopAllWatchers(): Result<Unit> = runCatching {
+        trezorService.stopAllWatchers()
+        TrezorDebugLog.log("WATCHER", "Stopped all watchers")
+    }.onFailure {
+        Logger.error("Stop all watchers failed", it, context = TAG)
+        _state.update { s -> s.copy(error = it.message) }
+    }
+
     fun clearError() {
         _state.update { it.copy(error = null) }
     }

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

@@ -4,6 +4,7 @@ import com.synonym.bitkitcore.AccountInfoResult
 import com.synonym.bitkitcore.AccountType
 import com.synonym.bitkitcore.ComposeParams
 import com.synonym.bitkitcore.ComposeResult
+import com.synonym.bitkitcore.EventListener
 import com.synonym.bitkitcore.SingleAddressInfoResult
 import com.synonym.bitkitcore.TransactionHistoryResult
 import com.synonym.bitkitcore.TrezorAddressResponse
@@ -19,11 +20,15 @@ import com.synonym.bitkitcore.TrezorSignedMessageResponse
 import com.synonym.bitkitcore.TrezorSignedTx
 import com.synonym.bitkitcore.TrezorVerifyMessageParams
 import com.synonym.bitkitcore.WalletSelection
+import com.synonym.bitkitcore.WatcherParams
 import com.synonym.bitkitcore.onchainBroadcastRawTx
 import com.synonym.bitkitcore.onchainComposeTransaction
 import com.synonym.bitkitcore.onchainGetAccountInfo
 import com.synonym.bitkitcore.onchainGetAddressInfo
 import com.synonym.bitkitcore.onchainGetTransactionHistory
+import com.synonym.bitkitcore.onchainStartWatcher
+import com.synonym.bitkitcore.onchainStopAllWatchers
+import com.synonym.bitkitcore.onchainStopWatcher
 import com.synonym.bitkitcore.trezorClearCredentials
 import com.synonym.bitkitcore.trezorConnect
 import com.synonym.bitkitcore.trezorDisconnect
@@ -266,4 +271,18 @@ class TrezorService @Inject constructor(
             )
         }
     }
+
+    suspend fun startWatcher(params: WatcherParams, listener: EventListener) {
+        ServiceQueue.CORE.background {
+            onchainStartWatcher(params = params, listener = listener)
+        }
+    }
+
+    fun stopWatcher(watcherId: String) {
+        onchainStopWatcher(watcherId = watcherId)
+    }
+
+    fun stopAllWatchers() {
+        onchainStopAllWatchers()
+    }
 }

app/src/main/java/to/bitkit/ui/screens/trezor/TrezorPreviewData.kt

@@ -17,6 +17,8 @@ import com.synonym.bitkitcore.TrezorSignedTx
 import com.synonym.bitkitcore.TrezorTransportType
 import com.synonym.bitkitcore.TxDirection
 import com.synonym.bitkitcore.WalletBalance
+import kotlinx.collections.immutable.persistentListOf
+import kotlinx.collections.immutable.toImmutableList
 import to.bitkit.repositories.ConnectedTrezorDevice
 import to.bitkit.repositories.KnownDevice
 import to.bitkit.repositories.KnownDeviceTransportType
@@ -305,6 +307,24 @@ internal object TrezorPreviewData {
         ),
     )
 
+    val uiStateWithActiveWatcher = TrezorUiState(
+        network = TrezorNetworkState(selectedNetwork = BitkitCoreNetwork.REGTEST),
+        watcher = TrezorWatcherState(
+            extendedKey = SAMPLE_XPUB,
+            activeWatcherId = "watcher-abc-123",
+            connectionStatus = WatcherConnectionStatus.CONNECTED,
+            balance = sampleWalletBalance,
+            transactions = sampleHistoryTransactions.toImmutableList(),
+            transactionCount = 2u,
+            blockHeight = 850_000u,
+            accountType = AccountType.NATIVE_SEGWIT,
+            events = persistentListOf(
+                "Watcher started: watcher-abc-123",
+                "TX update: 2 txs, balance=155000 sats",
+            ),
+        ),
+    )
+
     val uiStateBroadcast = TrezorUiState(
         network = TrezorNetworkState(selectedNetwork = BitkitCoreNetwork.REGTEST),
         send = TrezorSendState(

app/src/main/java/to/bitkit/ui/screens/trezor/TrezorScreen.kt

@@ -167,6 +167,11 @@ private fun TrezorScreenContent(
             onResetSend = viewModel::resetSendFlow,
             onTxHistoryInputChange = viewModel::setTxHistoryInput,
             onLookupTxHistory = viewModel::lookupTransactionHistory,
+            onWatcherExtendedKeyChange = viewModel::setWatcherExtendedKey,
+            onWatcherGapLimitChange = viewModel::setWatcherGapLimit,
+            onStartWatcher = viewModel::startWatcher,
+            onStopWatcher = viewModel::stopWatcher,
+            onPopulateWatcherFromXpub = viewModel::populateWatcherFromXpub,
             permissionsGranted = permissionsState.allPermissionsGranted,
         )
     }
@@ -207,6 +212,11 @@ private fun Content(
     onResetSend: () -> Unit = {},
     onTxHistoryInputChange: (String) -> Unit = {},
     onLookupTxHistory: () -> Unit = {},
+    onWatcherExtendedKeyChange: (String) -> Unit = {},
+    onWatcherGapLimitChange: (String) -> Unit = {},
+    onStartWatcher: () -> Unit = {},
+    onStopWatcher: () -> Unit = {},
+    onPopulateWatcherFromXpub: () -> Unit = {},
     permissionsGranted: Boolean = true,
 ) {
     Column(
@@ -419,14 +429,26 @@ private fun Content(
                     onResetSend = onResetSend,
                 )
 
-                // Transaction History (always visible, no device needed)
+                // Transaction History (one-shot snapshot, no device needed)
                 VerticalSpacer(32.dp)
                 TransactionHistorySection(
                     uiState = uiState,
                     onInputChange = onTxHistoryInputChange,
                     onLookup = onLookupTxHistory,
                 )
 
+                // Event Watcher (live subscription, no device needed)
+                VerticalSpacer(32.dp)
+                WatcherSection(
+                    uiState = uiState,
+                    trezorState = trezorState,
+                    onExtendedKeyChange = onWatcherExtendedKeyChange,
+                    onGapLimitChange = onWatcherGapLimitChange,
+                    onStartWatcher = onStartWatcher,
+                    onStopWatcher = onStopWatcher,
+                    onPopulateFromXpub = onPopulateWatcherFromXpub,
+                )
+
                 // Debug Log Window
                 DebugLogSection()
             }
@@ -668,7 +690,7 @@ private fun StatusRow(trezorState: TrezorState) {
 }
 
 @Composable
-private fun StatusBadge(text: String, color: Color) {
+internal fun StatusBadge(text: String, color: Color) {
     Caption(
         text = text,
         color = color,