fix(mpc-system): GetSessionStatus API 返回 threshold_t 和 threshold_n

问题：
- Account 服务的 GetSessionStatus HTTP API 没有返回 threshold 字段
- 导致 service-party-app 获取到的 threshold 始终是 0
- TSS keygen 无法使用正确的阈值参数

修复：
- Account gRPC client 添加 ThresholdT 和 ThresholdN 字段映射
- Account HTTP handler 返回 threshold_t 和 threshold_n
- service-party-app 优先使用后端返回的 threshold 值
- checkAndTriggerKeygen 使用后端 threshold 更新 activeKeygenSession

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

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

backend/mpc-system/services/account/adapters/input/http/co_managed_handler.go

@@ -314,6 +314,8 @@ func (h *CoManagedHTTPHandler) GetSessionStatus(c *gin.Context) {
 		"session_id":        sessionID,
 		"status":            resp.Status,
 		"session_type":      resp.SessionType,
+		"threshold_t":       resp.ThresholdT,
+		"threshold_n":       resp.ThresholdN,
 		"completed_parties": resp.CompletedParties,
 		"total_parties":     resp.TotalParties,
 	}

backend/mpc-system/services/account/adapters/output/grpc/session_coordinator_client.go

@@ -225,6 +225,8 @@ func (c *SessionCoordinatorClient) GetSessionStatus(
 		Status:           resp.Status,
 		CompletedParties: resp.CompletedParties,
 		TotalParties:     resp.TotalParties,
+		ThresholdT:       resp.ThresholdT,
+		ThresholdN:       resp.ThresholdN,
 		SessionType:      resp.SessionType,
 		PublicKey:        resp.PublicKey,
 		Signature:        resp.Signature,
@@ -293,6 +295,8 @@ type SessionStatusResponse struct {
 	Status           string
 	CompletedParties int32
 	TotalParties     int32
+	ThresholdT       int32  // Minimum parties needed to sign (e.g., 2 in 2-of-3)
+	ThresholdN       int32  // Total number of parties required (e.g., 3 in 2-of-3)
 	SessionType      string // "keygen" or "sign"
 	PublicKey        []byte
 	Signature        []byte

backend/mpc-system/services/service-party-app/electron/main.ts

@@ -166,10 +166,13 @@ async function checkAndTriggerKeygen(sessionId: string) {
         continue;
       }
 
-      const expectedN = status.total_parties || activeKeygenSession.threshold.n;
+      // 优先使用后端返回的 threshold 值
+      const thresholdN = status.threshold_n || status.total_parties || activeKeygenSession.threshold.n;
+      const thresholdT = status.threshold_t || activeKeygenSession.threshold.t;
+      const expectedN = thresholdN;
       const currentParticipants = status.participants?.length || 0;
 
-      debugLog.debug('main', `Session ${sessionId} status: ${status.status}, participants: ${currentParticipants}/${expectedN}`);
+      debugLog.debug('main', `Session ${sessionId} status: ${status.status}, participants: ${currentParticipants}/${expectedN}, threshold: ${thresholdT}-of-${thresholdN}`);
 
       // 检查是否满足启动条件
       const hasAllParticipants = currentParticipants >= expectedN;
@@ -207,13 +210,16 @@ async function checkAndTriggerKeygen(sessionId: string) {
           })))}`);
         }
 
+        // 更新 activeKeygenSession 的 threshold（使用后端返回的正确值）
+        activeKeygenSession.threshold = { t: thresholdT, n: thresholdN };
+
         const selectedParties = activeKeygenSession.participants.map(p => p.partyId);
 
         await handleSessionStart({
           eventType: 'session_started',
           sessionId: sessionId,
-          thresholdN: activeKeygenSession.threshold.n,
-          thresholdT: activeKeygenSession.threshold.t,
+          thresholdN: thresholdN,
+          thresholdT: thresholdT,
           selectedParties: selectedParties,
         });
 
@@ -869,8 +875,11 @@ function setupIpcHandlers() {
   ipcMain.handle('grpc:getSessionStatus', async (_event, { sessionId }) => {
     try {
       const result = await accountClient?.getSessionStatus(sessionId);
-      // 从 activeKeygenSession 获取更完整的信息
-      const threshold = activeKeygenSession?.threshold || { t: 0, n: result?.total_parties || 0 };
+      // 优先使用后端返回的 threshold，否则从 activeKeygenSession 获取
+      const threshold = {
+        t: result?.threshold_t || activeKeygenSession?.threshold?.t || 0,
+        n: result?.threshold_n || result?.total_parties || activeKeygenSession?.threshold?.n || 0,
+      };
       const participants = result?.participants?.map((p, idx) => ({
         partyId: p.party_id,
         partyIndex: p.party_index,

backend/mpc-system/services/service-party-app/electron/modules/account-client.ts

@@ -73,6 +73,8 @@ export interface ParticipantStatusInfo {
 export interface GetSessionStatusResponse {
   session_id: string;
   status: string;
+  threshold_t: number;  // Minimum parties needed to sign (e.g., 2 in 2-of-3)
+  threshold_n: number;  // Total number of parties required (e.g., 3 in 2-of-3)
   completed_parties: number;
   total_parties: number;
   session_type: string;