feat: add a field on command to deprecate

Author: joobisb

Diff for: command.go

@@ -43,6 +43,11 @@ type Command struct {
 	// Hidden determines whether the command should be hidden from help.
 	Hidden bool
 
+	// Deprecated indicates whether this command is deprecated.
+	// If empty, the command is not deprecated.
+	// If set, the value is used as the deprecation message.
+	Deprecated string `json:"deprecated,omitempty"`
+
 	// RawArgs determines whether the command should receive unparsed arguments.
 	// No flags are parsed when set, and the command is responsible for parsing
 	// its own flags.
@@ -316,6 +321,13 @@ func (inv *Invocation) CurWords() (prev string, cur string) {
 // allArgs is wired through the stack so that global flags can be accepted
 // anywhere in the command invocation.
 func (inv *Invocation) run(state *runState) error {
+	if inv.Command.Deprecated != "" {
+		fmt.Fprintf(inv.Stderr, "%s %q is deprecated!. %s\n",
+			prettyHeader("warning"),
+			inv.Command.FullName(),
+			inv.Command.Deprecated,
+		)
+	}
 	err := inv.Command.Options.ParseEnv(inv.Environ)
 	if err != nil {
 		return xerrors.Errorf("parsing env: %w", err)

Diff for: command_test.go

@@ -376,6 +376,27 @@ func TestCommand(t *testing.T) {
 		err := i.Run()
 		require.NoError(t, err, fio.Stdout.String())
 	})
+
+	t.Run("DeprecatedCommand", func(t *testing.T) {
+		t.Parallel()
+
+		deprecatedCmd := &serpent.Command{
+			Use:        "deprecated-cmd",
+			Deprecated: "This command is deprecated and will be removed in the future.",
+			Handler: func(i *serpent.Invocation) error {
+				_, _ = i.Stdout.Write([]byte("Running deprecated command"))
+				return nil
+			},
+		}
+
+		i := deprecatedCmd.Invoke()
+		io := fakeIO(i)
+		err := i.Run()
+		require.NoError(t, err)
+		expectedWarning := fmt.Sprintf("WARNING: %q is deprecated!. %s\n", deprecatedCmd.Use, deprecatedCmd.Deprecated)
+		require.Equal(t, io.Stderr.String(), expectedWarning)
+		require.Contains(t, io.Stdout.String(), "Running deprecated command")
+	})
 }
 
 func TestCommand_DeepNest(t *testing.T) {

Diff for: help.go

@@ -62,14 +62,21 @@ func helpColor(s string) termenv.Color {
 	return helpColorProfile.Color(s)
 }
 
+// prettyHeader formats a header string with consistent styling.
+// It uppercases the text, adds a colon, and applies the header color.
+func prettyHeader(s string) string {
+	headerFg := pretty.FgColor(helpColor("#337CA0"))
+	s = strings.ToUpper(s)
+	txt := pretty.String(s, ":")
+	headerFg.Format(txt)
+	return txt.String()
+}
+
 var defaultHelpTemplate = func() *template.Template {
 	var (
 		optionFg = pretty.FgColor(
 			helpColor("#04A777"),
 		)
-		headerFg = pretty.FgColor(
-			helpColor("#337CA0"),
-		)
 	)
 	return template.Must(
 		template.New("usage").Funcs(
@@ -85,12 +92,7 @@ var defaultHelpTemplate = func() *template.Template {
 					optionFg.Format(txt)
 					return txt.String()
 				},
-				"prettyHeader": func(s string) string {
-					s = strings.ToUpper(s)
-					txt := pretty.String(s, ":")
-					headerFg.Format(txt)
-					return txt.String()
-				},
+				"prettyHeader": prettyHeader,
 				"typeHelper": func(opt *Option) string {
 					switch v := opt.Value.(type) {
 					case *Enum:

Diff for: help.tpl

@@ -8,6 +8,11 @@
 {{"\n"}}
 {{- end}}
 
+{{- with .Deprecated }}
+{{- indent (printf "DEPRECATED: %s" .) 2 | wrapTTY }}
+{{"\n"}}
+{{- end }}
+
 {{ with .Aliases }}
 {{"  Aliases: "}} {{- joinStrings .}}
 {{- end }}