fix(android): fetch session status after creation to show all participants

- Add getPartyId() method to TssRepository
- Call getSessionStatus after createKeygenSession to fetch all participants
  including server-party-co-managed that have already auto-joined
- This matches Electron's behavior of calling getSessionStatus on session page

🤖 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/data/repository/TssRepository.kt

@@ -46,6 +46,11 @@ class TssRepository @Inject constructor(
     private var messageCollectionJob: Job? = null
     private var sessionEventJob: Job? = null
 
+    /**
+     * Get the current party ID
+     */
+    fun getPartyId(): String = partyId
+
     // Track current message routing params for reconnection recovery
     private var currentMessageRoutingSessionId: String? = null
     private var currentMessageRoutingPartyIndex: Int? = null

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

@@ -235,13 +235,35 @@ class MainViewModel @Inject constructor(
                 onSuccess = { sessionResult ->
                     _createdInviteCode.value = sessionResult.inviteCode
                     _currentSessionId.value = sessionResult.sessionId
-                    // Add self as first participant
-                    _sessionParticipants.value = listOf(participantName)
                     // Store party index for later use
                     _currentRound.value = 0
-                    _uiState.update { it.copy(isLoading = false) }
 
                     android.util.Log.d("MainViewModel", "Keygen session created: sessionId=${sessionResult.sessionId}, partyIndex=${sessionResult.partyIndex}")
+
+                    // Fetch current session status to get all participants (including server-party-co-managed)
+                    // This matches Electron's behavior of calling getSessionStatus after session creation
+                    val statusResult = repository.getSessionStatus(sessionResult.sessionId)
+                    statusResult.fold(
+                        onSuccess = { status ->
+                            val participantNames = status.participants.mapIndexed { index, p ->
+                                if (p.partyId == repository.getPartyId()) {
+                                    participantName  // Use the name provided by user for self
+                                } else {
+                                    "参与方 ${index + 1}"  // Generic name for others
+                                }
+                            }
+                            _sessionParticipants.value = participantNames
+                            android.util.Log.d("MainViewModel", "Session status fetched: ${status.participants.size} participants already joined")
+                            android.util.Log.d("MainViewModel", "  Participants: ${status.participants.map { it.partyId }}")
+                        },
+                        onFailure = { e ->
+                            // Fallback to just self if status fetch fails
+                            _sessionParticipants.value = listOf(participantName)
+                            android.util.Log.w("MainViewModel", "Failed to fetch session status: ${e.message}, using self only")
+                        }
+                    )
+
+                    _uiState.update { it.copy(isLoading = false) }
                 },
                 onFailure = { e ->
                     _uiState.update { it.copy(isLoading = false, error = e.message) }