feat(android): add 5-minute countdown timer UI for keygen/sign sessions

Displays remaining time during the 5-minute polling timeout:
- Shows countdown in CreateWalletScreen (SessionScreen)
- Shows countdown in JoinKeygenScreen (JoiningScreen, KeygenProgressScreen)
- Shows countdown in CoSignJoinScreen (JoiningScreen, SigningProgressScreen)
- Format: mm:ss with Timer icon in tertiary container card
- Countdown starts on all_joined event and stops on session start/cancel

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

backend/mpc-system/services/service-party-android/app/src/main/java/com/durian/tssparty/MainActivity.kt

@@ -242,6 +242,7 @@ fun TssPartyApp(
                     currentRound = currentRound,
                     totalRounds = 9,
                     publicKey = publicKey,
+                    countdownSeconds = uiState.countdownSeconds,
                     onCreateSession = { name, t, n, participantName ->
                         viewModel.createKeygenSession(name, t, n, participantName)
                     },
@@ -292,6 +293,7 @@ fun TssPartyApp(
                     currentRound = joinKeygenRound,
                     totalRounds = 9,
                     publicKey = joinKeygenPublicKey,
+                    countdownSeconds = uiState.countdownSeconds,
                     onValidateInviteCode = { inviteCode ->
                         viewModel.validateInviteCode(inviteCode)
                     },
@@ -347,6 +349,7 @@ fun TssPartyApp(
                     currentRound = coSignRound,
                     totalRounds = 9,
                     signature = coSignSignature,
+                    countdownSeconds = uiState.countdownSeconds,
                     onValidateInviteCode = { inviteCode ->
                         viewModel.validateSignInviteCode(inviteCode)
                     },

backend/mpc-system/services/service-party-android/app/src/main/java/com/durian/tssparty/data/repository/TssRepository.kt

@@ -63,6 +63,10 @@ class TssRepository @Inject constructor(
     // Called when 5-minute polling timeout is reached without session starting
     private var keygenTimeoutCallback: ((String) -> Unit)? = null
 
+    // Countdown tick callback (set by ViewModel)
+    // Called every second with remaining seconds for UI countdown display
+    private var countdownTickCallback: ((Long) -> Unit)? = null
+
     // Repository-level CoroutineScope for background tasks
     // Uses SupervisorJob so individual task failures don't cancel other tasks
     private val repositoryScope = CoroutineScope(SupervisorJob() + Dispatchers.IO)
@@ -281,6 +285,15 @@ class TssRepository @Inject constructor(
         keygenTimeoutCallback = callback
     }
 
+    /**
+     * Set countdown tick callback (called by ViewModel)
+     * This callback is invoked every second with the remaining seconds
+     * for displaying countdown in the UI
+     */
+    fun setCountdownTickCallback(callback: (Long) -> Unit) {
+        countdownTickCallback = callback
+    }
+
     /**
      * Start polling session status as fallback mechanism
      * This matches Electron's checkAndTriggerKeygen() polling behavior:
@@ -301,14 +314,28 @@ class TssRepository @Inject constructor(
 
         android.util.Log.d("TssRepository", "[POLLING] Starting session status polling for $sessionType session: $sessionId")
 
+        // Notify UI that countdown has started (5 minutes = 300 seconds)
+        countdownTickCallback?.invoke(MAX_WAIT_MS / 1000)
+
         sessionStatusPollingJob = repositoryScope.launch {
             val startTime = System.currentTimeMillis()
             var pollCount = 0
+            var lastTickSecond = MAX_WAIT_MS / 1000
 
             while (isActive && (System.currentTimeMillis() - startTime) < MAX_WAIT_MS) {
                 pollCount++
                 android.util.Log.d("TssRepository", "[POLLING] Poll #$pollCount for session: $sessionId")
 
+                // Calculate and emit remaining seconds for countdown display
+                val elapsedMs = System.currentTimeMillis() - startTime
+                val remainingSeconds = (MAX_WAIT_MS - elapsedMs) / 1000
+                if (remainingSeconds != lastTickSecond) {
+                    lastTickSecond = remainingSeconds
+                    withContext(Dispatchers.Main) {
+                        countdownTickCallback?.invoke(remainingSeconds)
+                    }
+                }
+
                 try {
                     val statusResult = getSessionStatus(sessionId)
 
@@ -320,6 +347,11 @@ class TssRepository @Inject constructor(
                             if (status.status == "in_progress") {
                                 android.util.Log.d("TssRepository", "[POLLING] Session is in_progress, triggering $sessionType via callback")
 
+                                // Clear countdown when session starts
+                                withContext(Dispatchers.Main) {
+                                    countdownTickCallback?.invoke(-1L)  // -1 indicates countdown stopped (success)
+                                }
+
                                 // Create synthetic session_started event to trigger keygen/sign
                                 // This matches Electron's behavior of checking status and triggering manually
                                 val eventData = SessionEventData(
@@ -346,12 +378,18 @@ class TssRepository @Inject constructor(
                             // Check if session failed or was cancelled
                             if (status.status == "failed" || status.status == "cancelled") {
                                 android.util.Log.d("TssRepository", "[POLLING] Session ${status.status}, stopping polling")
+                                withContext(Dispatchers.Main) {
+                                    countdownTickCallback?.invoke(-1L)  // Clear countdown
+                                }
                                 return@launch
                             }
 
                             // Check if session already completed (keygen finished)
                             if (status.status == "completed") {
                                 android.util.Log.d("TssRepository", "[POLLING] Session completed, stopping polling")
+                                withContext(Dispatchers.Main) {
+                                    countdownTickCallback?.invoke(-1L)  // Clear countdown
+                                }
                                 return@launch
                             }
                         },
@@ -374,6 +412,7 @@ class TssRepository @Inject constructor(
                 android.util.Log.e("TssRepository", "[POLLING] Timeout after ${elapsedSeconds}s waiting for $sessionType to start")
 
                 withContext(Dispatchers.Main) {
+                    countdownTickCallback?.invoke(0L)  // Countdown reached zero
                     keygenTimeoutCallback?.invoke("等待 $sessionType 启动超时（5分钟）")
                 }
             }
@@ -390,6 +429,8 @@ class TssRepository @Inject constructor(
     fun stopSessionStatusPolling() {
         sessionStatusPollingJob?.cancel()
         sessionStatusPollingJob = null
+        // Clear countdown display when polling is stopped
+        countdownTickCallback?.invoke(-1L)
         android.util.Log.d("TssRepository", "[POLLING] Session status polling stopped")
     }
 

backend/mpc-system/services/service-party-android/app/src/main/java/com/durian/tssparty/presentation/screens/CoSignJoinScreen.kt

@@ -36,6 +36,16 @@ data class SignSessionInfo(
     val currentParticipants: Int
 )
 
+/**
+ * Format countdown seconds to mm:ss display
+ */
+private fun formatCountdown(seconds: Long): String {
+    if (seconds < 0) return ""
+    val minutes = seconds / 60
+    val secs = seconds % 60
+    return "%d:%02d".format(minutes, secs)
+}
+
 /**
  * CoSign Join screen matching service-party-app/src/renderer/src/pages/Sign.tsx
  * Flow: input → select_share → joining → signing → completed
@@ -52,6 +62,7 @@ fun CoSignJoinScreen(
     currentRound: Int = 0,
     totalRounds: Int = 9,
     signature: String? = null,
+    countdownSeconds: Long = -1L,  // 5-minute countdown: -1 = not counting, >0 = remaining seconds
     onValidateInviteCode: (inviteCode: String) -> Unit,
     onJoinSign: (inviteCode: String, shareId: Long, password: String) -> Unit,
     onCancel: () -> Unit,
@@ -205,12 +216,16 @@ fun CoSignJoinScreen(
             },
             onCancel = resetToInput
         )
-        "joining" -> JoiningScreen(onCancel = resetToInput)  // Reset to input state, stay on page
+        "joining" -> JoiningScreen(
+            countdownSeconds = countdownSeconds,
+            onCancel = resetToInput
+        )  // Reset to input state, stay on page
         "signing" -> SigningProgressScreen(
             sessionStatus = sessionStatus,
             participants = participants,
             currentRound = currentRound,
             totalRounds = totalRounds,
+            countdownSeconds = countdownSeconds,
             onCancel = resetToInput  // Reset to input state, stay on page
         )
         "completed" -> SigningCompletedScreen(
@@ -699,6 +714,7 @@ private fun SelectShareScreen(
 
 @Composable
 private fun JoiningScreen(
+    countdownSeconds: Long = -1L,
     onCancel: () -> Unit
 ) {
     Column(
@@ -729,6 +745,35 @@ private fun JoiningScreen(
             color = MaterialTheme.colorScheme.onSurfaceVariant
         )
 
+        // Countdown timer (if counting down)
+        if (countdownSeconds > 0) {
+            Spacer(modifier = Modifier.height(24.dp))
+            Card(
+                colors = CardDefaults.cardColors(
+                    containerColor = MaterialTheme.colorScheme.tertiaryContainer
+                )
+            ) {
+                Row(
+                    modifier = Modifier.padding(horizontal = 24.dp, vertical = 12.dp),
+                    verticalAlignment = Alignment.CenterVertically
+                ) {
+                    Icon(
+                        Icons.Default.Timer,
+                        contentDescription = null,
+                        tint = MaterialTheme.colorScheme.onTertiaryContainer,
+                        modifier = Modifier.size(20.dp)
+                    )
+                    Spacer(modifier = Modifier.width(8.dp))
+                    Text(
+                        text = "等待启动: ${formatCountdown(countdownSeconds)}",
+                        style = MaterialTheme.typography.titleMedium,
+                        fontWeight = FontWeight.Bold,
+                        color = MaterialTheme.colorScheme.onTertiaryContainer
+                    )
+                }
+            }
+        }
+
         Spacer(modifier = Modifier.height(32.dp))
 
         OutlinedButton(onClick = onCancel) {
@@ -745,6 +790,7 @@ private fun SigningProgressScreen(
     participants: List<String>,
     currentRound: Int,
     totalRounds: Int,
+    countdownSeconds: Long = -1L,
     onCancel: () -> Unit
 ) {
     Column(
@@ -804,6 +850,46 @@ private fun SigningProgressScreen(
             }
         }
 
+        // Countdown timer (if counting down - waiting for sign to start)
+        if (countdownSeconds > 0) {
+            Spacer(modifier = Modifier.height(16.dp))
+            Card(
+                modifier = Modifier.fillMaxWidth(),
+                colors = CardDefaults.cardColors(
+                    containerColor = MaterialTheme.colorScheme.tertiaryContainer
+                )
+            ) {
+                Row(
+                    modifier = Modifier
+                        .fillMaxWidth()
+                        .padding(16.dp),
+                    horizontalArrangement = Arrangement.Center,
+                    verticalAlignment = Alignment.CenterVertically
+                ) {
+                    Icon(
+                        Icons.Default.Timer,
+                        contentDescription = null,
+                        tint = MaterialTheme.colorScheme.onTertiaryContainer,
+                        modifier = Modifier.size(24.dp)
+                    )
+                    Spacer(modifier = Modifier.width(12.dp))
+                    Column {
+                        Text(
+                            text = "等待签名启动",
+                            style = MaterialTheme.typography.labelMedium,
+                            color = MaterialTheme.colorScheme.onTertiaryContainer
+                        )
+                        Text(
+                            text = formatCountdown(countdownSeconds),
+                            style = MaterialTheme.typography.headlineMedium,
+                            fontWeight = FontWeight.Bold,
+                            color = MaterialTheme.colorScheme.onTertiaryContainer
+                        )
+                    }
+                }
+            }
+        }
+
         Spacer(modifier = Modifier.height(16.dp))
 
         // Participants card

backend/mpc-system/services/service-party-android/app/src/main/java/com/durian/tssparty/presentation/screens/CreateWalletScreen.kt

@@ -49,6 +49,7 @@ fun CreateWalletScreen(
     currentRound: Int = 0,
     totalRounds: Int = 9,
     publicKey: String? = null,
+    countdownSeconds: Long = -1L,  // 5-minute countdown: -1 = not counting, >0 = remaining seconds
     onCreateSession: (walletName: String, thresholdT: Int, thresholdN: Int, participantName: String) -> Unit,
     onCopyInviteCode: () -> Unit,
     onEnterSession: () -> Unit,
@@ -115,6 +116,7 @@ fun CreateWalletScreen(
             totalRounds = totalRounds,
             publicKey = publicKey,
             inviteCode = inviteCode,
+            countdownSeconds = countdownSeconds,
             onCopyInviteCode = onCopyInviteCode,
             onBackToHome = onBackToHome
         )
@@ -610,6 +612,16 @@ private fun generateQRCodeBitmap(content: String, size: Int): Bitmap? {
     }
 }
 
+/**
+ * Format countdown seconds to mm:ss display
+ */
+private fun formatCountdown(seconds: Long): String {
+    if (seconds < 0) return ""
+    val minutes = seconds / 60
+    val secs = seconds % 60
+    return "%d:%02d".format(minutes, secs)
+}
+
 @Composable
 private fun SessionScreen(
     walletName: String,
@@ -622,6 +634,7 @@ private fun SessionScreen(
     totalRounds: Int,
     publicKey: String?,
     inviteCode: String?,
+    countdownSeconds: Long = -1L,
     onCopyInviteCode: () -> Unit,
     onBackToHome: () -> Unit
 ) {
@@ -763,6 +776,46 @@ private fun SessionScreen(
             Spacer(modifier = Modifier.height(16.dp))
         }
 
+        // Countdown timer (if counting down - waiting for keygen to start after all joined)
+        if (countdownSeconds > 0) {
+            Card(
+                modifier = Modifier.fillMaxWidth(),
+                colors = CardDefaults.cardColors(
+                    containerColor = MaterialTheme.colorScheme.tertiaryContainer
+                )
+            ) {
+                Row(
+                    modifier = Modifier
+                        .fillMaxWidth()
+                        .padding(16.dp),
+                    horizontalArrangement = Arrangement.Center,
+                    verticalAlignment = Alignment.CenterVertically
+                ) {
+                    Icon(
+                        Icons.Default.Timer,
+                        contentDescription = null,
+                        tint = MaterialTheme.colorScheme.onTertiaryContainer,
+                        modifier = Modifier.size(24.dp)
+                    )
+                    Spacer(modifier = Modifier.width(12.dp))
+                    Column {
+                        Text(
+                            text = "等待密钥生成启动",
+                            style = MaterialTheme.typography.labelMedium,
+                            color = MaterialTheme.colorScheme.onTertiaryContainer
+                        )
+                        Text(
+                            text = formatCountdown(countdownSeconds),
+                            style = MaterialTheme.typography.headlineMedium,
+                            fontWeight = FontWeight.Bold,
+                            color = MaterialTheme.colorScheme.onTertiaryContainer
+                        )
+                    }
+                }
+            }
+            Spacer(modifier = Modifier.height(16.dp))
+        }
+
         // Progress Bar (if in progress)
         if (sessionStatus == SessionStatus.IN_PROGRESS) {
             Card(

backend/mpc-system/services/service-party-android/app/src/main/java/com/durian/tssparty/presentation/screens/JoinKeygenScreen.kt

@@ -32,6 +32,16 @@ data class JoinSessionInfo(
     val totalParticipants: Int
 )
 
+/**
+ * Format countdown seconds to mm:ss display
+ */
+private fun formatCountdown(seconds: Long): String {
+    if (seconds < 0) return ""
+    val minutes = seconds / 60
+    val secs = seconds % 60
+    return "%d:%02d".format(minutes, secs)
+}
+
 /**
  * JoinKeygen screen matching service-party-app/src/renderer/src/pages/Join.tsx
  * Simplified flow without password: input → confirm → joining
@@ -47,6 +57,7 @@ fun JoinKeygenScreen(
     currentRound: Int = 0,
     totalRounds: Int = 9,
     publicKey: String? = null,
+    countdownSeconds: Long = -1L,  // 5-minute countdown: -1 = not counting, >0 = remaining seconds
     onValidateInviteCode: (inviteCode: String) -> Unit,
     onJoinKeygen: (inviteCode: String, password: String) -> Unit,
     onCancel: () -> Unit,
@@ -143,12 +154,16 @@ fun JoinKeygenScreen(
             },
             onCancel = resetToInput  // Reset to input state, stay on page
         )
-        "joining" -> JoiningScreen(onCancel = resetToInput)  // Reset to input state, stay on page
+        "joining" -> JoiningScreen(
+            countdownSeconds = countdownSeconds,
+            onCancel = resetToInput
+        )  // Reset to input state, stay on page
         "progress" -> KeygenProgressScreen(
             sessionStatus = sessionStatus,
             participants = participants,
             currentRound = currentRound,
             totalRounds = totalRounds,
+            countdownSeconds = countdownSeconds,
             onCancel = resetToInput  // Reset to input state, stay on page
         )
         "completed" -> KeygenCompletedScreen(
@@ -512,7 +527,10 @@ private fun ConfirmScreen(
 }
 
 @Composable
-private fun JoiningScreen(onCancel: () -> Unit) {
+private fun JoiningScreen(
+    countdownSeconds: Long = -1L,
+    onCancel: () -> Unit
+) {
     Column(
         modifier = Modifier
             .fillMaxSize()
@@ -541,6 +559,35 @@ private fun JoiningScreen(onCancel: () -> Unit) {
             color = MaterialTheme.colorScheme.onSurfaceVariant
         )
 
+        // Countdown timer (if counting down)
+        if (countdownSeconds > 0) {
+            Spacer(modifier = Modifier.height(24.dp))
+            Card(
+                colors = CardDefaults.cardColors(
+                    containerColor = MaterialTheme.colorScheme.tertiaryContainer
+                )
+            ) {
+                Row(
+                    modifier = Modifier.padding(horizontal = 24.dp, vertical = 12.dp),
+                    verticalAlignment = Alignment.CenterVertically
+                ) {
+                    Icon(
+                        Icons.Default.Timer,
+                        contentDescription = null,
+                        tint = MaterialTheme.colorScheme.onTertiaryContainer,
+                        modifier = Modifier.size(20.dp)
+                    )
+                    Spacer(modifier = Modifier.width(8.dp))
+                    Text(
+                        text = "等待启动: ${formatCountdown(countdownSeconds)}",
+                        style = MaterialTheme.typography.titleMedium,
+                        fontWeight = FontWeight.Bold,
+                        color = MaterialTheme.colorScheme.onTertiaryContainer
+                    )
+                }
+            }
+        }
+
         Spacer(modifier = Modifier.height(32.dp))
 
         // Cancel button
@@ -558,6 +605,7 @@ private fun KeygenProgressScreen(
     participants: List<String>,
     currentRound: Int,
     totalRounds: Int,
+    countdownSeconds: Long = -1L,
     onCancel: () -> Unit
 ) {
     Column(
@@ -617,6 +665,46 @@ private fun KeygenProgressScreen(
             }
         }
 
+        // Countdown timer (if counting down - waiting for keygen to start)
+        if (countdownSeconds > 0) {
+            Spacer(modifier = Modifier.height(16.dp))
+            Card(
+                modifier = Modifier.fillMaxWidth(),
+                colors = CardDefaults.cardColors(
+                    containerColor = MaterialTheme.colorScheme.tertiaryContainer
+                )
+            ) {
+                Row(
+                    modifier = Modifier
+                        .fillMaxWidth()
+                        .padding(16.dp),
+                    horizontalArrangement = Arrangement.Center,
+                    verticalAlignment = Alignment.CenterVertically
+                ) {
+                    Icon(
+                        Icons.Default.Timer,
+                        contentDescription = null,
+                        tint = MaterialTheme.colorScheme.onTertiaryContainer,
+                        modifier = Modifier.size(24.dp)
+                    )
+                    Spacer(modifier = Modifier.width(12.dp))
+                    Column {
+                        Text(
+                            text = "等待密钥生成启动",
+                            style = MaterialTheme.typography.labelMedium,
+                            color = MaterialTheme.colorScheme.onTertiaryContainer
+                        )
+                        Text(
+                            text = formatCountdown(countdownSeconds),
+                            style = MaterialTheme.typography.headlineMedium,
+                            fontWeight = FontWeight.Bold,
+                            color = MaterialTheme.colorScheme.onTertiaryContainer
+                        )
+                    }
+                }
+            }
+        }
+
         Spacer(modifier = Modifier.height(16.dp))
 
         // Participants card

backend/mpc-system/services/service-party-android/app/src/main/java/com/durian/tssparty/presentation/viewmodel/MainViewModel.kt

@@ -289,7 +289,13 @@ class MainViewModel @Inject constructor(
         // Setup keygen timeout callback (matching Electron's 5-minute timeout in checkAndTriggerKeygen)
         repository.setKeygenTimeoutCallback { errorMessage ->
             android.util.Log.e("MainViewModel", "Keygen timeout: $errorMessage")
-            _uiState.update { it.copy(isLoading = false, error = errorMessage) }
+            _uiState.update { it.copy(isLoading = false, error = errorMessage, countdownSeconds = -1L) }
+        }
+
+        // Setup countdown tick callback for UI countdown display
+        repository.setCountdownTickCallback { remainingSeconds ->
+            android.util.Log.d("MainViewModel", "Countdown tick: $remainingSeconds seconds remaining")
+            _uiState.update { it.copy(countdownSeconds = remainingSeconds) }
         }
 
         repository.setSessionEventCallback { event ->
@@ -1217,7 +1223,10 @@ data class MainUiState(
     val error: String? = null,
     val successMessage: String? = null,
     val lastCreatedAddress: String? = null,
-    val lastSignature: String? = null
+    val lastSignature: String? = null,
+    // 5-minute countdown for keygen/sign startup timeout
+    // -1 = not counting, 0 = timeout, >0 = remaining seconds
+    val countdownSeconds: Long = -1L
 )
 
 /**