fix(sign): fetch partyIndex from Account Service instead of local storage

- Query keygen session status to get correct party_index for signing
- Keep original design: don't save partyIndex locally during keygen
- Add parties to createSignSession response
- Make partyIndex optional in database type definitions
- Transfer.tsx: use signParties from createSignSession response

🤖 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

@@ -574,17 +574,18 @@ func (h *CoManagedHTTPHandler) CreateSignSession(c *gin.Context) {
 		zap.Int("num_parties", len(resp.SelectedParties)))
 
 	c.JSON(http.StatusCreated, gin.H{
-		"session_id":          resp.SessionID,
-		"keygen_session_id":   req.KeygenSessionID,
-		"wallet_name":         req.WalletName,
-		"invite_code":         inviteCode,
-		"join_token":          wildcardToken,
-		"threshold_t":         req.ThresholdT,
-		"selected_parties":    resp.SelectedParties,
-		"status":              "waiting_for_participants",
-		"current_participants": 0,
+		"session_id":            resp.SessionID,
+		"keygen_session_id":     req.KeygenSessionID,
+		"wallet_name":           req.WalletName,
+		"invite_code":           inviteCode,
+		"join_token":            wildcardToken,
+		"threshold_t":           req.ThresholdT,
+		"parties":               req.Parties, // 返回完整的 parties (包含 party_id 和 party_index)
+		"selected_parties":      resp.SelectedParties,
+		"status":                "waiting_for_participants",
+		"current_participants":  0,
 		"required_participants": len(req.Parties),
-		"expires_at":          resp.ExpiresAt,
+		"expires_at":            resp.ExpiresAt,
 	})
 }
 

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

@@ -564,10 +564,10 @@ async function handleKeygenComplete(result: KeygenResult) {
   try {
     // 1. 保存 share 到本地数据库
     const publicKeyHex = result.publicKey.toString('hex');
-    // 转换 participants 格式：保存 partyId, partyIndex, name
+    // 转换 participants 格式：从 { partyId, partyIndex, name } 到 { partyId, name }
+    // 注意：partyIndex 不保存到本地，签名时需要从 Account Service 获取
     const participantsForSave = activeKeygenSession.participants.map(p => ({
       partyId: p.partyId,
-      partyIndex: p.partyIndex,
       name: p.name,
     }));
     const saved = database.saveShare({
@@ -1219,11 +1219,16 @@ function setupIpcHandlers() {
         return { success: false, error: 'Share not found or incorrect password' };
       }
 
-      // 解析 participants_json 获取参与方列表
-      const participants = JSON.parse(share.participants_json || '[]');
-      const parties = participants.map((p: { partyId: string; partyIndex?: number }, index: number) => ({
-        party_id: p.partyId,
-        party_index: p.partyIndex ?? index, // 优先使用保存的 partyIndex，否则使用数组索引
+      // 从 Account Service 查询 keygen session 获取正确的 participants（包含 party_index）
+      const sessionStatus = await accountClient?.getSessionStatus(share.session_id);
+      if (!sessionStatus?.participants || sessionStatus.participants.length === 0) {
+        return { success: false, error: 'Failed to get participants from keygen session' };
+      }
+
+      // 使用后端返回的 participants（包含正确的 party_index）
+      const parties = sessionStatus.participants.map(p => ({
+        party_id: p.party_id,
+        party_index: p.party_index,
       }));
 
       const result = await accountClient?.createSignSession({
@@ -1241,6 +1246,7 @@ function setupIpcHandlers() {
         inviteCode: result?.invite_code,
         expiresAt: result?.expires_at,
         joinToken: result?.join_token,
+        parties: result?.parties, // 包含正确的 party_id 和 party_index
       };
     } catch (error) {
       return { success: false, error: (error as Error).message };

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

@@ -339,7 +339,7 @@ export class DatabaseManager {
     thresholdN: number;
     publicKeyHex: string;
     rawShare: string;
-    participants: Array<{ partyId: string; name: string }>;
+    participants: Array<{ partyId: string; partyIndex?: number; name: string }>;
   }, password: string): ShareRecord {
     if (!this.db) throw new Error('Database not initialized');
 

backend/mpc-system/services/service-party-app/src/pages/Transfer.tsx

@@ -60,6 +60,7 @@ export default function Transfer() {
   // 签名会话
   const [inviteCode, setInviteCode] = useState('');
   const [signSessionId, setSignSessionId] = useState('');
+  const [signParties, setSignParties] = useState<Array<{ party_id: string; party_index: number }>>([]);
 
   // 错误信息
   const [error, setError] = useState('');
@@ -215,6 +216,7 @@ export default function Transfer() {
 
         setInviteCode(result.inviteCode || '');
         setSignSessionId(result.sessionId || '');
+        setSignParties(result.parties || []);
         setTxHash(messageHash);
 
         // 显示邀请码，等待用户通知其他参与方
@@ -231,11 +233,17 @@ export default function Transfer() {
     if (!txParams || !share || !txHash || !signSessionId) return;
 
     try {
-      // 构建 participants 列表
-      const participants = (share.participants || []).map((p, index) => ({
-        partyId: p.partyId,
-        partyIndex: p.partyIndex ?? index, // 优先使用保存的 partyIndex
-      }));
+      // 使用创建签名会话时返回的 parties（包含正确的 party_index）
+      // 如果没有，则 fallback 到本地 share 的 participants
+      const participants = signParties.length > 0
+        ? signParties.map(p => ({
+            partyId: p.party_id,
+            partyIndex: p.party_index,
+          }))
+        : (share.participants || []).map((p, index) => ({
+            partyId: p.partyId,
+            partyIndex: p.partyIndex ?? index,
+          }));
 
       // 执行 TSS 签名
       if (window.electronAPI) {