[client/ui] Add async Up mode to avoid blocking profile switches

The daemon's Up RPC previously always blocked in waitForUp (up to 50s)
until the engine connected. The UI does not need this — status updates
already flow through the SubscribeStatus stream.

Add bool async = 4 to UpRequest. When true the daemon starts
connectWithRetryRuns and returns immediately; the CLI path (async=false,
the default) is unchanged.

ProfileSwitcher.SwitchActive now sets Async:true so all three RPCs
(Status, Switch, Down, Up) return quickly. The background goroutine and
its associated race condition are removed entirely.

client/proto/daemon.pb.go

@@ -1,7 +1,7 @@
 // Code generated by protoc-gen-go. DO NOT EDIT.
 // versions:
 // 	protoc-gen-go v1.36.6
-// 	protoc        v7.34.1
+// 	protoc        v3.21.12
 // source: daemon.proto
 
 package proto
@@ -823,9 +823,15 @@ func (x *WaitSSOLoginResponse) GetEmail() string {
 }
 
 type UpRequest struct {
-	state         protoimpl.MessageState `protogen:"open.v1"`
-	ProfileName   *string                `protobuf:"bytes,1,opt,name=profileName,proto3,oneof" json:"profileName,omitempty"`
-	Username      *string                `protobuf:"bytes,2,opt,name=username,proto3,oneof" json:"username,omitempty"`
+	state       protoimpl.MessageState `protogen:"open.v1"`
+	ProfileName *string                `protobuf:"bytes,1,opt,name=profileName,proto3,oneof" json:"profileName,omitempty"`
+	Username    *string                `protobuf:"bytes,2,opt,name=username,proto3,oneof" json:"username,omitempty"`
+	// async instructs the daemon to start the connection attempt and return
+	// immediately without waiting for the engine to become ready. Status updates
+	// are delivered via the SubscribeStatus stream. When false (the default) the
+	// RPC blocks until the engine is running or gives up, which is the behaviour
+	// needed by the CLI.
+	Async         bool `protobuf:"varint,4,opt,name=async,proto3" json:"async,omitempty"`
 	unknownFields protoimpl.UnknownFields
 	sizeCache     protoimpl.SizeCache
 }
@@ -874,6 +880,13 @@ func (x *UpRequest) GetUsername() string {
 	return ""
 }
 
+func (x *UpRequest) GetAsync() bool {
+	if x != nil {
+		return x.Async
+	}
+	return false
+}
+
 type UpResponse struct {
 	state         protoimpl.MessageState `protogen:"open.v1"`
 	unknownFields protoimpl.UnknownFields
@@ -6309,10 +6322,11 @@ const file_daemon_proto_rawDesc = "" +
 	"\buserCode\x18\x01 \x01(\tR\buserCode\x12\x1a\n" +
 	"\bhostname\x18\x02 \x01(\tR\bhostname\",\n" +
 	"\x14WaitSSOLoginResponse\x12\x14\n" +
-	"\x05email\x18\x01 \x01(\tR\x05email\"v\n" +
+	"\x05email\x18\x01 \x01(\tR\x05email\"\x8c\x01\n" +
 	"\tUpRequest\x12%\n" +
 	"\vprofileName\x18\x01 \x01(\tH\x00R\vprofileName\x88\x01\x01\x12\x1f\n" +
-	"\busername\x18\x02 \x01(\tH\x01R\busername\x88\x01\x01B\x0e\n" +
+	"\busername\x18\x02 \x01(\tH\x01R\busername\x88\x01\x01\x12\x14\n" +
+	"\x05async\x18\x04 \x01(\bR\x05asyncB\x0e\n" +
 	"\f_profileNameB\v\n" +
 	"\t_usernameJ\x04\b\x03\x10\x04\"\f\n" +
 	"\n" +

client/proto/daemon.proto

@@ -233,6 +233,12 @@ message UpRequest {
   optional string profileName = 1;
   optional string username = 2;
   reserved 3;
+  // async instructs the daemon to start the connection attempt and return
+  // immediately without waiting for the engine to become ready. Status updates
+  // are delivered via the SubscribeStatus stream. When false (the default) the
+  // RPC blocks until the engine is running or gives up, which is the behaviour
+  // needed by the CLI.
+  bool async = 4;
 }
 
 message UpResponse {}

client/server/server.go

@@ -747,6 +747,9 @@ func (s *Server) Up(callerCtx context.Context, msg *proto.UpRequest) (*proto.UpR
 	go s.connectWithRetryRuns(ctx, s.config, s.statusRecorder, s.clientRunningChan, s.clientGiveUpChan)
 
 	s.mutex.Unlock()
+	if msg.GetAsync() {
+		return &proto.UpResponse{}, nil
+	}
 	return s.waitForUp(callerCtx)
 }
 

client/ui/services/connection.go

@@ -42,6 +42,11 @@ type WaitSSOParams struct {
 type UpParams struct {
 	ProfileName string `json:"profileName"`
 	Username    string `json:"username"`
+	// Async instructs the daemon to start the connection and return
+	// immediately. Status updates flow via the SubscribeStatus stream.
+	// When false (the default) the RPC blocks until connected, which is
+	// the CLI behaviour.
+	Async bool `json:"async"`
 }
 
 // LogoutParams selects the profile the daemon should log out.
@@ -147,7 +152,7 @@ func (s *Connection) Up(ctx context.Context, p UpParams) error {
 	if err != nil {
 		return err
 	}
-	req := &proto.UpRequest{}
+	req := &proto.UpRequest{Async: p.Async}
 	if p.ProfileName != "" {
 		req.ProfileName = ptrStr(p.ProfileName)
 	}

client/ui/services/profileswitcher.go

@@ -37,8 +37,9 @@ func NewProfileSwitcher(profiles *Profiles, connection *Connection, peers *Peers
 }
 
 // SwitchActive switches to the named profile applying the reconnect policy.
-// It returns after the Switch RPC completes so the caller can refresh its UI
-// immediately; Down and Up run in a background goroutine.
+// All RPCs complete quickly: Up uses async mode so the daemon starts the
+// connection attempt and returns immediately; status updates flow via the
+// SubscribeStatus stream.
 func (s *ProfileSwitcher) SwitchActive(ctx context.Context, p ProfileRef) error {
 	prevStatus := ""
 	if st, err := s.peers.Get(ctx); err == nil {
@@ -61,22 +62,21 @@ func (s *ProfileSwitcher) SwitchActive(ctx context.Context, p ProfileRef) error
 		return fmt.Errorf("switch profile %q: %w", p.ProfileName, err)
 	}
 
-	go func() {
-		bgCtx := context.Background()
-		if needsDown {
-			if err := s.connection.Down(bgCtx); err != nil {
-				log.Errorf("profileswitcher: Down: %v", err)
-			}
+	if needsDown {
+		if err := s.connection.Down(ctx); err != nil {
+			log.Errorf("profileswitcher: Down: %v", err)
 		}
-		if wasActive {
-			if err := s.connection.Up(bgCtx, UpParams{
-				ProfileName: p.ProfileName,
-				Username:    p.Username,
-			}); err != nil {
-				log.Errorf("profileswitcher: Up %s: %v", p.ProfileName, err)
-			}
+	}
+
+	if wasActive {
+		if err := s.connection.Up(ctx, UpParams{
+			ProfileName: p.ProfileName,
+			Username:    p.Username,
+			Async:       true,
+		}); err != nil {
+			return fmt.Errorf("reconnect %q: %w", p.ProfileName, err)
 		}
-	}()
+	}
 
 	return nil
 }