Add plugin list command (#215)

Implement 'mcpd config plugins list' command to display configured plugins. Supports filtering by category or showing all categories with output in text, JSON, or YAML formats.

Author: peteski22

cmd/config/plugins/list.go

@@ -5,21 +5,107 @@ import (
 
 	"github.com/spf13/cobra"
 
-	"github.com/mozilla-ai/mcpd/v2/internal/cmd"
-	"github.com/mozilla-ai/mcpd/v2/internal/cmd/options"
+	internalcmd "github.com/mozilla-ai/mcpd/v2/internal/cmd"
+	cmdopts "github.com/mozilla-ai/mcpd/v2/internal/cmd/options"
+	"github.com/mozilla-ai/mcpd/v2/internal/cmd/output"
+	"github.com/mozilla-ai/mcpd/v2/internal/config"
+	"github.com/mozilla-ai/mcpd/v2/internal/printer"
 )
 
-// NewListCmd creates the list command for plugins.
-// TODO: Implement in a future PR.
-func NewListCmd(baseCmd *cmd.BaseCmd, opt ...options.CmdOption) (*cobra.Command, error) {
+// ListCmd represents the command for listing configured plugins.
+// Use NewListCmd to create instances of ListCmd.
+type ListCmd struct {
+	*internalcmd.BaseCmd
+
+	// cfgLoader is used to load the configuration.
+	cfgLoader config.Loader
+
+	// printer is used to output configured plugins.
+	printer output.Printer[printer.PluginListResult]
+
+	// format stores the format flag when specified.
+	format internalcmd.OutputFormat
+
+	// category stores the category flag when specified.
+	category config.Category
+}
+
+// NewListCmd creates a new list command for displaying configured plugins.
+func NewListCmd(baseCmd *internalcmd.BaseCmd, opt ...cmdopts.CmdOption) (*cobra.Command, error) {
+	opts, err := cmdopts.NewOptions(opt...)
+	if err != nil {
+		return nil, err
+	}
+
+	c := &ListCmd{
+		BaseCmd:   baseCmd,
+		cfgLoader: opts.ConfigLoader,
+		printer:   &printer.PluginListPrinter{},
+		format:    internalcmd.FormatText, // Default to plain text
+	}
+
 	cobraCmd := &cobra.Command{
 		Use:   "list",
-		Short: "List plugin entries",
-		Long:  "List plugin entries in a specific category or across all categories",
-		RunE: func(cmd *cobra.Command, args []string) error {
-			return fmt.Errorf("not yet implemented")
-		},
+		Short: "List configured plugin entries",
+		Long:  "List configured plugin entries in a specific category or across all categories",
+		Example: `  # List plugins in authentication category
+  mcpd config plugins list --category=authentication
+
+  # List all plugins across all categories
+  mcpd config plugins list
+
+  # List with JSON output
+  mcpd config plugins list --category=observability --format=json`,
+		RunE: c.run,
+		Args: cobra.NoArgs,
 	}
 
+	allowedOutputFormats := internalcmd.AllowedOutputFormats()
+	cobraCmd.Flags().Var(
+		&c.format,
+		"format",
+		fmt.Sprintf("Specify the output format (one of: %s)", allowedOutputFormats.String()),
+	)
+
+	allowedCategories := config.OrderedCategories()
+	cobraCmd.Flags().Var(
+		&c.category,
+		"category",
+		fmt.Sprintf("Specify the category (one of: %s)", allowedCategories.String()),
+	)
+
 	return cobraCmd, nil
 }
+
+func (c *ListCmd) run(cmd *cobra.Command, _ []string) error {
+	handler, err := internalcmd.FormatHandler(cmd.OutOrStdout(), c.format, c.printer)
+	if err != nil {
+		return err
+	}
+
+	cfg, err := c.LoadConfig(c.cfgLoader)
+	if err != nil {
+		return handler.HandleError(err)
+	}
+
+	if cfg.Plugins == nil {
+		result := printer.NewPluginListResult(nil)
+		return handler.HandleResult(result)
+	}
+
+	var categories map[config.Category][]config.PluginEntry
+
+	if c.category != "" {
+		// List single category.
+		categories = map[config.Category][]config.PluginEntry{
+			c.category: cfg.Plugins.ListPlugins(c.category),
+		}
+	} else {
+		// List all categories.
+		categories = cfg.Plugins.AllCategories()
+	}
+
+	result := printer.NewPluginListResult(categories)
+
+	return handler.HandleResult(result)
+}