Add [master] config section to agent for registration

Heartbeat client now reads master connection settings from the agent
config ([master] section) with env var fallback. Includes address,
ca_cert, token_path, and role fields.

Agent's Run() creates and starts the heartbeat client automatically
when [master] is configured.

Tested on all three nodes: rift (master), svc (edge), orion (worker)
all registered with the master and sending heartbeats every 30s.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

gen/mcp/v1/master.pb.go

@@ -712,6 +712,238 @@ func (x *NodeInfo) GetServices() int32 {
 	return 0
 }
 
+type RegisterRequest struct {
+	state         protoimpl.MessageState `protogen:"open.v1"`
+	Name          string                 `protobuf:"bytes,1,opt,name=name,proto3" json:"name,omitempty"`
+	Role          string                 `protobuf:"bytes,2,opt,name=role,proto3" json:"role,omitempty"`       // "worker", "edge", or "master"
+	Address       string                 `protobuf:"bytes,3,opt,name=address,proto3" json:"address,omitempty"` // agent gRPC address
+	Arch          string                 `protobuf:"bytes,4,opt,name=arch,proto3" json:"arch,omitempty"`       // "amd64" or "arm64"
+	unknownFields protoimpl.UnknownFields
+	sizeCache     protoimpl.SizeCache
+}
+
+func (x *RegisterRequest) Reset() {
+	*x = RegisterRequest{}
+	mi := &file_proto_mcp_v1_master_proto_msgTypes[12]
+	ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
+	ms.StoreMessageInfo(mi)
+}
+
+func (x *RegisterRequest) String() string {
+	return protoimpl.X.MessageStringOf(x)
+}
+
+func (*RegisterRequest) ProtoMessage() {}
+
+func (x *RegisterRequest) ProtoReflect() protoreflect.Message {
+	mi := &file_proto_mcp_v1_master_proto_msgTypes[12]
+	if x != nil {
+		ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
+		if ms.LoadMessageInfo() == nil {
+			ms.StoreMessageInfo(mi)
+		}
+		return ms
+	}
+	return mi.MessageOf(x)
+}
+
+// Deprecated: Use RegisterRequest.ProtoReflect.Descriptor instead.
+func (*RegisterRequest) Descriptor() ([]byte, []int) {
+	return file_proto_mcp_v1_master_proto_rawDescGZIP(), []int{12}
+}
+
+func (x *RegisterRequest) GetName() string {
+	if x != nil {
+		return x.Name
+	}
+	return ""
+}
+
+func (x *RegisterRequest) GetRole() string {
+	if x != nil {
+		return x.Role
+	}
+	return ""
+}
+
+func (x *RegisterRequest) GetAddress() string {
+	if x != nil {
+		return x.Address
+	}
+	return ""
+}
+
+func (x *RegisterRequest) GetArch() string {
+	if x != nil {
+		return x.Arch
+	}
+	return ""
+}
+
+type RegisterResponse struct {
+	state         protoimpl.MessageState `protogen:"open.v1"`
+	Accepted      bool                   `protobuf:"varint,1,opt,name=accepted,proto3" json:"accepted,omitempty"`
+	unknownFields protoimpl.UnknownFields
+	sizeCache     protoimpl.SizeCache
+}
+
+func (x *RegisterResponse) Reset() {
+	*x = RegisterResponse{}
+	mi := &file_proto_mcp_v1_master_proto_msgTypes[13]
+	ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
+	ms.StoreMessageInfo(mi)
+}
+
+func (x *RegisterResponse) String() string {
+	return protoimpl.X.MessageStringOf(x)
+}
+
+func (*RegisterResponse) ProtoMessage() {}
+
+func (x *RegisterResponse) ProtoReflect() protoreflect.Message {
+	mi := &file_proto_mcp_v1_master_proto_msgTypes[13]
+	if x != nil {
+		ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
+		if ms.LoadMessageInfo() == nil {
+			ms.StoreMessageInfo(mi)
+		}
+		return ms
+	}
+	return mi.MessageOf(x)
+}
+
+// Deprecated: Use RegisterResponse.ProtoReflect.Descriptor instead.
+func (*RegisterResponse) Descriptor() ([]byte, []int) {
+	return file_proto_mcp_v1_master_proto_rawDescGZIP(), []int{13}
+}
+
+func (x *RegisterResponse) GetAccepted() bool {
+	if x != nil {
+		return x.Accepted
+	}
+	return false
+}
+
+type HeartbeatRequest struct {
+	state         protoimpl.MessageState `protogen:"open.v1"`
+	Name          string                 `protobuf:"bytes,1,opt,name=name,proto3" json:"name,omitempty"`
+	CpuMillicores int64                  `protobuf:"varint,2,opt,name=cpu_millicores,json=cpuMillicores,proto3" json:"cpu_millicores,omitempty"`
+	MemoryBytes   int64                  `protobuf:"varint,3,opt,name=memory_bytes,json=memoryBytes,proto3" json:"memory_bytes,omitempty"`
+	DiskBytes     int64                  `protobuf:"varint,4,opt,name=disk_bytes,json=diskBytes,proto3" json:"disk_bytes,omitempty"`
+	Containers    int32                  `protobuf:"varint,5,opt,name=containers,proto3" json:"containers,omitempty"`
+	unknownFields protoimpl.UnknownFields
+	sizeCache     protoimpl.SizeCache
+}
+
+func (x *HeartbeatRequest) Reset() {
+	*x = HeartbeatRequest{}
+	mi := &file_proto_mcp_v1_master_proto_msgTypes[14]
+	ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
+	ms.StoreMessageInfo(mi)
+}
+
+func (x *HeartbeatRequest) String() string {
+	return protoimpl.X.MessageStringOf(x)
+}
+
+func (*HeartbeatRequest) ProtoMessage() {}
+
+func (x *HeartbeatRequest) ProtoReflect() protoreflect.Message {
+	mi := &file_proto_mcp_v1_master_proto_msgTypes[14]
+	if x != nil {
+		ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
+		if ms.LoadMessageInfo() == nil {
+			ms.StoreMessageInfo(mi)
+		}
+		return ms
+	}
+	return mi.MessageOf(x)
+}
+
+// Deprecated: Use HeartbeatRequest.ProtoReflect.Descriptor instead.
+func (*HeartbeatRequest) Descriptor() ([]byte, []int) {
+	return file_proto_mcp_v1_master_proto_rawDescGZIP(), []int{14}
+}
+
+func (x *HeartbeatRequest) GetName() string {
+	if x != nil {
+		return x.Name
+	}
+	return ""
+}
+
+func (x *HeartbeatRequest) GetCpuMillicores() int64 {
+	if x != nil {
+		return x.CpuMillicores
+	}
+	return 0
+}
+
+func (x *HeartbeatRequest) GetMemoryBytes() int64 {
+	if x != nil {
+		return x.MemoryBytes
+	}
+	return 0
+}
+
+func (x *HeartbeatRequest) GetDiskBytes() int64 {
+	if x != nil {
+		return x.DiskBytes
+	}
+	return 0
+}
+
+func (x *HeartbeatRequest) GetContainers() int32 {
+	if x != nil {
+		return x.Containers
+	}
+	return 0
+}
+
+type HeartbeatResponse struct {
+	state         protoimpl.MessageState `protogen:"open.v1"`
+	Acknowledged  bool                   `protobuf:"varint,1,opt,name=acknowledged,proto3" json:"acknowledged,omitempty"`
+	unknownFields protoimpl.UnknownFields
+	sizeCache     protoimpl.SizeCache
+}
+
+func (x *HeartbeatResponse) Reset() {
+	*x = HeartbeatResponse{}
+	mi := &file_proto_mcp_v1_master_proto_msgTypes[15]
+	ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
+	ms.StoreMessageInfo(mi)
+}
+
+func (x *HeartbeatResponse) String() string {
+	return protoimpl.X.MessageStringOf(x)
+}
+
+func (*HeartbeatResponse) ProtoMessage() {}
+
+func (x *HeartbeatResponse) ProtoReflect() protoreflect.Message {
+	mi := &file_proto_mcp_v1_master_proto_msgTypes[15]
+	if x != nil {
+		ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
+		if ms.LoadMessageInfo() == nil {
+			ms.StoreMessageInfo(mi)
+		}
+		return ms
+	}
+	return mi.MessageOf(x)
+}
+
+// Deprecated: Use HeartbeatResponse.ProtoReflect.Descriptor instead.
+func (*HeartbeatResponse) Descriptor() ([]byte, []int) {
+	return file_proto_mcp_v1_master_proto_rawDescGZIP(), []int{15}
+}
+
+func (x *HeartbeatResponse) GetAcknowledged() bool {
+	if x != nil {
+		return x.Acknowledged
+	}
+	return false
+}
+
 var File_proto_mcp_v1_master_proto protoreflect.FileDescriptor
 
 const file_proto_mcp_v1_master_proto_rawDesc = "" +
@@ -765,12 +997,32 @@ const file_proto_mcp_v1_master_proto_rawDesc = "" +
 	"containers\x18\x06 \x01(\x05R\n" +
 	"containers\x12%\n" +
 	"\x0elast_heartbeat\x18\a \x01(\tR\rlastHeartbeat\x12\x1a\n" +
-	"\bservices\x18\b \x01(\x05R\bservices2\xa9\x02\n" +
+	"\bservices\x18\b \x01(\x05R\bservices\"g\n" +
+	"\x0fRegisterRequest\x12\x12\n" +
+	"\x04name\x18\x01 \x01(\tR\x04name\x12\x12\n" +
+	"\x04role\x18\x02 \x01(\tR\x04role\x12\x18\n" +
+	"\aaddress\x18\x03 \x01(\tR\aaddress\x12\x12\n" +
+	"\x04arch\x18\x04 \x01(\tR\x04arch\".\n" +
+	"\x10RegisterResponse\x12\x1a\n" +
+	"\baccepted\x18\x01 \x01(\bR\baccepted\"\xaf\x01\n" +
+	"\x10HeartbeatRequest\x12\x12\n" +
+	"\x04name\x18\x01 \x01(\tR\x04name\x12%\n" +
+	"\x0ecpu_millicores\x18\x02 \x01(\x03R\rcpuMillicores\x12!\n" +
+	"\fmemory_bytes\x18\x03 \x01(\x03R\vmemoryBytes\x12\x1d\n" +
+	"\n" +
+	"disk_bytes\x18\x04 \x01(\x03R\tdiskBytes\x12\x1e\n" +
+	"\n" +
+	"containers\x18\x05 \x01(\x05R\n" +
+	"containers\"7\n" +
+	"\x11HeartbeatResponse\x12\"\n" +
+	"\facknowledged\x18\x01 \x01(\bR\facknowledged2\xaa\x03\n" +
 	"\x10McpMasterService\x12C\n" +
 	"\x06Deploy\x12\x1b.mcp.v1.MasterDeployRequest\x1a\x1c.mcp.v1.MasterDeployResponse\x12I\n" +
 	"\bUndeploy\x12\x1d.mcp.v1.MasterUndeployRequest\x1a\x1e.mcp.v1.MasterUndeployResponse\x12C\n" +
 	"\x06Status\x12\x1b.mcp.v1.MasterStatusRequest\x1a\x1c.mcp.v1.MasterStatusResponse\x12@\n" +
-	"\tListNodes\x12\x18.mcp.v1.ListNodesRequest\x1a\x19.mcp.v1.ListNodesResponseB*Z(git.wntrmute.dev/mc/mcp/gen/mcp/v1;mcpv1b\x06proto3"
+	"\tListNodes\x12\x18.mcp.v1.ListNodesRequest\x1a\x19.mcp.v1.ListNodesResponse\x12=\n" +
+	"\bRegister\x12\x17.mcp.v1.RegisterRequest\x1a\x18.mcp.v1.RegisterResponse\x12@\n" +
+	"\tHeartbeat\x12\x18.mcp.v1.HeartbeatRequest\x1a\x19.mcp.v1.HeartbeatResponseB*Z(git.wntrmute.dev/mc/mcp/gen/mcp/v1;mcpv1b\x06proto3"
 
 var (
 	file_proto_mcp_v1_master_proto_rawDescOnce sync.Once
@@ -784,7 +1036,7 @@ func file_proto_mcp_v1_master_proto_rawDescGZIP() []byte {
 	return file_proto_mcp_v1_master_proto_rawDescData
 }
 
-var file_proto_mcp_v1_master_proto_msgTypes = make([]protoimpl.MessageInfo, 12)
+var file_proto_mcp_v1_master_proto_msgTypes = make([]protoimpl.MessageInfo, 16)
 var file_proto_mcp_v1_master_proto_goTypes = []any{
 	(*MasterDeployRequest)(nil),    // 0: mcp.v1.MasterDeployRequest
 	(*MasterDeployResponse)(nil),   // 1: mcp.v1.MasterDeployResponse
@@ -798,10 +1050,14 @@ var file_proto_mcp_v1_master_proto_goTypes = []any{
 	(*ListNodesRequest)(nil),       // 9: mcp.v1.ListNodesRequest
 	(*ListNodesResponse)(nil),      // 10: mcp.v1.ListNodesResponse
 	(*NodeInfo)(nil),               // 11: mcp.v1.NodeInfo
-	(*ServiceSpec)(nil),            // 12: mcp.v1.ServiceSpec
+	(*RegisterRequest)(nil),        // 12: mcp.v1.RegisterRequest
+	(*RegisterResponse)(nil),       // 13: mcp.v1.RegisterResponse
+	(*HeartbeatRequest)(nil),       // 14: mcp.v1.HeartbeatRequest
+	(*HeartbeatResponse)(nil),      // 15: mcp.v1.HeartbeatResponse
+	(*ServiceSpec)(nil),            // 16: mcp.v1.ServiceSpec
 }
 var file_proto_mcp_v1_master_proto_depIdxs = []int32{
-	12, // 0: mcp.v1.MasterDeployRequest.service:type_name -> mcp.v1.ServiceSpec
+	16, // 0: mcp.v1.MasterDeployRequest.service:type_name -> mcp.v1.ServiceSpec
 	2,  // 1: mcp.v1.MasterDeployResponse.deploy_result:type_name -> mcp.v1.StepResult
 	2,  // 2: mcp.v1.MasterDeployResponse.edge_route_result:type_name -> mcp.v1.StepResult
 	2,  // 3: mcp.v1.MasterDeployResponse.dns_result:type_name -> mcp.v1.StepResult
@@ -812,12 +1068,16 @@ var file_proto_mcp_v1_master_proto_depIdxs = []int32{
 	3,  // 8: mcp.v1.McpMasterService.Undeploy:input_type -> mcp.v1.MasterUndeployRequest
 	5,  // 9: mcp.v1.McpMasterService.Status:input_type -> mcp.v1.MasterStatusRequest
 	9,  // 10: mcp.v1.McpMasterService.ListNodes:input_type -> mcp.v1.ListNodesRequest
-	1,  // 11: mcp.v1.McpMasterService.Deploy:output_type -> mcp.v1.MasterDeployResponse
+	12, // 11: mcp.v1.McpMasterService.Register:input_type -> mcp.v1.RegisterRequest
-	4,  // 12: mcp.v1.McpMasterService.Undeploy:output_type -> mcp.v1.MasterUndeployResponse
+	14, // 12: mcp.v1.McpMasterService.Heartbeat:input_type -> mcp.v1.HeartbeatRequest
-	6,  // 13: mcp.v1.McpMasterService.Status:output_type -> mcp.v1.MasterStatusResponse
+	1,  // 13: mcp.v1.McpMasterService.Deploy:output_type -> mcp.v1.MasterDeployResponse
-	10, // 14: mcp.v1.McpMasterService.ListNodes:output_type -> mcp.v1.ListNodesResponse
+	4,  // 14: mcp.v1.McpMasterService.Undeploy:output_type -> mcp.v1.MasterUndeployResponse
-	11, // [11:15] is the sub-list for method output_type
+	6,  // 15: mcp.v1.McpMasterService.Status:output_type -> mcp.v1.MasterStatusResponse
-	7,  // [7:11] is the sub-list for method input_type
+	10, // 16: mcp.v1.McpMasterService.ListNodes:output_type -> mcp.v1.ListNodesResponse
+	13, // 17: mcp.v1.McpMasterService.Register:output_type -> mcp.v1.RegisterResponse
+	15, // 18: mcp.v1.McpMasterService.Heartbeat:output_type -> mcp.v1.HeartbeatResponse
+	13, // [13:19] is the sub-list for method output_type
+	7,  // [7:13] is the sub-list for method input_type
 	7,  // [7:7] is the sub-list for extension type_name
 	7,  // [7:7] is the sub-list for extension extendee
 	0,  // [0:7] is the sub-list for field type_name
@@ -835,7 +1095,7 @@ func file_proto_mcp_v1_master_proto_init() {
 			GoPackagePath: reflect.TypeOf(x{}).PkgPath(),
 			RawDescriptor: unsafe.Slice(unsafe.StringData(file_proto_mcp_v1_master_proto_rawDesc), len(file_proto_mcp_v1_master_proto_rawDesc)),
 			NumEnums:      0,
-			NumMessages:   12,
+			NumMessages:   16,
 			NumExtensions: 0,
 			NumServices:   1,
 		},

gen/mcp/v1/master_grpc.pb.go

@@ -25,6 +25,8 @@ const (
 	McpMasterService_Undeploy_FullMethodName  = "/mcp.v1.McpMasterService/Undeploy"
 	McpMasterService_Status_FullMethodName    = "/mcp.v1.McpMasterService/Status"
 	McpMasterService_ListNodes_FullMethodName = "/mcp.v1.McpMasterService/ListNodes"
+	McpMasterService_Register_FullMethodName  = "/mcp.v1.McpMasterService/Register"
+	McpMasterService_Heartbeat_FullMethodName = "/mcp.v1.McpMasterService/Heartbeat"
 )
 
 // McpMasterServiceClient is the client API for McpMasterService service.
@@ -40,6 +42,9 @@ type McpMasterServiceClient interface {
 	Undeploy(ctx context.Context, in *MasterUndeployRequest, opts ...grpc.CallOption) (*MasterUndeployResponse, error)
 	Status(ctx context.Context, in *MasterStatusRequest, opts ...grpc.CallOption) (*MasterStatusResponse, error)
 	ListNodes(ctx context.Context, in *ListNodesRequest, opts ...grpc.CallOption) (*ListNodesResponse, error)
+	// Agent registration and health (called by agents).
+	Register(ctx context.Context, in *RegisterRequest, opts ...grpc.CallOption) (*RegisterResponse, error)
+	Heartbeat(ctx context.Context, in *HeartbeatRequest, opts ...grpc.CallOption) (*HeartbeatResponse, error)
 }
 
 type mcpMasterServiceClient struct {
@@ -90,6 +95,26 @@ func (c *mcpMasterServiceClient) ListNodes(ctx context.Context, in *ListNodesReq
 	return out, nil
 }
 
+func (c *mcpMasterServiceClient) Register(ctx context.Context, in *RegisterRequest, opts ...grpc.CallOption) (*RegisterResponse, error) {
+	cOpts := append([]grpc.CallOption{grpc.StaticMethod()}, opts...)
+	out := new(RegisterResponse)
+	err := c.cc.Invoke(ctx, McpMasterService_Register_FullMethodName, in, out, cOpts...)
+	if err != nil {
+		return nil, err
+	}
+	return out, nil
+}
+
+func (c *mcpMasterServiceClient) 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, McpMasterService_Heartbeat_FullMethodName, in, out, cOpts...)
+	if err != nil {
+		return nil, err
+	}
+	return out, nil
+}
+
 // McpMasterServiceServer is the server API for McpMasterService service.
 // All implementations must embed UnimplementedMcpMasterServiceServer
 // for forward compatibility.
@@ -103,6 +128,9 @@ type McpMasterServiceServer interface {
 	Undeploy(context.Context, *MasterUndeployRequest) (*MasterUndeployResponse, error)
 	Status(context.Context, *MasterStatusRequest) (*MasterStatusResponse, error)
 	ListNodes(context.Context, *ListNodesRequest) (*ListNodesResponse, error)
+	// Agent registration and health (called by agents).
+	Register(context.Context, *RegisterRequest) (*RegisterResponse, error)
+	Heartbeat(context.Context, *HeartbeatRequest) (*HeartbeatResponse, error)
 	mustEmbedUnimplementedMcpMasterServiceServer()
 }
 
@@ -125,6 +153,12 @@ func (UnimplementedMcpMasterServiceServer) Status(context.Context, *MasterStatus
 func (UnimplementedMcpMasterServiceServer) ListNodes(context.Context, *ListNodesRequest) (*ListNodesResponse, error) {
 	return nil, status.Error(codes.Unimplemented, "method ListNodes not implemented")
 }
+func (UnimplementedMcpMasterServiceServer) Register(context.Context, *RegisterRequest) (*RegisterResponse, error) {
+	return nil, status.Error(codes.Unimplemented, "method Register not implemented")
+}
+func (UnimplementedMcpMasterServiceServer) Heartbeat(context.Context, *HeartbeatRequest) (*HeartbeatResponse, error) {
+	return nil, status.Error(codes.Unimplemented, "method Heartbeat not implemented")
+}
 func (UnimplementedMcpMasterServiceServer) mustEmbedUnimplementedMcpMasterServiceServer() {}
 func (UnimplementedMcpMasterServiceServer) testEmbeddedByValue()                          {}
 
@@ -218,6 +252,42 @@ func _McpMasterService_ListNodes_Handler(srv interface{}, ctx context.Context, d
 	return interceptor(ctx, in, info, handler)
 }
 
+func _McpMasterService_Register_Handler(srv interface{}, ctx context.Context, dec func(interface{}) error, interceptor grpc.UnaryServerInterceptor) (interface{}, error) {
+	in := new(RegisterRequest)
+	if err := dec(in); err != nil {
+		return nil, err
+	}
+	if interceptor == nil {
+		return srv.(McpMasterServiceServer).Register(ctx, in)
+	}
+	info := &grpc.UnaryServerInfo{
+		Server:     srv,
+		FullMethod: McpMasterService_Register_FullMethodName,
+	}
+	handler := func(ctx context.Context, req interface{}) (interface{}, error) {
+		return srv.(McpMasterServiceServer).Register(ctx, req.(*RegisterRequest))
+	}
+	return interceptor(ctx, in, info, handler)
+}
+
+func _McpMasterService_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.(McpMasterServiceServer).Heartbeat(ctx, in)
+	}
+	info := &grpc.UnaryServerInfo{
+		Server:     srv,
+		FullMethod: McpMasterService_Heartbeat_FullMethodName,
+	}
+	handler := func(ctx context.Context, req interface{}) (interface{}, error) {
+		return srv.(McpMasterServiceServer).Heartbeat(ctx, req.(*HeartbeatRequest))
+	}
+	return interceptor(ctx, in, info, handler)
+}
+
 // McpMasterService_ServiceDesc is the grpc.ServiceDesc for McpMasterService service.
 // It's only intended for direct use with grpc.RegisterService,
 // and not to be introspected or modified (even as a copy)
@@ -241,6 +311,14 @@ var McpMasterService_ServiceDesc = grpc.ServiceDesc{
 			MethodName: "ListNodes",
 			Handler:    _McpMasterService_ListNodes_Handler,
 		},
+		{
+			MethodName: "Register",
+			Handler:    _McpMasterService_Register_Handler,
+		},
+		{
+			MethodName: "Heartbeat",
+			Handler:    _McpMasterService_Heartbeat_Handler,
+		},
 	},
 	Streams:  []grpc.StreamDesc{},
 	Metadata: "proto/mcp/v1/master.proto",

internal/agent/agent.go

@@ -131,6 +131,15 @@ func Run(cfg *config.AgentConfig, version string) error {
 		}
 	}
 
+	// Start heartbeat client (registers with master and sends heartbeats).
+	hbClient, hbErr := NewHeartbeatClient(*cfg, logger)
+	if hbErr != nil {
+		logger.Warn("heartbeat client failed to start", "err", hbErr)
+	} else if hbClient != nil {
+		hbClient.Start()
+		logger.Info("heartbeat client started", "master", cfg.Master.Address)
+	}
+
 	mon.Start()
 
 	ctx, stop := signal.NotifyContext(context.Background(), syscall.SIGINT, syscall.SIGTERM)
@@ -144,6 +153,9 @@ func Run(cfg *config.AgentConfig, version string) error {
 	select {
 	case <-ctx.Done():
 		logger.Info("shutting down")
+		if hbClient != nil {
+			hbClient.Stop()
+		}
 		mon.Stop()
 		server.GracefulStop()
 		_ = proxy.Close()

internal/agent/heartbeat.go

@@ -0,0 +1,197 @@
+package agent
+
+import (
+	"context"
+	"crypto/tls"
+	"crypto/x509"
+	"fmt"
+	"os"
+	"runtime"
+	"strings"
+	"sync"
+	"time"
+
+	mcpv1 "git.wntrmute.dev/mc/mcp/gen/mcp/v1"
+	"git.wntrmute.dev/mc/mcp/internal/config"
+	"google.golang.org/grpc"
+	"google.golang.org/grpc/credentials"
+	"google.golang.org/grpc/metadata"
+)
+
+// MasterConfig holds the optional master connection settings for the agent.
+// When configured, the agent self-registers and sends periodic heartbeats.
+type MasterConfig struct {
+	Address   string `toml:"address"`   // master gRPC address
+	CACert    string `toml:"ca_cert"`   // CA cert to verify master's TLS
+	TokenPath string `toml:"token_path"` // MCIAS service token for auth
+}
+
+// HeartbeatClient manages the agent's connection to the master for
+// registration and heartbeats.
+type HeartbeatClient struct {
+	client   mcpv1.McpMasterServiceClient
+	conn     *grpc.ClientConn
+	nodeName string
+	role     string
+	address  string // agent's own gRPC address
+	arch     string
+	interval time.Duration
+	stop     chan struct{}
+	wg       sync.WaitGroup
+	logger   interface{ Info(string, ...any); Warn(string, ...any); Error(string, ...any) }
+}
+
+// NewHeartbeatClient creates a client that registers with the master and
+// sends periodic heartbeats. Returns nil if master address is not configured.
+func NewHeartbeatClient(cfg config.AgentConfig, logger interface{ Info(string, ...any); Warn(string, ...any); Error(string, ...any) }) (*HeartbeatClient, error) {
+	// Config takes precedence, env vars as fallback.
+	masterAddr := cfg.Master.Address
+	if masterAddr == "" {
+		masterAddr = os.Getenv("MCP_MASTER_ADDRESS")
+	}
+	masterCACert := cfg.Master.CACert
+	if masterCACert == "" {
+		masterCACert = os.Getenv("MCP_MASTER_CA_CERT")
+	}
+	masterTokenPath := cfg.Master.TokenPath
+	if masterTokenPath == "" {
+		masterTokenPath = os.Getenv("MCP_MASTER_TOKEN_PATH")
+	}
+	role := cfg.Master.Role
+	if role == "" {
+		role = "worker"
+	}
+
+	if masterAddr == "" {
+		return nil, nil // master not configured
+	}
+
+	token := ""
+	if masterTokenPath != "" {
+		data, err := os.ReadFile(masterTokenPath) //nolint:gosec // trusted config
+		if err != nil {
+			return nil, fmt.Errorf("read master token: %w", err)
+		}
+		token = strings.TrimSpace(string(data))
+	}
+
+	tlsConfig := &tls.Config{MinVersion: tls.VersionTLS13}
+	if masterCACert != "" {
+		caCert, err := os.ReadFile(masterCACert) //nolint:gosec // trusted config
+		if err != nil {
+			return nil, fmt.Errorf("read master CA cert: %w", err)
+		}
+		pool := x509.NewCertPool()
+		if !pool.AppendCertsFromPEM(caCert) {
+			return nil, fmt.Errorf("invalid master CA cert")
+		}
+		tlsConfig.RootCAs = pool
+	}
+
+	conn, err := grpc.NewClient(
+		masterAddr,
+		grpc.WithTransportCredentials(credentials.NewTLS(tlsConfig)),
+		grpc.WithUnaryInterceptor(func(ctx context.Context, method string, req, reply any, cc *grpc.ClientConn, invoker grpc.UnaryInvoker, opts ...grpc.CallOption) error {
+			if token != "" {
+				ctx = metadata.AppendToOutgoingContext(ctx, "authorization", "Bearer "+token)
+			}
+			return invoker(ctx, method, req, reply, cc, opts...)
+		}),
+	)
+	if err != nil {
+		return nil, fmt.Errorf("dial master: %w", err)
+	}
+
+	return &HeartbeatClient{
+		client:   mcpv1.NewMcpMasterServiceClient(conn),
+		conn:     conn,
+		nodeName: cfg.Agent.NodeName,
+		role:     role,
+		address:  cfg.Server.GRPCAddr,
+		arch:     runtime.GOARCH,
+		interval: 30 * time.Second,
+		stop:     make(chan struct{}),
+		logger:   logger,
+	}, nil
+}
+
+// Start registers with the master and begins the heartbeat loop.
+func (hc *HeartbeatClient) Start() {
+	if hc == nil {
+		return
+	}
+
+	// Register with the master (retry with backoff).
+	hc.wg.Add(1)
+	go func() {
+		defer hc.wg.Done()
+
+		backoff := time.Second
+		for {
+			ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
+			resp, err := hc.client.Register(ctx, &mcpv1.RegisterRequest{
+				Name:    hc.nodeName,
+				Role:    hc.role,
+				Address: hc.address,
+				Arch:    hc.arch,
+			})
+			cancel()
+
+			if err == nil && resp.GetAccepted() {
+				hc.logger.Info("registered with master",
+					"node", hc.nodeName, "master_accepted", true)
+				break
+			}
+
+			hc.logger.Warn("registration failed, retrying",
+				"node", hc.nodeName, "err", err, "backoff", backoff)
+
+			select {
+			case <-hc.stop:
+				return
+			case <-time.After(backoff):
+			}
+
+			backoff *= 2
+			if backoff > 60*time.Second {
+				backoff = 60 * time.Second
+			}
+		}
+
+		// Heartbeat loop.
+		ticker := time.NewTicker(hc.interval)
+		defer ticker.Stop()
+
+		for {
+			select {
+			case <-hc.stop:
+				return
+			case <-ticker.C:
+				hc.sendHeartbeat()
+			}
+		}
+	}()
+}
+
+func (hc *HeartbeatClient) sendHeartbeat() {
+	ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
+	defer cancel()
+
+	_, err := hc.client.Heartbeat(ctx, &mcpv1.HeartbeatRequest{
+		Name:       hc.nodeName,
+		Containers: 0, // TODO: count from runtime
+	})
+	if err != nil {
+		hc.logger.Warn("heartbeat failed", "node", hc.nodeName, "err", err)
+	}
+}
+
+// Stop stops the heartbeat loop and closes the master connection.
+func (hc *HeartbeatClient) Stop() {
+	if hc == nil {
+		return
+	}
+	close(hc.stop)
+	hc.wg.Wait()
+	_ = hc.conn.Close()
+}

internal/config/agent.go

@@ -20,6 +20,16 @@ type AgentConfig struct {
 	Monitor   MonitorConfig   `toml:"monitor"`
 	Log       LogConfig       `toml:"log"`
 	Boot   BootConfig        `toml:"boot"`
+	Master AgentMasterConfig `toml:"master"`
+}
+
+// AgentMasterConfig holds the optional master connection settings.
+// When configured, the agent self-registers and sends heartbeats.
+type AgentMasterConfig struct {
+	Address   string `toml:"address"`    // master gRPC address
+	CACert    string `toml:"ca_cert"`    // CA cert to verify master's TLS
+	TokenPath string `toml:"token_path"` // MCIAS service token for auth
+	Role      string `toml:"role"`       // "worker", "edge", or "master"
 }
 
 // BootConfig holds the boot sequence for the master node.

internal/master/master.go

@@ -124,6 +124,10 @@ func Run(cfg *config.MasterConfig, version string) error {
 		"nodes", len(cfg.Nodes),
 	)
 
+	// Start heartbeat monitor.
+	hbMonitor := NewHeartbeatMonitor(m)
+	hbMonitor.Start()
+
 	// Signal handling.
 	ctx, stop := signal.NotifyContext(context.Background(), syscall.SIGINT, syscall.SIGTERM)
 	defer stop()
@@ -136,10 +140,12 @@ func Run(cfg *config.MasterConfig, version string) error {
 	select {
 	case <-ctx.Done():
 		logger.Info("shutting down")
+		hbMonitor.Stop()
 		server.GracefulStop()
 		pool.Close()
 		return nil
 	case err := <-errCh:
+		hbMonitor.Stop()
 		pool.Close()
 		return fmt.Errorf("serve: %w", err)
 	}

internal/master/registration.go

@@ -0,0 +1,235 @@
+package master
+
+import (
+	"context"
+	"strings"
+	"sync"
+	"time"
+
+	mcpv1 "git.wntrmute.dev/mc/mcp/gen/mcp/v1"
+	"git.wntrmute.dev/mc/mcp/internal/auth"
+	"git.wntrmute.dev/mc/mcp/internal/masterdb"
+	"google.golang.org/grpc/codes"
+	"google.golang.org/grpc/status"
+)
+
+// Register handles agent self-registration. Identity-bound: the agent's
+// MCIAS service name must match the claimed node name (agent-rift → rift).
+func (m *Master) Register(ctx context.Context, req *mcpv1.RegisterRequest) (*mcpv1.RegisterResponse, error) {
+	// Extract caller identity from the auth context.
+	tokenInfo := auth.TokenInfoFromContext(ctx)
+	if tokenInfo == nil {
+		return nil, status.Error(codes.Unauthenticated, "no auth context")
+	}
+
+	// Identity binding: agent-rift can only register name="rift".
+	expectedName := strings.TrimPrefix(tokenInfo.Username, "agent-")
+	if expectedName == tokenInfo.Username {
+		// Not an agent-* account — also allow mcp-agent (legacy).
+		expectedName = req.GetName()
+	}
+	if req.GetName() != expectedName {
+		m.Logger.Warn("registration rejected: name mismatch",
+			"claimed", req.GetName(), "identity", tokenInfo.Username)
+		return nil, status.Errorf(codes.PermissionDenied,
+			"identity %q cannot register as %q", tokenInfo.Username, req.GetName())
+	}
+
+	// Check allowlist.
+	if len(m.Config.Registration.AllowedAgents) > 0 {
+		allowed := false
+		for _, a := range m.Config.Registration.AllowedAgents {
+			if a == tokenInfo.Username {
+				allowed = true
+				break
+			}
+		}
+		if !allowed {
+			m.Logger.Warn("registration rejected: not in allowlist",
+				"identity", tokenInfo.Username)
+			return nil, status.Errorf(codes.PermissionDenied,
+				"identity %q not in registration allowlist", tokenInfo.Username)
+		}
+	}
+
+	// Check max nodes.
+	nodes, err := masterdb.ListNodes(m.DB)
+	if err == nil && len(nodes) >= m.Config.Registration.MaxNodes {
+		// Check if this is a re-registration (existing node).
+		found := false
+		for _, n := range nodes {
+			if n.Name == req.GetName() {
+				found = true
+				break
+			}
+		}
+		if !found {
+			return nil, status.Error(codes.ResourceExhausted, "max nodes reached")
+		}
+	}
+
+	// Upsert node in registry.
+	role := req.GetRole()
+	if role == "" {
+		role = "worker"
+	}
+	arch := req.GetArch()
+	if arch == "" {
+		arch = "amd64"
+	}
+
+	if err := masterdb.UpsertNode(m.DB, req.GetName(), req.GetAddress(), role, arch); err != nil {
+		m.Logger.Error("registration upsert failed", "node", req.GetName(), "err", err)
+		return nil, status.Error(codes.Internal, "registration failed")
+	}
+	if err := masterdb.UpdateNodeStatus(m.DB, req.GetName(), "healthy"); err != nil {
+		m.Logger.Warn("update node status", "node", req.GetName(), "err", err)
+	}
+
+	// Update the agent pool connection.
+	if addErr := m.Pool.AddNode(req.GetName(), req.GetAddress()); addErr != nil {
+		m.Logger.Warn("pool update failed", "node", req.GetName(), "err", addErr)
+	}
+
+	m.Logger.Info("agent registered",
+		"node", req.GetName(), "address", req.GetAddress(),
+		"role", role, "arch", arch, "identity", tokenInfo.Username)
+
+	return &mcpv1.RegisterResponse{Accepted: true}, nil
+}
+
+// Heartbeat handles agent heartbeats. Updates the node's resource data
+// and last-heartbeat timestamp. Derives the node name from the MCIAS
+// identity, not the request (security: don't trust self-reported name).
+func (m *Master) Heartbeat(ctx context.Context, req *mcpv1.HeartbeatRequest) (*mcpv1.HeartbeatResponse, error) {
+	// Derive node name from identity.
+	tokenInfo := auth.TokenInfoFromContext(ctx)
+	if tokenInfo == nil {
+		return nil, status.Error(codes.Unauthenticated, "no auth context")
+	}
+
+	nodeName := strings.TrimPrefix(tokenInfo.Username, "agent-")
+	if nodeName == tokenInfo.Username {
+		// Legacy mcp-agent account — use the request name.
+		nodeName = req.GetName()
+	}
+
+	// Verify the node is registered.
+	node, err := masterdb.GetNode(m.DB, nodeName)
+	if err != nil || node == nil {
+		return nil, status.Errorf(codes.NotFound, "node %q not registered", nodeName)
+	}
+
+	// Update heartbeat data.
+	now := time.Now().UTC().Format(time.RFC3339)
+	_, err = m.DB.Exec(`
+		UPDATE nodes SET
+			containers = ?,
+			status = 'healthy',
+			last_heartbeat = ?,
+			updated_at = datetime('now')
+		WHERE name = ?
+	`, req.GetContainers(), now, nodeName)
+	if err != nil {
+		m.Logger.Warn("heartbeat update failed", "node", nodeName, "err", err)
+	}
+
+	return &mcpv1.HeartbeatResponse{Acknowledged: true}, nil
+}
+
+// HeartbeatMonitor runs in the background, checking for agents that have
+// missed heartbeats and probing them via HealthCheck.
+type HeartbeatMonitor struct {
+	master   *Master
+	interval time.Duration // heartbeat check interval (default: 30s)
+	timeout  time.Duration // missed heartbeat threshold (default: 90s)
+	stop     chan struct{}
+	wg       sync.WaitGroup
+}
+
+// NewHeartbeatMonitor creates a heartbeat monitor.
+func NewHeartbeatMonitor(m *Master) *HeartbeatMonitor {
+	return &HeartbeatMonitor{
+		master:   m,
+		interval: 30 * time.Second,
+		timeout:  90 * time.Second,
+		stop:     make(chan struct{}),
+	}
+}
+
+// Start begins the heartbeat monitoring loop.
+func (hm *HeartbeatMonitor) Start() {
+	hm.wg.Add(1)
+	go func() {
+		defer hm.wg.Done()
+		// Initial warm-up: don't alert for the first cycle.
+		time.Sleep(hm.timeout)
+
+		ticker := time.NewTicker(hm.interval)
+		defer ticker.Stop()
+
+		for {
+			select {
+			case <-hm.stop:
+				return
+			case <-ticker.C:
+				hm.check()
+			}
+		}
+	}()
+}
+
+// Stop stops the heartbeat monitor.
+func (hm *HeartbeatMonitor) Stop() {
+	close(hm.stop)
+	hm.wg.Wait()
+}
+
+func (hm *HeartbeatMonitor) check() {
+	nodes, err := masterdb.ListNodes(hm.master.DB)
+	if err != nil {
+		hm.master.Logger.Warn("heartbeat check: list nodes", "err", err)
+		return
+	}
+
+	now := time.Now()
+	for _, node := range nodes {
+		if node.Status == "unhealthy" {
+			continue // already marked, don't spam probes
+		}
+
+		if node.LastHeartbeat == nil {
+			continue // never sent a heartbeat, skip
+		}
+
+		if now.Sub(*node.LastHeartbeat) > hm.timeout {
+			hm.master.Logger.Warn("missed heartbeats, probing",
+				"node", node.Name,
+				"last_heartbeat", node.LastHeartbeat.Format(time.RFC3339))
+
+			// Probe the agent.
+			client, err := hm.master.Pool.Get(node.Name)
+			if err != nil {
+				hm.master.Logger.Warn("probe failed: no connection",
+					"node", node.Name, "err", err)
+				_ = masterdb.UpdateNodeStatus(hm.master.DB, node.Name, "unhealthy")
+				continue
+			}
+
+			ctx, cancel := context.WithTimeout(context.Background(),
+				hm.master.Config.Timeouts.HealthCheck.Duration)
+			_, probeErr := client.HealthCheck(ctx, &mcpv1.HealthCheckRequest{})
+			cancel()
+
+			if probeErr != nil {
+				hm.master.Logger.Warn("probe failed",
+					"node", node.Name, "err", probeErr)
+				_ = masterdb.UpdateNodeStatus(hm.master.DB, node.Name, "unhealthy")
+			} else {
+				// Probe succeeded — node is alive, just not sending heartbeats.
+				hm.master.Logger.Info("probe succeeded (heartbeats stale)",
+					"node", node.Name)
+			}
+		}
+	}
+}

proto/mcp/v1/master.proto

@@ -16,6 +16,10 @@ service McpMasterService {
   rpc Undeploy(MasterUndeployRequest) returns (MasterUndeployResponse);
   rpc Status(MasterStatusRequest) returns (MasterStatusResponse);
   rpc ListNodes(ListNodesRequest) returns (ListNodesResponse);
+
+  // Agent registration and health (called by agents).
+  rpc Register(RegisterRequest) returns (RegisterResponse);
+  rpc Heartbeat(HeartbeatRequest) returns (HeartbeatResponse);
 }
 
 // --- Deploy ---
@@ -93,3 +97,30 @@ message NodeInfo {
   string last_heartbeat = 7;  // RFC3339
   int32  services       = 8;  // placement count
 }
+
+// --- Registration ---
+
+message RegisterRequest {
+  string name    = 1;
+  string role    = 2;  // "worker", "edge", or "master"
+  string address = 3;  // agent gRPC address
+  string arch    = 4;  // "amd64" or "arm64"
+}
+
+message RegisterResponse {
+  bool accepted = 1;
+}
+
+// --- Heartbeat ---
+
+message HeartbeatRequest {
+  string name           = 1;
+  int64  cpu_millicores = 2;
+  int64  memory_bytes   = 3;
+  int64  disk_bytes     = 4;
+  int32  containers     = 5;
+}
+
+message HeartbeatResponse {
+  bool acknowledged = 1;
+}