feat: complete keygen_session_id implementation for signing sessions

- Regenerate protobuf Go code with KeygenSessionId fields
- Session Coordinator correctly parses, stores, and returns keygen_session_id
- Message Router Client parses keygen_session_id in JoinSession response
- participate_signing.go uses keygen_session_id for precise share lookup
- Database schema already includes keygen_session_id column

This fixes the signing issue where wrong keyshares were loaded for multi-account scenarios.

backend/.claude/settings.local.json

@@ -28,7 +28,8 @@
       "Bash(bash scripts/deploy.sh:*)",
       "Bash(go run:*)",
       "Bash(timeout /t 5 /nobreak)",
-      "Bash(bash:*)"
+      "Bash(bash:*)",
+      "Bash(docker compose:*)"
     ],
     "deny": [],
     "ask": []

backend/mpc-system/api/grpc/coordinator/v1/session_coordinator.pb.go

@@ -33,8 +33,10 @@ type CreateSessionRequest struct {
 	PartyComposition *PartyComposition      `protobuf:"bytes,7,opt,name=party_composition,json=partyComposition,proto3" json:"party_composition,omitempty"`    // Optional: party composition requirements for auto-selection
 	// For sign sessions with delegate party: user must provide their encrypted share
 	DelegateUserShare *DelegateUserShare `protobuf:"bytes,8,opt,name=delegate_user_share,json=delegateUserShare,proto3" json:"delegate_user_share,omitempty"`
-	unknownFields     protoimpl.UnknownFields
+	// For sign sessions: which keygen session's shares to use
-	sizeCache         protoimpl.SizeCache
+	KeygenSessionId string `protobuf:"bytes,9,opt,name=keygen_session_id,json=keygenSessionId,proto3" json:"keygen_session_id,omitempty"`
+	unknownFields   protoimpl.UnknownFields
+	sizeCache       protoimpl.SizeCache
 }
 
 func (x *CreateSessionRequest) Reset() {
@@ -123,6 +125,13 @@ func (x *CreateSessionRequest) GetDelegateUserShare() *DelegateUserShare {
 	return nil
 }
 
+func (x *CreateSessionRequest) GetKeygenSessionId() string {
+	if x != nil {
+		return x.KeygenSessionId
+	}
+	return ""
+}
+
 // DelegateUserShare contains user's share for delegate party to use in signing
 type DelegateUserShare struct {
 	state           protoimpl.MessageState `protogen:"open.v1"`
@@ -584,15 +593,17 @@ func (x *JoinSessionResponse) GetPartyIndex() int32 {
 
 // SessionInfo contains session information
 type SessionInfo struct {
-	state         protoimpl.MessageState `protogen:"open.v1"`
+	state       protoimpl.MessageState `protogen:"open.v1"`
-	SessionId     string                 `protobuf:"bytes,1,opt,name=session_id,json=sessionId,proto3" json:"session_id,omitempty"`
+	SessionId   string                 `protobuf:"bytes,1,opt,name=session_id,json=sessionId,proto3" json:"session_id,omitempty"`
-	SessionType   string                 `protobuf:"bytes,2,opt,name=session_type,json=sessionType,proto3" json:"session_type,omitempty"`
+	SessionType string                 `protobuf:"bytes,2,opt,name=session_type,json=sessionType,proto3" json:"session_type,omitempty"`
-	ThresholdN    int32                  `protobuf:"varint,3,opt,name=threshold_n,json=thresholdN,proto3" json:"threshold_n,omitempty"`
+	ThresholdN  int32                  `protobuf:"varint,3,opt,name=threshold_n,json=thresholdN,proto3" json:"threshold_n,omitempty"`
-	ThresholdT    int32                  `protobuf:"varint,4,opt,name=threshold_t,json=thresholdT,proto3" json:"threshold_t,omitempty"`
+	ThresholdT  int32                  `protobuf:"varint,4,opt,name=threshold_t,json=thresholdT,proto3" json:"threshold_t,omitempty"`
-	MessageHash   []byte                 `protobuf:"bytes,5,opt,name=message_hash,json=messageHash,proto3" json:"message_hash,omitempty"`
+	MessageHash []byte                 `protobuf:"bytes,5,opt,name=message_hash,json=messageHash,proto3" json:"message_hash,omitempty"`
-	Status        string                 `protobuf:"bytes,6,opt,name=status,proto3" json:"status,omitempty"`
+	Status      string                 `protobuf:"bytes,6,opt,name=status,proto3" json:"status,omitempty"`
-	unknownFields protoimpl.UnknownFields
+	// For sign sessions: which keygen session's shares to use
-	sizeCache     protoimpl.SizeCache
+	KeygenSessionId string `protobuf:"bytes,7,opt,name=keygen_session_id,json=keygenSessionId,proto3" json:"keygen_session_id,omitempty"`
+	unknownFields   protoimpl.UnknownFields
+	sizeCache       protoimpl.SizeCache
 }
 
 func (x *SessionInfo) Reset() {
@@ -667,6 +678,13 @@ func (x *SessionInfo) GetStatus() string {
 	return ""
 }
 
+func (x *SessionInfo) GetKeygenSessionId() string {
+	if x != nil {
+		return x.KeygenSessionId
+	}
+	return ""
+}
+
 // PartyInfo contains party information
 type PartyInfo struct {
 	state         protoimpl.MessageState `protogen:"open.v1"`
@@ -1497,7 +1515,7 @@ var File_api_proto_session_coordinator_proto protoreflect.FileDescriptor
 
 const file_api_proto_session_coordinator_proto_rawDesc = "" +
 	"\n" +
-	"#api/proto/session_coordinator.proto\x12\x12mpc.coordinator.v1\"\xbf\x03\n" +
+	"#api/proto/session_coordinator.proto\x12\x12mpc.coordinator.v1\"\xeb\x03\n" +
 	"\x14CreateSessionRequest\x12!\n" +
 	"\fsession_type\x18\x01 \x01(\tR\vsessionType\x12\x1f\n" +
 	"\vthreshold_n\x18\x02 \x01(\x05R\n" +
@@ -1508,7 +1526,8 @@ const file_api_proto_session_coordinator_proto_rawDesc = "" +
 	"\fmessage_hash\x18\x05 \x01(\fR\vmessageHash\x12,\n" +
 	"\x12expires_in_seconds\x18\x06 \x01(\x03R\x10expiresInSeconds\x12Q\n" +
 	"\x11party_composition\x18\a \x01(\v2$.mpc.coordinator.v1.PartyCompositionR\x10partyComposition\x12U\n" +
-	"\x13delegate_user_share\x18\b \x01(\v2%.mpc.coordinator.v1.DelegateUserShareR\x11delegateUserShare\"\x89\x01\n" +
+	"\x13delegate_user_share\x18\b \x01(\v2%.mpc.coordinator.v1.DelegateUserShareR\x11delegateUserShare\x12*\n" +
+	"\x11keygen_session_id\x18\t \x01(\tR\x0fkeygenSessionId\"\x89\x01\n" +
 	"\x11DelegateUserShare\x12*\n" +
 	"\x11delegate_party_id\x18\x01 \x01(\tR\x0fdelegatePartyId\x12'\n" +
 	"\x0fencrypted_share\x18\x02 \x01(\fR\x0eencryptedShare\x12\x1f\n" +
@@ -1555,7 +1574,7 @@ const file_api_proto_session_coordinator_proto_rawDesc = "" +
 	"\fsession_info\x18\x02 \x01(\v2\x1f.mpc.coordinator.v1.SessionInfoR\vsessionInfo\x12B\n" +
 	"\rother_parties\x18\x03 \x03(\v2\x1d.mpc.coordinator.v1.PartyInfoR\fotherParties\x12\x1f\n" +
 	"\vparty_index\x18\x04 \x01(\x05R\n" +
-	"partyIndex\"\xcc\x01\n" +
+	"partyIndex\"\xf8\x01\n" +
 	"\vSessionInfo\x12\x1d\n" +
 	"\n" +
 	"session_id\x18\x01 \x01(\tR\tsessionId\x12!\n" +
@@ -1565,7 +1584,8 @@ const file_api_proto_session_coordinator_proto_rawDesc = "" +
 	"\vthreshold_t\x18\x04 \x01(\x05R\n" +
 	"thresholdT\x12!\n" +
 	"\fmessage_hash\x18\x05 \x01(\fR\vmessageHash\x12\x16\n" +
-	"\x06status\x18\x06 \x01(\tR\x06status\"\x88\x01\n" +
+	"\x06status\x18\x06 \x01(\tR\x06status\x12*\n" +
+	"\x11keygen_session_id\x18\a \x01(\tR\x0fkeygenSessionId\"\x88\x01\n" +
 	"\tPartyInfo\x12\x19\n" +
 	"\bparty_id\x18\x01 \x01(\tR\apartyId\x12\x1f\n" +
 	"\vparty_index\x18\x02 \x01(\x05R\n" +

backend/mpc-system/api/grpc/router/v1/message_router.pb.go

@@ -1716,15 +1716,16 @@ func (x *PartyInfo) GetDeviceInfo() *DeviceInfo {
 
 // SessionInfo contains session information
 type SessionInfo struct {
-	state         protoimpl.MessageState `protogen:"open.v1"`
+	state           protoimpl.MessageState `protogen:"open.v1"`
-	SessionId     string                 `protobuf:"bytes,1,opt,name=session_id,json=sessionId,proto3" json:"session_id,omitempty"`
+	SessionId       string                 `protobuf:"bytes,1,opt,name=session_id,json=sessionId,proto3" json:"session_id,omitempty"`
-	SessionType   string                 `protobuf:"bytes,2,opt,name=session_type,json=sessionType,proto3" json:"session_type,omitempty"` // keygen, sign
+	SessionType     string                 `protobuf:"bytes,2,opt,name=session_type,json=sessionType,proto3" json:"session_type,omitempty"` // keygen, sign
-	ThresholdN    int32                  `protobuf:"varint,3,opt,name=threshold_n,json=thresholdN,proto3" json:"threshold_n,omitempty"`
+	ThresholdN      int32                  `protobuf:"varint,3,opt,name=threshold_n,json=thresholdN,proto3" json:"threshold_n,omitempty"`
-	ThresholdT    int32                  `protobuf:"varint,4,opt,name=threshold_t,json=thresholdT,proto3" json:"threshold_t,omitempty"`
+	ThresholdT      int32                  `protobuf:"varint,4,opt,name=threshold_t,json=thresholdT,proto3" json:"threshold_t,omitempty"`
-	MessageHash   []byte                 `protobuf:"bytes,5,opt,name=message_hash,json=messageHash,proto3" json:"message_hash,omitempty"` // For sign sessions
+	MessageHash     []byte                 `protobuf:"bytes,5,opt,name=message_hash,json=messageHash,proto3" json:"message_hash,omitempty"` // For sign sessions
-	Status        string                 `protobuf:"bytes,6,opt,name=status,proto3" json:"status,omitempty"`
+	Status          string                 `protobuf:"bytes,6,opt,name=status,proto3" json:"status,omitempty"`
-	unknownFields protoimpl.UnknownFields
+	KeygenSessionId string                 `protobuf:"bytes,7,opt,name=keygen_session_id,json=keygenSessionId,proto3" json:"keygen_session_id,omitempty"` // For sign sessions: which keygen session's shares to use
-	sizeCache     protoimpl.SizeCache
+	unknownFields   protoimpl.UnknownFields
+	sizeCache       protoimpl.SizeCache
 }
 
 func (x *SessionInfo) Reset() {
@@ -1799,6 +1800,13 @@ func (x *SessionInfo) GetStatus() string {
 	return ""
 }
 
+func (x *SessionInfo) GetKeygenSessionId() string {
+	if x != nil {
+		return x.KeygenSessionId
+	}
+	return ""
+}
+
 // JoinSessionRequest joins a session
 type JoinSessionRequest struct {
 	state         protoimpl.MessageState `protogen:"open.v1"`
@@ -2574,7 +2582,7 @@ const file_api_proto_message_router_proto_rawDesc = "" +
 	"\vparty_index\x18\x02 \x01(\x05R\n" +
 	"partyIndex\x12:\n" +
 	"\vdevice_info\x18\x03 \x01(\v2\x19.mpc.router.v1.DeviceInfoR\n" +
-	"deviceInfo\"\xcc\x01\n" +
+	"deviceInfo\"\xf8\x01\n" +
 	"\vSessionInfo\x12\x1d\n" +
 	"\n" +
 	"session_id\x18\x01 \x01(\tR\tsessionId\x12!\n" +
@@ -2584,7 +2592,8 @@ const file_api_proto_message_router_proto_rawDesc = "" +
 	"\vthreshold_t\x18\x04 \x01(\x05R\n" +
 	"thresholdT\x12!\n" +
 	"\fmessage_hash\x18\x05 \x01(\fR\vmessageHash\x12\x16\n" +
-	"\x06status\x18\x06 \x01(\tR\x06status\"\xa9\x01\n" +
+	"\x06status\x18\x06 \x01(\tR\x06status\x12*\n" +
+	"\x11keygen_session_id\x18\a \x01(\tR\x0fkeygenSessionId\"\xa9\x01\n" +
 	"\x12JoinSessionRequest\x12\x1d\n" +
 	"\n" +
 	"session_id\x18\x01 \x01(\tR\tsessionId\x12\x19\n" +

backend/mpc-system/api/proto/message_router.proto

@@ -286,6 +286,7 @@ message SessionInfo {
   int32 threshold_t = 4;
   bytes message_hash = 5;                    // For sign sessions
   string status = 6;
+  string keygen_session_id = 7;              // For sign sessions: which keygen session's shares to use
 }
 
 // JoinSessionRequest joins a session

backend/mpc-system/api/proto/message_router_grpc.pb.go

@@ -0,0 +1,700 @@
+// Code generated by protoc-gen-go-grpc. DO NOT EDIT.
+// versions:
+// - protoc-gen-go-grpc v1.6.0
+// - protoc             v6.33.1
+// source: api/proto/message_router.proto
+
+package router
+
+import (
+	context "context"
+	grpc "google.golang.org/grpc"
+	codes "google.golang.org/grpc/codes"
+	status "google.golang.org/grpc/status"
+)
+
+// This is a compile-time assertion to ensure that this generated file
+// is compatible with the grpc package it is being compiled against.
+// Requires gRPC-Go v1.64.0 or later.
+const _ = grpc.SupportPackageIsVersion9
+
+const (
+	MessageRouter_RouteMessage_FullMethodName           = "/mpc.router.v1.MessageRouter/RouteMessage"
+	MessageRouter_SubscribeMessages_FullMethodName      = "/mpc.router.v1.MessageRouter/SubscribeMessages"
+	MessageRouter_GetPendingMessages_FullMethodName     = "/mpc.router.v1.MessageRouter/GetPendingMessages"
+	MessageRouter_AcknowledgeMessage_FullMethodName     = "/mpc.router.v1.MessageRouter/AcknowledgeMessage"
+	MessageRouter_GetMessageStatus_FullMethodName       = "/mpc.router.v1.MessageRouter/GetMessageStatus"
+	MessageRouter_RegisterParty_FullMethodName          = "/mpc.router.v1.MessageRouter/RegisterParty"
+	MessageRouter_Heartbeat_FullMethodName              = "/mpc.router.v1.MessageRouter/Heartbeat"
+	MessageRouter_SubscribeSessionEvents_FullMethodName = "/mpc.router.v1.MessageRouter/SubscribeSessionEvents"
+	MessageRouter_PublishSessionEvent_FullMethodName    = "/mpc.router.v1.MessageRouter/PublishSessionEvent"
+	MessageRouter_GetRegisteredParties_FullMethodName   = "/mpc.router.v1.MessageRouter/GetRegisteredParties"
+	MessageRouter_JoinSession_FullMethodName            = "/mpc.router.v1.MessageRouter/JoinSession"
+	MessageRouter_MarkPartyReady_FullMethodName         = "/mpc.router.v1.MessageRouter/MarkPartyReady"
+	MessageRouter_ReportCompletion_FullMethodName       = "/mpc.router.v1.MessageRouter/ReportCompletion"
+	MessageRouter_GetSessionStatus_FullMethodName       = "/mpc.router.v1.MessageRouter/GetSessionStatus"
+	MessageRouter_SubmitDelegateShare_FullMethodName    = "/mpc.router.v1.MessageRouter/SubmitDelegateShare"
+)
+
+// MessageRouterClient is the client API for MessageRouter service.
+//
+// For semantics around ctx use and closing/ending streaming RPCs, please refer to https://pkg.go.dev/google.golang.org/grpc/?tab=doc#ClientConn.NewStream.
+//
+// MessageRouter service handles MPC message routing
+// This is the ONLY service that server-parties need to connect to.
+// All session operations are proxied through Message Router to Session Coordinator.
+type MessageRouterClient interface {
+	// RouteMessage routes a message from one party to others
+	RouteMessage(ctx context.Context, in *RouteMessageRequest, opts ...grpc.CallOption) (*RouteMessageResponse, error)
+	// SubscribeMessages subscribes to messages for a party (streaming)
+	SubscribeMessages(ctx context.Context, in *SubscribeMessagesRequest, opts ...grpc.CallOption) (grpc.ServerStreamingClient[MPCMessage], error)
+	// GetPendingMessages retrieves pending messages (polling alternative)
+	GetPendingMessages(ctx context.Context, in *GetPendingMessagesRequest, opts ...grpc.CallOption) (*GetPendingMessagesResponse, error)
+	// AcknowledgeMessage acknowledges receipt of a message
+	// Must be called after processing a message to confirm delivery
+	AcknowledgeMessage(ctx context.Context, in *AcknowledgeMessageRequest, opts ...grpc.CallOption) (*AcknowledgeMessageResponse, error)
+	// GetMessageStatus gets the delivery status of a message
+	GetMessageStatus(ctx context.Context, in *GetMessageStatusRequest, opts ...grpc.CallOption) (*GetMessageStatusResponse, error)
+	// RegisterParty registers a party with the message router (party actively connects)
+	RegisterParty(ctx context.Context, in *RegisterPartyRequest, opts ...grpc.CallOption) (*RegisterPartyResponse, error)
+	// Heartbeat sends a heartbeat to keep the party alive
+	Heartbeat(ctx context.Context, in *HeartbeatRequest, opts ...grpc.CallOption) (*HeartbeatResponse, error)
+	// SubscribeSessionEvents subscribes to session lifecycle events (session start, etc.)
+	SubscribeSessionEvents(ctx context.Context, in *SubscribeSessionEventsRequest, opts ...grpc.CallOption) (grpc.ServerStreamingClient[SessionEvent], error)
+	// PublishSessionEvent publishes a session event (called by Session Coordinator)
+	PublishSessionEvent(ctx context.Context, in *PublishSessionEventRequest, opts ...grpc.CallOption) (*PublishSessionEventResponse, error)
+	// GetRegisteredParties returns all registered parties (for Session Coordinator party discovery)
+	GetRegisteredParties(ctx context.Context, in *GetRegisteredPartiesRequest, opts ...grpc.CallOption) (*GetRegisteredPartiesResponse, error)
+	// JoinSession joins a session (proxied to Session Coordinator)
+	JoinSession(ctx context.Context, in *JoinSessionRequest, opts ...grpc.CallOption) (*JoinSessionResponse, error)
+	// MarkPartyReady marks a party as ready (proxied to Session Coordinator)
+	MarkPartyReady(ctx context.Context, in *MarkPartyReadyRequest, opts ...grpc.CallOption) (*MarkPartyReadyResponse, error)
+	// ReportCompletion reports completion (proxied to Session Coordinator)
+	ReportCompletion(ctx context.Context, in *ReportCompletionRequest, opts ...grpc.CallOption) (*ReportCompletionResponse, error)
+	// GetSessionStatus gets session status (proxied to Session Coordinator)
+	GetSessionStatus(ctx context.Context, in *GetSessionStatusRequest, opts ...grpc.CallOption) (*GetSessionStatusResponse, error)
+	// SubmitDelegateShare submits user's share from delegate party (proxied to Session Coordinator)
+	SubmitDelegateShare(ctx context.Context, in *SubmitDelegateShareRequest, opts ...grpc.CallOption) (*SubmitDelegateShareResponse, error)
+}
+
+type messageRouterClient struct {
+	cc grpc.ClientConnInterface
+}
+
+func NewMessageRouterClient(cc grpc.ClientConnInterface) MessageRouterClient {
+	return &messageRouterClient{cc}
+}
+
+func (c *messageRouterClient) RouteMessage(ctx context.Context, in *RouteMessageRequest, opts ...grpc.CallOption) (*RouteMessageResponse, error) {
+	cOpts := append([]grpc.CallOption{grpc.StaticMethod()}, opts...)
+	out := new(RouteMessageResponse)
+	err := c.cc.Invoke(ctx, MessageRouter_RouteMessage_FullMethodName, in, out, cOpts...)
+	if err != nil {
+		return nil, err
+	}
+	return out, nil
+}
+
+func (c *messageRouterClient) SubscribeMessages(ctx context.Context, in *SubscribeMessagesRequest, opts ...grpc.CallOption) (grpc.ServerStreamingClient[MPCMessage], error) {
+	cOpts := append([]grpc.CallOption{grpc.StaticMethod()}, opts...)
+	stream, err := c.cc.NewStream(ctx, &MessageRouter_ServiceDesc.Streams[0], MessageRouter_SubscribeMessages_FullMethodName, cOpts...)
+	if err != nil {
+		return nil, err
+	}
+	x := &grpc.GenericClientStream[SubscribeMessagesRequest, MPCMessage]{ClientStream: stream}
+	if err := x.ClientStream.SendMsg(in); err != nil {
+		return nil, err
+	}
+	if err := x.ClientStream.CloseSend(); err != nil {
+		return nil, err
+	}
+	return x, nil
+}
+
+// This type alias is provided for backwards compatibility with existing code that references the prior non-generic stream type by name.
+type MessageRouter_SubscribeMessagesClient = grpc.ServerStreamingClient[MPCMessage]
+
+func (c *messageRouterClient) GetPendingMessages(ctx context.Context, in *GetPendingMessagesRequest, opts ...grpc.CallOption) (*GetPendingMessagesResponse, error) {
+	cOpts := append([]grpc.CallOption{grpc.StaticMethod()}, opts...)
+	out := new(GetPendingMessagesResponse)
+	err := c.cc.Invoke(ctx, MessageRouter_GetPendingMessages_FullMethodName, in, out, cOpts...)
+	if err != nil {
+		return nil, err
+	}
+	return out, nil
+}
+
+func (c *messageRouterClient) AcknowledgeMessage(ctx context.Context, in *AcknowledgeMessageRequest, opts ...grpc.CallOption) (*AcknowledgeMessageResponse, error) {
+	cOpts := append([]grpc.CallOption{grpc.StaticMethod()}, opts...)
+	out := new(AcknowledgeMessageResponse)
+	err := c.cc.Invoke(ctx, MessageRouter_AcknowledgeMessage_FullMethodName, in, out, cOpts...)
+	if err != nil {
+		return nil, err
+	}
+	return out, nil
+}
+
+func (c *messageRouterClient) GetMessageStatus(ctx context.Context, in *GetMessageStatusRequest, opts ...grpc.CallOption) (*GetMessageStatusResponse, error) {
+	cOpts := append([]grpc.CallOption{grpc.StaticMethod()}, opts...)
+	out := new(GetMessageStatusResponse)
+	err := c.cc.Invoke(ctx, MessageRouter_GetMessageStatus_FullMethodName, in, out, cOpts...)
+	if err != nil {
+		return nil, err
+	}
+	return out, nil
+}
+
+func (c *messageRouterClient) RegisterParty(ctx context.Context, in *RegisterPartyRequest, opts ...grpc.CallOption) (*RegisterPartyResponse, error) {
+	cOpts := append([]grpc.CallOption{grpc.StaticMethod()}, opts...)
+	out := new(RegisterPartyResponse)
+	err := c.cc.Invoke(ctx, MessageRouter_RegisterParty_FullMethodName, in, out, cOpts...)
+	if err != nil {
+		return nil, err
+	}
+	return out, nil
+}
+
+func (c *messageRouterClient) Heartbeat(ctx context.Context, in *HeartbeatRequest, opts ...grpc.CallOption) (*HeartbeatResponse, error) {
+	cOpts := append([]grpc.CallOption{grpc.StaticMethod()}, opts...)
+	out := new(HeartbeatResponse)
+	err := c.cc.Invoke(ctx, MessageRouter_Heartbeat_FullMethodName, in, out, cOpts...)
+	if err != nil {
+		return nil, err
+	}
+	return out, nil
+}
+
+func (c *messageRouterClient) SubscribeSessionEvents(ctx context.Context, in *SubscribeSessionEventsRequest, opts ...grpc.CallOption) (grpc.ServerStreamingClient[SessionEvent], error) {
+	cOpts := append([]grpc.CallOption{grpc.StaticMethod()}, opts...)
+	stream, err := c.cc.NewStream(ctx, &MessageRouter_ServiceDesc.Streams[1], MessageRouter_SubscribeSessionEvents_FullMethodName, cOpts...)
+	if err != nil {
+		return nil, err
+	}
+	x := &grpc.GenericClientStream[SubscribeSessionEventsRequest, SessionEvent]{ClientStream: stream}
+	if err := x.ClientStream.SendMsg(in); err != nil {
+		return nil, err
+	}
+	if err := x.ClientStream.CloseSend(); err != nil {
+		return nil, err
+	}
+	return x, nil
+}
+
+// This type alias is provided for backwards compatibility with existing code that references the prior non-generic stream type by name.
+type MessageRouter_SubscribeSessionEventsClient = grpc.ServerStreamingClient[SessionEvent]
+
+func (c *messageRouterClient) PublishSessionEvent(ctx context.Context, in *PublishSessionEventRequest, opts ...grpc.CallOption) (*PublishSessionEventResponse, error) {
+	cOpts := append([]grpc.CallOption{grpc.StaticMethod()}, opts...)
+	out := new(PublishSessionEventResponse)
+	err := c.cc.Invoke(ctx, MessageRouter_PublishSessionEvent_FullMethodName, in, out, cOpts...)
+	if err != nil {
+		return nil, err
+	}
+	return out, nil
+}
+
+func (c *messageRouterClient) GetRegisteredParties(ctx context.Context, in *GetRegisteredPartiesRequest, opts ...grpc.CallOption) (*GetRegisteredPartiesResponse, error) {
+	cOpts := append([]grpc.CallOption{grpc.StaticMethod()}, opts...)
+	out := new(GetRegisteredPartiesResponse)
+	err := c.cc.Invoke(ctx, MessageRouter_GetRegisteredParties_FullMethodName, in, out, cOpts...)
+	if err != nil {
+		return nil, err
+	}
+	return out, nil
+}
+
+func (c *messageRouterClient) JoinSession(ctx context.Context, in *JoinSessionRequest, opts ...grpc.CallOption) (*JoinSessionResponse, error) {
+	cOpts := append([]grpc.CallOption{grpc.StaticMethod()}, opts...)
+	out := new(JoinSessionResponse)
+	err := c.cc.Invoke(ctx, MessageRouter_JoinSession_FullMethodName, in, out, cOpts...)
+	if err != nil {
+		return nil, err
+	}
+	return out, nil
+}
+
+func (c *messageRouterClient) MarkPartyReady(ctx context.Context, in *MarkPartyReadyRequest, opts ...grpc.CallOption) (*MarkPartyReadyResponse, error) {
+	cOpts := append([]grpc.CallOption{grpc.StaticMethod()}, opts...)
+	out := new(MarkPartyReadyResponse)
+	err := c.cc.Invoke(ctx, MessageRouter_MarkPartyReady_FullMethodName, in, out, cOpts...)
+	if err != nil {
+		return nil, err
+	}
+	return out, nil
+}
+
+func (c *messageRouterClient) ReportCompletion(ctx context.Context, in *ReportCompletionRequest, opts ...grpc.CallOption) (*ReportCompletionResponse, error) {
+	cOpts := append([]grpc.CallOption{grpc.StaticMethod()}, opts...)
+	out := new(ReportCompletionResponse)
+	err := c.cc.Invoke(ctx, MessageRouter_ReportCompletion_FullMethodName, in, out, cOpts...)
+	if err != nil {
+		return nil, err
+	}
+	return out, nil
+}
+
+func (c *messageRouterClient) GetSessionStatus(ctx context.Context, in *GetSessionStatusRequest, opts ...grpc.CallOption) (*GetSessionStatusResponse, error) {
+	cOpts := append([]grpc.CallOption{grpc.StaticMethod()}, opts...)
+	out := new(GetSessionStatusResponse)
+	err := c.cc.Invoke(ctx, MessageRouter_GetSessionStatus_FullMethodName, in, out, cOpts...)
+	if err != nil {
+		return nil, err
+	}
+	return out, nil
+}
+
+func (c *messageRouterClient) SubmitDelegateShare(ctx context.Context, in *SubmitDelegateShareRequest, opts ...grpc.CallOption) (*SubmitDelegateShareResponse, error) {
+	cOpts := append([]grpc.CallOption{grpc.StaticMethod()}, opts...)
+	out := new(SubmitDelegateShareResponse)
+	err := c.cc.Invoke(ctx, MessageRouter_SubmitDelegateShare_FullMethodName, in, out, cOpts...)
+	if err != nil {
+		return nil, err
+	}
+	return out, nil
+}
+
+// MessageRouterServer is the server API for MessageRouter service.
+// All implementations must embed UnimplementedMessageRouterServer
+// for forward compatibility.
+//
+// MessageRouter service handles MPC message routing
+// This is the ONLY service that server-parties need to connect to.
+// All session operations are proxied through Message Router to Session Coordinator.
+type MessageRouterServer interface {
+	// RouteMessage routes a message from one party to others
+	RouteMessage(context.Context, *RouteMessageRequest) (*RouteMessageResponse, error)
+	// SubscribeMessages subscribes to messages for a party (streaming)
+	SubscribeMessages(*SubscribeMessagesRequest, grpc.ServerStreamingServer[MPCMessage]) error
+	// GetPendingMessages retrieves pending messages (polling alternative)
+	GetPendingMessages(context.Context, *GetPendingMessagesRequest) (*GetPendingMessagesResponse, error)
+	// AcknowledgeMessage acknowledges receipt of a message
+	// Must be called after processing a message to confirm delivery
+	AcknowledgeMessage(context.Context, *AcknowledgeMessageRequest) (*AcknowledgeMessageResponse, error)
+	// GetMessageStatus gets the delivery status of a message
+	GetMessageStatus(context.Context, *GetMessageStatusRequest) (*GetMessageStatusResponse, error)
+	// RegisterParty registers a party with the message router (party actively connects)
+	RegisterParty(context.Context, *RegisterPartyRequest) (*RegisterPartyResponse, error)
+	// Heartbeat sends a heartbeat to keep the party alive
+	Heartbeat(context.Context, *HeartbeatRequest) (*HeartbeatResponse, error)
+	// SubscribeSessionEvents subscribes to session lifecycle events (session start, etc.)
+	SubscribeSessionEvents(*SubscribeSessionEventsRequest, grpc.ServerStreamingServer[SessionEvent]) error
+	// PublishSessionEvent publishes a session event (called by Session Coordinator)
+	PublishSessionEvent(context.Context, *PublishSessionEventRequest) (*PublishSessionEventResponse, error)
+	// GetRegisteredParties returns all registered parties (for Session Coordinator party discovery)
+	GetRegisteredParties(context.Context, *GetRegisteredPartiesRequest) (*GetRegisteredPartiesResponse, error)
+	// JoinSession joins a session (proxied to Session Coordinator)
+	JoinSession(context.Context, *JoinSessionRequest) (*JoinSessionResponse, error)
+	// MarkPartyReady marks a party as ready (proxied to Session Coordinator)
+	MarkPartyReady(context.Context, *MarkPartyReadyRequest) (*MarkPartyReadyResponse, error)
+	// ReportCompletion reports completion (proxied to Session Coordinator)
+	ReportCompletion(context.Context, *ReportCompletionRequest) (*ReportCompletionResponse, error)
+	// GetSessionStatus gets session status (proxied to Session Coordinator)
+	GetSessionStatus(context.Context, *GetSessionStatusRequest) (*GetSessionStatusResponse, error)
+	// SubmitDelegateShare submits user's share from delegate party (proxied to Session Coordinator)
+	SubmitDelegateShare(context.Context, *SubmitDelegateShareRequest) (*SubmitDelegateShareResponse, error)
+	mustEmbedUnimplementedMessageRouterServer()
+}
+
+// UnimplementedMessageRouterServer must be embedded to have
+// forward compatible implementations.
+//
+// NOTE: this should be embedded by value instead of pointer to avoid a nil
+// pointer dereference when methods are called.
+type UnimplementedMessageRouterServer struct{}
+
+func (UnimplementedMessageRouterServer) RouteMessage(context.Context, *RouteMessageRequest) (*RouteMessageResponse, error) {
+	return nil, status.Error(codes.Unimplemented, "method RouteMessage not implemented")
+}
+func (UnimplementedMessageRouterServer) SubscribeMessages(*SubscribeMessagesRequest, grpc.ServerStreamingServer[MPCMessage]) error {
+	return status.Error(codes.Unimplemented, "method SubscribeMessages not implemented")
+}
+func (UnimplementedMessageRouterServer) GetPendingMessages(context.Context, *GetPendingMessagesRequest) (*GetPendingMessagesResponse, error) {
+	return nil, status.Error(codes.Unimplemented, "method GetPendingMessages not implemented")
+}
+func (UnimplementedMessageRouterServer) AcknowledgeMessage(context.Context, *AcknowledgeMessageRequest) (*AcknowledgeMessageResponse, error) {
+	return nil, status.Error(codes.Unimplemented, "method AcknowledgeMessage not implemented")
+}
+func (UnimplementedMessageRouterServer) GetMessageStatus(context.Context, *GetMessageStatusRequest) (*GetMessageStatusResponse, error) {
+	return nil, status.Error(codes.Unimplemented, "method GetMessageStatus not implemented")
+}
+func (UnimplementedMessageRouterServer) RegisterParty(context.Context, *RegisterPartyRequest) (*RegisterPartyResponse, error) {
+	return nil, status.Error(codes.Unimplemented, "method RegisterParty not implemented")
+}
+func (UnimplementedMessageRouterServer) Heartbeat(context.Context, *HeartbeatRequest) (*HeartbeatResponse, error) {
+	return nil, status.Error(codes.Unimplemented, "method Heartbeat not implemented")
+}
+func (UnimplementedMessageRouterServer) SubscribeSessionEvents(*SubscribeSessionEventsRequest, grpc.ServerStreamingServer[SessionEvent]) error {
+	return status.Error(codes.Unimplemented, "method SubscribeSessionEvents not implemented")
+}
+func (UnimplementedMessageRouterServer) PublishSessionEvent(context.Context, *PublishSessionEventRequest) (*PublishSessionEventResponse, error) {
+	return nil, status.Error(codes.Unimplemented, "method PublishSessionEvent not implemented")
+}
+func (UnimplementedMessageRouterServer) GetRegisteredParties(context.Context, *GetRegisteredPartiesRequest) (*GetRegisteredPartiesResponse, error) {
+	return nil, status.Error(codes.Unimplemented, "method GetRegisteredParties not implemented")
+}
+func (UnimplementedMessageRouterServer) JoinSession(context.Context, *JoinSessionRequest) (*JoinSessionResponse, error) {
+	return nil, status.Error(codes.Unimplemented, "method JoinSession not implemented")
+}
+func (UnimplementedMessageRouterServer) MarkPartyReady(context.Context, *MarkPartyReadyRequest) (*MarkPartyReadyResponse, error) {
+	return nil, status.Error(codes.Unimplemented, "method MarkPartyReady not implemented")
+}
+func (UnimplementedMessageRouterServer) ReportCompletion(context.Context, *ReportCompletionRequest) (*ReportCompletionResponse, error) {
+	return nil, status.Error(codes.Unimplemented, "method ReportCompletion not implemented")
+}
+func (UnimplementedMessageRouterServer) GetSessionStatus(context.Context, *GetSessionStatusRequest) (*GetSessionStatusResponse, error) {
+	return nil, status.Error(codes.Unimplemented, "method GetSessionStatus not implemented")
+}
+func (UnimplementedMessageRouterServer) SubmitDelegateShare(context.Context, *SubmitDelegateShareRequest) (*SubmitDelegateShareResponse, error) {
+	return nil, status.Error(codes.Unimplemented, "method SubmitDelegateShare not implemented")
+}
+func (UnimplementedMessageRouterServer) mustEmbedUnimplementedMessageRouterServer() {}
+func (UnimplementedMessageRouterServer) testEmbeddedByValue()                       {}
+
+// UnsafeMessageRouterServer may be embedded to opt out of forward compatibility for this service.
+// Use of this interface is not recommended, as added methods to MessageRouterServer will
+// result in compilation errors.
+type UnsafeMessageRouterServer interface {
+	mustEmbedUnimplementedMessageRouterServer()
+}
+
+func RegisterMessageRouterServer(s grpc.ServiceRegistrar, srv MessageRouterServer) {
+	// If the following call panics, it indicates UnimplementedMessageRouterServer was
+	// embedded by pointer and is nil.  This will cause panics if an
+	// unimplemented method is ever invoked, so we test this at initialization
+	// time to prevent it from happening at runtime later due to I/O.
+	if t, ok := srv.(interface{ testEmbeddedByValue() }); ok {
+		t.testEmbeddedByValue()
+	}
+	s.RegisterService(&MessageRouter_ServiceDesc, srv)
+}
+
+func _MessageRouter_RouteMessage_Handler(srv interface{}, ctx context.Context, dec func(interface{}) error, interceptor grpc.UnaryServerInterceptor) (interface{}, error) {
+	in := new(RouteMessageRequest)
+	if err := dec(in); err != nil {
+		return nil, err
+	}
+	if interceptor == nil {
+		return srv.(MessageRouterServer).RouteMessage(ctx, in)
+	}
+	info := &grpc.UnaryServerInfo{
+		Server:     srv,
+		FullMethod: MessageRouter_RouteMessage_FullMethodName,
+	}
+	handler := func(ctx context.Context, req interface{}) (interface{}, error) {
+		return srv.(MessageRouterServer).RouteMessage(ctx, req.(*RouteMessageRequest))
+	}
+	return interceptor(ctx, in, info, handler)
+}
+
+func _MessageRouter_SubscribeMessages_Handler(srv interface{}, stream grpc.ServerStream) error {
+	m := new(SubscribeMessagesRequest)
+	if err := stream.RecvMsg(m); err != nil {
+		return err
+	}
+	return srv.(MessageRouterServer).SubscribeMessages(m, &grpc.GenericServerStream[SubscribeMessagesRequest, MPCMessage]{ServerStream: stream})
+}
+
+// This type alias is provided for backwards compatibility with existing code that references the prior non-generic stream type by name.
+type MessageRouter_SubscribeMessagesServer = grpc.ServerStreamingServer[MPCMessage]
+
+func _MessageRouter_GetPendingMessages_Handler(srv interface{}, ctx context.Context, dec func(interface{}) error, interceptor grpc.UnaryServerInterceptor) (interface{}, error) {
+	in := new(GetPendingMessagesRequest)
+	if err := dec(in); err != nil {
+		return nil, err
+	}
+	if interceptor == nil {
+		return srv.(MessageRouterServer).GetPendingMessages(ctx, in)
+	}
+	info := &grpc.UnaryServerInfo{
+		Server:     srv,
+		FullMethod: MessageRouter_GetPendingMessages_FullMethodName,
+	}
+	handler := func(ctx context.Context, req interface{}) (interface{}, error) {
+		return srv.(MessageRouterServer).GetPendingMessages(ctx, req.(*GetPendingMessagesRequest))
+	}
+	return interceptor(ctx, in, info, handler)
+}
+
+func _MessageRouter_AcknowledgeMessage_Handler(srv interface{}, ctx context.Context, dec func(interface{}) error, interceptor grpc.UnaryServerInterceptor) (interface{}, error) {
+	in := new(AcknowledgeMessageRequest)
+	if err := dec(in); err != nil {
+		return nil, err
+	}
+	if interceptor == nil {
+		return srv.(MessageRouterServer).AcknowledgeMessage(ctx, in)
+	}
+	info := &grpc.UnaryServerInfo{
+		Server:     srv,
+		FullMethod: MessageRouter_AcknowledgeMessage_FullMethodName,
+	}
+	handler := func(ctx context.Context, req interface{}) (interface{}, error) {
+		return srv.(MessageRouterServer).AcknowledgeMessage(ctx, req.(*AcknowledgeMessageRequest))
+	}
+	return interceptor(ctx, in, info, handler)
+}
+
+func _MessageRouter_GetMessageStatus_Handler(srv interface{}, ctx context.Context, dec func(interface{}) error, interceptor grpc.UnaryServerInterceptor) (interface{}, error) {
+	in := new(GetMessageStatusRequest)
+	if err := dec(in); err != nil {
+		return nil, err
+	}
+	if interceptor == nil {
+		return srv.(MessageRouterServer).GetMessageStatus(ctx, in)
+	}
+	info := &grpc.UnaryServerInfo{
+		Server:     srv,
+		FullMethod: MessageRouter_GetMessageStatus_FullMethodName,
+	}
+	handler := func(ctx context.Context, req interface{}) (interface{}, error) {
+		return srv.(MessageRouterServer).GetMessageStatus(ctx, req.(*GetMessageStatusRequest))
+	}
+	return interceptor(ctx, in, info, handler)
+}
+
+func _MessageRouter_RegisterParty_Handler(srv interface{}, ctx context.Context, dec func(interface{}) error, interceptor grpc.UnaryServerInterceptor) (interface{}, error) {
+	in := new(RegisterPartyRequest)
+	if err := dec(in); err != nil {
+		return nil, err
+	}
+	if interceptor == nil {
+		return srv.(MessageRouterServer).RegisterParty(ctx, in)
+	}
+	info := &grpc.UnaryServerInfo{
+		Server:     srv,
+		FullMethod: MessageRouter_RegisterParty_FullMethodName,
+	}
+	handler := func(ctx context.Context, req interface{}) (interface{}, error) {
+		return srv.(MessageRouterServer).RegisterParty(ctx, req.(*RegisterPartyRequest))
+	}
+	return interceptor(ctx, in, info, handler)
+}
+
+func _MessageRouter_Heartbeat_Handler(srv interface{}, ctx context.Context, dec func(interface{}) error, interceptor grpc.UnaryServerInterceptor) (interface{}, error) {
+	in := new(HeartbeatRequest)
+	if err := dec(in); err != nil {
+		return nil, err
+	}
+	if interceptor == nil {
+		return srv.(MessageRouterServer).Heartbeat(ctx, in)
+	}
+	info := &grpc.UnaryServerInfo{
+		Server:     srv,
+		FullMethod: MessageRouter_Heartbeat_FullMethodName,
+	}
+	handler := func(ctx context.Context, req interface{}) (interface{}, error) {
+		return srv.(MessageRouterServer).Heartbeat(ctx, req.(*HeartbeatRequest))
+	}
+	return interceptor(ctx, in, info, handler)
+}
+
+func _MessageRouter_SubscribeSessionEvents_Handler(srv interface{}, stream grpc.ServerStream) error {
+	m := new(SubscribeSessionEventsRequest)
+	if err := stream.RecvMsg(m); err != nil {
+		return err
+	}
+	return srv.(MessageRouterServer).SubscribeSessionEvents(m, &grpc.GenericServerStream[SubscribeSessionEventsRequest, SessionEvent]{ServerStream: stream})
+}
+
+// This type alias is provided for backwards compatibility with existing code that references the prior non-generic stream type by name.
+type MessageRouter_SubscribeSessionEventsServer = grpc.ServerStreamingServer[SessionEvent]
+
+func _MessageRouter_PublishSessionEvent_Handler(srv interface{}, ctx context.Context, dec func(interface{}) error, interceptor grpc.UnaryServerInterceptor) (interface{}, error) {
+	in := new(PublishSessionEventRequest)
+	if err := dec(in); err != nil {
+		return nil, err
+	}
+	if interceptor == nil {
+		return srv.(MessageRouterServer).PublishSessionEvent(ctx, in)
+	}
+	info := &grpc.UnaryServerInfo{
+		Server:     srv,
+		FullMethod: MessageRouter_PublishSessionEvent_FullMethodName,
+	}
+	handler := func(ctx context.Context, req interface{}) (interface{}, error) {
+		return srv.(MessageRouterServer).PublishSessionEvent(ctx, req.(*PublishSessionEventRequest))
+	}
+	return interceptor(ctx, in, info, handler)
+}
+
+func _MessageRouter_GetRegisteredParties_Handler(srv interface{}, ctx context.Context, dec func(interface{}) error, interceptor grpc.UnaryServerInterceptor) (interface{}, error) {
+	in := new(GetRegisteredPartiesRequest)
+	if err := dec(in); err != nil {
+		return nil, err
+	}
+	if interceptor == nil {
+		return srv.(MessageRouterServer).GetRegisteredParties(ctx, in)
+	}
+	info := &grpc.UnaryServerInfo{
+		Server:     srv,
+		FullMethod: MessageRouter_GetRegisteredParties_FullMethodName,
+	}
+	handler := func(ctx context.Context, req interface{}) (interface{}, error) {
+		return srv.(MessageRouterServer).GetRegisteredParties(ctx, req.(*GetRegisteredPartiesRequest))
+	}
+	return interceptor(ctx, in, info, handler)
+}
+
+func _MessageRouter_JoinSession_Handler(srv interface{}, ctx context.Context, dec func(interface{}) error, interceptor grpc.UnaryServerInterceptor) (interface{}, error) {
+	in := new(JoinSessionRequest)
+	if err := dec(in); err != nil {
+		return nil, err
+	}
+	if interceptor == nil {
+		return srv.(MessageRouterServer).JoinSession(ctx, in)
+	}
+	info := &grpc.UnaryServerInfo{
+		Server:     srv,
+		FullMethod: MessageRouter_JoinSession_FullMethodName,
+	}
+	handler := func(ctx context.Context, req interface{}) (interface{}, error) {
+		return srv.(MessageRouterServer).JoinSession(ctx, req.(*JoinSessionRequest))
+	}
+	return interceptor(ctx, in, info, handler)
+}
+
+func _MessageRouter_MarkPartyReady_Handler(srv interface{}, ctx context.Context, dec func(interface{}) error, interceptor grpc.UnaryServerInterceptor) (interface{}, error) {
+	in := new(MarkPartyReadyRequest)
+	if err := dec(in); err != nil {
+		return nil, err
+	}
+	if interceptor == nil {
+		return srv.(MessageRouterServer).MarkPartyReady(ctx, in)
+	}
+	info := &grpc.UnaryServerInfo{
+		Server:     srv,
+		FullMethod: MessageRouter_MarkPartyReady_FullMethodName,
+	}
+	handler := func(ctx context.Context, req interface{}) (interface{}, error) {
+		return srv.(MessageRouterServer).MarkPartyReady(ctx, req.(*MarkPartyReadyRequest))
+	}
+	return interceptor(ctx, in, info, handler)
+}
+
+func _MessageRouter_ReportCompletion_Handler(srv interface{}, ctx context.Context, dec func(interface{}) error, interceptor grpc.UnaryServerInterceptor) (interface{}, error) {
+	in := new(ReportCompletionRequest)
+	if err := dec(in); err != nil {
+		return nil, err
+	}
+	if interceptor == nil {
+		return srv.(MessageRouterServer).ReportCompletion(ctx, in)
+	}
+	info := &grpc.UnaryServerInfo{
+		Server:     srv,
+		FullMethod: MessageRouter_ReportCompletion_FullMethodName,
+	}
+	handler := func(ctx context.Context, req interface{}) (interface{}, error) {
+		return srv.(MessageRouterServer).ReportCompletion(ctx, req.(*ReportCompletionRequest))
+	}
+	return interceptor(ctx, in, info, handler)
+}
+
+func _MessageRouter_GetSessionStatus_Handler(srv interface{}, ctx context.Context, dec func(interface{}) error, interceptor grpc.UnaryServerInterceptor) (interface{}, error) {
+	in := new(GetSessionStatusRequest)
+	if err := dec(in); err != nil {
+		return nil, err
+	}
+	if interceptor == nil {
+		return srv.(MessageRouterServer).GetSessionStatus(ctx, in)
+	}
+	info := &grpc.UnaryServerInfo{
+		Server:     srv,
+		FullMethod: MessageRouter_GetSessionStatus_FullMethodName,
+	}
+	handler := func(ctx context.Context, req interface{}) (interface{}, error) {
+		return srv.(MessageRouterServer).GetSessionStatus(ctx, req.(*GetSessionStatusRequest))
+	}
+	return interceptor(ctx, in, info, handler)
+}
+
+func _MessageRouter_SubmitDelegateShare_Handler(srv interface{}, ctx context.Context, dec func(interface{}) error, interceptor grpc.UnaryServerInterceptor) (interface{}, error) {
+	in := new(SubmitDelegateShareRequest)
+	if err := dec(in); err != nil {
+		return nil, err
+	}
+	if interceptor == nil {
+		return srv.(MessageRouterServer).SubmitDelegateShare(ctx, in)
+	}
+	info := &grpc.UnaryServerInfo{
+		Server:     srv,
+		FullMethod: MessageRouter_SubmitDelegateShare_FullMethodName,
+	}
+	handler := func(ctx context.Context, req interface{}) (interface{}, error) {
+		return srv.(MessageRouterServer).SubmitDelegateShare(ctx, req.(*SubmitDelegateShareRequest))
+	}
+	return interceptor(ctx, in, info, handler)
+}
+
+// MessageRouter_ServiceDesc is the grpc.ServiceDesc for MessageRouter service.
+// It's only intended for direct use with grpc.RegisterService,
+// and not to be introspected or modified (even as a copy)
+var MessageRouter_ServiceDesc = grpc.ServiceDesc{
+	ServiceName: "mpc.router.v1.MessageRouter",
+	HandlerType: (*MessageRouterServer)(nil),
+	Methods: []grpc.MethodDesc{
+		{
+			MethodName: "RouteMessage",
+			Handler:    _MessageRouter_RouteMessage_Handler,
+		},
+		{
+			MethodName: "GetPendingMessages",
+			Handler:    _MessageRouter_GetPendingMessages_Handler,
+		},
+		{
+			MethodName: "AcknowledgeMessage",
+			Handler:    _MessageRouter_AcknowledgeMessage_Handler,
+		},
+		{
+			MethodName: "GetMessageStatus",
+			Handler:    _MessageRouter_GetMessageStatus_Handler,
+		},
+		{
+			MethodName: "RegisterParty",
+			Handler:    _MessageRouter_RegisterParty_Handler,
+		},
+		{
+			MethodName: "Heartbeat",
+			Handler:    _MessageRouter_Heartbeat_Handler,
+		},
+		{
+			MethodName: "PublishSessionEvent",
+			Handler:    _MessageRouter_PublishSessionEvent_Handler,
+		},
+		{
+			MethodName: "GetRegisteredParties",
+			Handler:    _MessageRouter_GetRegisteredParties_Handler,
+		},
+		{
+			MethodName: "JoinSession",
+			Handler:    _MessageRouter_JoinSession_Handler,
+		},
+		{
+			MethodName: "MarkPartyReady",
+			Handler:    _MessageRouter_MarkPartyReady_Handler,
+		},
+		{
+			MethodName: "ReportCompletion",
+			Handler:    _MessageRouter_ReportCompletion_Handler,
+		},
+		{
+			MethodName: "GetSessionStatus",
+			Handler:    _MessageRouter_GetSessionStatus_Handler,
+		},
+		{
+			MethodName: "SubmitDelegateShare",
+			Handler:    _MessageRouter_SubmitDelegateShare_Handler,
+		},
+	},
+	Streams: []grpc.StreamDesc{
+		{
+			StreamName:    "SubscribeMessages",
+			Handler:       _MessageRouter_SubscribeMessages_Handler,
+			ServerStreams: true,
+		},
+		{
+			StreamName:    "SubscribeSessionEvents",
+			Handler:       _MessageRouter_SubscribeSessionEvents_Handler,
+			ServerStreams: true,
+		},
+	},
+	Metadata: "api/proto/message_router.proto",
+}

backend/mpc-system/api/proto/session_coordinator_grpc.pb.go

@@ -1,395 +0,0 @@
-// Code generated by protoc-gen-go-grpc. DO NOT EDIT.
-// versions:
-// - protoc-gen-go-grpc v1.6.0
-// - protoc             v6.33.1
-// source: api/proto/session_coordinator.proto
-
-package coordinator
-
-import (
-	context "context"
-	grpc "google.golang.org/grpc"
-	codes "google.golang.org/grpc/codes"
-	status "google.golang.org/grpc/status"
-)
-
-// This is a compile-time assertion to ensure that this generated file
-// is compatible with the grpc package it is being compiled against.
-// Requires gRPC-Go v1.64.0 or later.
-const _ = grpc.SupportPackageIsVersion9
-
-const (
-	SessionCoordinator_CreateSession_FullMethodName       = "/mpc.coordinator.v1.SessionCoordinator/CreateSession"
-	SessionCoordinator_JoinSession_FullMethodName         = "/mpc.coordinator.v1.SessionCoordinator/JoinSession"
-	SessionCoordinator_GetSessionStatus_FullMethodName    = "/mpc.coordinator.v1.SessionCoordinator/GetSessionStatus"
-	SessionCoordinator_MarkPartyReady_FullMethodName      = "/mpc.coordinator.v1.SessionCoordinator/MarkPartyReady"
-	SessionCoordinator_StartSession_FullMethodName        = "/mpc.coordinator.v1.SessionCoordinator/StartSession"
-	SessionCoordinator_ReportCompletion_FullMethodName    = "/mpc.coordinator.v1.SessionCoordinator/ReportCompletion"
-	SessionCoordinator_CloseSession_FullMethodName        = "/mpc.coordinator.v1.SessionCoordinator/CloseSession"
-	SessionCoordinator_SubmitDelegateShare_FullMethodName = "/mpc.coordinator.v1.SessionCoordinator/SubmitDelegateShare"
-)
-
-// SessionCoordinatorClient is the client API for SessionCoordinator service.
-//
-// For semantics around ctx use and closing/ending streaming RPCs, please refer to https://pkg.go.dev/google.golang.org/grpc/?tab=doc#ClientConn.NewStream.
-//
-// SessionCoordinator service manages MPC sessions
-type SessionCoordinatorClient interface {
-	// Session management
-	CreateSession(ctx context.Context, in *CreateSessionRequest, opts ...grpc.CallOption) (*CreateSessionResponse, error)
-	JoinSession(ctx context.Context, in *JoinSessionRequest, opts ...grpc.CallOption) (*JoinSessionResponse, error)
-	GetSessionStatus(ctx context.Context, in *GetSessionStatusRequest, opts ...grpc.CallOption) (*GetSessionStatusResponse, error)
-	MarkPartyReady(ctx context.Context, in *MarkPartyReadyRequest, opts ...grpc.CallOption) (*MarkPartyReadyResponse, error)
-	StartSession(ctx context.Context, in *StartSessionRequest, opts ...grpc.CallOption) (*StartSessionResponse, error)
-	ReportCompletion(ctx context.Context, in *ReportCompletionRequest, opts ...grpc.CallOption) (*ReportCompletionResponse, error)
-	CloseSession(ctx context.Context, in *CloseSessionRequest, opts ...grpc.CallOption) (*CloseSessionResponse, error)
-	// Delegate party share submission (delegate party submits user's share after keygen)
-	SubmitDelegateShare(ctx context.Context, in *SubmitDelegateShareRequest, opts ...grpc.CallOption) (*SubmitDelegateShareResponse, error)
-}
-
-type sessionCoordinatorClient struct {
-	cc grpc.ClientConnInterface
-}
-
-func NewSessionCoordinatorClient(cc grpc.ClientConnInterface) SessionCoordinatorClient {
-	return &sessionCoordinatorClient{cc}
-}
-
-func (c *sessionCoordinatorClient) CreateSession(ctx context.Context, in *CreateSessionRequest, opts ...grpc.CallOption) (*CreateSessionResponse, error) {
-	cOpts := append([]grpc.CallOption{grpc.StaticMethod()}, opts...)
-	out := new(CreateSessionResponse)
-	err := c.cc.Invoke(ctx, SessionCoordinator_CreateSession_FullMethodName, in, out, cOpts...)
-	if err != nil {
-		return nil, err
-	}
-	return out, nil
-}
-
-func (c *sessionCoordinatorClient) JoinSession(ctx context.Context, in *JoinSessionRequest, opts ...grpc.CallOption) (*JoinSessionResponse, error) {
-	cOpts := append([]grpc.CallOption{grpc.StaticMethod()}, opts...)
-	out := new(JoinSessionResponse)
-	err := c.cc.Invoke(ctx, SessionCoordinator_JoinSession_FullMethodName, in, out, cOpts...)
-	if err != nil {
-		return nil, err
-	}
-	return out, nil
-}
-
-func (c *sessionCoordinatorClient) GetSessionStatus(ctx context.Context, in *GetSessionStatusRequest, opts ...grpc.CallOption) (*GetSessionStatusResponse, error) {
-	cOpts := append([]grpc.CallOption{grpc.StaticMethod()}, opts...)
-	out := new(GetSessionStatusResponse)
-	err := c.cc.Invoke(ctx, SessionCoordinator_GetSessionStatus_FullMethodName, in, out, cOpts...)
-	if err != nil {
-		return nil, err
-	}
-	return out, nil
-}
-
-func (c *sessionCoordinatorClient) MarkPartyReady(ctx context.Context, in *MarkPartyReadyRequest, opts ...grpc.CallOption) (*MarkPartyReadyResponse, error) {
-	cOpts := append([]grpc.CallOption{grpc.StaticMethod()}, opts...)
-	out := new(MarkPartyReadyResponse)
-	err := c.cc.Invoke(ctx, SessionCoordinator_MarkPartyReady_FullMethodName, in, out, cOpts...)
-	if err != nil {
-		return nil, err
-	}
-	return out, nil
-}
-
-func (c *sessionCoordinatorClient) StartSession(ctx context.Context, in *StartSessionRequest, opts ...grpc.CallOption) (*StartSessionResponse, error) {
-	cOpts := append([]grpc.CallOption{grpc.StaticMethod()}, opts...)
-	out := new(StartSessionResponse)
-	err := c.cc.Invoke(ctx, SessionCoordinator_StartSession_FullMethodName, in, out, cOpts...)
-	if err != nil {
-		return nil, err
-	}
-	return out, nil
-}
-
-func (c *sessionCoordinatorClient) ReportCompletion(ctx context.Context, in *ReportCompletionRequest, opts ...grpc.CallOption) (*ReportCompletionResponse, error) {
-	cOpts := append([]grpc.CallOption{grpc.StaticMethod()}, opts...)
-	out := new(ReportCompletionResponse)
-	err := c.cc.Invoke(ctx, SessionCoordinator_ReportCompletion_FullMethodName, in, out, cOpts...)
-	if err != nil {
-		return nil, err
-	}
-	return out, nil
-}
-
-func (c *sessionCoordinatorClient) CloseSession(ctx context.Context, in *CloseSessionRequest, opts ...grpc.CallOption) (*CloseSessionResponse, error) {
-	cOpts := append([]grpc.CallOption{grpc.StaticMethod()}, opts...)
-	out := new(CloseSessionResponse)
-	err := c.cc.Invoke(ctx, SessionCoordinator_CloseSession_FullMethodName, in, out, cOpts...)
-	if err != nil {
-		return nil, err
-	}
-	return out, nil
-}
-
-func (c *sessionCoordinatorClient) SubmitDelegateShare(ctx context.Context, in *SubmitDelegateShareRequest, opts ...grpc.CallOption) (*SubmitDelegateShareResponse, error) {
-	cOpts := append([]grpc.CallOption{grpc.StaticMethod()}, opts...)
-	out := new(SubmitDelegateShareResponse)
-	err := c.cc.Invoke(ctx, SessionCoordinator_SubmitDelegateShare_FullMethodName, in, out, cOpts...)
-	if err != nil {
-		return nil, err
-	}
-	return out, nil
-}
-
-// SessionCoordinatorServer is the server API for SessionCoordinator service.
-// All implementations must embed UnimplementedSessionCoordinatorServer
-// for forward compatibility.
-//
-// SessionCoordinator service manages MPC sessions
-type SessionCoordinatorServer interface {
-	// Session management
-	CreateSession(context.Context, *CreateSessionRequest) (*CreateSessionResponse, error)
-	JoinSession(context.Context, *JoinSessionRequest) (*JoinSessionResponse, error)
-	GetSessionStatus(context.Context, *GetSessionStatusRequest) (*GetSessionStatusResponse, error)
-	MarkPartyReady(context.Context, *MarkPartyReadyRequest) (*MarkPartyReadyResponse, error)
-	StartSession(context.Context, *StartSessionRequest) (*StartSessionResponse, error)
-	ReportCompletion(context.Context, *ReportCompletionRequest) (*ReportCompletionResponse, error)
-	CloseSession(context.Context, *CloseSessionRequest) (*CloseSessionResponse, error)
-	// Delegate party share submission (delegate party submits user's share after keygen)
-	SubmitDelegateShare(context.Context, *SubmitDelegateShareRequest) (*SubmitDelegateShareResponse, error)
-	mustEmbedUnimplementedSessionCoordinatorServer()
-}
-
-// UnimplementedSessionCoordinatorServer must be embedded to have
-// forward compatible implementations.
-//
-// NOTE: this should be embedded by value instead of pointer to avoid a nil
-// pointer dereference when methods are called.
-type UnimplementedSessionCoordinatorServer struct{}
-
-func (UnimplementedSessionCoordinatorServer) CreateSession(context.Context, *CreateSessionRequest) (*CreateSessionResponse, error) {
-	return nil, status.Error(codes.Unimplemented, "method CreateSession not implemented")
-}
-func (UnimplementedSessionCoordinatorServer) JoinSession(context.Context, *JoinSessionRequest) (*JoinSessionResponse, error) {
-	return nil, status.Error(codes.Unimplemented, "method JoinSession not implemented")
-}
-func (UnimplementedSessionCoordinatorServer) GetSessionStatus(context.Context, *GetSessionStatusRequest) (*GetSessionStatusResponse, error) {
-	return nil, status.Error(codes.Unimplemented, "method GetSessionStatus not implemented")
-}
-func (UnimplementedSessionCoordinatorServer) MarkPartyReady(context.Context, *MarkPartyReadyRequest) (*MarkPartyReadyResponse, error) {
-	return nil, status.Error(codes.Unimplemented, "method MarkPartyReady not implemented")
-}
-func (UnimplementedSessionCoordinatorServer) StartSession(context.Context, *StartSessionRequest) (*StartSessionResponse, error) {
-	return nil, status.Error(codes.Unimplemented, "method StartSession not implemented")
-}
-func (UnimplementedSessionCoordinatorServer) ReportCompletion(context.Context, *ReportCompletionRequest) (*ReportCompletionResponse, error) {
-	return nil, status.Error(codes.Unimplemented, "method ReportCompletion not implemented")
-}
-func (UnimplementedSessionCoordinatorServer) CloseSession(context.Context, *CloseSessionRequest) (*CloseSessionResponse, error) {
-	return nil, status.Error(codes.Unimplemented, "method CloseSession not implemented")
-}
-func (UnimplementedSessionCoordinatorServer) SubmitDelegateShare(context.Context, *SubmitDelegateShareRequest) (*SubmitDelegateShareResponse, error) {
-	return nil, status.Error(codes.Unimplemented, "method SubmitDelegateShare not implemented")
-}
-func (UnimplementedSessionCoordinatorServer) mustEmbedUnimplementedSessionCoordinatorServer() {}
-func (UnimplementedSessionCoordinatorServer) testEmbeddedByValue()                            {}
-
-// UnsafeSessionCoordinatorServer may be embedded to opt out of forward compatibility for this service.
-// Use of this interface is not recommended, as added methods to SessionCoordinatorServer will
-// result in compilation errors.
-type UnsafeSessionCoordinatorServer interface {
-	mustEmbedUnimplementedSessionCoordinatorServer()
-}
-
-func RegisterSessionCoordinatorServer(s grpc.ServiceRegistrar, srv SessionCoordinatorServer) {
-	// If the following call panics, it indicates UnimplementedSessionCoordinatorServer was
-	// embedded by pointer and is nil.  This will cause panics if an
-	// unimplemented method is ever invoked, so we test this at initialization
-	// time to prevent it from happening at runtime later due to I/O.
-	if t, ok := srv.(interface{ testEmbeddedByValue() }); ok {
-		t.testEmbeddedByValue()
-	}
-	s.RegisterService(&SessionCoordinator_ServiceDesc, srv)
-}
-
-func _SessionCoordinator_CreateSession_Handler(srv interface{}, ctx context.Context, dec func(interface{}) error, interceptor grpc.UnaryServerInterceptor) (interface{}, error) {
-	in := new(CreateSessionRequest)
-	if err := dec(in); err != nil {
-		return nil, err
-	}
-	if interceptor == nil {
-		return srv.(SessionCoordinatorServer).CreateSession(ctx, in)
-	}
-	info := &grpc.UnaryServerInfo{
-		Server:     srv,
-		FullMethod: SessionCoordinator_CreateSession_FullMethodName,
-	}
-	handler := func(ctx context.Context, req interface{}) (interface{}, error) {
-		return srv.(SessionCoordinatorServer).CreateSession(ctx, req.(*CreateSessionRequest))
-	}
-	return interceptor(ctx, in, info, handler)
-}
-
-func _SessionCoordinator_JoinSession_Handler(srv interface{}, ctx context.Context, dec func(interface{}) error, interceptor grpc.UnaryServerInterceptor) (interface{}, error) {
-	in := new(JoinSessionRequest)
-	if err := dec(in); err != nil {
-		return nil, err
-	}
-	if interceptor == nil {
-		return srv.(SessionCoordinatorServer).JoinSession(ctx, in)
-	}
-	info := &grpc.UnaryServerInfo{
-		Server:     srv,
-		FullMethod: SessionCoordinator_JoinSession_FullMethodName,
-	}
-	handler := func(ctx context.Context, req interface{}) (interface{}, error) {
-		return srv.(SessionCoordinatorServer).JoinSession(ctx, req.(*JoinSessionRequest))
-	}
-	return interceptor(ctx, in, info, handler)
-}
-
-func _SessionCoordinator_GetSessionStatus_Handler(srv interface{}, ctx context.Context, dec func(interface{}) error, interceptor grpc.UnaryServerInterceptor) (interface{}, error) {
-	in := new(GetSessionStatusRequest)
-	if err := dec(in); err != nil {
-		return nil, err
-	}
-	if interceptor == nil {
-		return srv.(SessionCoordinatorServer).GetSessionStatus(ctx, in)
-	}
-	info := &grpc.UnaryServerInfo{
-		Server:     srv,
-		FullMethod: SessionCoordinator_GetSessionStatus_FullMethodName,
-	}
-	handler := func(ctx context.Context, req interface{}) (interface{}, error) {
-		return srv.(SessionCoordinatorServer).GetSessionStatus(ctx, req.(*GetSessionStatusRequest))
-	}
-	return interceptor(ctx, in, info, handler)
-}
-
-func _SessionCoordinator_MarkPartyReady_Handler(srv interface{}, ctx context.Context, dec func(interface{}) error, interceptor grpc.UnaryServerInterceptor) (interface{}, error) {
-	in := new(MarkPartyReadyRequest)
-	if err := dec(in); err != nil {
-		return nil, err
-	}
-	if interceptor == nil {
-		return srv.(SessionCoordinatorServer).MarkPartyReady(ctx, in)
-	}
-	info := &grpc.UnaryServerInfo{
-		Server:     srv,
-		FullMethod: SessionCoordinator_MarkPartyReady_FullMethodName,
-	}
-	handler := func(ctx context.Context, req interface{}) (interface{}, error) {
-		return srv.(SessionCoordinatorServer).MarkPartyReady(ctx, req.(*MarkPartyReadyRequest))
-	}
-	return interceptor(ctx, in, info, handler)
-}
-
-func _SessionCoordinator_StartSession_Handler(srv interface{}, ctx context.Context, dec func(interface{}) error, interceptor grpc.UnaryServerInterceptor) (interface{}, error) {
-	in := new(StartSessionRequest)
-	if err := dec(in); err != nil {
-		return nil, err
-	}
-	if interceptor == nil {
-		return srv.(SessionCoordinatorServer).StartSession(ctx, in)
-	}
-	info := &grpc.UnaryServerInfo{
-		Server:     srv,
-		FullMethod: SessionCoordinator_StartSession_FullMethodName,
-	}
-	handler := func(ctx context.Context, req interface{}) (interface{}, error) {
-		return srv.(SessionCoordinatorServer).StartSession(ctx, req.(*StartSessionRequest))
-	}
-	return interceptor(ctx, in, info, handler)
-}
-
-func _SessionCoordinator_ReportCompletion_Handler(srv interface{}, ctx context.Context, dec func(interface{}) error, interceptor grpc.UnaryServerInterceptor) (interface{}, error) {
-	in := new(ReportCompletionRequest)
-	if err := dec(in); err != nil {
-		return nil, err
-	}
-	if interceptor == nil {
-		return srv.(SessionCoordinatorServer).ReportCompletion(ctx, in)
-	}
-	info := &grpc.UnaryServerInfo{
-		Server:     srv,
-		FullMethod: SessionCoordinator_ReportCompletion_FullMethodName,
-	}
-	handler := func(ctx context.Context, req interface{}) (interface{}, error) {
-		return srv.(SessionCoordinatorServer).ReportCompletion(ctx, req.(*ReportCompletionRequest))
-	}
-	return interceptor(ctx, in, info, handler)
-}
-
-func _SessionCoordinator_CloseSession_Handler(srv interface{}, ctx context.Context, dec func(interface{}) error, interceptor grpc.UnaryServerInterceptor) (interface{}, error) {
-	in := new(CloseSessionRequest)
-	if err := dec(in); err != nil {
-		return nil, err
-	}
-	if interceptor == nil {
-		return srv.(SessionCoordinatorServer).CloseSession(ctx, in)
-	}
-	info := &grpc.UnaryServerInfo{
-		Server:     srv,
-		FullMethod: SessionCoordinator_CloseSession_FullMethodName,
-	}
-	handler := func(ctx context.Context, req interface{}) (interface{}, error) {
-		return srv.(SessionCoordinatorServer).CloseSession(ctx, req.(*CloseSessionRequest))
-	}
-	return interceptor(ctx, in, info, handler)
-}
-
-func _SessionCoordinator_SubmitDelegateShare_Handler(srv interface{}, ctx context.Context, dec func(interface{}) error, interceptor grpc.UnaryServerInterceptor) (interface{}, error) {
-	in := new(SubmitDelegateShareRequest)
-	if err := dec(in); err != nil {
-		return nil, err
-	}
-	if interceptor == nil {
-		return srv.(SessionCoordinatorServer).SubmitDelegateShare(ctx, in)
-	}
-	info := &grpc.UnaryServerInfo{
-		Server:     srv,
-		FullMethod: SessionCoordinator_SubmitDelegateShare_FullMethodName,
-	}
-	handler := func(ctx context.Context, req interface{}) (interface{}, error) {
-		return srv.(SessionCoordinatorServer).SubmitDelegateShare(ctx, req.(*SubmitDelegateShareRequest))
-	}
-	return interceptor(ctx, in, info, handler)
-}
-
-// SessionCoordinator_ServiceDesc is the grpc.ServiceDesc for SessionCoordinator service.
-// It's only intended for direct use with grpc.RegisterService,
-// and not to be introspected or modified (even as a copy)
-var SessionCoordinator_ServiceDesc = grpc.ServiceDesc{
-	ServiceName: "mpc.coordinator.v1.SessionCoordinator",
-	HandlerType: (*SessionCoordinatorServer)(nil),
-	Methods: []grpc.MethodDesc{
-		{
-			MethodName: "CreateSession",
-			Handler:    _SessionCoordinator_CreateSession_Handler,
-		},
-		{
-			MethodName: "JoinSession",
-			Handler:    _SessionCoordinator_JoinSession_Handler,
-		},
-		{
-			MethodName: "GetSessionStatus",
-			Handler:    _SessionCoordinator_GetSessionStatus_Handler,
-		},
-		{
-			MethodName: "MarkPartyReady",
-			Handler:    _SessionCoordinator_MarkPartyReady_Handler,
-		},
-		{
-			MethodName: "StartSession",
-			Handler:    _SessionCoordinator_StartSession_Handler,
-		},
-		{
-			MethodName: "ReportCompletion",
-			Handler:    _SessionCoordinator_ReportCompletion_Handler,
-		},
-		{
-			MethodName: "CloseSession",
-			Handler:    _SessionCoordinator_CloseSession_Handler,
-		},
-		{
-			MethodName: "SubmitDelegateShare",
-			Handler:    _SessionCoordinator_SubmitDelegateShare_Handler,
-		},
-	},
-	Streams:  []grpc.StreamDesc{},
-	Metadata: "api/proto/session_coordinator.proto",
-}

backend/mpc-system/services/message-router/adapters/input/grpc/message_grpc_handler.go

@@ -510,11 +510,12 @@ func (s *MessageRouterServer) JoinSession(
 
 	if coordResp.SessionInfo != nil {
 		resp.SessionInfo = &pb.SessionInfo{
-			SessionId:   req.SessionId,
+			SessionId:       req.SessionId,
-			SessionType: coordResp.SessionInfo.SessionType,
+			SessionType:     coordResp.SessionInfo.SessionType,
-			ThresholdN:  coordResp.SessionInfo.ThresholdN,
+			ThresholdN:      coordResp.SessionInfo.ThresholdN,
-			ThresholdT:  coordResp.SessionInfo.ThresholdT,
+			ThresholdT:      coordResp.SessionInfo.ThresholdT,
-			MessageHash: coordResp.SessionInfo.MessageHash,
+			MessageHash:     coordResp.SessionInfo.MessageHash,
+			KeygenSessionId: coordResp.SessionInfo.KeygenSessionId,
 		}
 	}
 

backend/mpc-system/services/server-party/adapters/output/grpc/message_router_client.go

@@ -673,6 +673,13 @@ func (c *MessageRouterClient) JoinSession(
 			sessionInfo.ThresholdN = int(resp.SessionInfo.ThresholdN)
 			sessionInfo.ThresholdT = int(resp.SessionInfo.ThresholdT)
 			sessionInfo.MessageHash = resp.SessionInfo.MessageHash
+
+			// Parse keygen_session_id if provided (for signing sessions)
+			if resp.SessionInfo.KeygenSessionId != "" {
+				if keygenID, err := uuid.Parse(resp.SessionInfo.KeygenSessionId); err == nil {
+					sessionInfo.KeygenSessionID = keygenID
+				}
+			}
 		}
 
 		logger.Info("Joined session via Message Router",

backend/mpc-system/services/session-coordinator/adapters/input/grpc/session_grpc_handler.go

@@ -160,6 +160,18 @@ func (s *SessionCoordinatorServer) CreateSession(
 		ExpiresIn:    time.Duration(req.ExpiresInSeconds) * time.Second,
 	}
 
+	// Parse and set keygen_session_id if provided (for signing sessions)
+	if req.KeygenSessionId != "" {
+		keygenSessionID, err := uuid.Parse(req.KeygenSessionId)
+		if err == nil {
+			inputData.KeygenSessionID = keygenSessionID
+		} else {
+			logger.Warn("Invalid keygen_session_id format",
+				zap.String("keygen_session_id", req.KeygenSessionId),
+				zap.Error(err))
+		}
+	}
+
 	// Add party composition if provided (for automatic party selection)
 	if req.PartyComposition != nil {
 		inputData.PartyComposition = &input.PartyComposition{
@@ -270,15 +282,22 @@ func (s *SessionCoordinatorServer) JoinSession(
 			zap.Int32("proto_party_index", otherParties[i].PartyIndex))
 	}
 
+	// Convert keygen_session_id to string (empty if nil)
+	keygenSessionIDStr := ""
+	if output.SessionInfo.KeygenSessionID != uuid.Nil {
+		keygenSessionIDStr = output.SessionInfo.KeygenSessionID.String()
+	}
+
 	return &pb.JoinSessionResponse{
 		Success: output.Success,
 		SessionInfo: &pb.SessionInfo{
-			SessionId:   output.SessionInfo.SessionID.String(),
+			SessionId:       output.SessionInfo.SessionID.String(),
-			SessionType: output.SessionInfo.SessionType,
+			SessionType:     output.SessionInfo.SessionType,
-			ThresholdN:  int32(output.SessionInfo.ThresholdN),
+			ThresholdN:      int32(output.SessionInfo.ThresholdN),
-			ThresholdT:  int32(output.SessionInfo.ThresholdT),
+			ThresholdT:      int32(output.SessionInfo.ThresholdT),
-			MessageHash: output.SessionInfo.MessageHash,
+			MessageHash:     output.SessionInfo.MessageHash,
-			Status:      output.SessionInfo.Status,
+			Status:          output.SessionInfo.Status,
+			KeygenSessionId: keygenSessionIDStr,
 		},
 		OtherParties: otherParties,
 		PartyIndex:   int32(output.PartyIndex),

backend/mpc-system/services/session-coordinator/adapters/output/postgres/session_postgres_repo.go

@@ -37,13 +37,14 @@ func (r *SessionPostgresRepo) Save(ctx context.Context, session *entities.MPCSes
 	_, err = tx.ExecContext(ctx, `
 		INSERT INTO mpc_sessions (
 			id, session_type, threshold_n, threshold_t, status,
-			message_hash, public_key, delegate_party_id, created_by, created_at, updated_at, expires_at, completed_at, version
+			message_hash, public_key, delegate_party_id, keygen_session_id, created_by, created_at, updated_at, expires_at, completed_at, version
-		) VALUES ($1, $2, $3, $4, $5, $6, $7, $8, $9, $10, $11, $12, $13, $14)
+		) VALUES ($1, $2, $3, $4, $5, $6, $7, $8, $9, $10, $11, $12, $13, $14, $15)
 		ON CONFLICT (id) DO UPDATE SET
 			status = EXCLUDED.status,
 			message_hash = EXCLUDED.message_hash,
 			public_key = EXCLUDED.public_key,
 			delegate_party_id = EXCLUDED.delegate_party_id,
+			keygen_session_id = EXCLUDED.keygen_session_id,
 			updated_at = EXCLUDED.updated_at,
 			completed_at = EXCLUDED.completed_at,
 			version = EXCLUDED.version
@@ -56,6 +57,7 @@ func (r *SessionPostgresRepo) Save(ctx context.Context, session *entities.MPCSes
 		session.MessageHash,
 		session.PublicKey,
 		session.DelegatePartyID,
+		nullUUID(session.KeygenSessionID),
 		session.CreatedBy,
 		session.CreatedAt,
 		session.UpdatedAt,
@@ -118,7 +120,7 @@ func (r *SessionPostgresRepo) FindByUUID(ctx context.Context, id uuid.UUID) (*en
 	var session sessionRow
 	err := r.db.QueryRowContext(ctx, `
 		SELECT id, session_type, threshold_n, threshold_t, status,
-			   message_hash, public_key, delegate_party_id, created_by, created_at, updated_at, expires_at, completed_at, version
+			   message_hash, public_key, delegate_party_id, keygen_session_id, created_by, created_at, updated_at, expires_at, completed_at, version
 		FROM mpc_sessions WHERE id = $1
 	`, id).Scan(
 		&session.ID,
@@ -129,6 +131,7 @@ func (r *SessionPostgresRepo) FindByUUID(ctx context.Context, id uuid.UUID) (*en
 		&session.MessageHash,
 		&session.PublicKey,
 		&session.DelegatePartyID,
+		&session.KeygenSessionID,
 		&session.CreatedBy,
 		&session.CreatedAt,
 		&session.UpdatedAt,
@@ -149,6 +152,12 @@ func (r *SessionPostgresRepo) FindByUUID(ctx context.Context, id uuid.UUID) (*en
 		return nil, err
 	}
 
+	// Convert nullable KeygenSessionID
+	var keygenSessionID uuid.UUID
+	if session.KeygenSessionID != nil {
+		keygenSessionID = *session.KeygenSessionID
+	}
+
 	return entities.ReconstructSession(
 		session.ID,
 		session.SessionType,
@@ -158,6 +167,7 @@ func (r *SessionPostgresRepo) FindByUUID(ctx context.Context, id uuid.UUID) (*en
 		session.MessageHash,
 		session.PublicKey,
 		session.DelegatePartyID,
+		keygenSessionID,
 		session.CreatedBy,
 		session.CreatedAt,
 		session.UpdatedAt,
@@ -172,7 +182,7 @@ func (r *SessionPostgresRepo) FindByUUID(ctx context.Context, id uuid.UUID) (*en
 func (r *SessionPostgresRepo) FindByStatus(ctx context.Context, status value_objects.SessionStatus) ([]*entities.MPCSession, error) {
 	rows, err := r.db.QueryContext(ctx, `
 		SELECT id, session_type, threshold_n, threshold_t, status,
-			   message_hash, public_key, delegate_party_id, created_by, created_at, updated_at, expires_at, completed_at, version
+			   message_hash, public_key, delegate_party_id, keygen_session_id, created_by, created_at, updated_at, expires_at, completed_at, version
 		FROM mpc_sessions WHERE status = $1
 	`, status.String())
 	if err != nil {
@@ -187,7 +197,7 @@ func (r *SessionPostgresRepo) FindByStatus(ctx context.Context, status value_obj
 func (r *SessionPostgresRepo) FindExpired(ctx context.Context) ([]*entities.MPCSession, error) {
 	rows, err := r.db.QueryContext(ctx, `
 		SELECT id, session_type, threshold_n, threshold_t, status,
-			   message_hash, public_key, delegate_party_id, created_by, created_at, updated_at, expires_at, completed_at, version
+			   message_hash, public_key, delegate_party_id, keygen_session_id, created_by, created_at, updated_at, expires_at, completed_at, version
 		FROM mpc_sessions
 		WHERE expires_at < NOW() AND status IN ('created', 'in_progress')
 	`)
@@ -203,7 +213,7 @@ func (r *SessionPostgresRepo) FindExpired(ctx context.Context) ([]*entities.MPCS
 func (r *SessionPostgresRepo) FindActive(ctx context.Context) ([]*entities.MPCSession, error) {
 	rows, err := r.db.QueryContext(ctx, `
 		SELECT id, session_type, threshold_n, threshold_t, status,
-			   message_hash, public_key, delegate_party_id, created_by, created_at, updated_at, expires_at, completed_at, version
+			   message_hash, public_key, delegate_party_id, keygen_session_id, created_by, created_at, updated_at, expires_at, completed_at, version
 		FROM mpc_sessions
 		WHERE status IN ('created', 'in_progress')
 		ORDER BY created_at ASC
@@ -220,7 +230,7 @@ func (r *SessionPostgresRepo) FindActive(ctx context.Context) ([]*entities.MPCSe
 func (r *SessionPostgresRepo) FindByCreator(ctx context.Context, creatorID string) ([]*entities.MPCSession, error) {
 	rows, err := r.db.QueryContext(ctx, `
 		SELECT id, session_type, threshold_n, threshold_t, status,
-			   message_hash, public_key, created_by, created_at, updated_at, expires_at, completed_at, version
+			   message_hash, public_key, delegate_party_id, keygen_session_id, created_by, created_at, updated_at, expires_at, completed_at, version
 		FROM mpc_sessions WHERE created_by = $1
 		ORDER BY created_at DESC
 	`, creatorID)
@@ -236,7 +246,7 @@ func (r *SessionPostgresRepo) FindByCreator(ctx context.Context, creatorID strin
 func (r *SessionPostgresRepo) FindActiveByParticipant(ctx context.Context, partyID value_objects.PartyID) ([]*entities.MPCSession, error) {
 	rows, err := r.db.QueryContext(ctx, `
 		SELECT s.id, s.session_type, s.threshold_n, s.threshold_t, s.status,
-			   s.message_hash, s.public_key, s.created_by, s.created_at, s.updated_at, s.expires_at, s.completed_at, s.version
+			   s.message_hash, s.public_key, s.delegate_party_id, s.keygen_session_id, s.created_by, s.created_at, s.updated_at, s.expires_at, s.completed_at, s.version
 		FROM mpc_sessions s
 		JOIN participants p ON s.id = p.session_id
 		WHERE p.party_id = $1 AND s.status IN ('created', 'in_progress')
@@ -487,6 +497,7 @@ func (r *SessionPostgresRepo) scanSessions(ctx context.Context, rows *sql.Rows)
 			&s.MessageHash,
 			&s.PublicKey,
 			&s.DelegatePartyID,
+			&s.KeygenSessionID,
 			&s.CreatedBy,
 			&s.CreatedAt,
 			&s.UpdatedAt,
@@ -503,6 +514,12 @@ func (r *SessionPostgresRepo) scanSessions(ctx context.Context, rows *sql.Rows)
 			return nil, err
 		}
 
+		// Convert nullable KeygenSessionID
+		var keygenSessionID uuid.UUID
+		if s.KeygenSessionID != nil {
+			keygenSessionID = *s.KeygenSessionID
+		}
+
 		session, err := entities.ReconstructSession(
 			s.ID,
 			s.SessionType,
@@ -512,6 +529,7 @@ func (r *SessionPostgresRepo) scanSessions(ctx context.Context, rows *sql.Rows)
 			s.MessageHash,
 			s.PublicKey,
 			s.DelegatePartyID,
+			keygenSessionID,
 			s.CreatedBy,
 			s.CreatedAt,
 			s.UpdatedAt,
@@ -539,6 +557,7 @@ type sessionRow struct {
 	MessageHash     []byte
 	PublicKey       []byte
 	DelegatePartyID string
+	KeygenSessionID *uuid.UUID
 	CreatedBy       string
 	CreatedAt       time.Time
 	UpdatedAt       time.Time
@@ -565,3 +584,11 @@ var _ repositories.SessionRepository = (*SessionPostgresRepo)(nil)
 
 // Use pq for array handling
 var _ = pq.Array
+
+// nullUUID converts a UUID to a nullable database value
+func nullUUID(u uuid.UUID) interface{} {
+	if u == uuid.Nil {
+		return nil
+	}
+	return u
+}

backend/mpc-system/services/session-coordinator/application/ports/input/session_management_port.go

@@ -54,6 +54,7 @@ type CreateSessionInput struct {
 	MessageHash       []byte             // For sign sessions
 	ExpiresIn         time.Duration
 	DelegateUserShare *DelegateUserShare // For sign sessions with delegate party
+	KeygenSessionID   uuid.UUID          // For sign sessions: which keygen session's shares to use
 }
 
 // ParticipantInfo contains information about a participant
@@ -87,12 +88,13 @@ type JoinSessionOutput struct {
 
 // SessionInfo contains session information
 type SessionInfo struct {
-	SessionID   uuid.UUID
+	SessionID       uuid.UUID
-	SessionType string
+	SessionType     string
-	ThresholdN  int
+	ThresholdN      int
-	ThresholdT  int
+	ThresholdT      int
-	MessageHash []byte
+	MessageHash     []byte
-	Status      string
+	Status          string
+	KeygenSessionID uuid.UUID // For sign sessions: which keygen session's shares to use
 }
 
 // PartyInfo contains party information

backend/mpc-system/services/session-coordinator/application/use_cases/create_session.go

@@ -130,6 +130,14 @@ func (uc *CreateSessionUseCase) Execute(
 		return nil, err
 	}
 
+	// 4.1 Set keygen_session_id for sign sessions
+	if req.KeygenSessionID != uuid.Nil {
+		session.KeygenSessionID = req.KeygenSessionID
+		logger.Info("Sign session created with keygen_session_id",
+			zap.String("session_id", session.ID.String()),
+			zap.String("keygen_session_id", req.KeygenSessionID.String()))
+	}
+
 	// 5. Add participants and generate join tokens
 	tokens := make(map[string]string)
 	if len(req.Participants) == 0 {

backend/mpc-system/services/session-coordinator/application/use_cases/join_session.go

@@ -166,12 +166,13 @@ func (uc *JoinSessionUseCase) Execute(
 		Success:    true,
 		PartyIndex: participant.PartyIndex,
 		SessionInfo: input.SessionInfo{
-			SessionID:   session.ID.UUID(),
+			SessionID:       session.ID.UUID(),
-			SessionType: string(session.SessionType),
+			SessionType:     string(session.SessionType),
-			ThresholdN:  session.Threshold.N(),
+			ThresholdN:      session.Threshold.N(),
-			ThresholdT:  session.Threshold.T(),
+			ThresholdT:      session.Threshold.T(),
-			MessageHash: session.MessageHash,
+			MessageHash:     session.MessageHash,
-			Status:      session.Status.String(),
+			Status:          session.Status.String(),
+			KeygenSessionID: session.KeygenSessionID,
 		},
 		OtherParties: partyInfos,
 	}, nil

backend/mpc-system/services/session-coordinator/domain/entities/mpc_session.go

@@ -385,6 +385,7 @@ func ReconstructSession(
 	status string,
 	messageHash, publicKey []byte,
 	delegatePartyID string,
+	keygenSessionID uuid.UUID,
 	createdBy string,
 	createdAt, updatedAt, expiresAt time.Time,
 	completedAt *time.Time,
@@ -403,18 +404,19 @@ func ReconstructSession(
 
 	return &MPCSession{
 		ID:              value_objects.SessionIDFromUUID(id),
-		SessionType:    SessionType(sessionType),
+		SessionType:     SessionType(sessionType),
-		Threshold:      threshold,
+		Threshold:       threshold,
-		Participants:   participants,
+		Participants:    participants,
-		Status:         sessionStatus,
+		Status:          sessionStatus,
-		MessageHash:    messageHash,
+		MessageHash:     messageHash,
-		PublicKey:      publicKey,
+		PublicKey:       publicKey,
 		DelegatePartyID: delegatePartyID,
-		CreatedBy:      createdBy,
+		KeygenSessionID: keygenSessionID,
-		CreatedAt:      createdAt,
+		CreatedBy:       createdBy,
-		UpdatedAt:      updatedAt,
+		CreatedAt:       createdAt,
-		ExpiresAt:      expiresAt,
+		UpdatedAt:       updatedAt,
-		CompletedAt:    completedAt,
+		ExpiresAt:       expiresAt,
-		Version:        version,
+		CompletedAt:     completedAt,
+		Version:         version,
 	}, nil
 }