*: run go fix (#2689)

Excluded:
- components/playground-ng/daemon_mode.go becuse of golang/go#77671

Author: dveeden

components/cluster/command/root.go

@@ -190,20 +190,20 @@ func printErrorMessageForNormalError(err error) {
 }
 
 func printErrorMessageForErrorX(err *errorx.Error) {
-	msg := ""
+	var msg strings.Builder
 	ident := 0
 	causeErrX := err
 	for causeErrX != nil {
 		if ident > 0 {
-			msg += strings.Repeat("  ", ident) + "caused by: "
+			msg.WriteString(strings.Repeat("  ", ident) + "caused by: ")
 		}
 		currentErrMsg := causeErrX.Message()
 		if len(currentErrMsg) > 0 {
 			if ident == 0 {
 				// Print error code only for top level error
-				msg += fmt.Sprintf("%s (%s)\n", currentErrMsg, causeErrX.Type().FullName())
+				msg.WriteString(fmt.Sprintf("%s (%s)\n", currentErrMsg, causeErrX.Type().FullName()))
 			} else {
-				msg += fmt.Sprintf("%s\n", currentErrMsg)
+				msg.WriteString(fmt.Sprintf("%s\n", currentErrMsg))
 			}
 			ident++
 		}
@@ -215,14 +215,14 @@ func printErrorMessageForErrorX(err *errorx.Error) {
 				if ident > 0 {
 					// The error may have empty message. In this case we treat it as a transparent error.
 					// Thus `ident == 0` can be possible.
-					msg += strings.Repeat("  ", ident) + "caused by: "
+					msg.WriteString(strings.Repeat("  ", ident) + "caused by: ")
 				}
-				msg += fmt.Sprintf("%s\n", cause.Error())
+				msg.WriteString(fmt.Sprintf("%s\n", cause.Error()))
 			}
 			break
 		}
 	}
-	_, _ = tui.ColorErrorMsg.Fprintf(os.Stderr, "\nError: %s", msg)
+	_, _ = tui.ColorErrorMsg.Fprintf(os.Stderr, "\nError: %s", msg.String())
 }
 
 func extractSuggestionFromErrorX(err *errorx.Error) string {

components/dm/command/root.go

@@ -178,20 +178,20 @@ func printErrorMessageForNormalError(err error) {
 }
 
 func printErrorMessageForErrorX(err *errorx.Error) {
-	msg := ""
+	var msg strings.Builder
 	ident := 0
 	causeErrX := err
 	for causeErrX != nil {
 		if ident > 0 {
-			msg += strings.Repeat("  ", ident) + "caused by: "
+			msg.WriteString(strings.Repeat("  ", ident) + "caused by: ")
 		}
 		currentErrMsg := causeErrX.Message()
 		if len(currentErrMsg) > 0 {
 			if ident == 0 {
 				// Print error code only for top level error
-				msg += fmt.Sprintf("%s (%s)\n", currentErrMsg, causeErrX.Type().FullName())
+				msg.WriteString(fmt.Sprintf("%s (%s)\n", currentErrMsg, causeErrX.Type().FullName()))
 			} else {
-				msg += fmt.Sprintf("%s\n", currentErrMsg)
+				msg.WriteString(fmt.Sprintf("%s\n", currentErrMsg))
 			}
 			ident++
 		}
@@ -203,14 +203,14 @@ func printErrorMessageForErrorX(err *errorx.Error) {
 				if ident > 0 {
 					// Out most error may have empty message. In this case we treat it as a transparent error.
 					// Thus `ident == 0` can be possible.
-					msg += strings.Repeat("  ", ident) + "caused by: "
+					msg.WriteString(strings.Repeat("  ", ident) + "caused by: ")
 				}
-				msg += fmt.Sprintf("%s\n", cause.Error())
+				msg.WriteString(fmt.Sprintf("%s\n", cause.Error()))
 			}
 			break
 		}
 	}
-	_, _ = tui.ColorErrorMsg.Fprintf(os.Stderr, "\nError: %s", msg)
+	_, _ = tui.ColorErrorMsg.Fprintf(os.Stderr, "\nError: %s", msg.String())
 }
 
 func extractSuggestionFromErrorX(err *errorx.Error) string {

components/dm/spec/topology_dm.go

@@ -36,10 +36,10 @@ const (
 )
 
 var (
-	globalOptionTypeName     = reflect.TypeOf(GlobalOptions{}).Name()
-	monitorOptionTypeName    = reflect.TypeOf(MonitoredOptions{}).Name()
-	serverConfigsTypeName    = reflect.TypeOf(DMServerConfigs{}).Name()
-	componentSourcesTypeName = reflect.TypeOf(ComponentSources{}).Name()
+	globalOptionTypeName     = reflect.TypeFor[GlobalOptions]().Name()
+	monitorOptionTypeName    = reflect.TypeFor[MonitoredOptions]().Name()
+	serverConfigsTypeName    = reflect.TypeFor[DMServerConfigs]().Name()
+	componentSourcesTypeName = reflect.TypeFor[ComponentSources]().Name()
 )
 
 func setDefaultDir(parent, role, port string, field reflect.Value) {
@@ -63,7 +63,7 @@ func findField(v reflect.Value, fieldName string) (int, bool) {
 
 // Skip global/monitored/job options
 func isSkipField(field reflect.Value) bool {
-	if field.Kind() == reflect.Ptr {
+	if field.Kind() == reflect.Pointer {
 		if field.IsZero() {
 			return true
 		}
@@ -321,7 +321,7 @@ func (s *Specification) platformConflictsDetect() error {
 
 	platformStats := map[string]conflict{}
 	topoSpec := reflect.ValueOf(s).Elem()
-	topoType := reflect.TypeOf(s).Elem()
+	topoType := reflect.TypeFor[Specification]()
 
 	for i := 0; i < topoSpec.NumField(); i++ {
 		if isSkipField(topoSpec.Field(i)) {
@@ -393,7 +393,7 @@ func (s *Specification) portConflictsDetect() error {
 	portStats := map[usedPort]conflict{}
 	uniqueHosts := set.NewStringSet()
 	topoSpec := reflect.ValueOf(s).Elem()
-	topoType := reflect.TypeOf(s).Elem()
+	topoType := reflect.TypeFor[Specification]()
 
 	for i := 0; i < topoSpec.NumField(); i++ {
 		if isSkipField(topoSpec.Field(i)) {
@@ -506,7 +506,7 @@ func (s *Specification) dirConflictsDetect() error {
 	)
 
 	topoSpec := reflect.ValueOf(s).Elem()
-	topoType := reflect.TypeOf(s).Elem()
+	topoType := reflect.TypeFor[Specification]()
 
 	for i := 0; i < topoSpec.NumField(); i++ {
 		if isSkipField(topoSpec.Field(i)) {
@@ -757,7 +757,7 @@ func setDMCustomDefaults(globalOptions *GlobalOptions, field reflect.Value) erro
 			return err
 		}
 		field.Set(ref.Elem())
-	case reflect.Ptr:
+	case reflect.Pointer:
 		if err := setDMCustomDefaults(globalOptions, field.Elem()); err != nil {
 			return err
 		}

components/playground-ng/boot_executor.go

@@ -140,7 +140,6 @@ func (e *bootExecutor) Download(ctx context.Context, plan BootPlan) error {
 		g, gctx := errgroup.WithContext(ctx)
 		g.SetLimit(maxParallelComponentDownloads)
 		for _, d := range prepared {
-			d := d
 			g.Go(func() error {
 				return downloadAndInstallComponent(gctx, mirror.Source(), profile, d, downloadInstallOptions{
 					disableDecompress: disableDecompress,
@@ -155,7 +154,6 @@ func (e *bootExecutor) Download(ctx context.Context, plan BootPlan) error {
 	g, _ := errgroup.WithContext(ctx)
 	g.SetLimit(maxParallelComponentDownloads)
 	for _, d := range downloads {
-		d := d
 		g.Go(func() error {
 			return e.src.EnsureInstalled(d.ComponentID, d.ResolvedVersion)
 		})

components/playground-ng/boot_executor_test.go

@@ -308,7 +308,7 @@ func TestBootExecutor_Download_RespectsConcurrencyLimit(t *testing.T) {
 	executor := newBootExecutor(nil, src)
 
 	plan := BootPlan{Downloads: make([]DownloadPlan, 0, total)}
-	for i := 0; i < total; i++ {
+	for i := range total {
 		plan.Downloads = append(plan.Downloads, DownloadPlan{
 			ComponentID:     "comp-" + strconv.Itoa(i),
 			ResolvedVersion: "v1.0.0",
@@ -320,7 +320,7 @@ func TestBootExecutor_Download_RespectsConcurrencyLimit(t *testing.T) {
 		errCh <- executor.Download(ctx, plan)
 	}()
 
-	for i := 0; i < maxParallelComponentDownloads; i++ {
+	for range maxParallelComponentDownloads {
 		select {
 		case <-entered:
 		case <-ctx.Done():

components/playground-ng/catalog_flags.go

@@ -117,7 +117,7 @@ func applyServiceDefaults(flagSet *pflag.FlagSet, opts *BootOptions) error {
 	// Apply default counts first (some later defaults depend on these).
 	{
 		specs := pgservice.AllSpecs()
-		for i := 0; i < 8; i++ {
+		for range 8 {
 			changed := false
 			for _, spec := range specs {
 				def := spec.Catalog
@@ -228,7 +228,6 @@ func registerLegacyScaleOutFlags(cmd *cobra.Command) *legacyScaleOutFlags {
 
 	flags := cmd.Flags()
 	for _, spec := range specs {
-		spec := spec
 		if spec.serviceID == "" || spec.flagPrefix == "" {
 			continue
 		}

components/playground-ng/command.go

@@ -473,7 +473,6 @@ func scaleIn(out io.Writer, reqs []ScaleInRequest, state *cliState) error {
 
 	var cmds []Command
 	for _, req := range reqs {
-		req := req
 		if req.Name == "" && req.PID <= 0 {
 			continue
 		}
@@ -505,7 +504,6 @@ func scaleOut(out io.Writer, reqs []ScaleOutRequest, state *cliState) (num int,
 
 	cmds := make([]Command, 0, len(reqs))
 	for _, req := range reqs {
-		req := req
 		cmds = append(cmds, Command{
 			Type:     ScaleOutCommandType,
 			ScaleOut: &req,

components/playground-ng/controller_state.go

@@ -44,7 +44,7 @@ func (s *controllerState) removeProcByPID(serviceID proc.ServiceID, pid int) (pr
 	}
 
 	list := s.procs[serviceID]
-	for i := 0; i < len(list); i++ {
+	for i := range list {
 		inst := list[i]
 		if inst == nil {
 			continue
@@ -66,7 +66,7 @@ func (s *controllerState) removeProc(serviceID proc.ServiceID, inst proc.Process
 	}
 
 	list := s.procs[serviceID]
-	for i := 0; i < len(list); i++ {
+	for i := range list {
 		if list[i] != inst {
 			continue
 		}

components/playground-ng/daemon_files.go

@@ -52,8 +52,8 @@ func readPIDFile(path string) (pidFile, error) {
 	var out pidFile
 	seenPID := false
 
-	lines := strings.Split(string(data), "\n")
-	for _, line := range lines {
+	lines := strings.SplitSeq(string(data), "\n")
+	for line := range lines {
 		line = strings.TrimSpace(line)
 		if line == "" {
 			continue

components/playground-ng/daemon_files_test.go

@@ -22,7 +22,7 @@ func TestReadPIDFile_ParsesStartedAtAndTag(t *testing.T) {
 	pidPath := filepath.Join(base, playgroundPIDFileName)
 
 	startedAt := "2026-01-13T20:00:00Z"
-	require.NoError(t, os.WriteFile(pidPath, []byte(fmt.Sprintf("pid=123\nstarted_at=%s\ntag=my-cluster\n", startedAt)), 0o644))
+	require.NoError(t, os.WriteFile(pidPath, fmt.Appendf(nil, "pid=123\nstarted_at=%s\ntag=my-cluster\n", startedAt), 0o644))
 
 	got, err := readPIDFile(pidPath)
 	require.NoError(t, err)
@@ -85,7 +85,7 @@ func TestCleanupStaleRuntimeFiles_RemovesStalePIDAndPort(t *testing.T) {
 
 	stalePID := 999999
 	found := false
-	for i := 0; i < 1000; i++ {
+	for i := range 1000 {
 		pid := stalePID + i
 		running, err := isPIDRunning(pid)
 		if err == nil && !running {