feat(proxy): restore SyncMappings bidirectional stream with ack back-pressure

Reinstates the SyncMappings RPC that landed on origin/main and the
client-side fallback to GetMappingUpdate.

- proto: SyncMappings RPC + SyncMappingsRequest{Init|Ack} +
  SyncMappingsResponse messages.
- management proxy.go: SyncMappings server handler, recvSyncInit,
  sendSnapshotSync (per-batch send-then-wait-for-ack), drainRecv,
  waitForAck; proxyConnection.syncStream + sendResponse routes the
  same sendChan onto the bidi stream when set.
- proxy/server.go: trySyncMappings + handleSyncMappingsStream that
  acks after each batch is processed; outer loop tries SyncMappings
  first and falls back to GetMappingUpdate on Unimplemented.
  Capabilities lifted into proxyCapabilities() so both code paths
  use the same flags.

management/internals/shared/grpc/proxy.go

@@ -9,6 +9,7 @@ import (
 	"encoding/hex"
 	"errors"
 	"fmt"
+	"io"
 	"net"
 	"net/http"
 	"net/url"
@@ -78,10 +79,7 @@ type ProxyServiceServer struct {
 	// Manager for peers
 	peersManager peers.Manager
 
-	// Manager for users — also resolves user.AutoGroups to *types.Group
-	// records via GetUserWithGroups, used to stamp human-readable
-	// group names into JWT claims and onto upstream identity-bearing
-	// requests (llm_identity_inject's tags header).
+	// Manager for users
 	usersManager users.Manager
 
 	// Store for one-time authentication tokens
@@ -139,9 +137,12 @@ type proxyConnection struct {
 	tokenID      string
 	capabilities *proto.ProxyCapabilities
 	stream       proto.ProxyService_GetMappingUpdateServer
-	sendChan     chan *proto.GetMappingUpdateResponse
-	ctx          context.Context
-	cancel       context.CancelFunc
+	// syncStream is set when the proxy connected via SyncMappings.
+	// When non-nil, the sender goroutine uses this instead of stream.
+	syncStream proto.ProxyService_SyncMappingsServer
+	sendChan   chan *proto.GetMappingUpdateResponse
+	ctx        context.Context
+	cancel     context.CancelFunc
 }
 
 func enforceAccountScope(ctx context.Context, requestAccountID string) error {
@@ -209,146 +210,322 @@ func (s *ProxyServiceServer) SetProxyController(proxyController proxy.Controller
 	s.proxyController = proxyController
 }
 
+// proxyConnectParams holds the validated parameters extracted from either
+// a GetMappingUpdateRequest or a SyncMappingsInit message.
+type proxyConnectParams struct {
+	proxyID      string
+	address      string
+	capabilities *proto.ProxyCapabilities
+}
+
 // GetMappingUpdate handles the control stream with proxy clients
 func (s *ProxyServiceServer) GetMappingUpdate(req *proto.GetMappingUpdateRequest, stream proto.ProxyService_GetMappingUpdateServer) error {
-	ctx := stream.Context()
-
-	peerInfo := PeerIPFromContext(ctx)
-	log.Infof("New proxy connection from %s", peerInfo)
-
-	proxyID := req.GetProxyId()
-	if proxyID == "" {
-		return status.Errorf(codes.InvalidArgument, "proxy_id is required")
-	}
-
-	proxyAddress := req.GetAddress()
-	if !isProxyAddressValid(proxyAddress) {
-		return status.Errorf(codes.InvalidArgument, "proxy address is invalid")
-	}
-
-	var accountID *string
-	token := GetProxyTokenFromContext(ctx)
-	if token != nil && token.AccountID != nil {
-		accountID = token.AccountID
-
-		available, err := s.proxyManager.IsClusterAddressAvailable(ctx, proxyAddress, *accountID)
-		if err != nil {
-			return status.Errorf(codes.Internal, "check cluster address: %v", err)
-		}
-		if !available {
-			return status.Errorf(codes.AlreadyExists, "cluster address %s is already in use", proxyAddress)
-		}
-	}
-
-	var tokenID string
-	if token != nil {
-		tokenID = token.ID
-	}
-
-	sessionID := uuid.NewString()
-
-	if old, loaded := s.connectedProxies.Load(proxyID); loaded {
-		oldConn := old.(*proxyConnection)
-		log.WithFields(log.Fields{
-			"proxy_id":       proxyID,
-			"old_session_id": oldConn.sessionID,
-			"new_session_id": sessionID,
-		}).Info("Superseding existing proxy connection")
-		oldConn.cancel()
-	}
-
-	connCtx, cancel := context.WithCancel(ctx)
-	conn := &proxyConnection{
-		proxyID:      proxyID,
-		sessionID:    sessionID,
-		address:      proxyAddress,
-		accountID:    accountID,
-		tokenID:      tokenID,
-		capabilities: req.GetCapabilities(),
-		stream:       stream,
-		sendChan:     make(chan *proto.GetMappingUpdateResponse, 100),
-		ctx:          connCtx,
-		cancel:       cancel,
-	}
-
-	var caps *proxy.Capabilities
-	if c := req.GetCapabilities(); c != nil {
-		caps = &proxy.Capabilities{
-			SupportsCustomPorts: c.SupportsCustomPorts,
-			RequireSubdomain:    c.RequireSubdomain,
-			SupportsCrowdsec:    c.SupportsCrowdsec,
-			Private:             c.Private,
-		}
-	}
-	proxyRecord, err := s.proxyManager.Connect(ctx, proxyID, sessionID, proxyAddress, peerInfo, accountID, caps)
+	params, err := s.validateProxyConnect(req.GetProxyId(), req.GetAddress(), stream.Context())
 	if err != nil {
-		cancel()
-		if accountID != nil {
-			return status.Errorf(codes.Internal, "failed to register BYOP proxy: %v", err)
-		}
-		log.WithContext(ctx).Warnf("failed to register proxy %s in database: %v", proxyID, err)
-		return status.Errorf(codes.Internal, "register proxy in database: %v", err)
+		return err
+	}
+	params.capabilities = req.GetCapabilities()
+
+	conn, proxyRecord, err := s.registerProxyConnection(stream.Context(), params, &proxyConnection{
+		stream: stream,
+	})
+	if err != nil {
+		return err
 	}
 
-	s.connectedProxies.Store(proxyID, conn)
-	if err := s.proxyController.RegisterProxyToCluster(ctx, conn.address, proxyID); err != nil {
-		log.WithContext(ctx).Warnf("Failed to register proxy %s in cluster: %v", proxyID, err)
-	}
-
-	if err := s.sendSnapshot(ctx, conn); err != nil {
-		if s.connectedProxies.CompareAndDelete(proxyID, conn) {
-			if unregErr := s.proxyController.UnregisterProxyFromCluster(context.Background(), conn.address, proxyID); unregErr != nil {
-				log.WithContext(ctx).Debugf("cleanup after snapshot failure for proxy %s: %v", proxyID, unregErr)
-			}
-		}
-		cancel()
-		if disconnErr := s.proxyManager.Disconnect(context.Background(), proxyID, sessionID); disconnErr != nil {
-			log.WithContext(ctx).Debugf("cleanup after snapshot failure for proxy %s: %v", proxyID, disconnErr)
-		}
-		return fmt.Errorf("send snapshot to proxy %s: %w", proxyID, err)
+	if err := s.sendSnapshot(stream.Context(), conn); err != nil {
+		s.cleanupFailedSnapshot(stream.Context(), conn)
+		return fmt.Errorf("send snapshot to proxy %s: %w", params.proxyID, err)
 	}
 
 	errChan := make(chan error, 2)
 	go s.sender(conn, errChan)
 
-	log.WithFields(log.Fields{
-		"proxy_id":      proxyID,
-		"session_id":    sessionID,
-		"address":       proxyAddress,
-		"cluster_addr":  proxyAddress,
-		"account_id":    accountID,
-		"total_proxies": len(s.GetConnectedProxies()),
-	}).Info("Proxy registered in cluster")
-	defer func() {
-		if !s.connectedProxies.CompareAndDelete(proxyID, conn) {
-			log.Infof("Proxy %s session %s: skipping cleanup, superseded by new connection", proxyID, sessionID)
-			cancel()
+	return s.serveProxyConnection(conn, proxyRecord, errChan, false)
+}
+
+// SyncMappings implements the bidirectional SyncMappings RPC.
+// It mirrors GetMappingUpdate but provides application-level back-pressure:
+// management waits for an ack from the proxy before sending the next batch.
+func (s *ProxyServiceServer) SyncMappings(stream proto.ProxyService_SyncMappingsServer) error {
+	init, err := recvSyncInit(stream)
+	if err != nil {
+		return err
+	}
+
+	params, err := s.validateProxyConnect(init.GetProxyId(), init.GetAddress(), stream.Context())
+	if err != nil {
+		return err
+	}
+	params.capabilities = init.GetCapabilities()
+
+	conn, proxyRecord, err := s.registerProxyConnection(stream.Context(), params, &proxyConnection{
+		syncStream: stream,
+	})
+	if err != nil {
+		return err
+	}
+
+	if err := s.sendSnapshotSync(stream.Context(), conn, stream); err != nil {
+		s.cleanupFailedSnapshot(stream.Context(), conn)
+		return fmt.Errorf("send snapshot to proxy %s: %w", params.proxyID, err)
+	}
+
+	errChan := make(chan error, 2)
+	go s.sender(conn, errChan)
+	go s.drainRecv(stream, errChan)
+
+	return s.serveProxyConnection(conn, proxyRecord, errChan, true)
+}
+
+// recvSyncInit receives and validates the first message on a SyncMappings stream.
+func recvSyncInit(stream proto.ProxyService_SyncMappingsServer) (*proto.SyncMappingsInit, error) {
+	firstMsg, err := stream.Recv()
+	if err != nil {
+		return nil, status.Errorf(codes.Internal, "receive init: %v", err)
+	}
+	init := firstMsg.GetInit()
+	if init == nil {
+		return nil, status.Errorf(codes.InvalidArgument, "first message must be init")
+	}
+	return init, nil
+}
+
+// validateProxyConnect validates the proxy ID and address, and checks cluster
+// address availability for account-scoped tokens.
+func (s *ProxyServiceServer) validateProxyConnect(proxyID, address string, ctx context.Context) (proxyConnectParams, error) {
+	if proxyID == "" {
+		return proxyConnectParams{}, status.Errorf(codes.InvalidArgument, "proxy_id is required")
+	}
+	if !isProxyAddressValid(address) {
+		return proxyConnectParams{}, status.Errorf(codes.InvalidArgument, "proxy address is invalid")
+	}
+
+	token := GetProxyTokenFromContext(ctx)
+	if token != nil && token.AccountID != nil {
+		available, err := s.proxyManager.IsClusterAddressAvailable(ctx, address, *token.AccountID)
+		if err != nil {
+			return proxyConnectParams{}, status.Errorf(codes.Internal, "check cluster address: %v", err)
+		}
+		if !available {
+			return proxyConnectParams{}, status.Errorf(codes.AlreadyExists, "cluster address %s is already in use", address)
+		}
+	}
+
+	return proxyConnectParams{proxyID: proxyID, address: address}, nil
+}
+
+// registerProxyConnection creates a proxyConnection, registers it with the
+// proxy manager and cluster, and stores it in connectedProxies. The caller
+// provides a partially initialised connSeed with stream-specific fields set;
+// the remaining fields are filled in here.
+func (s *ProxyServiceServer) registerProxyConnection(ctx context.Context, params proxyConnectParams, connSeed *proxyConnection) (*proxyConnection, *proxy.Proxy, error) {
+	peerInfo := PeerIPFromContext(ctx)
+
+	var accountID *string
+	var tokenID string
+	if token := GetProxyTokenFromContext(ctx); token != nil {
+		if token.AccountID != nil {
+			accountID = token.AccountID
+		}
+		tokenID = token.ID
+	}
+
+	sessionID := uuid.NewString()
+	s.supersedePriorConnection(params.proxyID, sessionID)
+
+	connCtx, cancel := context.WithCancel(ctx)
+	connSeed.proxyID = params.proxyID
+	connSeed.sessionID = sessionID
+	connSeed.address = params.address
+	connSeed.accountID = accountID
+	connSeed.tokenID = tokenID
+	connSeed.capabilities = params.capabilities
+	connSeed.sendChan = make(chan *proto.GetMappingUpdateResponse, 100)
+	connSeed.ctx = connCtx
+	connSeed.cancel = cancel
+
+	var caps *proxy.Capabilities
+	if c := params.capabilities; c != nil {
+		caps = &proxy.Capabilities{
+			SupportsCustomPorts: c.SupportsCustomPorts,
+			RequireSubdomain:    c.RequireSubdomain,
+			SupportsCrowdsec:    c.SupportsCrowdsec,
+		}
+	}
+
+	proxyRecord, err := s.proxyManager.Connect(ctx, params.proxyID, sessionID, params.address, peerInfo, accountID, caps)
+	if err != nil {
+		cancel()
+		if accountID != nil {
+			return nil, nil, status.Errorf(codes.Internal, "failed to register BYOP proxy: %v", err)
+		}
+		log.WithContext(ctx).Warnf("failed to register proxy %s in database: %v", params.proxyID, err)
+		return nil, nil, status.Errorf(codes.Internal, "register proxy in database: %v", err)
+	}
+
+	s.connectedProxies.Store(params.proxyID, connSeed)
+	if err := s.proxyController.RegisterProxyToCluster(ctx, params.address, params.proxyID); err != nil {
+		log.WithContext(ctx).Warnf("Failed to register proxy %s in cluster: %v", params.proxyID, err)
+	}
+
+	return connSeed, proxyRecord, nil
+}
+
+// supersedePriorConnection cancels any existing connection for the given proxy.
+func (s *ProxyServiceServer) supersedePriorConnection(proxyID, newSessionID string) {
+	if old, loaded := s.connectedProxies.Load(proxyID); loaded {
+		oldConn := old.(*proxyConnection)
+		log.WithFields(log.Fields{
+			"proxy_id":       proxyID,
+			"old_session_id": oldConn.sessionID,
+			"new_session_id": newSessionID,
+		}).Info("Superseding existing proxy connection")
+		oldConn.cancel()
+	}
+}
+
+// cleanupFailedSnapshot removes the connection from the cluster and store
+// after a snapshot send failure.
+func (s *ProxyServiceServer) cleanupFailedSnapshot(ctx context.Context, conn *proxyConnection) {
+	if s.connectedProxies.CompareAndDelete(conn.proxyID, conn) {
+		if err := s.proxyController.UnregisterProxyFromCluster(context.Background(), conn.address, conn.proxyID); err != nil {
+			log.WithContext(ctx).Debugf("cleanup after snapshot failure for proxy %s: %v", conn.proxyID, err)
+		}
+	}
+	conn.cancel()
+	if err := s.proxyManager.Disconnect(context.Background(), conn.proxyID, conn.sessionID); err != nil {
+		log.WithContext(ctx).Debugf("cleanup after snapshot failure for proxy %s: %v", conn.proxyID, err)
+	}
+}
+
+// drainRecv consumes and discards messages from a bidirectional stream.
+// The proxy sends an ack for every incremental update; we don't need them
+// after the snapshot phase. Recv errors are forwarded to errChan.
+func (s *ProxyServiceServer) drainRecv(stream proto.ProxyService_SyncMappingsServer, errChan chan<- error) {
+	for {
+		if _, err := stream.Recv(); err != nil {
+			errChan <- err
 			return
 		}
+	}
+}
 
-		if err := s.proxyController.UnregisterProxyFromCluster(context.Background(), conn.address, proxyID); err != nil {
-			log.Warnf("Failed to unregister proxy %s from cluster: %v", proxyID, err)
-		}
-		if err := s.proxyManager.Disconnect(context.Background(), proxyID, sessionID); err != nil {
-			log.Warnf("Failed to mark proxy %s as disconnected: %v", proxyID, err)
-		}
+// serveProxyConnection runs the post-snapshot lifecycle: heartbeat, sender,
+// and wait for termination. When bidi is true, normal stream closure (EOF,
+// canceled) is treated as a clean disconnect rather than an error.
+func (s *ProxyServiceServer) serveProxyConnection(conn *proxyConnection, proxyRecord *proxy.Proxy, errChan <-chan error, bidi bool) error {
+	log.WithFields(log.Fields{
+		"proxy_id":      conn.proxyID,
+		"session_id":    conn.sessionID,
+		"address":       conn.address,
+		"cluster_addr":  conn.address,
+		"account_id":    conn.accountID,
+		"total_proxies": len(s.GetConnectedProxies()),
+	}).Info("Proxy registered in cluster")
 
-		cancel()
-		log.Infof("Proxy %s session %s disconnected", proxyID, sessionID)
-	}()
-
-	go s.heartbeat(connCtx, conn, proxyRecord)
+	defer s.disconnectProxy(conn)
+	go s.heartbeat(conn.ctx, conn, proxyRecord)
 
 	select {
 	case err := <-errChan:
-		log.WithContext(ctx).Warnf("Failed to send update: %v", err)
-		return fmt.Errorf("send update to proxy %s: %w", proxyID, err)
-	case <-connCtx.Done():
-		log.WithContext(ctx).Infof("Proxy %s context canceled", proxyID)
-		return connCtx.Err()
+		if bidi && isStreamClosed(err) {
+			log.Infof("Proxy %s stream closed", conn.proxyID)
+			return nil
+		}
+		log.Warnf("Failed to send update: %v", err)
+		return fmt.Errorf("send update to proxy %s: %w", conn.proxyID, err)
+	case <-conn.ctx.Done():
+		log.Infof("Proxy %s context canceled", conn.proxyID)
+		return conn.ctx.Err()
 	}
 }
 
+// disconnectProxy removes the connection from cluster and store, unless it
+// has already been superseded by a newer connection.
+func (s *ProxyServiceServer) disconnectProxy(conn *proxyConnection) {
+	if !s.connectedProxies.CompareAndDelete(conn.proxyID, conn) {
+		log.Infof("Proxy %s session %s: skipping cleanup, superseded by new connection", conn.proxyID, conn.sessionID)
+		conn.cancel()
+		return
+	}
+
+	if err := s.proxyController.UnregisterProxyFromCluster(context.Background(), conn.address, conn.proxyID); err != nil {
+		log.Warnf("Failed to unregister proxy %s from cluster: %v", conn.proxyID, err)
+	}
+	if err := s.proxyManager.Disconnect(context.Background(), conn.proxyID, conn.sessionID); err != nil {
+		log.Warnf("Failed to mark proxy %s as disconnected: %v", conn.proxyID, err)
+	}
+
+	conn.cancel()
+	log.Infof("Proxy %s session %s disconnected", conn.proxyID, conn.sessionID)
+}
+
+// sendSnapshotSync sends the initial snapshot with back-pressure: it sends
+// one batch, then waits for the proxy to ack before sending the next.
+func (s *ProxyServiceServer) sendSnapshotSync(ctx context.Context, conn *proxyConnection, stream proto.ProxyService_SyncMappingsServer) error {
+	if !isProxyAddressValid(conn.address) {
+		return fmt.Errorf("proxy address is invalid")
+	}
+	if s.snapshotBatchSize <= 0 {
+		return fmt.Errorf("invalid snapshot batch size: %d", s.snapshotBatchSize)
+	}
+
+	mappings, err := s.snapshotServiceMappings(ctx, conn)
+	if err != nil {
+		return err
+	}
+
+	for i := 0; i < len(mappings); i += s.snapshotBatchSize {
+		end := i + s.snapshotBatchSize
+		if end > len(mappings) {
+			end = len(mappings)
+		}
+		for _, m := range mappings[i:end] {
+			token, err := s.tokenStore.GenerateToken(m.AccountId, m.Id, s.proxyTokenTTL())
+			if err != nil {
+				return fmt.Errorf("generate auth token for service %s: %w", m.Id, err)
+			}
+			m.AuthToken = token
+		}
+		if err := stream.Send(&proto.SyncMappingsResponse{
+			Mapping:             mappings[i:end],
+			InitialSyncComplete: end == len(mappings),
+		}); err != nil {
+			return fmt.Errorf("send snapshot batch: %w", err)
+		}
+
+		if err := waitForAck(stream); err != nil {
+			return err
+		}
+	}
+
+	if len(mappings) == 0 {
+		if err := stream.Send(&proto.SyncMappingsResponse{
+			InitialSyncComplete: true,
+		}); err != nil {
+			return fmt.Errorf("send snapshot completion: %w", err)
+		}
+
+		if err := waitForAck(stream); err != nil {
+			return err
+		}
+	}
+
+	return nil
+}
+
+func waitForAck(stream proto.ProxyService_SyncMappingsServer) error {
+	msg, err := stream.Recv()
+	if err != nil {
+		return fmt.Errorf("receive ack: %w", err)
+	}
+	if msg.GetAck() == nil {
+		return fmt.Errorf("expected ack, got %T", msg.GetMsg())
+	}
+	return nil
+}
+
 // heartbeat updates the proxy's last_seen timestamp every minute and
 // disconnects the proxy if its access token has been revoked.
 func (s *ProxyServiceServer) heartbeat(ctx context.Context, conn *proxyConnection, p *proxy.Proxy) {
@@ -385,6 +562,9 @@ func (s *ProxyServiceServer) sendSnapshot(ctx context.Context, conn *proxyConnec
 	if !isProxyAddressValid(conn.address) {
 		return fmt.Errorf("proxy address is invalid")
 	}
+	if s.snapshotBatchSize <= 0 {
+		return fmt.Errorf("invalid snapshot batch size: %d", s.snapshotBatchSize)
+	}
 
 	mappings, err := s.snapshotServiceMappings(ctx, conn)
 	if err != nil {
@@ -464,12 +644,26 @@ func isProxyAddressValid(addr string) bool {
 	return err == nil
 }
 
-// sender handles sending messages to proxy
+// isStreamClosed returns true for errors that indicate normal stream
+// termination: io.EOF, context cancellation, or gRPC Canceled.
+func isStreamClosed(err error) bool {
+	if err == nil {
+		return false
+	}
+	if errors.Is(err, io.EOF) || errors.Is(err, context.Canceled) {
+		return true
+	}
+	return status.Code(err) == codes.Canceled
+}
+
+// sender handles sending messages to proxy.
+// When conn.syncStream is set the message is sent as SyncMappingsResponse;
+// otherwise the legacy GetMappingUpdateResponse stream is used.
 func (s *ProxyServiceServer) sender(conn *proxyConnection, errChan chan<- error) {
 	for {
 		select {
 		case resp := <-conn.sendChan:
-			if err := conn.stream.Send(resp); err != nil {
+			if err := conn.sendResponse(resp); err != nil {
 				errChan <- err
 				return
 			}
@@ -479,6 +673,17 @@ func (s *ProxyServiceServer) sender(conn *proxyConnection, errChan chan<- error)
 	}
 }
 
+// sendResponse sends a mapping update on whichever stream the proxy connected with.
+func (conn *proxyConnection) sendResponse(resp *proto.GetMappingUpdateResponse) error {
+	if conn.syncStream != nil {
+		return conn.syncStream.Send(&proto.SyncMappingsResponse{
+			Mapping:             resp.Mapping,
+			InitialSyncComplete: resp.InitialSyncComplete,
+		})
+	}
+	return conn.stream.Send(resp)
+}
+
 // SendAccessLog processes access log from proxy
 func (s *ProxyServiceServer) SendAccessLog(ctx context.Context, req *proto.SendAccessLogRequest) (*proto.SendAccessLogResponse, error) {
 	accessLog := req.GetLog()
@@ -551,7 +756,7 @@ func (s *ProxyServiceServer) SendServiceUpdate(update *proto.GetMappingUpdateRes
 		}
 		// Drop mappings the proxy lacks capability for (e.g. private without SupportsPrivateService).
 		connUpdate = filterMappingsForProxy(conn, connUpdate)
-		if len(connUpdate.Mapping) == 0 {
+		if connUpdate == nil || len(connUpdate.Mapping) == 0 {
 			return true
 		}
 		resp := s.perProxyMessage(connUpdate, conn.proxyID)
@@ -663,7 +868,7 @@ func (s *ProxyServiceServer) SendServiceUpdateToCluster(ctx context.Context, upd
 			continue
 		}
 		if !proxyAcceptsMapping(conn, update) {
-			log.WithContext(ctx).Debugf("Skipping proxy %s: missing capability for mapping %s", proxyID, update.Id)
+			log.WithContext(ctx).Debugf("Skipping proxy %s: does not support custom ports for mapping %s", proxyID, update.Id)
 			continue
 		}
 		msg := s.perProxyMessage(updateResponse, proxyID)
@@ -682,7 +887,10 @@ func (s *ProxyServiceServer) SendServiceUpdateToCluster(ctx context.Context, upd
 	}
 }
 
-// proxyAcceptsMapping returns whether the proxy can receive this mapping. Private requires SupportsPrivateService; custom-port L4 requires SupportsCustomPorts. Removes always pass.
+// proxyAcceptsMapping returns whether the proxy can receive this mapping.
+// Private mappings require SupportsPrivateService; custom-port L4 mappings
+// require SupportsCustomPorts. Remove operations always pass so proxies can
+// clean up.
 func proxyAcceptsMapping(conn *proxyConnection, mapping *proto.ProxyMapping) bool {
 	if mapping.Type == proto.ProxyMappingUpdateType_UPDATE_TYPE_REMOVED {
 		return true
@@ -696,23 +904,30 @@ func proxyAcceptsMapping(conn *proxyConnection, mapping *proto.ProxyMapping) boo
 	if mapping.ListenPort == 0 || mapping.Mode == "tls" {
 		return true
 	}
+	// Old proxies that never reported capabilities don't understand
+	// custom port mappings.
 	return conn.capabilities != nil && conn.capabilities.SupportsCustomPorts != nil
 }
 
-// filterMappingsForProxy drops mappings the proxy can't safely receive.
+// filterMappingsForProxy drops mappings the proxy cannot safely receive
+// (e.g. private mappings to a proxy without SupportsPrivateService).
+// Returns the input unchanged when no filtering is needed.
 func filterMappingsForProxy(conn *proxyConnection, update *proto.GetMappingUpdateResponse) *proto.GetMappingUpdateResponse {
-	if update == nil {
+	if update == nil || len(update.Mapping) == 0 {
 		return update
 	}
-	filtered := make([]*proto.ProxyMapping, 0, len(update.Mapping))
+	kept := make([]*proto.ProxyMapping, 0, len(update.Mapping))
 	for _, m := range update.Mapping {
 		if !proxyAcceptsMapping(conn, m) {
 			continue
 		}
-		filtered = append(filtered, m)
+		kept = append(kept, m)
+	}
+	if len(kept) == len(update.Mapping) {
+		return update
 	}
 	return &proto.GetMappingUpdateResponse{
-		Mapping:             filtered,
+		Mapping:             kept,
 		InitialSyncComplete: update.InitialSyncComplete,
 	}
 }
@@ -762,7 +977,6 @@ func shallowCloneMapping(m *proto.ProxyMapping) *proto.ProxyMapping {
 		Mode:               m.Mode,
 		ListenPort:         m.ListenPort,
 		AccessRestrictions: m.AccessRestrictions,
-		Private:            m.Private,
 	}
 }
 
@@ -771,7 +985,7 @@ func (s *ProxyServiceServer) Authenticate(ctx context.Context, req *proto.Authen
 		return nil, err
 	}
 
-	service, err := s.lookupServiceByID(ctx, req.GetAccountId(), req.GetId())
+	service, err := s.serviceManager.GetServiceByID(ctx, req.GetAccountId(), req.GetId())
 	if err != nil {
 		log.WithContext(ctx).Debugf("failed to get service from store: %v", err)
 		return nil, status.Errorf(codes.FailedPrecondition, "get service from store: %v", err)
@@ -895,12 +1109,9 @@ func (s *ProxyServiceServer) generateSessionToken(ctx context.Context, authentic
 }
 
 // pairGroupIDsAndNames splits a slice of resolved *types.Group records
-// into parallel id and name slices. Used to feed JWT claims and
-// response messages from a single GetUserWithGroups call. Position i
-// of the returned slices always pairs the same group: ids[i] is the
-// group id, names[i] is its display name. Records the manager skipped
-// (orphan ids in user.AutoGroups with no matching group row) are
-// already absent here, so the consumer can rely on positional pairing.
+// into parallel id and name slices. ids[i] and names[i] always pair to
+// the same group. nil entries (orphan ids the manager couldn't resolve)
+// are skipped so the consumer can rely on positional pairing.
 func pairGroupIDsAndNames(groups []*types.Group) (ids, names []string) {
 	if len(groups) == 0 {
 		return nil, nil
@@ -1063,7 +1274,19 @@ func (s *ProxyServiceServer) GetOIDCURL(ctx context.Context, req *proto.GetOIDCU
 		return nil, status.Errorf(codes.InvalidArgument, "redirect URL must use http or https scheme")
 	}
 	// Validate redirectURL against known service endpoints to avoid abuse of OIDC redirection.
-	if _, err := s.getAccountServiceByDomain(ctx, req.GetAccountId(), redirectURL.Hostname()); err != nil {
+	services, err := s.serviceManager.GetAccountServices(ctx, req.GetAccountId())
+	if err != nil {
+		log.WithContext(ctx).Errorf("failed to get account services: %v", err)
+		return nil, status.Errorf(codes.FailedPrecondition, "get account services: %v", err)
+	}
+	var found bool
+	for _, service := range services {
+		if service.Domain == redirectURL.Hostname() {
+			found = true
+			break
+		}
+	}
+	if !found {
 		log.WithContext(ctx).Debugf("OIDC redirect URL %q does not match any service domain", redirectURL.Hostname())
 		return nil, status.Errorf(codes.FailedPrecondition, "service not found in store")
 	}
@@ -1266,11 +1489,6 @@ func (s *ProxyServiceServer) getAccountServiceByDomain(ctx context.Context, acco
 	return nil, fmt.Errorf("service not found for domain %s in account %s", domain, accountID)
 }
 
-// lookupServiceByID resolves a service by ID via the persisted store.
-func (s *ProxyServiceServer) lookupServiceByID(ctx context.Context, accountID, serviceID string) (*rpservice.Service, error) {
-	return s.serviceManager.GetServiceByID(ctx, accountID, serviceID)
-}
-
 // ValidateSession validates a session token and checks if the user has access to the domain.
 func (s *ProxyServiceServer) ValidateSession(ctx context.Context, req *proto.ValidateSessionRequest) (*proto.ValidateSessionResponse, error) {
 	domain := req.GetDomain()
@@ -1392,138 +1610,6 @@ func (s *ProxyServiceServer) getServiceByDomain(ctx context.Context, domain stri
 	return s.serviceManager.GetServiceByDomain(ctx, domain)
 }
 
-// ValidateTunnelPeer resolves an inbound peer by its WireGuard tunnel IP and
-// checks the peer's group membership against the service's access groups.
-// Peers without a user (machine agents, automation workloads) are
-// first-class callers, so authorisation runs off peer-group memberships
-// rather than the optional owning user's auto-groups.
-//
-// The minted session JWT carries peer.ID (Subject) and a display identity
-// (Email): user.Email when the peer is attached to a user, else peer.Name.
-// Downstream identity-stamping middlewares emit this display identity on
-// upstream requests, so per-human attribution lines up across a user's
-// devices and unattached peers still produce a stable, human-readable id.
-func (s *ProxyServiceServer) ValidateTunnelPeer(ctx context.Context, req *proto.ValidateTunnelPeerRequest) (*proto.ValidateTunnelPeerResponse, error) {
-	domain := req.GetDomain()
-	tunnelIPStr := req.GetTunnelIp()
-
-	if domain == "" || tunnelIPStr == "" {
-		return &proto.ValidateTunnelPeerResponse{
-			Valid:        false,
-			DeniedReason: "missing domain or tunnel_ip",
-		}, nil
-	}
-
-	tunnelIP := net.ParseIP(tunnelIPStr)
-	if tunnelIP == nil {
-		return &proto.ValidateTunnelPeerResponse{
-			Valid:        false,
-			DeniedReason: "invalid_tunnel_ip",
-		}, nil
-	}
-
-	service, err := s.getServiceByDomain(ctx, domain)
-	if err != nil {
-		log.WithFields(log.Fields{
-			"domain": domain,
-			"error":  err.Error(),
-		}).Debug("ValidateTunnelPeer: service not found")
-		//nolint:nilerr
-		return &proto.ValidateTunnelPeerResponse{
-			Valid:        false,
-			DeniedReason: "service_not_found",
-		}, nil
-	}
-
-	peer, err := s.peersManager.GetPeerByTunnelIP(ctx, service.AccountID, tunnelIP)
-	if err != nil || peer == nil {
-		log.WithFields(log.Fields{
-			"domain":    domain,
-			"tunnel_ip": tunnelIPStr,
-		}).Debug("ValidateTunnelPeer: peer not found")
-		//nolint:nilerr
-		return &proto.ValidateTunnelPeerResponse{
-			Valid:        false,
-			DeniedReason: "peer_not_found",
-		}, nil
-	}
-
-	_, peerGroups, err := s.peersManager.GetPeerWithGroups(ctx, service.AccountID, peer.ID)
-	if err != nil {
-		log.WithFields(log.Fields{
-			"domain":  domain,
-			"peer_id": peer.ID,
-			"error":   err.Error(),
-		}).Debug("ValidateTunnelPeer: peer groups lookup failed")
-		//nolint:nilerr
-		return &proto.ValidateTunnelPeerResponse{
-			Valid:        false,
-			DeniedReason: "peer_not_found",
-		}, nil
-	}
-
-	groupIDs, groupNames := pairGroupIDsAndNames(peerGroups)
-
-	// Resolve the principal: when the peer is linked to a user, the
-	// human is the principal — multiple peers belonging to the same
-	// user share one access-log identity AND one consumption-counter
-	// dimension (caps are per-human, not per-device). Unlinked peers
-	// (machine agents, automation workloads) are their own principals
-	// keyed on peer.ID. displayIdentity is what upstream gateways
-	// (LiteLLM, Portkey) tag spend with — user.Email when linked, the
-	// peer's hostname when not.
-	principalID := peer.ID
-	displayIdentity := peer.Name
-	if peer.UserID != "" {
-		if user, uerr := s.usersManager.GetUser(ctx, peer.UserID); uerr == nil && user != nil {
-			principalID = user.Id
-			if user.Email != "" {
-				displayIdentity = user.Email
-			}
-		}
-	}
-
-	if err := checkPeerGroupAccess(service, groupIDs); err != nil {
-		log.WithFields(log.Fields{
-			"domain":  domain,
-			"peer_id": peer.ID,
-			"error":   err.Error(),
-		}).Debug("ValidateTunnelPeer: access denied")
-		//nolint:nilerr
-		return &proto.ValidateTunnelPeerResponse{
-			Valid:          false,
-			UserId:         principalID,
-			UserEmail:      displayIdentity,
-			DeniedReason:   "not_in_group",
-			PeerGroupIds:   groupIDs,
-			PeerGroupNames: groupNames,
-		}, nil
-	}
-
-	token, err := s.generateSessionToken(ctx, true, service, principalID, displayIdentity, proxyauth.MethodOIDC, groupIDs, groupNames)
-	if err != nil {
-		return nil, err
-	}
-
-	log.WithFields(log.Fields{
-		"domain":       domain,
-		"tunnel_ip":    tunnelIPStr,
-		"peer_id":      peer.ID,
-		"peer_name":    peer.Name,
-		"principal_id": principalID,
-		"identity":     displayIdentity,
-	}).Debug("ValidateTunnelPeer: access granted")
-
-	return &proto.ValidateTunnelPeerResponse{
-		Valid:          true,
-		UserId:         principalID,
-		UserEmail:      displayIdentity,
-		SessionToken:   token,
-		PeerGroupIds:   groupIDs,
-		PeerGroupNames: groupNames,
-	}, nil
-}
-
 func (s *ProxyServiceServer) checkGroupAccess(service *rpservice.Service, user *types.User) error {
 	if service.Auth.BearerAuth == nil || !service.Auth.BearerAuth.Enabled {
 		return nil
@@ -1548,7 +1634,122 @@ func (s *ProxyServiceServer) checkGroupAccess(service *rpservice.Service, user *
 	return fmt.Errorf("user not in allowed groups")
 }
 
-// checkPeerGroupAccess gates ValidateTunnelPeer; private with empty AccessGroups fails closed.
+func ptr[T any](v T) *T { return &v }
+
+// ValidateTunnelPeer resolves an inbound peer by its WireGuard tunnel IP and
+// checks the peer's group membership against the service's access groups.
+// Peers without a user (machine agents, automation workloads) are first-class
+// callers; authorisation runs off peer-group memberships rather than the
+// optional owning user's auto-groups. On success a session JWT is minted so
+// the proxy can install a cookie and skip subsequent management round-trips.
+func (s *ProxyServiceServer) ValidateTunnelPeer(ctx context.Context, req *proto.ValidateTunnelPeerRequest) (*proto.ValidateTunnelPeerResponse, error) {
+	domain := req.GetDomain()
+	tunnelIPStr := req.GetTunnelIp()
+
+	if domain == "" || tunnelIPStr == "" {
+		return &proto.ValidateTunnelPeerResponse{
+			Valid:        false,
+			DeniedReason: "missing domain or tunnel_ip",
+		}, nil
+	}
+
+	tunnelIP := net.ParseIP(tunnelIPStr)
+	if tunnelIP == nil {
+		return &proto.ValidateTunnelPeerResponse{
+			Valid:        false,
+			DeniedReason: "invalid_tunnel_ip",
+		}, nil
+	}
+
+	service, err := s.getServiceByDomain(ctx, domain)
+	if err != nil {
+		log.WithFields(log.Fields{"domain": domain, "error": err.Error()}).Debug("ValidateTunnelPeer: service not found")
+		//nolint:nilerr
+		return &proto.ValidateTunnelPeerResponse{
+			Valid:        false,
+			DeniedReason: "service_not_found",
+		}, nil
+	}
+
+	peer, err := s.peersManager.GetPeerByTunnelIP(ctx, service.AccountID, tunnelIP)
+	if err != nil || peer == nil {
+		log.WithFields(log.Fields{"domain": domain, "tunnel_ip": tunnelIPStr}).Debug("ValidateTunnelPeer: peer not found")
+		//nolint:nilerr
+		return &proto.ValidateTunnelPeerResponse{
+			Valid:        false,
+			DeniedReason: "peer_not_found",
+		}, nil
+	}
+
+	_, peerGroups, err := s.peersManager.GetPeerWithGroups(ctx, service.AccountID, peer.ID)
+	if err != nil {
+		log.WithFields(log.Fields{"domain": domain, "peer_id": peer.ID, "error": err.Error()}).Debug("ValidateTunnelPeer: peer groups lookup failed")
+		//nolint:nilerr
+		return &proto.ValidateTunnelPeerResponse{
+			Valid:        false,
+			DeniedReason: "peer_not_found",
+		}, nil
+	}
+
+	groupIDs, groupNames := pairGroupIDsAndNames(peerGroups)
+
+	// Resolve the principal: when the peer is linked to a user, the human
+	// is the principal so multiple peers owned by the same user share a
+	// single identity. Unlinked peers (machine agents) are their own
+	// principal keyed on peer.ID. displayIdentity is what upstream gateways
+	// tag spend with — user.Email when linked, peer.Name when not.
+	principalID := peer.ID
+	displayIdentity := peer.Name
+	if peer.UserID != "" {
+		if user, uerr := s.usersManager.GetUser(ctx, peer.UserID); uerr == nil && user != nil {
+			principalID = user.Id
+			if user.Email != "" {
+				displayIdentity = user.Email
+			}
+		}
+	}
+
+	if err := checkPeerGroupAccess(service, groupIDs); err != nil {
+		log.WithFields(log.Fields{"domain": domain, "peer_id": peer.ID, "error": err.Error()}).Debug("ValidateTunnelPeer: access denied")
+		//nolint:nilerr
+		return &proto.ValidateTunnelPeerResponse{
+			Valid:          false,
+			UserId:         principalID,
+			UserEmail:      displayIdentity,
+			DeniedReason:   "not_in_group",
+			PeerGroupIds:   groupIDs,
+			PeerGroupNames: groupNames,
+		}, nil
+	}
+
+	token, err := s.generateSessionToken(ctx, true, service, principalID, displayIdentity, proxyauth.MethodOIDC, groupIDs, groupNames)
+	if err != nil {
+		return nil, err
+	}
+
+	log.WithFields(log.Fields{
+		"domain":       domain,
+		"tunnel_ip":    tunnelIPStr,
+		"peer_id":      peer.ID,
+		"principal_id": principalID,
+	}).Debug("ValidateTunnelPeer: access granted")
+
+	return &proto.ValidateTunnelPeerResponse{
+		Valid:          true,
+		UserId:         principalID,
+		UserEmail:      displayIdentity,
+		SessionToken:   token,
+		PeerGroupIds:   groupIDs,
+		PeerGroupNames: groupNames,
+	}, nil
+}
+
+// checkPeerGroupAccess gates ValidateTunnelPeer by the service's required
+// groups. Private services authorise against AccessGroups (empty list fails
+// closed — Validate() rejects that at save time but the RPC is the security
+// boundary and must not trust upstream state). Bearer-auth services authorise
+// against DistributionGroups when populated. Non-private non-bearer services
+// are open.
 func checkPeerGroupAccess(service *rpservice.Service, peerGroupIDs []string) error {
 	if service.Private {
 		if len(service.AccessGroups) == 0 {
@@ -1556,28 +1757,26 @@ func checkPeerGroupAccess(service *rpservice.Service, peerGroupIDs []string) err
 		}
 		return matchAnyGroup(service.AccessGroups, peerGroupIDs)
 	}
-
-	if service.Auth.BearerAuth != nil && service.Auth.BearerAuth.Enabled {
-		if len(service.Auth.BearerAuth.DistributionGroups) == 0 {
-			return nil
-		}
+	if service.Auth.BearerAuth != nil && service.Auth.BearerAuth.Enabled && len(service.Auth.BearerAuth.DistributionGroups) > 0 {
 		return matchAnyGroup(service.Auth.BearerAuth.DistributionGroups, peerGroupIDs)
 	}
-
 	return nil
 }
 
+// matchAnyGroup returns nil when peerGroupIDs intersects allowedGroups,
+// else a non-nil error.
 func matchAnyGroup(allowedGroups, peerGroupIDs []string) error {
-	allowedSet := make(map[string]bool, len(allowedGroups))
-	for _, groupID := range allowedGroups {
-		allowedSet[groupID] = true
+	if len(allowedGroups) == 0 {
+		return fmt.Errorf("no allowed groups configured")
 	}
-	for _, groupID := range peerGroupIDs {
-		if allowedSet[groupID] {
+	allowed := make(map[string]struct{}, len(allowedGroups))
+	for _, g := range allowedGroups {
+		allowed[g] = struct{}{}
+	}
+	for _, g := range peerGroupIDs {
+		if _, ok := allowed[g]; ok {
 			return nil
 		}
 	}
 	return fmt.Errorf("peer not in allowed groups")
 }
-
-func ptr[T any](v T) *T { return &v }

management/internals/shared/grpc/sync_mappings_test.go

@@ -0,0 +1,411 @@
+package grpc
+
+import (
+	"context"
+	"fmt"
+	"sync"
+	"testing"
+	"time"
+
+	"github.com/golang/mock/gomock"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+	"google.golang.org/grpc"
+	"google.golang.org/grpc/metadata"
+
+	rpservice "github.com/netbirdio/netbird/management/internals/modules/reverseproxy/service"
+	"github.com/netbirdio/netbird/shared/management/proto"
+)
+
+// syncRecordingStream is a mock ProxyService_SyncMappingsServer that records
+// sent messages and returns pre-loaded ack responses from Recv.
+type syncRecordingStream struct {
+	grpc.ServerStream
+
+	mu       sync.Mutex
+	sent     []*proto.SyncMappingsResponse
+	recvMsgs []*proto.SyncMappingsRequest
+	recvIdx  int
+}
+
+func (s *syncRecordingStream) Send(m *proto.SyncMappingsResponse) error {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+	s.sent = append(s.sent, m)
+	return nil
+}
+
+func (s *syncRecordingStream) Recv() (*proto.SyncMappingsRequest, error) {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+	if s.recvIdx >= len(s.recvMsgs) {
+		return nil, fmt.Errorf("no more recv messages")
+	}
+	msg := s.recvMsgs[s.recvIdx]
+	s.recvIdx++
+	return msg, nil
+}
+
+func (s *syncRecordingStream) Context() context.Context     { return context.Background() }
+func (s *syncRecordingStream) SetHeader(metadata.MD) error  { return nil }
+func (s *syncRecordingStream) SendHeader(metadata.MD) error { return nil }
+func (s *syncRecordingStream) SetTrailer(metadata.MD)       {}
+func (s *syncRecordingStream) SendMsg(any) error            { return nil }
+func (s *syncRecordingStream) RecvMsg(any) error            { return nil }
+
+func ackMsg() *proto.SyncMappingsRequest {
+	return &proto.SyncMappingsRequest{
+		Msg: &proto.SyncMappingsRequest_Ack{Ack: &proto.SyncMappingsAck{}},
+	}
+}
+
+func TestSendSnapshotSync_BatchesWithAcks(t *testing.T) {
+	const cluster = "cluster.example.com"
+	const batchSize = 3
+	const totalServices = 7 // 3 + 3 + 1 → 3 batches, 3 acks (one per batch, including final)
+
+	ctrl := gomock.NewController(t)
+	mgr := rpservice.NewMockManager(ctrl)
+	mgr.EXPECT().GetGlobalServices(gomock.Any()).Return(makeServices(totalServices, cluster), nil)
+
+	s := newSnapshotTestServer(t, batchSize)
+	s.serviceManager = mgr
+
+	stream := &syncRecordingStream{
+		recvMsgs: []*proto.SyncMappingsRequest{ackMsg(), ackMsg(), ackMsg()},
+	}
+	conn := &proxyConnection{
+		proxyID:    "proxy-a",
+		address:    cluster,
+		syncStream: stream,
+	}
+
+	err := s.sendSnapshotSync(context.Background(), conn, stream)
+	require.NoError(t, err)
+
+	require.Len(t, stream.sent, 3, "should send ceil(7/3) = 3 batches")
+
+	assert.Len(t, stream.sent[0].Mapping, 3)
+	assert.False(t, stream.sent[0].InitialSyncComplete)
+
+	assert.Len(t, stream.sent[1].Mapping, 3)
+	assert.False(t, stream.sent[1].InitialSyncComplete)
+
+	assert.Len(t, stream.sent[2].Mapping, 1)
+	assert.True(t, stream.sent[2].InitialSyncComplete)
+
+	// All 3 acks consumed — including the final batch.
+	assert.Equal(t, 3, stream.recvIdx)
+}
+
+func TestSendSnapshotSync_SingleBatchWaitsForAck(t *testing.T) {
+	const cluster = "cluster.example.com"
+	const batchSize = 100
+	const totalServices = 5
+
+	ctrl := gomock.NewController(t)
+	mgr := rpservice.NewMockManager(ctrl)
+	mgr.EXPECT().GetGlobalServices(gomock.Any()).Return(makeServices(totalServices, cluster), nil)
+
+	s := newSnapshotTestServer(t, batchSize)
+	s.serviceManager = mgr
+
+	stream := &syncRecordingStream{
+		recvMsgs: []*proto.SyncMappingsRequest{ackMsg()},
+	}
+	conn := &proxyConnection{
+		proxyID:    "proxy-a",
+		address:    cluster,
+		syncStream: stream,
+	}
+
+	err := s.sendSnapshotSync(context.Background(), conn, stream)
+	require.NoError(t, err)
+
+	require.Len(t, stream.sent, 1)
+	assert.Len(t, stream.sent[0].Mapping, totalServices)
+	assert.True(t, stream.sent[0].InitialSyncComplete)
+	assert.Equal(t, 1, stream.recvIdx, "final batch ack must be consumed")
+}
+
+func TestSendSnapshotSync_EmptySnapshot(t *testing.T) {
+	const cluster = "cluster.example.com"
+
+	ctrl := gomock.NewController(t)
+	mgr := rpservice.NewMockManager(ctrl)
+	mgr.EXPECT().GetGlobalServices(gomock.Any()).Return(nil, nil)
+
+	s := newSnapshotTestServer(t, 500)
+	s.serviceManager = mgr
+
+	stream := &syncRecordingStream{
+		recvMsgs: []*proto.SyncMappingsRequest{ackMsg()},
+	}
+	conn := &proxyConnection{
+		proxyID:    "proxy-a",
+		address:    cluster,
+		syncStream: stream,
+	}
+
+	err := s.sendSnapshotSync(context.Background(), conn, stream)
+	require.NoError(t, err)
+
+	require.Len(t, stream.sent, 1, "empty snapshot must still send sync-complete")
+	assert.Empty(t, stream.sent[0].Mapping)
+	assert.True(t, stream.sent[0].InitialSyncComplete)
+	assert.Equal(t, 1, stream.recvIdx, "empty snapshot ack must be consumed")
+}
+
+func TestSendSnapshotSync_MissingAckReturnsError(t *testing.T) {
+	const cluster = "cluster.example.com"
+	const batchSize = 2
+	const totalServices = 4 // 2 batches → 1 ack needed, but we provide none
+
+	ctrl := gomock.NewController(t)
+	mgr := rpservice.NewMockManager(ctrl)
+	mgr.EXPECT().GetGlobalServices(gomock.Any()).Return(makeServices(totalServices, cluster), nil)
+
+	s := newSnapshotTestServer(t, batchSize)
+	s.serviceManager = mgr
+
+	// No acks available — Recv will return error.
+	stream := &syncRecordingStream{}
+	conn := &proxyConnection{
+		proxyID:    "proxy-a",
+		address:    cluster,
+		syncStream: stream,
+	}
+
+	err := s.sendSnapshotSync(context.Background(), conn, stream)
+	require.Error(t, err)
+	assert.Contains(t, err.Error(), "receive ack")
+	// First batch should have been sent before the error.
+	require.Len(t, stream.sent, 1)
+}
+
+func TestSendSnapshotSync_WrongMessageInsteadOfAck(t *testing.T) {
+	const cluster = "cluster.example.com"
+	const batchSize = 2
+	const totalServices = 4
+
+	ctrl := gomock.NewController(t)
+	mgr := rpservice.NewMockManager(ctrl)
+	mgr.EXPECT().GetGlobalServices(gomock.Any()).Return(makeServices(totalServices, cluster), nil)
+
+	s := newSnapshotTestServer(t, batchSize)
+	s.serviceManager = mgr
+
+	// Send an init message instead of an ack.
+	stream := &syncRecordingStream{
+		recvMsgs: []*proto.SyncMappingsRequest{
+			{Msg: &proto.SyncMappingsRequest_Init{Init: &proto.SyncMappingsInit{ProxyId: "bad"}}},
+		},
+	}
+	conn := &proxyConnection{
+		proxyID:    "proxy-a",
+		address:    cluster,
+		syncStream: stream,
+	}
+
+	err := s.sendSnapshotSync(context.Background(), conn, stream)
+	require.Error(t, err)
+	assert.Contains(t, err.Error(), "expected ack")
+}
+
+func TestSendSnapshotSync_BackPressureOrdering(t *testing.T) {
+	// Verify batches are sent strictly sequentially — batch N+1 is not sent
+	// until the ack for batch N is received, including the final batch.
+	const cluster = "cluster.example.com"
+	const batchSize = 2
+	const totalServices = 6 // 3 batches, 3 acks
+
+	ctrl := gomock.NewController(t)
+	mgr := rpservice.NewMockManager(ctrl)
+	mgr.EXPECT().GetGlobalServices(gomock.Any()).Return(makeServices(totalServices, cluster), nil)
+
+	s := newSnapshotTestServer(t, batchSize)
+	s.serviceManager = mgr
+
+	var mu sync.Mutex
+	var events []string
+
+	// Build a stream that logs send/recv events so we can verify ordering.
+	ackCh := make(chan struct{}, 3)
+	stream := &orderTrackingStream{
+		mu:     &mu,
+		events: &events,
+		ackCh:  ackCh,
+	}
+	conn := &proxyConnection{
+		proxyID:    "proxy-a",
+		address:    cluster,
+		syncStream: stream,
+	}
+
+	// Feed acks asynchronously after a short delay to simulate real proxy.
+	go func() {
+		for range 3 {
+			time.Sleep(10 * time.Millisecond)
+			ackCh <- struct{}{}
+		}
+	}()
+
+	err := s.sendSnapshotSync(context.Background(), conn, stream)
+	require.NoError(t, err)
+
+	mu.Lock()
+	defer mu.Unlock()
+
+	// Expected: send, recv-ack, send, recv-ack, send, recv-ack.
+	require.Len(t, events, 6)
+	assert.Equal(t, "send", events[0])
+	assert.Equal(t, "recv", events[1])
+	assert.Equal(t, "send", events[2])
+	assert.Equal(t, "recv", events[3])
+	assert.Equal(t, "send", events[4])
+	assert.Equal(t, "recv", events[5])
+}
+
+// orderTrackingStream logs "send" and "recv" events and blocks Recv until
+// an ack is signaled via ackCh.
+type orderTrackingStream struct {
+	grpc.ServerStream
+	mu     *sync.Mutex
+	events *[]string
+	ackCh  chan struct{}
+}
+
+func (s *orderTrackingStream) Send(_ *proto.SyncMappingsResponse) error {
+	s.mu.Lock()
+	*s.events = append(*s.events, "send")
+	s.mu.Unlock()
+	return nil
+}
+
+func (s *orderTrackingStream) Recv() (*proto.SyncMappingsRequest, error) {
+	<-s.ackCh
+	s.mu.Lock()
+	*s.events = append(*s.events, "recv")
+	s.mu.Unlock()
+	return ackMsg(), nil
+}
+
+func (s *orderTrackingStream) Context() context.Context     { return context.Background() }
+func (s *orderTrackingStream) SetHeader(metadata.MD) error  { return nil }
+func (s *orderTrackingStream) SendHeader(metadata.MD) error { return nil }
+func (s *orderTrackingStream) SetTrailer(metadata.MD)       {}
+func (s *orderTrackingStream) SendMsg(any) error            { return nil }
+func (s *orderTrackingStream) RecvMsg(any) error            { return nil }
+
+func TestSendSnapshotSync_TokensGeneratedPerBatch(t *testing.T) {
+	const cluster = "cluster.example.com"
+	const batchSize = 2
+	const totalServices = 4
+	const ttl = 100 * time.Millisecond
+	const ackDelay = 200 * time.Millisecond
+
+	ctrl := gomock.NewController(t)
+	mgr := rpservice.NewMockManager(ctrl)
+	mgr.EXPECT().GetGlobalServices(gomock.Any()).Return(makeServices(totalServices, cluster), nil)
+
+	s := newSnapshotTestServer(t, batchSize)
+	s.serviceManager = mgr
+	s.tokenTTL = ttl
+
+	// Build a stream that validates tokens immediately on Send, then
+	// delays the ack to ensure the next batch's tokens are generated fresh.
+	var validateErrs []error
+	ackCh := make(chan struct{}, 2)
+	stream := &tokenValidatingSyncStream{
+		tokenStore:   s.tokenStore,
+		validateErrs: &validateErrs,
+		ackCh:        ackCh,
+	}
+	conn := &proxyConnection{
+		proxyID:    "proxy-a",
+		address:    cluster,
+		syncStream: stream,
+	}
+
+	go func() {
+		// Delay first ack so that if tokens were all generated upfront they'd expire.
+		time.Sleep(ackDelay)
+		ackCh <- struct{}{}
+		// Final batch ack — immediate.
+		ackCh <- struct{}{}
+	}()
+
+	err := s.sendSnapshotSync(context.Background(), conn, stream)
+	require.NoError(t, err)
+	require.Empty(t, validateErrs,
+		"tokens must remain valid: per-batch generation guarantees freshness")
+}
+
+type tokenValidatingSyncStream struct {
+	grpc.ServerStream
+	tokenStore   *OneTimeTokenStore
+	validateErrs *[]error
+	ackCh        chan struct{}
+}
+
+func (s *tokenValidatingSyncStream) Send(m *proto.SyncMappingsResponse) error {
+	for _, mapping := range m.Mapping {
+		if err := s.tokenStore.ValidateAndConsume(mapping.AuthToken, mapping.AccountId, mapping.Id); err != nil {
+			*s.validateErrs = append(*s.validateErrs, fmt.Errorf("svc %s: %w", mapping.Id, err))
+		}
+	}
+	return nil
+}
+
+func (s *tokenValidatingSyncStream) Recv() (*proto.SyncMappingsRequest, error) {
+	<-s.ackCh
+	return ackMsg(), nil
+}
+
+func (s *tokenValidatingSyncStream) Context() context.Context     { return context.Background() }
+func (s *tokenValidatingSyncStream) SetHeader(metadata.MD) error  { return nil }
+func (s *tokenValidatingSyncStream) SendHeader(metadata.MD) error { return nil }
+func (s *tokenValidatingSyncStream) SetTrailer(metadata.MD)       {}
+func (s *tokenValidatingSyncStream) SendMsg(any) error            { return nil }
+func (s *tokenValidatingSyncStream) RecvMsg(any) error            { return nil }
+
+func TestConnectionSendResponse_RoutesToSyncStream(t *testing.T) {
+	stream := &syncRecordingStream{}
+	conn := &proxyConnection{
+		syncStream: stream,
+	}
+
+	resp := &proto.GetMappingUpdateResponse{
+		Mapping: []*proto.ProxyMapping{
+			{Id: "svc-1", AccountId: "acct-1", Domain: "example.com"},
+		},
+		InitialSyncComplete: true,
+	}
+
+	err := conn.sendResponse(resp)
+	require.NoError(t, err)
+
+	require.Len(t, stream.sent, 1)
+	assert.Len(t, stream.sent[0].Mapping, 1)
+	assert.Equal(t, "svc-1", stream.sent[0].Mapping[0].Id)
+	assert.True(t, stream.sent[0].InitialSyncComplete)
+}
+
+func TestConnectionSendResponse_RoutesToLegacyStream(t *testing.T) {
+	stream := &recordingStream{}
+	conn := &proxyConnection{
+		stream: stream,
+	}
+
+	resp := &proto.GetMappingUpdateResponse{
+		Mapping: []*proto.ProxyMapping{
+			{Id: "svc-2", AccountId: "acct-2"},
+		},
+	}
+
+	err := conn.sendResponse(resp)
+	require.NoError(t, err)
+
+	require.Len(t, stream.messages, 1)
+	assert.Equal(t, "svc-2", stream.messages[0].Mapping[0].Id)
+}

proxy/server.go

@@ -32,9 +32,11 @@ import (
 	"go.opentelemetry.io/otel/sdk/metric"
 	"golang.org/x/exp/maps"
 	"google.golang.org/grpc"
+	"google.golang.org/grpc/codes"
 	"google.golang.org/grpc/credentials"
 	"google.golang.org/grpc/credentials/insecure"
 	"google.golang.org/grpc/keepalive"
+	grpcstatus "google.golang.org/grpc/status"
 	"google.golang.org/protobuf/encoding/protojson"
 	"google.golang.org/protobuf/types/known/timestamppb"
 
@@ -1145,6 +1147,10 @@ func (s *Server) newManagementMappingWorker(ctx context.Context, client proto.Pr
 		Clock:               backoff.SystemClock,
 	}
 
+	// syncSupported tracks whether management supports SyncMappings.
+	// Starts true; set to false on the first Unimplemented error so
+	// subsequent retries skip straight to GetMappingUpdate.
+	syncSupported := true
 	initialSyncDone := false
 
 	operation := func() error {
@@ -1156,41 +1162,25 @@ func (s *Server) newManagementMappingWorker(ctx context.Context, client proto.Pr
 			s.healthChecker.SetManagementConnected(false)
 		}
 
-		supportsCrowdSec := s.crowdsecRegistry.Available()
-		privateCapability := s.Private
-		// Always true: this build enforces ProxyMapping.private via the auth middleware.
-		supportsPrivateService := true
-		mappingClient, err := client.GetMappingUpdate(ctx, &proto.GetMappingUpdateRequest{
-			ProxyId:   s.ID,
-			Version:   s.Version,
-			StartedAt: timestamppb.New(s.startTime),
-			Address:   s.ProxyURL,
-			Capabilities: &proto.ProxyCapabilities{
-				SupportsCustomPorts:    &s.SupportsCustomPorts,
-				RequireSubdomain:       &s.RequireSubdomain,
-				SupportsCrowdsec:       &supportsCrowdSec,
-				Private:                &privateCapability,
-				SupportsPrivateService: &supportsPrivateService,
-			},
-		})
-		if err != nil {
-			return fmt.Errorf("create mapping stream: %w", err)
+		var streamErr error
+		if syncSupported {
+			streamErr = s.trySyncMappings(ctx, client, &initialSyncDone)
+			if isSyncUnimplemented(streamErr) {
+				syncSupported = false
+				s.Logger.Info("management does not support SyncMappings, falling back to GetMappingUpdate")
+				streamErr = s.tryGetMappingUpdate(ctx, client, &initialSyncDone)
+			}
+		} else {
+			streamErr = s.tryGetMappingUpdate(ctx, client, &initialSyncDone)
 		}
 
-		if s.healthChecker != nil {
-			s.healthChecker.SetManagementConnected(true)
-		}
-		s.Logger.Debug("management mapping stream established")
-
-		// Stream established — reset backoff so the next failure retries quickly.
-		bo.Reset()
-
-		streamErr := s.handleMappingStream(ctx, mappingClient, &initialSyncDone, time.Now())
-
 		if s.healthChecker != nil {
 			s.healthChecker.SetManagementConnected(false)
 		}
 
+		// Stream established — reset backoff so the next failure retries quickly.
+		bo.Reset()
+
 		if streamErr == nil {
 			return fmt.Errorf("stream closed by server")
 		}
@@ -1207,6 +1197,134 @@ func (s *Server) newManagementMappingWorker(ctx context.Context, client proto.Pr
 	}
 }
 
+func (s *Server) proxyCapabilities() *proto.ProxyCapabilities {
+	supportsCrowdSec := s.crowdsecRegistry.Available()
+	privateCapability := s.Private
+	// Always true: this build enforces ProxyMapping.private via the auth middleware.
+	supportsPrivateService := true
+	return &proto.ProxyCapabilities{
+		SupportsCustomPorts:    &s.SupportsCustomPorts,
+		RequireSubdomain:       &s.RequireSubdomain,
+		SupportsCrowdsec:       &supportsCrowdSec,
+		Private:                &privateCapability,
+		SupportsPrivateService: &supportsPrivateService,
+	}
+}
+
+func (s *Server) tryGetMappingUpdate(ctx context.Context, client proto.ProxyServiceClient, initialSyncDone *bool) error {
+	connectTime := time.Now()
+	mappingClient, err := client.GetMappingUpdate(ctx, &proto.GetMappingUpdateRequest{
+		ProxyId:      s.ID,
+		Version:      s.Version,
+		StartedAt:    timestamppb.New(s.startTime),
+		Address:      s.ProxyURL,
+		Capabilities: s.proxyCapabilities(),
+	})
+	if err != nil {
+		return fmt.Errorf("create mapping stream: %w", err)
+	}
+
+	if s.healthChecker != nil {
+		s.healthChecker.SetManagementConnected(true)
+	}
+	s.Logger.Debug("management mapping stream established (GetMappingUpdate)")
+
+	return s.handleMappingStream(ctx, mappingClient, initialSyncDone, connectTime)
+}
+
+func (s *Server) trySyncMappings(ctx context.Context, client proto.ProxyServiceClient, initialSyncDone *bool) error {
+	connectTime := time.Now()
+	stream, err := client.SyncMappings(ctx)
+	if err != nil {
+		return fmt.Errorf("create sync stream: %w", err)
+	}
+
+	if err := stream.Send(&proto.SyncMappingsRequest{
+		Msg: &proto.SyncMappingsRequest_Init{
+			Init: &proto.SyncMappingsInit{
+				ProxyId:      s.ID,
+				Version:      s.Version,
+				StartedAt:    timestamppb.New(s.startTime),
+				Address:      s.ProxyURL,
+				Capabilities: s.proxyCapabilities(),
+			},
+		},
+	}); err != nil {
+		return fmt.Errorf("send sync init: %w", err)
+	}
+
+	if s.healthChecker != nil {
+		s.healthChecker.SetManagementConnected(true)
+	}
+	s.Logger.Debug("management mapping stream established (SyncMappings)")
+
+	return s.handleSyncMappingsStream(ctx, stream, initialSyncDone, connectTime)
+}
+
+func isSyncUnimplemented(err error) bool {
+	if err == nil {
+		return false
+	}
+	st, ok := grpcstatus.FromError(err)
+	return ok && st.Code() == codes.Unimplemented
+}
+
+// handleSyncMappingsStream consumes batches from a bidirectional SyncMappings
+// stream, sending an ack after each batch is fully processed. Management waits
+// for the ack before sending the next batch, providing application-level
+// back-pressure.
+func (s *Server) handleSyncMappingsStream(ctx context.Context, stream proto.ProxyService_SyncMappingsClient, initialSyncDone *bool, _ time.Time) error {
+	select {
+	case <-s.routerReady:
+	case <-ctx.Done():
+		return ctx.Err()
+	}
+
+	var snapshotIDs map[types.ServiceID]struct{}
+	if !*initialSyncDone {
+		snapshotIDs = make(map[types.ServiceID]struct{})
+	}
+
+	for {
+		select {
+		case <-ctx.Done():
+			return ctx.Err()
+		default:
+			msg, err := stream.Recv()
+			switch {
+			case errors.Is(err, io.EOF):
+				return nil
+			case err != nil:
+				return fmt.Errorf("receive msg: %w", err)
+			}
+			s.Logger.Debug("Received mapping update, starting processing")
+			s.processMappings(ctx, msg.GetMapping())
+			s.Logger.Debug("Processing mapping update completed")
+
+			if !*initialSyncDone {
+				for _, m := range msg.GetMapping() {
+					snapshotIDs[types.ServiceID(m.GetId())] = struct{}{}
+				}
+				if msg.GetInitialSyncComplete() {
+					s.reconcileSnapshot(ctx, snapshotIDs)
+					snapshotIDs = nil
+					if s.healthChecker != nil {
+						s.healthChecker.SetInitialSyncComplete()
+					}
+					*initialSyncDone = true
+					s.Logger.Info("Initial mapping sync complete")
+				}
+			}
+
+			if err := stream.Send(&proto.SyncMappingsRequest{
+				Msg: &proto.SyncMappingsRequest_Ack{Ack: &proto.SyncMappingsAck{}},
+			}); err != nil {
+				return fmt.Errorf("send ack: %w", err)
+			}
+		}
+	}
+}
+
 func (s *Server) handleMappingStream(ctx context.Context, mappingClient proto.ProxyService_GetMappingUpdateClient, initialSyncDone *bool, _ time.Time) error {
 	select {
 	case <-s.routerReady:

proxy/sync_mappings_test.go

@@ -0,0 +1,525 @@
+package proxy
+
+import (
+	"context"
+	"errors"
+	"fmt"
+	"net"
+	"sync/atomic"
+	"testing"
+	"time"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+	"google.golang.org/grpc"
+	"google.golang.org/grpc/codes"
+	"google.golang.org/grpc/credentials/insecure"
+	grpcstatus "google.golang.org/grpc/status"
+
+	"github.com/netbirdio/netbird/management/internals/modules/reverseproxy/service"
+	"github.com/netbirdio/netbird/shared/management/proto"
+)
+
+func TestIntegration_SyncMappings_HappyPath(t *testing.T) {
+	setup := setupIntegrationTest(t)
+	defer setup.cleanup()
+
+	conn, err := grpc.NewClient(setup.grpcAddr, grpc.WithTransportCredentials(insecure.NewCredentials()))
+	require.NoError(t, err)
+	defer conn.Close()
+
+	client := proto.NewProxyServiceClient(conn)
+
+	ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
+	defer cancel()
+
+	stream, err := client.SyncMappings(ctx)
+	require.NoError(t, err)
+
+	// Send init.
+	err = stream.Send(&proto.SyncMappingsRequest{
+		Msg: &proto.SyncMappingsRequest_Init{
+			Init: &proto.SyncMappingsInit{
+				ProxyId: "sync-proxy-1",
+				Version: "test-v1",
+				Address: "test.proxy.io",
+			},
+		},
+	})
+	require.NoError(t, err)
+
+	mappingsByID := make(map[string]*proto.ProxyMapping)
+	for {
+		msg, err := stream.Recv()
+		require.NoError(t, err)
+		for _, m := range msg.GetMapping() {
+			mappingsByID[m.GetId()] = m
+		}
+
+		// Ack every batch.
+		err = stream.Send(&proto.SyncMappingsRequest{
+			Msg: &proto.SyncMappingsRequest_Ack{Ack: &proto.SyncMappingsAck{}},
+		})
+		require.NoError(t, err)
+
+		if msg.GetInitialSyncComplete() {
+			break
+		}
+	}
+
+	assert.Len(t, mappingsByID, 2, "Should receive 2 mappings")
+
+	rp1 := mappingsByID["rp-1"]
+	require.NotNil(t, rp1)
+	assert.Equal(t, "app1.test.proxy.io", rp1.GetDomain())
+	assert.Equal(t, "test-account-1", rp1.GetAccountId())
+	assert.Equal(t, proto.ProxyMappingUpdateType_UPDATE_TYPE_CREATED, rp1.GetType())
+	assert.NotEmpty(t, rp1.GetAuthToken(), "Should have auth token")
+
+	rp2 := mappingsByID["rp-2"]
+	require.NotNil(t, rp2)
+	assert.Equal(t, "app2.test.proxy.io", rp2.GetDomain())
+}
+
+func TestIntegration_SyncMappings_BackPressure(t *testing.T) {
+	setup := setupIntegrationTest(t)
+	defer setup.cleanup()
+
+	// Add enough services to guarantee multiple batches (default batch size 500).
+	addServicesToStore(t, setup, 600, "test.proxy.io")
+
+	conn, err := grpc.NewClient(setup.grpcAddr, grpc.WithTransportCredentials(insecure.NewCredentials()))
+	require.NoError(t, err)
+	defer conn.Close()
+
+	client := proto.NewProxyServiceClient(conn)
+
+	ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
+	defer cancel()
+
+	stream, err := client.SyncMappings(ctx)
+	require.NoError(t, err)
+
+	err = stream.Send(&proto.SyncMappingsRequest{
+		Msg: &proto.SyncMappingsRequest_Init{
+			Init: &proto.SyncMappingsInit{
+				ProxyId: "sync-proxy-backpressure",
+				Version: "test-v1",
+				Address: "test.proxy.io",
+			},
+		},
+	})
+	require.NoError(t, err)
+
+	// Strategy: receive batch 1, then hold for a significant delay before
+	// acking. If back-pressure works, batch 2 cannot arrive until after
+	// the ack is sent — so its receive timestamp must be >= the ack
+	// timestamp. If management were fire-and-forget, all batches would
+	// already be buffered in the gRPC transport and batch 2 would arrive
+	// well before the ack time.
+	const ackDelay = 300 * time.Millisecond
+
+	type batchEvent struct {
+		recvAt time.Time
+		ackAt  time.Time
+		count  int
+	}
+	var batches []batchEvent
+	var totalMappings int
+
+	for {
+		msg, err := stream.Recv()
+		require.NoError(t, err)
+
+		recvAt := time.Now()
+		totalMappings += len(msg.GetMapping())
+
+		// Delay the ack on non-final batches to create a measurable gap.
+		if !msg.GetInitialSyncComplete() {
+			time.Sleep(ackDelay)
+		}
+
+		ackAt := time.Now()
+		batches = append(batches, batchEvent{
+			recvAt: recvAt,
+			ackAt:  ackAt,
+			count:  len(msg.GetMapping()),
+		})
+
+		err = stream.Send(&proto.SyncMappingsRequest{
+			Msg: &proto.SyncMappingsRequest_Ack{Ack: &proto.SyncMappingsAck{}},
+		})
+		require.NoError(t, err)
+
+		if msg.GetInitialSyncComplete() {
+			break
+		}
+	}
+
+	// 2 original + 600 added = 602 services total.
+	assert.Equal(t, 602, totalMappings, "should receive all 602 mappings")
+	require.GreaterOrEqual(t, len(batches), 2, "need at least 2 batches to verify back-pressure")
+
+	// For every batch after the first, its receive time must be after the
+	// previous batch's ack time. This proves management waited for the ack
+	// before sending the next batch.
+	for i := 1; i < len(batches); i++ {
+		prevAckAt := batches[i-1].ackAt
+		thisRecvAt := batches[i].recvAt
+		assert.True(t, !thisRecvAt.Before(prevAckAt),
+			"batch %d received at %v, but batch %d was acked at %v — "+
+				"management sent the next batch before receiving the ack",
+			i, thisRecvAt, i-1, prevAckAt)
+	}
+}
+
+func TestIntegration_SyncMappings_IncrementalUpdate(t *testing.T) {
+	setup := setupIntegrationTest(t)
+	defer setup.cleanup()
+
+	conn, err := grpc.NewClient(setup.grpcAddr, grpc.WithTransportCredentials(insecure.NewCredentials()))
+	require.NoError(t, err)
+	defer conn.Close()
+
+	client := proto.NewProxyServiceClient(conn)
+
+	ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
+	defer cancel()
+
+	stream, err := client.SyncMappings(ctx)
+	require.NoError(t, err)
+
+	err = stream.Send(&proto.SyncMappingsRequest{
+		Msg: &proto.SyncMappingsRequest_Init{
+			Init: &proto.SyncMappingsInit{
+				ProxyId: "sync-proxy-incremental",
+				Version: "test-v1",
+				Address: "test.proxy.io",
+			},
+		},
+	})
+	require.NoError(t, err)
+
+	// Drain initial snapshot.
+	for {
+		msg, err := stream.Recv()
+		require.NoError(t, err)
+
+		err = stream.Send(&proto.SyncMappingsRequest{
+			Msg: &proto.SyncMappingsRequest_Ack{Ack: &proto.SyncMappingsAck{}},
+		})
+		require.NoError(t, err)
+
+		if msg.GetInitialSyncComplete() {
+			break
+		}
+	}
+
+	// Now send an incremental update via the management server.
+	setup.proxyService.SendServiceUpdate(&proto.GetMappingUpdateResponse{
+		Mapping: []*proto.ProxyMapping{{
+			Type:      proto.ProxyMappingUpdateType_UPDATE_TYPE_REMOVED,
+			Id:        "rp-1",
+			AccountId: "test-account-1",
+			Domain:    "app1.test.proxy.io",
+		}},
+	})
+
+	// Receive the incremental update on the sync stream.
+	msg, err := stream.Recv()
+	require.NoError(t, err)
+	require.NotEmpty(t, msg.GetMapping())
+	assert.Equal(t, "rp-1", msg.GetMapping()[0].GetId())
+	assert.Equal(t, proto.ProxyMappingUpdateType_UPDATE_TYPE_REMOVED, msg.GetMapping()[0].GetType())
+}
+
+func TestIntegration_SyncMappings_MixedProxyVersions(t *testing.T) {
+	setup := setupIntegrationTest(t)
+	defer setup.cleanup()
+
+	conn, err := grpc.NewClient(setup.grpcAddr, grpc.WithTransportCredentials(insecure.NewCredentials()))
+	require.NoError(t, err)
+	defer conn.Close()
+
+	client := proto.NewProxyServiceClient(conn)
+	ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
+	defer cancel()
+
+	// Old proxy uses GetMappingUpdate.
+	legacyStream, err := client.GetMappingUpdate(ctx, &proto.GetMappingUpdateRequest{
+		ProxyId: "legacy-proxy",
+		Version: "old-v1",
+		Address: "test.proxy.io",
+	})
+	require.NoError(t, err)
+
+	var legacyMappings []*proto.ProxyMapping
+	for {
+		msg, err := legacyStream.Recv()
+		require.NoError(t, err)
+		legacyMappings = append(legacyMappings, msg.GetMapping()...)
+		if msg.GetInitialSyncComplete() {
+			break
+		}
+	}
+
+	// New proxy uses SyncMappings.
+	syncStream, err := client.SyncMappings(ctx)
+	require.NoError(t, err)
+
+	err = syncStream.Send(&proto.SyncMappingsRequest{
+		Msg: &proto.SyncMappingsRequest_Init{
+			Init: &proto.SyncMappingsInit{
+				ProxyId: "new-proxy",
+				Version: "new-v2",
+				Address: "test.proxy.io",
+			},
+		},
+	})
+	require.NoError(t, err)
+
+	var syncMappings []*proto.ProxyMapping
+	for {
+		msg, err := syncStream.Recv()
+		require.NoError(t, err)
+		syncMappings = append(syncMappings, msg.GetMapping()...)
+
+		err = syncStream.Send(&proto.SyncMappingsRequest{
+			Msg: &proto.SyncMappingsRequest_Ack{Ack: &proto.SyncMappingsAck{}},
+		})
+		require.NoError(t, err)
+
+		if msg.GetInitialSyncComplete() {
+			break
+		}
+	}
+
+	// Both should receive the same set of mappings.
+	assert.Equal(t, len(legacyMappings), len(syncMappings),
+		"legacy and sync proxies should receive the same number of mappings")
+
+	legacyIDs := make(map[string]bool)
+	for _, m := range legacyMappings {
+		legacyIDs[m.GetId()] = true
+	}
+	for _, m := range syncMappings {
+		assert.True(t, legacyIDs[m.GetId()],
+			"mapping %s should be present in both streams", m.GetId())
+	}
+
+	// Both proxies should be connected.
+	proxies := setup.proxyService.GetConnectedProxies()
+	assert.Contains(t, proxies, "legacy-proxy")
+	assert.Contains(t, proxies, "new-proxy")
+
+	// Both should receive incremental updates.
+	setup.proxyService.SendServiceUpdate(&proto.GetMappingUpdateResponse{
+		Mapping: []*proto.ProxyMapping{{
+			Type:      proto.ProxyMappingUpdateType_UPDATE_TYPE_REMOVED,
+			Id:        "rp-1",
+			AccountId: "test-account-1",
+			Domain:    "app1.test.proxy.io",
+		}},
+	})
+
+	// Legacy proxy receives via GetMappingUpdateResponse.
+	legacyMsg, err := legacyStream.Recv()
+	require.NoError(t, err)
+	assert.Equal(t, "rp-1", legacyMsg.GetMapping()[0].GetId())
+
+	// Sync proxy receives via SyncMappingsResponse.
+	syncMsg, err := syncStream.Recv()
+	require.NoError(t, err)
+	assert.Equal(t, "rp-1", syncMsg.GetMapping()[0].GetId())
+}
+
+func TestIntegration_SyncMappings_Reconnect(t *testing.T) {
+	setup := setupIntegrationTest(t)
+	defer setup.cleanup()
+
+	conn, err := grpc.NewClient(setup.grpcAddr, grpc.WithTransportCredentials(insecure.NewCredentials()))
+	require.NoError(t, err)
+	defer conn.Close()
+
+	client := proto.NewProxyServiceClient(conn)
+	proxyID := "sync-proxy-reconnect"
+
+	receiveMappings := func() []*proto.ProxyMapping {
+		ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
+		defer cancel()
+
+		stream, err := client.SyncMappings(ctx)
+		require.NoError(t, err)
+
+		err = stream.Send(&proto.SyncMappingsRequest{
+			Msg: &proto.SyncMappingsRequest_Init{
+				Init: &proto.SyncMappingsInit{
+					ProxyId: proxyID,
+					Version: "test-v1",
+					Address: "test.proxy.io",
+				},
+			},
+		})
+		require.NoError(t, err)
+
+		var mappings []*proto.ProxyMapping
+		for {
+			msg, err := stream.Recv()
+			require.NoError(t, err)
+			mappings = append(mappings, msg.GetMapping()...)
+
+			err = stream.Send(&proto.SyncMappingsRequest{
+				Msg: &proto.SyncMappingsRequest_Ack{Ack: &proto.SyncMappingsAck{}},
+			})
+			require.NoError(t, err)
+
+			if msg.GetInitialSyncComplete() {
+				break
+			}
+		}
+		return mappings
+	}
+
+	first := receiveMappings()
+	time.Sleep(100 * time.Millisecond)
+	second := receiveMappings()
+
+	assert.Equal(t, len(first), len(second),
+		"should receive same mappings on reconnect")
+
+	firstIDs := make(map[string]bool)
+	for _, m := range first {
+		firstIDs[m.GetId()] = true
+	}
+	for _, m := range second {
+		assert.True(t, firstIDs[m.GetId()],
+			"mapping %s should be present in both connections", m.GetId())
+	}
+}
+
+// --- Fallback tests: old management returns Unimplemented ---
+
+// unimplementedProxyServer embeds UnimplementedProxyServiceServer so
+// SyncMappings returns codes.Unimplemented while GetMappingUpdate works.
+type unimplementedSyncServer struct {
+	proto.UnimplementedProxyServiceServer
+	getMappingCalls atomic.Int32
+}
+
+func (s *unimplementedSyncServer) GetMappingUpdate(_ *proto.GetMappingUpdateRequest, stream proto.ProxyService_GetMappingUpdateServer) error {
+	s.getMappingCalls.Add(1)
+	return stream.Send(&proto.GetMappingUpdateResponse{
+		Mapping:             []*proto.ProxyMapping{{Id: "svc-1", AccountId: "acct-1", Domain: "example.com"}},
+		InitialSyncComplete: true,
+	})
+}
+
+func TestIntegration_FallbackToGetMappingUpdate(t *testing.T) {
+	// Start a gRPC server that does NOT implement SyncMappings.
+	lis, err := net.Listen("tcp", "127.0.0.1:0")
+	require.NoError(t, err)
+
+	srv := &unimplementedSyncServer{}
+	grpcServer := grpc.NewServer()
+	proto.RegisterProxyServiceServer(grpcServer, srv)
+	go func() { _ = grpcServer.Serve(lis) }()
+	defer grpcServer.GracefulStop()
+
+	conn, err := grpc.NewClient(lis.Addr().String(), grpc.WithTransportCredentials(insecure.NewCredentials()))
+	require.NoError(t, err)
+	defer conn.Close()
+
+	client := proto.NewProxyServiceClient(conn)
+
+	// Try SyncMappings — should get Unimplemented.
+	ctx, cancel := context.WithTimeout(context.Background(), 2*time.Second)
+	defer cancel()
+
+	stream, err := client.SyncMappings(ctx)
+	require.NoError(t, err)
+
+	err = stream.Send(&proto.SyncMappingsRequest{
+		Msg: &proto.SyncMappingsRequest_Init{
+			Init: &proto.SyncMappingsInit{
+				ProxyId: "test-proxy",
+				Address: "test.example.com",
+			},
+		},
+	})
+	require.NoError(t, err)
+
+	_, err = stream.Recv()
+	require.Error(t, err)
+	st, ok := grpcstatus.FromError(err)
+	require.True(t, ok)
+	assert.Equal(t, codes.Unimplemented, st.Code(),
+		"unimplemented SyncMappings should return Unimplemented code")
+
+	// isSyncUnimplemented should detect this.
+	assert.True(t, isSyncUnimplemented(err))
+
+	// The actual fallback: GetMappingUpdate should work.
+	legacyStream, err := client.GetMappingUpdate(ctx, &proto.GetMappingUpdateRequest{
+		ProxyId: "test-proxy",
+		Address: "test.example.com",
+	})
+	require.NoError(t, err)
+
+	msg, err := legacyStream.Recv()
+	require.NoError(t, err)
+	assert.True(t, msg.GetInitialSyncComplete())
+	assert.Len(t, msg.GetMapping(), 1)
+	assert.Equal(t, int32(1), srv.getMappingCalls.Load())
+}
+
+func TestIsSyncUnimplemented(t *testing.T) {
+	tests := []struct {
+		name string
+		err  error
+		want bool
+	}{
+		{"nil error", nil, false},
+		{"non-grpc error", errors.New("random"), false},
+		{"grpc internal", grpcstatus.Error(codes.Internal, "fail"), false},
+		{"grpc unavailable", grpcstatus.Error(codes.Unavailable, "fail"), false},
+		{"grpc unimplemented", grpcstatus.Error(codes.Unimplemented, "method not found"), true},
+		{
+			"wrapped unimplemented",
+			fmt.Errorf("create sync stream: %w", grpcstatus.Error(codes.Unimplemented, "nope")),
+			// grpc/status.FromError unwraps in recent versions of grpc-go.
+			true,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			assert.Equal(t, tt.want, isSyncUnimplemented(tt.err))
+		})
+	}
+}
+
+// addServicesToStore adds n extra services to the test store for the given cluster.
+func addServicesToStore(t *testing.T, setup *integrationTestSetup, n int, cluster string) {
+	t.Helper()
+	ctx := context.Background()
+	for i := 0; i < n; i++ {
+		svc := &service.Service{
+			ID:           fmt.Sprintf("extra-svc-%d", i),
+			AccountID:    "test-account-1",
+			Name:         fmt.Sprintf("Extra Service %d", i),
+			Domain:       fmt.Sprintf("extra-%d.test.proxy.io", i),
+			ProxyCluster: cluster,
+			Enabled:      true,
+			Targets: []*service.Target{{
+				Path:       strPtr("/"),
+				Host:       fmt.Sprintf("10.0.1.%d", i%256),
+				Port:       8080,
+				Protocol:   "http",
+				TargetId:   fmt.Sprintf("peer-extra-%d", i),
+				TargetType: "peer",
+				Enabled:    true,
+			}},
+		}
+		require.NoError(t, setup.store.CreateService(ctx, svc))
+	}
+}

shared/management/proto/proxy_service.pb.go

@@ -2291,6 +2291,269 @@ func (x *ValidateTunnelPeerResponse) GetPeerGroupNames() []string {
 	return nil
 }
 
+// SyncMappingsRequest is sent by the proxy on the bidirectional SyncMappings
+// stream. The first message MUST be an init; all subsequent messages MUST be
+// acks.
+type SyncMappingsRequest struct {
+	state         protoimpl.MessageState
+	sizeCache     protoimpl.SizeCache
+	unknownFields protoimpl.UnknownFields
+
+	// Types that are assignable to Msg:
+	//
+	//	*SyncMappingsRequest_Init
+	//	*SyncMappingsRequest_Ack
+	Msg isSyncMappingsRequest_Msg `protobuf_oneof:"msg"`
+}
+
+func (x *SyncMappingsRequest) Reset() {
+	*x = SyncMappingsRequest{}
+	if protoimpl.UnsafeEnabled {
+		mi := &file_proxy_service_proto_msgTypes[28]
+		ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
+		ms.StoreMessageInfo(mi)
+	}
+}
+
+func (x *SyncMappingsRequest) String() string {
+	return protoimpl.X.MessageStringOf(x)
+}
+
+func (*SyncMappingsRequest) ProtoMessage() {}
+
+func (x *SyncMappingsRequest) ProtoReflect() protoreflect.Message {
+	mi := &file_proxy_service_proto_msgTypes[28]
+	if protoimpl.UnsafeEnabled && x != nil {
+		ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
+		if ms.LoadMessageInfo() == nil {
+			ms.StoreMessageInfo(mi)
+		}
+		return ms
+	}
+	return mi.MessageOf(x)
+}
+
+// Deprecated: Use SyncMappingsRequest.ProtoReflect.Descriptor instead.
+func (*SyncMappingsRequest) Descriptor() ([]byte, []int) {
+	return file_proxy_service_proto_rawDescGZIP(), []int{28}
+}
+
+func (m *SyncMappingsRequest) GetMsg() isSyncMappingsRequest_Msg {
+	if m != nil {
+		return m.Msg
+	}
+	return nil
+}
+
+func (x *SyncMappingsRequest) GetInit() *SyncMappingsInit {
+	if x, ok := x.GetMsg().(*SyncMappingsRequest_Init); ok {
+		return x.Init
+	}
+	return nil
+}
+
+func (x *SyncMappingsRequest) GetAck() *SyncMappingsAck {
+	if x, ok := x.GetMsg().(*SyncMappingsRequest_Ack); ok {
+		return x.Ack
+	}
+	return nil
+}
+
+type isSyncMappingsRequest_Msg interface {
+	isSyncMappingsRequest_Msg()
+}
+
+type SyncMappingsRequest_Init struct {
+	Init *SyncMappingsInit `protobuf:"bytes,1,opt,name=init,proto3,oneof"`
+}
+
+type SyncMappingsRequest_Ack struct {
+	Ack *SyncMappingsAck `protobuf:"bytes,2,opt,name=ack,proto3,oneof"`
+}
+
+func (*SyncMappingsRequest_Init) isSyncMappingsRequest_Msg() {}
+
+func (*SyncMappingsRequest_Ack) isSyncMappingsRequest_Msg() {}
+
+// SyncMappingsInit is the first message on the stream, carrying the same
+// identification fields as GetMappingUpdateRequest.
+type SyncMappingsInit struct {
+	state         protoimpl.MessageState
+	sizeCache     protoimpl.SizeCache
+	unknownFields protoimpl.UnknownFields
+
+	ProxyId      string                 `protobuf:"bytes,1,opt,name=proxy_id,json=proxyId,proto3" json:"proxy_id,omitempty"`
+	Version      string                 `protobuf:"bytes,2,opt,name=version,proto3" json:"version,omitempty"`
+	StartedAt    *timestamppb.Timestamp `protobuf:"bytes,3,opt,name=started_at,json=startedAt,proto3" json:"started_at,omitempty"`
+	Address      string                 `protobuf:"bytes,4,opt,name=address,proto3" json:"address,omitempty"`
+	Capabilities *ProxyCapabilities     `protobuf:"bytes,5,opt,name=capabilities,proto3" json:"capabilities,omitempty"`
+}
+
+func (x *SyncMappingsInit) Reset() {
+	*x = SyncMappingsInit{}
+	if protoimpl.UnsafeEnabled {
+		mi := &file_proxy_service_proto_msgTypes[29]
+		ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
+		ms.StoreMessageInfo(mi)
+	}
+}
+
+func (x *SyncMappingsInit) String() string {
+	return protoimpl.X.MessageStringOf(x)
+}
+
+func (*SyncMappingsInit) ProtoMessage() {}
+
+func (x *SyncMappingsInit) ProtoReflect() protoreflect.Message {
+	mi := &file_proxy_service_proto_msgTypes[29]
+	if protoimpl.UnsafeEnabled && x != nil {
+		ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
+		if ms.LoadMessageInfo() == nil {
+			ms.StoreMessageInfo(mi)
+		}
+		return ms
+	}
+	return mi.MessageOf(x)
+}
+
+// Deprecated: Use SyncMappingsInit.ProtoReflect.Descriptor instead.
+func (*SyncMappingsInit) Descriptor() ([]byte, []int) {
+	return file_proxy_service_proto_rawDescGZIP(), []int{29}
+}
+
+func (x *SyncMappingsInit) GetProxyId() string {
+	if x != nil {
+		return x.ProxyId
+	}
+	return ""
+}
+
+func (x *SyncMappingsInit) GetVersion() string {
+	if x != nil {
+		return x.Version
+	}
+	return ""
+}
+
+func (x *SyncMappingsInit) GetStartedAt() *timestamppb.Timestamp {
+	if x != nil {
+		return x.StartedAt
+	}
+	return nil
+}
+
+func (x *SyncMappingsInit) GetAddress() string {
+	if x != nil {
+		return x.Address
+	}
+	return ""
+}
+
+func (x *SyncMappingsInit) GetCapabilities() *ProxyCapabilities {
+	if x != nil {
+		return x.Capabilities
+	}
+	return nil
+}
+
+// SyncMappingsAck is sent by the proxy after it has fully processed a batch.
+// Management waits for this before sending the next batch.
+type SyncMappingsAck struct {
+	state         protoimpl.MessageState
+	sizeCache     protoimpl.SizeCache
+	unknownFields protoimpl.UnknownFields
+}
+
+func (x *SyncMappingsAck) Reset() {
+	*x = SyncMappingsAck{}
+	if protoimpl.UnsafeEnabled {
+		mi := &file_proxy_service_proto_msgTypes[30]
+		ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
+		ms.StoreMessageInfo(mi)
+	}
+}
+
+func (x *SyncMappingsAck) String() string {
+	return protoimpl.X.MessageStringOf(x)
+}
+
+func (*SyncMappingsAck) ProtoMessage() {}
+
+func (x *SyncMappingsAck) ProtoReflect() protoreflect.Message {
+	mi := &file_proxy_service_proto_msgTypes[30]
+	if protoimpl.UnsafeEnabled && x != nil {
+		ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
+		if ms.LoadMessageInfo() == nil {
+			ms.StoreMessageInfo(mi)
+		}
+		return ms
+	}
+	return mi.MessageOf(x)
+}
+
+// Deprecated: Use SyncMappingsAck.ProtoReflect.Descriptor instead.
+func (*SyncMappingsAck) Descriptor() ([]byte, []int) {
+	return file_proxy_service_proto_rawDescGZIP(), []int{30}
+}
+
+// SyncMappingsResponse is a batch of mappings sent by management.
+// Identical semantics to GetMappingUpdateResponse.
+type SyncMappingsResponse struct {
+	state         protoimpl.MessageState
+	sizeCache     protoimpl.SizeCache
+	unknownFields protoimpl.UnknownFields
+
+	Mapping []*ProxyMapping `protobuf:"bytes,1,rep,name=mapping,proto3" json:"mapping,omitempty"`
+	// initial_sync_complete is set on the last message of the initial snapshot.
+	InitialSyncComplete bool `protobuf:"varint,2,opt,name=initial_sync_complete,json=initialSyncComplete,proto3" json:"initial_sync_complete,omitempty"`
+}
+
+func (x *SyncMappingsResponse) Reset() {
+	*x = SyncMappingsResponse{}
+	if protoimpl.UnsafeEnabled {
+		mi := &file_proxy_service_proto_msgTypes[31]
+		ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
+		ms.StoreMessageInfo(mi)
+	}
+}
+
+func (x *SyncMappingsResponse) String() string {
+	return protoimpl.X.MessageStringOf(x)
+}
+
+func (*SyncMappingsResponse) ProtoMessage() {}
+
+func (x *SyncMappingsResponse) ProtoReflect() protoreflect.Message {
+	mi := &file_proxy_service_proto_msgTypes[31]
+	if protoimpl.UnsafeEnabled && x != nil {
+		ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
+		if ms.LoadMessageInfo() == nil {
+			ms.StoreMessageInfo(mi)
+		}
+		return ms
+	}
+	return mi.MessageOf(x)
+}
+
+// Deprecated: Use SyncMappingsResponse.ProtoReflect.Descriptor instead.
+func (*SyncMappingsResponse) Descriptor() ([]byte, []int) {
+	return file_proxy_service_proto_rawDescGZIP(), []int{31}
+}
+
+func (x *SyncMappingsResponse) GetMapping() []*ProxyMapping {
+	if x != nil {
+		return x.Mapping
+	}
+	return nil
+}
+
+func (x *SyncMappingsResponse) GetInitialSyncComplete() bool {
+	if x != nil {
+		return x.InitialSyncComplete
+	}
+	return false
+}
+
 var File_proxy_service_proto protoreflect.FileDescriptor
 
 var file_proxy_service_proto_rawDesc = []byte{
@@ -2628,37 +2891,74 @@ var file_proxy_service_proto_rawDesc = []byte{
 	0x72, 0x6f, 0x75, 0x70, 0x49, 0x64, 0x73, 0x12, 0x28, 0x0a, 0x10, 0x70, 0x65, 0x65, 0x72, 0x5f,
 	0x67, 0x72, 0x6f, 0x75, 0x70, 0x5f, 0x6e, 0x61, 0x6d, 0x65, 0x73, 0x18, 0x07, 0x20, 0x03, 0x28,
 	0x09, 0x52, 0x0e, 0x70, 0x65, 0x65, 0x72, 0x47, 0x72, 0x6f, 0x75, 0x70, 0x4e, 0x61, 0x6d, 0x65,
-	0x73, 0x2a, 0x64, 0x0a, 0x16, 0x50, 0x72, 0x6f, 0x78, 0x79, 0x4d, 0x61, 0x70, 0x70, 0x69, 0x6e,
-	0x67, 0x55, 0x70, 0x64, 0x61, 0x74, 0x65, 0x54, 0x79, 0x70, 0x65, 0x12, 0x17, 0x0a, 0x13, 0x55,
-	0x50, 0x44, 0x41, 0x54, 0x45, 0x5f, 0x54, 0x59, 0x50, 0x45, 0x5f, 0x43, 0x52, 0x45, 0x41, 0x54,
-	0x45, 0x44, 0x10, 0x00, 0x12, 0x18, 0x0a, 0x14, 0x55, 0x50, 0x44, 0x41, 0x54, 0x45, 0x5f, 0x54,
-	0x59, 0x50, 0x45, 0x5f, 0x4d, 0x4f, 0x44, 0x49, 0x46, 0x49, 0x45, 0x44, 0x10, 0x01, 0x12, 0x17,
-	0x0a, 0x13, 0x55, 0x50, 0x44, 0x41, 0x54, 0x45, 0x5f, 0x54, 0x59, 0x50, 0x45, 0x5f, 0x52, 0x45,
-	0x4d, 0x4f, 0x56, 0x45, 0x44, 0x10, 0x02, 0x2a, 0x46, 0x0a, 0x0f, 0x50, 0x61, 0x74, 0x68, 0x52,
-	0x65, 0x77, 0x72, 0x69, 0x74, 0x65, 0x4d, 0x6f, 0x64, 0x65, 0x12, 0x18, 0x0a, 0x14, 0x50, 0x41,
-	0x54, 0x48, 0x5f, 0x52, 0x45, 0x57, 0x52, 0x49, 0x54, 0x45, 0x5f, 0x44, 0x45, 0x46, 0x41, 0x55,
-	0x4c, 0x54, 0x10, 0x00, 0x12, 0x19, 0x0a, 0x15, 0x50, 0x41, 0x54, 0x48, 0x5f, 0x52, 0x45, 0x57,
-	0x52, 0x49, 0x54, 0x45, 0x5f, 0x50, 0x52, 0x45, 0x53, 0x45, 0x52, 0x56, 0x45, 0x10, 0x01, 0x2a,
-	0xc8, 0x01, 0x0a, 0x0b, 0x50, 0x72, 0x6f, 0x78, 0x79, 0x53, 0x74, 0x61, 0x74, 0x75, 0x73, 0x12,
-	0x18, 0x0a, 0x14, 0x50, 0x52, 0x4f, 0x58, 0x59, 0x5f, 0x53, 0x54, 0x41, 0x54, 0x55, 0x53, 0x5f,
-	0x50, 0x45, 0x4e, 0x44, 0x49, 0x4e, 0x47, 0x10, 0x00, 0x12, 0x17, 0x0a, 0x13, 0x50, 0x52, 0x4f,
-	0x58, 0x59, 0x5f, 0x53, 0x54, 0x41, 0x54, 0x55, 0x53, 0x5f, 0x41, 0x43, 0x54, 0x49, 0x56, 0x45,
-	0x10, 0x01, 0x12, 0x23, 0x0a, 0x1f, 0x50, 0x52, 0x4f, 0x58, 0x59, 0x5f, 0x53, 0x54, 0x41, 0x54,
-	0x55, 0x53, 0x5f, 0x54, 0x55, 0x4e, 0x4e, 0x45, 0x4c, 0x5f, 0x4e, 0x4f, 0x54, 0x5f, 0x43, 0x52,
-	0x45, 0x41, 0x54, 0x45, 0x44, 0x10, 0x02, 0x12, 0x24, 0x0a, 0x20, 0x50, 0x52, 0x4f, 0x58, 0x59,
-	0x5f, 0x53, 0x54, 0x41, 0x54, 0x55, 0x53, 0x5f, 0x43, 0x45, 0x52, 0x54, 0x49, 0x46, 0x49, 0x43,
-	0x41, 0x54, 0x45, 0x5f, 0x50, 0x45, 0x4e, 0x44, 0x49, 0x4e, 0x47, 0x10, 0x03, 0x12, 0x23, 0x0a,
-	0x1f, 0x50, 0x52, 0x4f, 0x58, 0x59, 0x5f, 0x53, 0x54, 0x41, 0x54, 0x55, 0x53, 0x5f, 0x43, 0x45,
-	0x52, 0x54, 0x49, 0x46, 0x49, 0x43, 0x41, 0x54, 0x45, 0x5f, 0x46, 0x41, 0x49, 0x4c, 0x45, 0x44,
-	0x10, 0x04, 0x12, 0x16, 0x0a, 0x12, 0x50, 0x52, 0x4f, 0x58, 0x59, 0x5f, 0x53, 0x54, 0x41, 0x54,
-	0x55, 0x53, 0x5f, 0x45, 0x52, 0x52, 0x4f, 0x52, 0x10, 0x05, 0x32, 0xe1, 0x05, 0x0a, 0x0c, 0x50,
-	0x72, 0x6f, 0x78, 0x79, 0x53, 0x65, 0x72, 0x76, 0x69, 0x63, 0x65, 0x12, 0x5f, 0x0a, 0x10, 0x47,
-	0x65, 0x74, 0x4d, 0x61, 0x70, 0x70, 0x69, 0x6e, 0x67, 0x55, 0x70, 0x64, 0x61, 0x74, 0x65, 0x12,
-	0x23, 0x2e, 0x6d, 0x61, 0x6e, 0x61, 0x67, 0x65, 0x6d, 0x65, 0x6e, 0x74, 0x2e, 0x47, 0x65, 0x74,
-	0x4d, 0x61, 0x70, 0x70, 0x69, 0x6e, 0x67, 0x55, 0x70, 0x64, 0x61, 0x74, 0x65, 0x52, 0x65, 0x71,
-	0x75, 0x65, 0x73, 0x74, 0x1a, 0x24, 0x2e, 0x6d, 0x61, 0x6e, 0x61, 0x67, 0x65, 0x6d, 0x65, 0x6e,
-	0x74, 0x2e, 0x47, 0x65, 0x74, 0x4d, 0x61, 0x70, 0x70, 0x69, 0x6e, 0x67, 0x55, 0x70, 0x64, 0x61,
-	0x74, 0x65, 0x52, 0x65, 0x73, 0x70, 0x6f, 0x6e, 0x73, 0x65, 0x30, 0x01, 0x12, 0x54, 0x0a, 0x0d,
+	0x73, 0x22, 0x81, 0x01, 0x0a, 0x13, 0x53, 0x79, 0x6e, 0x63, 0x4d, 0x61, 0x70, 0x70, 0x69, 0x6e,
+	0x67, 0x73, 0x52, 0x65, 0x71, 0x75, 0x65, 0x73, 0x74, 0x12, 0x32, 0x0a, 0x04, 0x69, 0x6e, 0x69,
+	0x74, 0x18, 0x01, 0x20, 0x01, 0x28, 0x0b, 0x32, 0x1c, 0x2e, 0x6d, 0x61, 0x6e, 0x61, 0x67, 0x65,
+	0x6d, 0x65, 0x6e, 0x74, 0x2e, 0x53, 0x79, 0x6e, 0x63, 0x4d, 0x61, 0x70, 0x70, 0x69, 0x6e, 0x67,
+	0x73, 0x49, 0x6e, 0x69, 0x74, 0x48, 0x00, 0x52, 0x04, 0x69, 0x6e, 0x69, 0x74, 0x12, 0x2f, 0x0a,
+	0x03, 0x61, 0x63, 0x6b, 0x18, 0x02, 0x20, 0x01, 0x28, 0x0b, 0x32, 0x1b, 0x2e, 0x6d, 0x61, 0x6e,
+	0x61, 0x67, 0x65, 0x6d, 0x65, 0x6e, 0x74, 0x2e, 0x53, 0x79, 0x6e, 0x63, 0x4d, 0x61, 0x70, 0x70,
+	0x69, 0x6e, 0x67, 0x73, 0x41, 0x63, 0x6b, 0x48, 0x00, 0x52, 0x03, 0x61, 0x63, 0x6b, 0x42, 0x05,
+	0x0a, 0x03, 0x6d, 0x73, 0x67, 0x22, 0xdf, 0x01, 0x0a, 0x10, 0x53, 0x79, 0x6e, 0x63, 0x4d, 0x61,
+	0x70, 0x70, 0x69, 0x6e, 0x67, 0x73, 0x49, 0x6e, 0x69, 0x74, 0x12, 0x19, 0x0a, 0x08, 0x70, 0x72,
+	0x6f, 0x78, 0x79, 0x5f, 0x69, 0x64, 0x18, 0x01, 0x20, 0x01, 0x28, 0x09, 0x52, 0x07, 0x70, 0x72,
+	0x6f, 0x78, 0x79, 0x49, 0x64, 0x12, 0x18, 0x0a, 0x07, 0x76, 0x65, 0x72, 0x73, 0x69, 0x6f, 0x6e,
+	0x18, 0x02, 0x20, 0x01, 0x28, 0x09, 0x52, 0x07, 0x76, 0x65, 0x72, 0x73, 0x69, 0x6f, 0x6e, 0x12,
+	0x39, 0x0a, 0x0a, 0x73, 0x74, 0x61, 0x72, 0x74, 0x65, 0x64, 0x5f, 0x61, 0x74, 0x18, 0x03, 0x20,
+	0x01, 0x28, 0x0b, 0x32, 0x1a, 0x2e, 0x67, 0x6f, 0x6f, 0x67, 0x6c, 0x65, 0x2e, 0x70, 0x72, 0x6f,
+	0x74, 0x6f, 0x62, 0x75, 0x66, 0x2e, 0x54, 0x69, 0x6d, 0x65, 0x73, 0x74, 0x61, 0x6d, 0x70, 0x52,
+	0x09, 0x73, 0x74, 0x61, 0x72, 0x74, 0x65, 0x64, 0x41, 0x74, 0x12, 0x18, 0x0a, 0x07, 0x61, 0x64,
+	0x64, 0x72, 0x65, 0x73, 0x73, 0x18, 0x04, 0x20, 0x01, 0x28, 0x09, 0x52, 0x07, 0x61, 0x64, 0x64,
+	0x72, 0x65, 0x73, 0x73, 0x12, 0x41, 0x0a, 0x0c, 0x63, 0x61, 0x70, 0x61, 0x62, 0x69, 0x6c, 0x69,
+	0x74, 0x69, 0x65, 0x73, 0x18, 0x05, 0x20, 0x01, 0x28, 0x0b, 0x32, 0x1d, 0x2e, 0x6d, 0x61, 0x6e,
+	0x61, 0x67, 0x65, 0x6d, 0x65, 0x6e, 0x74, 0x2e, 0x50, 0x72, 0x6f, 0x78, 0x79, 0x43, 0x61, 0x70,
+	0x61, 0x62, 0x69, 0x6c, 0x69, 0x74, 0x69, 0x65, 0x73, 0x52, 0x0c, 0x63, 0x61, 0x70, 0x61, 0x62,
+	0x69, 0x6c, 0x69, 0x74, 0x69, 0x65, 0x73, 0x22, 0x11, 0x0a, 0x0f, 0x53, 0x79, 0x6e, 0x63, 0x4d,
+	0x61, 0x70, 0x70, 0x69, 0x6e, 0x67, 0x73, 0x41, 0x63, 0x6b, 0x22, 0x7e, 0x0a, 0x14, 0x53, 0x79,
+	0x6e, 0x63, 0x4d, 0x61, 0x70, 0x70, 0x69, 0x6e, 0x67, 0x73, 0x52, 0x65, 0x73, 0x70, 0x6f, 0x6e,
+	0x73, 0x65, 0x12, 0x32, 0x0a, 0x07, 0x6d, 0x61, 0x70, 0x70, 0x69, 0x6e, 0x67, 0x18, 0x01, 0x20,
+	0x03, 0x28, 0x0b, 0x32, 0x18, 0x2e, 0x6d, 0x61, 0x6e, 0x61, 0x67, 0x65, 0x6d, 0x65, 0x6e, 0x74,
+	0x2e, 0x50, 0x72, 0x6f, 0x78, 0x79, 0x4d, 0x61, 0x70, 0x70, 0x69, 0x6e, 0x67, 0x52, 0x07, 0x6d,
+	0x61, 0x70, 0x70, 0x69, 0x6e, 0x67, 0x12, 0x32, 0x0a, 0x15, 0x69, 0x6e, 0x69, 0x74, 0x69, 0x61,
+	0x6c, 0x5f, 0x73, 0x79, 0x6e, 0x63, 0x5f, 0x63, 0x6f, 0x6d, 0x70, 0x6c, 0x65, 0x74, 0x65, 0x18,
+	0x02, 0x20, 0x01, 0x28, 0x08, 0x52, 0x13, 0x69, 0x6e, 0x69, 0x74, 0x69, 0x61, 0x6c, 0x53, 0x79,
+	0x6e, 0x63, 0x43, 0x6f, 0x6d, 0x70, 0x6c, 0x65, 0x74, 0x65, 0x2a, 0x64, 0x0a, 0x16, 0x50, 0x72,
+	0x6f, 0x78, 0x79, 0x4d, 0x61, 0x70, 0x70, 0x69, 0x6e, 0x67, 0x55, 0x70, 0x64, 0x61, 0x74, 0x65,
+	0x54, 0x79, 0x70, 0x65, 0x12, 0x17, 0x0a, 0x13, 0x55, 0x50, 0x44, 0x41, 0x54, 0x45, 0x5f, 0x54,
+	0x59, 0x50, 0x45, 0x5f, 0x43, 0x52, 0x45, 0x41, 0x54, 0x45, 0x44, 0x10, 0x00, 0x12, 0x18, 0x0a,
+	0x14, 0x55, 0x50, 0x44, 0x41, 0x54, 0x45, 0x5f, 0x54, 0x59, 0x50, 0x45, 0x5f, 0x4d, 0x4f, 0x44,
+	0x49, 0x46, 0x49, 0x45, 0x44, 0x10, 0x01, 0x12, 0x17, 0x0a, 0x13, 0x55, 0x50, 0x44, 0x41, 0x54,
+	0x45, 0x5f, 0x54, 0x59, 0x50, 0x45, 0x5f, 0x52, 0x45, 0x4d, 0x4f, 0x56, 0x45, 0x44, 0x10, 0x02,
+	0x2a, 0x46, 0x0a, 0x0f, 0x50, 0x61, 0x74, 0x68, 0x52, 0x65, 0x77, 0x72, 0x69, 0x74, 0x65, 0x4d,
+	0x6f, 0x64, 0x65, 0x12, 0x18, 0x0a, 0x14, 0x50, 0x41, 0x54, 0x48, 0x5f, 0x52, 0x45, 0x57, 0x52,
+	0x49, 0x54, 0x45, 0x5f, 0x44, 0x45, 0x46, 0x41, 0x55, 0x4c, 0x54, 0x10, 0x00, 0x12, 0x19, 0x0a,
+	0x15, 0x50, 0x41, 0x54, 0x48, 0x5f, 0x52, 0x45, 0x57, 0x52, 0x49, 0x54, 0x45, 0x5f, 0x50, 0x52,
+	0x45, 0x53, 0x45, 0x52, 0x56, 0x45, 0x10, 0x01, 0x2a, 0xc8, 0x01, 0x0a, 0x0b, 0x50, 0x72, 0x6f,
+	0x78, 0x79, 0x53, 0x74, 0x61, 0x74, 0x75, 0x73, 0x12, 0x18, 0x0a, 0x14, 0x50, 0x52, 0x4f, 0x58,
+	0x59, 0x5f, 0x53, 0x54, 0x41, 0x54, 0x55, 0x53, 0x5f, 0x50, 0x45, 0x4e, 0x44, 0x49, 0x4e, 0x47,
+	0x10, 0x00, 0x12, 0x17, 0x0a, 0x13, 0x50, 0x52, 0x4f, 0x58, 0x59, 0x5f, 0x53, 0x54, 0x41, 0x54,
+	0x55, 0x53, 0x5f, 0x41, 0x43, 0x54, 0x49, 0x56, 0x45, 0x10, 0x01, 0x12, 0x23, 0x0a, 0x1f, 0x50,
+	0x52, 0x4f, 0x58, 0x59, 0x5f, 0x53, 0x54, 0x41, 0x54, 0x55, 0x53, 0x5f, 0x54, 0x55, 0x4e, 0x4e,
+	0x45, 0x4c, 0x5f, 0x4e, 0x4f, 0x54, 0x5f, 0x43, 0x52, 0x45, 0x41, 0x54, 0x45, 0x44, 0x10, 0x02,
+	0x12, 0x24, 0x0a, 0x20, 0x50, 0x52, 0x4f, 0x58, 0x59, 0x5f, 0x53, 0x54, 0x41, 0x54, 0x55, 0x53,
+	0x5f, 0x43, 0x45, 0x52, 0x54, 0x49, 0x46, 0x49, 0x43, 0x41, 0x54, 0x45, 0x5f, 0x50, 0x45, 0x4e,
+	0x44, 0x49, 0x4e, 0x47, 0x10, 0x03, 0x12, 0x23, 0x0a, 0x1f, 0x50, 0x52, 0x4f, 0x58, 0x59, 0x5f,
+	0x53, 0x54, 0x41, 0x54, 0x55, 0x53, 0x5f, 0x43, 0x45, 0x52, 0x54, 0x49, 0x46, 0x49, 0x43, 0x41,
+	0x54, 0x45, 0x5f, 0x46, 0x41, 0x49, 0x4c, 0x45, 0x44, 0x10, 0x04, 0x12, 0x16, 0x0a, 0x12, 0x50,
+	0x52, 0x4f, 0x58, 0x59, 0x5f, 0x53, 0x54, 0x41, 0x54, 0x55, 0x53, 0x5f, 0x45, 0x52, 0x52, 0x4f,
+	0x52, 0x10, 0x05, 0x32, 0xb8, 0x06, 0x0a, 0x0c, 0x50, 0x72, 0x6f, 0x78, 0x79, 0x53, 0x65, 0x72,
+	0x76, 0x69, 0x63, 0x65, 0x12, 0x5f, 0x0a, 0x10, 0x47, 0x65, 0x74, 0x4d, 0x61, 0x70, 0x70, 0x69,
+	0x6e, 0x67, 0x55, 0x70, 0x64, 0x61, 0x74, 0x65, 0x12, 0x23, 0x2e, 0x6d, 0x61, 0x6e, 0x61, 0x67,
+	0x65, 0x6d, 0x65, 0x6e, 0x74, 0x2e, 0x47, 0x65, 0x74, 0x4d, 0x61, 0x70, 0x70, 0x69, 0x6e, 0x67,
+	0x55, 0x70, 0x64, 0x61, 0x74, 0x65, 0x52, 0x65, 0x71, 0x75, 0x65, 0x73, 0x74, 0x1a, 0x24, 0x2e,
+	0x6d, 0x61, 0x6e, 0x61, 0x67, 0x65, 0x6d, 0x65, 0x6e, 0x74, 0x2e, 0x47, 0x65, 0x74, 0x4d, 0x61,
+	0x70, 0x70, 0x69, 0x6e, 0x67, 0x55, 0x70, 0x64, 0x61, 0x74, 0x65, 0x52, 0x65, 0x73, 0x70, 0x6f,
+	0x6e, 0x73, 0x65, 0x30, 0x01, 0x12, 0x55, 0x0a, 0x0c, 0x53, 0x79, 0x6e, 0x63, 0x4d, 0x61, 0x70,
+	0x70, 0x69, 0x6e, 0x67, 0x73, 0x12, 0x1f, 0x2e, 0x6d, 0x61, 0x6e, 0x61, 0x67, 0x65, 0x6d, 0x65,
+	0x6e, 0x74, 0x2e, 0x53, 0x79, 0x6e, 0x63, 0x4d, 0x61, 0x70, 0x70, 0x69, 0x6e, 0x67, 0x73, 0x52,
+	0x65, 0x71, 0x75, 0x65, 0x73, 0x74, 0x1a, 0x20, 0x2e, 0x6d, 0x61, 0x6e, 0x61, 0x67, 0x65, 0x6d,
+	0x65, 0x6e, 0x74, 0x2e, 0x53, 0x79, 0x6e, 0x63, 0x4d, 0x61, 0x70, 0x70, 0x69, 0x6e, 0x67, 0x73,
+	0x52, 0x65, 0x73, 0x70, 0x6f, 0x6e, 0x73, 0x65, 0x28, 0x01, 0x30, 0x01, 0x12, 0x54, 0x0a, 0x0d,
 	0x53, 0x65, 0x6e, 0x64, 0x41, 0x63, 0x63, 0x65, 0x73, 0x73, 0x4c, 0x6f, 0x67, 0x12, 0x20, 0x2e,
 	0x6d, 0x61, 0x6e, 0x61, 0x67, 0x65, 0x6d, 0x65, 0x6e, 0x74, 0x2e, 0x53, 0x65, 0x6e, 0x64, 0x41,
 	0x63, 0x63, 0x65, 0x73, 0x73, 0x4c, 0x6f, 0x67, 0x52, 0x65, 0x71, 0x75, 0x65, 0x73, 0x74, 0x1a,
@@ -2714,7 +3014,7 @@ func file_proxy_service_proto_rawDescGZIP() []byte {
 }
 
 var file_proxy_service_proto_enumTypes = make([]protoimpl.EnumInfo, 3)
-var file_proxy_service_proto_msgTypes = make([]protoimpl.MessageInfo, 30)
+var file_proxy_service_proto_msgTypes = make([]protoimpl.MessageInfo, 34)
 var file_proxy_service_proto_goTypes = []interface{}{
 	(ProxyMappingUpdateType)(0),        // 0: management.ProxyMappingUpdateType
 	(PathRewriteMode)(0),               // 1: management.PathRewriteMode
@@ -2747,19 +3047,23 @@ var file_proxy_service_proto_goTypes = []interface{}{
 	(*ValidateSessionResponse)(nil),    // 28: management.ValidateSessionResponse
 	(*ValidateTunnelPeerRequest)(nil),  // 29: management.ValidateTunnelPeerRequest
 	(*ValidateTunnelPeerResponse)(nil), // 30: management.ValidateTunnelPeerResponse
-	nil,                                // 31: management.PathTargetOptions.CustomHeadersEntry
-	nil,                                // 32: management.AccessLog.MetadataEntry
-	(*timestamppb.Timestamp)(nil),      // 33: google.protobuf.Timestamp
-	(*durationpb.Duration)(nil),        // 34: google.protobuf.Duration
+	(*SyncMappingsRequest)(nil),        // 31: management.SyncMappingsRequest
+	(*SyncMappingsInit)(nil),           // 32: management.SyncMappingsInit
+	(*SyncMappingsAck)(nil),            // 33: management.SyncMappingsAck
+	(*SyncMappingsResponse)(nil),       // 34: management.SyncMappingsResponse
+	nil,                                // 35: management.PathTargetOptions.CustomHeadersEntry
+	nil,                                // 36: management.AccessLog.MetadataEntry
+	(*timestamppb.Timestamp)(nil),      // 37: google.protobuf.Timestamp
+	(*durationpb.Duration)(nil),        // 38: google.protobuf.Duration
 }
 var file_proxy_service_proto_depIdxs = []int32{
-	33, // 0: management.GetMappingUpdateRequest.started_at:type_name -> google.protobuf.Timestamp
+	37, // 0: management.GetMappingUpdateRequest.started_at:type_name -> google.protobuf.Timestamp
 	3,  // 1: management.GetMappingUpdateRequest.capabilities:type_name -> management.ProxyCapabilities
 	11, // 2: management.GetMappingUpdateResponse.mapping:type_name -> management.ProxyMapping
-	34, // 3: management.PathTargetOptions.request_timeout:type_name -> google.protobuf.Duration
+	38, // 3: management.PathTargetOptions.request_timeout:type_name -> google.protobuf.Duration
 	1,  // 4: management.PathTargetOptions.path_rewrite:type_name -> management.PathRewriteMode
-	31, // 5: management.PathTargetOptions.custom_headers:type_name -> management.PathTargetOptions.CustomHeadersEntry
-	34, // 6: management.PathTargetOptions.session_idle_timeout:type_name -> google.protobuf.Duration
+	35, // 5: management.PathTargetOptions.custom_headers:type_name -> management.PathTargetOptions.CustomHeadersEntry
+	38, // 6: management.PathTargetOptions.session_idle_timeout:type_name -> google.protobuf.Duration
 	6,  // 7: management.PathMapping.options:type_name -> management.PathTargetOptions
 	8,  // 8: management.Authentication.header_auths:type_name -> management.HeaderAuth
 	0,  // 9: management.ProxyMapping.type:type_name -> management.ProxyMappingUpdateType
@@ -2767,34 +3071,41 @@ var file_proxy_service_proto_depIdxs = []int32{
 	9,  // 11: management.ProxyMapping.auth:type_name -> management.Authentication
 	10, // 12: management.ProxyMapping.access_restrictions:type_name -> management.AccessRestrictions
 	14, // 13: management.SendAccessLogRequest.log:type_name -> management.AccessLog
-	33, // 14: management.AccessLog.timestamp:type_name -> google.protobuf.Timestamp
-	32, // 15: management.AccessLog.metadata:type_name -> management.AccessLog.MetadataEntry
+	37, // 14: management.AccessLog.timestamp:type_name -> google.protobuf.Timestamp
+	36, // 15: management.AccessLog.metadata:type_name -> management.AccessLog.MetadataEntry
 	17, // 16: management.AuthenticateRequest.password:type_name -> management.PasswordRequest
 	18, // 17: management.AuthenticateRequest.pin:type_name -> management.PinRequest
 	16, // 18: management.AuthenticateRequest.header_auth:type_name -> management.HeaderAuthRequest
 	2,  // 19: management.SendStatusUpdateRequest.status:type_name -> management.ProxyStatus
 	21, // 20: management.SendStatusUpdateRequest.inbound_listener:type_name -> management.ProxyInboundListener
-	4,  // 21: management.ProxyService.GetMappingUpdate:input_type -> management.GetMappingUpdateRequest
-	12, // 22: management.ProxyService.SendAccessLog:input_type -> management.SendAccessLogRequest
-	15, // 23: management.ProxyService.Authenticate:input_type -> management.AuthenticateRequest
-	20, // 24: management.ProxyService.SendStatusUpdate:input_type -> management.SendStatusUpdateRequest
-	23, // 25: management.ProxyService.CreateProxyPeer:input_type -> management.CreateProxyPeerRequest
-	25, // 26: management.ProxyService.GetOIDCURL:input_type -> management.GetOIDCURLRequest
-	27, // 27: management.ProxyService.ValidateSession:input_type -> management.ValidateSessionRequest
-	29, // 28: management.ProxyService.ValidateTunnelPeer:input_type -> management.ValidateTunnelPeerRequest
-	5,  // 29: management.ProxyService.GetMappingUpdate:output_type -> management.GetMappingUpdateResponse
-	13, // 30: management.ProxyService.SendAccessLog:output_type -> management.SendAccessLogResponse
-	19, // 31: management.ProxyService.Authenticate:output_type -> management.AuthenticateResponse
-	22, // 32: management.ProxyService.SendStatusUpdate:output_type -> management.SendStatusUpdateResponse
-	24, // 33: management.ProxyService.CreateProxyPeer:output_type -> management.CreateProxyPeerResponse
-	26, // 34: management.ProxyService.GetOIDCURL:output_type -> management.GetOIDCURLResponse
-	28, // 35: management.ProxyService.ValidateSession:output_type -> management.ValidateSessionResponse
-	30, // 36: management.ProxyService.ValidateTunnelPeer:output_type -> management.ValidateTunnelPeerResponse
-	29, // [29:37] is the sub-list for method output_type
-	21, // [21:29] is the sub-list for method input_type
-	21, // [21:21] is the sub-list for extension type_name
-	21, // [21:21] is the sub-list for extension extendee
-	0,  // [0:21] is the sub-list for field type_name
+	32, // 21: management.SyncMappingsRequest.init:type_name -> management.SyncMappingsInit
+	33, // 22: management.SyncMappingsRequest.ack:type_name -> management.SyncMappingsAck
+	37, // 23: management.SyncMappingsInit.started_at:type_name -> google.protobuf.Timestamp
+	3,  // 24: management.SyncMappingsInit.capabilities:type_name -> management.ProxyCapabilities
+	11, // 25: management.SyncMappingsResponse.mapping:type_name -> management.ProxyMapping
+	4,  // 26: management.ProxyService.GetMappingUpdate:input_type -> management.GetMappingUpdateRequest
+	31, // 27: management.ProxyService.SyncMappings:input_type -> management.SyncMappingsRequest
+	12, // 28: management.ProxyService.SendAccessLog:input_type -> management.SendAccessLogRequest
+	15, // 29: management.ProxyService.Authenticate:input_type -> management.AuthenticateRequest
+	20, // 30: management.ProxyService.SendStatusUpdate:input_type -> management.SendStatusUpdateRequest
+	23, // 31: management.ProxyService.CreateProxyPeer:input_type -> management.CreateProxyPeerRequest
+	25, // 32: management.ProxyService.GetOIDCURL:input_type -> management.GetOIDCURLRequest
+	27, // 33: management.ProxyService.ValidateSession:input_type -> management.ValidateSessionRequest
+	29, // 34: management.ProxyService.ValidateTunnelPeer:input_type -> management.ValidateTunnelPeerRequest
+	5,  // 35: management.ProxyService.GetMappingUpdate:output_type -> management.GetMappingUpdateResponse
+	34, // 36: management.ProxyService.SyncMappings:output_type -> management.SyncMappingsResponse
+	13, // 37: management.ProxyService.SendAccessLog:output_type -> management.SendAccessLogResponse
+	19, // 38: management.ProxyService.Authenticate:output_type -> management.AuthenticateResponse
+	22, // 39: management.ProxyService.SendStatusUpdate:output_type -> management.SendStatusUpdateResponse
+	24, // 40: management.ProxyService.CreateProxyPeer:output_type -> management.CreateProxyPeerResponse
+	26, // 41: management.ProxyService.GetOIDCURL:output_type -> management.GetOIDCURLResponse
+	28, // 42: management.ProxyService.ValidateSession:output_type -> management.ValidateSessionResponse
+	30, // 43: management.ProxyService.ValidateTunnelPeer:output_type -> management.ValidateTunnelPeerResponse
+	35, // [35:44] is the sub-list for method output_type
+	26, // [26:35] is the sub-list for method input_type
+	26, // [26:26] is the sub-list for extension type_name
+	26, // [26:26] is the sub-list for extension extendee
+	0,  // [0:26] is the sub-list for field type_name
 }
 
 func init() { file_proxy_service_proto_init() }
@@ -3139,6 +3450,54 @@ func file_proxy_service_proto_init() {
 				return nil
 			}
 		}
+		file_proxy_service_proto_msgTypes[28].Exporter = func(v interface{}, i int) interface{} {
+			switch v := v.(*SyncMappingsRequest); i {
+			case 0:
+				return &v.state
+			case 1:
+				return &v.sizeCache
+			case 2:
+				return &v.unknownFields
+			default:
+				return nil
+			}
+		}
+		file_proxy_service_proto_msgTypes[29].Exporter = func(v interface{}, i int) interface{} {
+			switch v := v.(*SyncMappingsInit); i {
+			case 0:
+				return &v.state
+			case 1:
+				return &v.sizeCache
+			case 2:
+				return &v.unknownFields
+			default:
+				return nil
+			}
+		}
+		file_proxy_service_proto_msgTypes[30].Exporter = func(v interface{}, i int) interface{} {
+			switch v := v.(*SyncMappingsAck); i {
+			case 0:
+				return &v.state
+			case 1:
+				return &v.sizeCache
+			case 2:
+				return &v.unknownFields
+			default:
+				return nil
+			}
+		}
+		file_proxy_service_proto_msgTypes[31].Exporter = func(v interface{}, i int) interface{} {
+			switch v := v.(*SyncMappingsResponse); i {
+			case 0:
+				return &v.state
+			case 1:
+				return &v.sizeCache
+			case 2:
+				return &v.unknownFields
+			default:
+				return nil
+			}
+		}
 	}
 	file_proxy_service_proto_msgTypes[0].OneofWrappers = []interface{}{}
 	file_proxy_service_proto_msgTypes[12].OneofWrappers = []interface{}{
@@ -3148,13 +3507,17 @@ func file_proxy_service_proto_init() {
 	}
 	file_proxy_service_proto_msgTypes[17].OneofWrappers = []interface{}{}
 	file_proxy_service_proto_msgTypes[21].OneofWrappers = []interface{}{}
+	file_proxy_service_proto_msgTypes[28].OneofWrappers = []interface{}{
+		(*SyncMappingsRequest_Init)(nil),
+		(*SyncMappingsRequest_Ack)(nil),
+	}
 	type x struct{}
 	out := protoimpl.TypeBuilder{
 		File: protoimpl.DescBuilder{
 			GoPackagePath: reflect.TypeOf(x{}).PkgPath(),
 			RawDescriptor: file_proxy_service_proto_rawDesc,
 			NumEnums:      3,
-			NumMessages:   30,
+			NumMessages:   34,
 			NumExtensions: 0,
 			NumServices:   1,
 		},

shared/management/proto/proxy_service.proto

@@ -12,6 +12,15 @@ import "google/protobuf/timestamp.proto";
 service ProxyService {
   rpc GetMappingUpdate(GetMappingUpdateRequest) returns (stream GetMappingUpdateResponse);
 
+  // SyncMappings is a bidirectional stream that replaces GetMappingUpdate for
+  // new proxies. The proxy sends an initial SyncMappingsRequest to start the
+  // stream and then sends an ack after each batch is fully processed.
+  // Management waits for the ack before sending the next batch, providing
+  // application-level back-pressure during large initial syncs.
+  // Old proxies continue using GetMappingUpdate; old management servers
+  // return Unimplemented for this RPC and proxies fall back.
+  rpc SyncMappings(stream SyncMappingsRequest) returns (stream SyncMappingsResponse);
+
   rpc SendAccessLog(SendAccessLogRequest) returns (SendAccessLogResponse);
 
   rpc Authenticate(AuthenticateRequest) returns (AuthenticateResponse);
@@ -335,3 +344,35 @@ message ValidateTunnelPeerResponse {
   repeated string peer_group_names = 7;
 }
 
+// SyncMappingsRequest is sent by the proxy on the bidirectional SyncMappings
+// stream. The first message MUST be an init; all subsequent messages MUST be
+// acks.
+message SyncMappingsRequest {
+  oneof msg {
+    SyncMappingsInit init = 1;
+    SyncMappingsAck ack = 2;
+  }
+}
+
+// SyncMappingsInit is the first message on the stream, carrying the same
+// identification fields as GetMappingUpdateRequest.
+message SyncMappingsInit {
+  string proxy_id = 1;
+  string version = 2;
+  google.protobuf.Timestamp started_at = 3;
+  string address = 4;
+  ProxyCapabilities capabilities = 5;
+}
+
+// SyncMappingsAck is sent by the proxy after it has fully processed a batch.
+// Management waits for this before sending the next batch.
+message SyncMappingsAck {}
+
+// SyncMappingsResponse is a batch of mappings sent by management.
+// Identical semantics to GetMappingUpdateResponse.
+message SyncMappingsResponse {
+  repeated ProxyMapping mapping = 1;
+  // initial_sync_complete is set on the last message of the initial snapshot.
+  bool initial_sync_complete = 2;
+}
+

shared/management/proto/proxy_service_grpc.pb.go

@@ -19,6 +19,14 @@ const _ = grpc.SupportPackageIsVersion7
 // 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.
 type ProxyServiceClient interface {
 	GetMappingUpdate(ctx context.Context, in *GetMappingUpdateRequest, opts ...grpc.CallOption) (ProxyService_GetMappingUpdateClient, error)
+	// SyncMappings is a bidirectional stream that replaces GetMappingUpdate for
+	// new proxies. The proxy sends an initial SyncMappingsRequest to start the
+	// stream and then sends an ack after each batch is fully processed.
+	// Management waits for the ack before sending the next batch, providing
+	// application-level back-pressure during large initial syncs.
+	// Old proxies continue using GetMappingUpdate; old management servers
+	// return Unimplemented for this RPC and proxies fall back.
+	SyncMappings(ctx context.Context, opts ...grpc.CallOption) (ProxyService_SyncMappingsClient, error)
 	SendAccessLog(ctx context.Context, in *SendAccessLogRequest, opts ...grpc.CallOption) (*SendAccessLogResponse, error)
 	Authenticate(ctx context.Context, in *AuthenticateRequest, opts ...grpc.CallOption) (*AuthenticateResponse, error)
 	SendStatusUpdate(ctx context.Context, in *SendStatusUpdateRequest, opts ...grpc.CallOption) (*SendStatusUpdateResponse, error)
@@ -77,6 +85,37 @@ func (x *proxyServiceGetMappingUpdateClient) Recv() (*GetMappingUpdateResponse,
 	return m, nil
 }
 
+func (c *proxyServiceClient) SyncMappings(ctx context.Context, opts ...grpc.CallOption) (ProxyService_SyncMappingsClient, error) {
+	stream, err := c.cc.NewStream(ctx, &ProxyService_ServiceDesc.Streams[1], "/management.ProxyService/SyncMappings", opts...)
+	if err != nil {
+		return nil, err
+	}
+	x := &proxyServiceSyncMappingsClient{stream}
+	return x, nil
+}
+
+type ProxyService_SyncMappingsClient interface {
+	Send(*SyncMappingsRequest) error
+	Recv() (*SyncMappingsResponse, error)
+	grpc.ClientStream
+}
+
+type proxyServiceSyncMappingsClient struct {
+	grpc.ClientStream
+}
+
+func (x *proxyServiceSyncMappingsClient) Send(m *SyncMappingsRequest) error {
+	return x.ClientStream.SendMsg(m)
+}
+
+func (x *proxyServiceSyncMappingsClient) Recv() (*SyncMappingsResponse, error) {
+	m := new(SyncMappingsResponse)
+	if err := x.ClientStream.RecvMsg(m); err != nil {
+		return nil, err
+	}
+	return m, nil
+}
+
 func (c *proxyServiceClient) SendAccessLog(ctx context.Context, in *SendAccessLogRequest, opts ...grpc.CallOption) (*SendAccessLogResponse, error) {
 	out := new(SendAccessLogResponse)
 	err := c.cc.Invoke(ctx, "/management.ProxyService/SendAccessLog", in, out, opts...)
@@ -145,6 +184,14 @@ func (c *proxyServiceClient) ValidateTunnelPeer(ctx context.Context, in *Validat
 // for forward compatibility
 type ProxyServiceServer interface {
 	GetMappingUpdate(*GetMappingUpdateRequest, ProxyService_GetMappingUpdateServer) error
+	// SyncMappings is a bidirectional stream that replaces GetMappingUpdate for
+	// new proxies. The proxy sends an initial SyncMappingsRequest to start the
+	// stream and then sends an ack after each batch is fully processed.
+	// Management waits for the ack before sending the next batch, providing
+	// application-level back-pressure during large initial syncs.
+	// Old proxies continue using GetMappingUpdate; old management servers
+	// return Unimplemented for this RPC and proxies fall back.
+	SyncMappings(ProxyService_SyncMappingsServer) error
 	SendAccessLog(context.Context, *SendAccessLogRequest) (*SendAccessLogResponse, error)
 	Authenticate(context.Context, *AuthenticateRequest) (*AuthenticateResponse, error)
 	SendStatusUpdate(context.Context, *SendStatusUpdateRequest) (*SendStatusUpdateResponse, error)
@@ -171,6 +218,9 @@ type UnimplementedProxyServiceServer struct {
 func (UnimplementedProxyServiceServer) GetMappingUpdate(*GetMappingUpdateRequest, ProxyService_GetMappingUpdateServer) error {
 	return status.Errorf(codes.Unimplemented, "method GetMappingUpdate not implemented")
 }
+func (UnimplementedProxyServiceServer) SyncMappings(ProxyService_SyncMappingsServer) error {
+	return status.Errorf(codes.Unimplemented, "method SyncMappings not implemented")
+}
 func (UnimplementedProxyServiceServer) SendAccessLog(context.Context, *SendAccessLogRequest) (*SendAccessLogResponse, error) {
 	return nil, status.Errorf(codes.Unimplemented, "method SendAccessLog not implemented")
 }
@@ -226,6 +276,32 @@ func (x *proxyServiceGetMappingUpdateServer) Send(m *GetMappingUpdateResponse) e
 	return x.ServerStream.SendMsg(m)
 }
 
+func _ProxyService_SyncMappings_Handler(srv interface{}, stream grpc.ServerStream) error {
+	return srv.(ProxyServiceServer).SyncMappings(&proxyServiceSyncMappingsServer{stream})
+}
+
+type ProxyService_SyncMappingsServer interface {
+	Send(*SyncMappingsResponse) error
+	Recv() (*SyncMappingsRequest, error)
+	grpc.ServerStream
+}
+
+type proxyServiceSyncMappingsServer struct {
+	grpc.ServerStream
+}
+
+func (x *proxyServiceSyncMappingsServer) Send(m *SyncMappingsResponse) error {
+	return x.ServerStream.SendMsg(m)
+}
+
+func (x *proxyServiceSyncMappingsServer) Recv() (*SyncMappingsRequest, error) {
+	m := new(SyncMappingsRequest)
+	if err := x.ServerStream.RecvMsg(m); err != nil {
+		return nil, err
+	}
+	return m, nil
+}
+
 func _ProxyService_SendAccessLog_Handler(srv interface{}, ctx context.Context, dec func(interface{}) error, interceptor grpc.UnaryServerInterceptor) (interface{}, error) {
 	in := new(SendAccessLogRequest)
 	if err := dec(in); err != nil {
@@ -394,6 +470,12 @@ var ProxyService_ServiceDesc = grpc.ServiceDesc{
 			Handler:       _ProxyService_GetMappingUpdate_Handler,
 			ServerStreams: true,
 		},
+		{
+			StreamName:    "SyncMappings",
+			Handler:       _ProxyService_SyncMappings_Handler,
+			ServerStreams: true,
+			ClientStreams: true,
+		},
 	},
 	Metadata: "proxy_service.proto",
 }