diff --git a/backend/mpc-system/services/service-party-app/electron/main.ts b/backend/mpc-system/services/service-party-app/electron/main.ts
index ebd4ceaf..8f9687a1 100644
--- a/backend/mpc-system/services/service-party-app/electron/main.ts
+++ b/backend/mpc-system/services/service-party-app/electron/main.ts
@@ -608,36 +608,44 @@ async function connectAndRegisterToMessageRouter() {
     });
 
     // 监听会话事件并处理
+    // Note: gRPC response uses snake_case field names due to keepCase: true in proto-loader
     grpcClient.on('sessionEvent', async (event: {
-      eventId: string;
-      eventType: string;
-      sessionId: string;
-      thresholdN: number;
-      thresholdT: number;
-      selectedParties: string[];
-      joinTokens: Record<string, string>;
-      messageHash?: Buffer;
+      event_id: string;
+      event_type: string;
+      session_id: string;
+      threshold_n: number;
+      threshold_t: number;
+      selected_parties: string[];
+      join_tokens: Record<string, string>;
+      message_hash?: Buffer;
     }) => {
-      debugLog.info('grpc', `Received session event: ${event.eventType} for session ${event.sessionId}`);
+      debugLog.info('grpc', `Received session event: ${event.event_type} for session ${event.session_id}`);
 
       const eventData: SessionEventData = {
-        type: event.eventType,
-        sessionId: event.sessionId,
-        thresholdN: event.thresholdN,
-        thresholdT: event.thresholdT,
-        selectedParties: event.selectedParties,
+        type: event.event_type,
+        sessionId: event.session_id,
+        thresholdN: event.threshold_n,
+        thresholdT: event.threshold_t,
+        selectedParties: event.selected_parties,
       };
 
       // 缓存事件（解决前端可能还未订阅的时序问题）
-      cacheSessionEvent(event.sessionId, eventData);
+      cacheSessionEvent(event.session_id, eventData);
 
       // 转发事件到前端
-      mainWindow?.webContents.send(`session:events:${event.sessionId}`, eventData);
+      mainWindow?.webContents.send(`session:events:${event.session_id}`, eventData);
 
       // 根据事件类型处理
-      if (event.eventType === 'session_started' || event.eventType === 'all_joined') {
+      if (event.event_type === 'session_started' || event.event_type === 'all_joined') {
         // 当会话开始或所有参与方都加入时，检查是否需要触发 keygen
-        await handleSessionStart(event);
+        // Convert snake_case to camelCase for handleSessionStart
+        await handleSessionStart({
+          eventType: event.event_type,
+          sessionId: event.session_id,
+          thresholdN: event.threshold_n,
+          thresholdT: event.threshold_t,
+          selectedParties: event.selected_parties,
+        });
       }
     });
   } catch (error) {
@@ -680,16 +688,17 @@ function setupIpcHandlers() {
       const result = await grpcClient?.joinSession(sessionId, partyId, joinToken);
       if (result?.success) {
         // 设置活跃的 keygen 会话信息
-        const participants: Array<{ partyId: string; partyIndex: number; name: string }> = result.otherParties?.map((p: { partyId: string; partyIndex: number }, idx: number) => ({
-          partyId: p.partyId,
-          partyIndex: p.partyIndex,
+        // Note: gRPC response uses snake_case field names due to keepCase: true in proto-loader
+        const participants: Array<{ partyId: string; partyIndex: number; name: string }> = result.other_parties?.map((p: { party_id: string; party_index: number }, idx: number) => ({
+          partyId: p.party_id,
+          partyIndex: p.party_index,
           name: `参与方 ${idx + 1}`, // 暂时使用默认名称
         })) || [];
 
         // 添加自己到参与者列表
         participants.push({
           partyId: partyId,
-          partyIndex: result.partyIndex,
+          partyIndex: result.party_index,
           name: '我',
         });
 
@@ -698,13 +707,13 @@ function setupIpcHandlers() {
 
         activeKeygenSession = {
           sessionId: sessionId,
-          partyIndex: result.partyIndex,
+          partyIndex: result.party_index,
           participants: participants,
           threshold: {
-            t: result.sessionInfo?.thresholdT || 0,
-            n: result.sessionInfo?.thresholdN || 0,
+            t: result.session_info?.threshold_t || 0,
+            n: result.session_info?.threshold_n || 0,
           },
-          walletName: walletName || result.sessionInfo?.sessionId || 'Shared Wallet',
+          walletName: walletName || result.session_info?.session_id || 'Shared Wallet',
           encryptionPassword: '', // 不使用加密密码
         };
 
@@ -768,18 +777,19 @@ function setupIpcHandlers() {
 
         if (joinResult?.success) {
           // 设置活跃的 keygen 会话信息
+          // Note: gRPC response uses snake_case field names due to keepCase: true in proto-loader
           const participants: Array<{ partyId: string; partyIndex: number; name: string }> = [];
 
           // 添加发起方（自己）
           participants.push({
             partyId: partyId,
-            partyIndex: joinResult.partyIndex,
+            partyIndex: joinResult.party_index,
             name: params.initiatorName || '发起者',
           });
 
           activeKeygenSession = {
             sessionId: result.session_id,
-            partyIndex: joinResult.partyIndex,
+            partyIndex: joinResult.party_index,
             participants: participants,
             threshold: {
               t: params.thresholdT,
diff --git a/backend/mpc-system/services/service-party-app/electron/modules/grpc-client.ts b/backend/mpc-system/services/service-party-app/electron/modules/grpc-client.ts
index 9348317f..81b58ca9 100644
--- a/backend/mpc-system/services/service-party-app/electron/modules/grpc-client.ts
+++ b/backend/mpc-system/services/service-party-app/electron/modules/grpc-client.ts
@@ -44,48 +44,65 @@ function loadProtoDefinition(): protoLoader.PackageDefinition {
   return packageDefinition;
 }
 
+// Note: field names must match proto definitions with keepCase: true
+// Proto uses snake_case: session_id, session_type, threshold_n, threshold_t
 interface SessionInfo {
-  sessionId: string;
-  sessionType: string;
-  thresholdN: number;
-  thresholdT: number;
-  messageHash?: Buffer;
-  keygenSessionId?: string;
+  session_id: string;
+  session_type: string;
+  threshold_n: number;
+  threshold_t: number;
+  message_hash?: Buffer;
+  keygen_session_id?: string;
+  status?: string;
 }
 
 interface PartyInfo {
-  partyId: string;
-  partyIndex: number;
+  party_id: string;
+  party_index: number;
 }
 
 interface JoinSessionResponse {
   success: boolean;
-  sessionInfo?: SessionInfo;
-  partyIndex: number;
-  otherParties: PartyInfo[];
+  session_info?: SessionInfo;
+  party_index: number;
+  other_parties: PartyInfo[];
 }
 
 interface MPCMessage {
-  messageId: string;
-  sessionId: string;
-  fromParty: string;
-  isBroadcast: boolean;
-  roundNumber: number;
+  message_id: string;
+  session_id: string;
+  from_party: string;
+  is_broadcast: boolean;
+  round_number: number;
   payload: Buffer;
-  createdAt: string;
+  created_at: string;
 }
 
 interface SessionEvent {
-  eventId: string;
-  eventType: string;
-  sessionId: string;
-  thresholdN: number;
-  thresholdT: number;
-  selectedParties: string[];
-  joinTokens: Record<string, string>;
-  messageHash?: Buffer;
+  event_id: string;
+  event_type: string;
+  session_id: string;
+  threshold_n: number;
+  threshold_t: number;
+  selected_parties: string[];
+  join_tokens: Record<string, string>;
+  message_hash?: Buffer;
 }
 
+// Raw proto response (snake_case)
+interface RegisteredPartyProto {
+  party_id: string;
+  role: string;
+  online: boolean;
+  registered_at: string;
+  last_seen_at: string;
+}
+
+interface GetRegisteredPartiesResponse {
+  parties: RegisteredPartyProto[];
+}
+
+// Converted response (camelCase) - used by callers
 interface RegisteredParty {
   partyId: string;
   role: string;
@@ -94,10 +111,6 @@ interface RegisteredParty {
   lastSeenAt: string;
 }
 
-interface GetRegisteredPartiesResponse {
-  parties: RegisteredParty[];
-}
-
 // 重连配置
 interface ReconnectConfig {
   maxRetries: number;