feat(01-03): add deterministic rich CLI output

- Inject bonfire.Output from stdin/stdout/stderr with stdlib widgets and x/term
- Degrade spinner, progress, table and prompts without a TTY or color
- Reject plugin command names that are not namespace:verb

bonfire/root.go

@@ -1,6 +1,7 @@
 package bonfire
 
 import (
+	"fmt"
 	"io"
 	"os"
 
@@ -9,10 +10,22 @@ import (
 
 // NewRoot builds the shared cobra root used by the summer tool and app binaries.
 // It accepts command values rather than a party registry to avoid an import cycle.
-func NewRoot(name string, commands []Command, out io.Writer) *cobra.Command {
+func NewRoot(name string, commands []Command, out io.Writer) (*cobra.Command, error) {
+	return NewRootIO(name, commands, os.Stdin, out, out)
+}
+
+// NewRootIO is NewRoot with injected stdin/stdout/stderr for tests.
+func NewRootIO(name string, commands []Command, in io.Reader, out, errW io.Writer) (*cobra.Command, error) {
 	if out == nil {
 		out = os.Stdout
 	}
+	if errW == nil {
+		errW = out
+	}
+	if in == nil {
+		in = os.Stdin
+	}
+	output := NewOutput(in, out, errW)
 	root := &cobra.Command{
 		Use:           name,
 		SilenceUsage:  true,
@@ -21,30 +34,32 @@ func NewRoot(name string, commands []Command, out io.Writer) *cobra.Command {
 			DisableDefaultCmd: true,
 		},
 	}
+	root.SetIn(in)
 	root.SetOut(out)
-	root.SetErr(out)
+	root.SetErr(errW)
 	for _, command := range commands {
-		root.AddCommand(wrap(command, out))
+		cmd, err := wrap(command, output)
+		if err != nil {
+			return nil, err
+		}
+		root.AddCommand(cmd)
 	}
-	return root
+	return root, nil
 }
 
-func wrap(c Command, out io.Writer) *cobra.Command {
+func wrap(c Command, out Output) (*cobra.Command, error) {
+	if !validCommandName(c.Name) {
+		return nil, fmt.Errorf("%w: %q", ErrCommandName, c.Name)
+	}
 	cmd := &cobra.Command{
-		Use:   c.Name,
+		Use:   commandUsage(c),
 		Short: c.Description,
-		Args:  cobra.ArbitraryArgs,
+		Args:  positionalArgs(c.Args),
 		RunE: func(cmd *cobra.Command, args []string) error {
 			if c.Run == nil {
 				return nil
 			}
-			writer := out
-			if cmd != nil {
-				if w := cmd.OutOrStdout(); w != nil {
-					writer = w
-				}
-			}
-			return c.Run(cmd.Context(), cobraInput{cmd: cmd, spec: c, args: args}, writerOutput{w: writer})
+			return c.Run(cmd.Context(), cobraInput{cmd: cmd, spec: c, args: args}, out)
 		},
 	}
 	for _, flag := range c.Flags {
@@ -54,5 +69,5 @@ func wrap(c Command, out io.Writer) *cobra.Command {
 		}
 		cmd.Flags().String(flag.Name, flag.Default, flag.Description)
 	}
-	return cmd
+	return cmd, nil
 }