feat: add list-hosts command to CLI

Adds a list-hosts command that mirrors the MCP list_hosts functionality,
allowing discovery of available deployment targets from the command line.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

cmd/homelab-deploy/main.go

@@ -16,7 +16,7 @@ import (
 	"github.com/urfave/cli/v3"
 )
 
-const version = "0.1.6"
+const version = "0.1.7"
 
 func main() {
 	app := &cli.Command{
@@ -27,6 +27,7 @@ func main() {
 			listenerCommand(),
 			mcpCommand(),
 			deployCommand(),
+			listHostsCommand(),
 		},
 	}
 
@@ -270,3 +271,88 @@ func deployCommand() *cli.Command {
 		},
 	}
 }
+
+func listHostsCommand() *cli.Command {
+	return &cli.Command{
+		Name:  "list-hosts",
+		Usage: "List available deployment targets",
+		Flags: []cli.Flag{
+			&cli.StringFlag{
+				Name:     "nats-url",
+				Usage:    "NATS server URL",
+				Sources:  cli.EnvVars("HOMELAB_DEPLOY_NATS_URL"),
+				Required: true,
+			},
+			&cli.StringFlag{
+				Name:     "nkey-file",
+				Usage:    "Path to NKey seed file for NATS authentication",
+				Sources:  cli.EnvVars("HOMELAB_DEPLOY_NKEY_FILE"),
+				Required: true,
+			},
+			&cli.StringFlag{
+				Name:    "tier",
+				Usage:   "Filter by tier (test or prod)",
+				Sources: cli.EnvVars("HOMELAB_DEPLOY_TIER"),
+			},
+			&cli.StringFlag{
+				Name:    "discover-subject",
+				Usage:   "NATS subject for host discovery",
+				Sources: cli.EnvVars("HOMELAB_DEPLOY_DISCOVER_SUBJECT"),
+				Value:   "deploy.discover",
+			},
+			&cli.IntFlag{
+				Name:    "timeout",
+				Usage:   "Timeout in seconds for discovery",
+				Sources: cli.EnvVars("HOMELAB_DEPLOY_DISCOVER_TIMEOUT"),
+				Value:   5,
+			},
+		},
+		Action: func(ctx context.Context, c *cli.Command) error {
+			tierFilter := c.String("tier")
+			if tierFilter != "" && tierFilter != "test" && tierFilter != "prod" {
+				return fmt.Errorf("tier must be 'test' or 'prod', got %q", tierFilter)
+			}
+
+			// Handle shutdown signals
+			ctx, cancel := signal.NotifyContext(ctx, syscall.SIGINT, syscall.SIGTERM)
+			defer cancel()
+
+			responses, err := deploycli.Discover(
+				ctx,
+				c.String("nats-url"),
+				c.String("nkey-file"),
+				c.String("discover-subject"),
+				time.Duration(c.Int("timeout"))*time.Second,
+			)
+			if err != nil {
+				return fmt.Errorf("discovery failed: %w", err)
+			}
+
+			if len(responses) == 0 {
+				fmt.Println("No hosts responded to discovery request")
+				return nil
+			}
+
+			fmt.Println("Available deployment targets:")
+			fmt.Println()
+
+			for _, resp := range responses {
+				if tierFilter != "" && resp.Tier != tierFilter {
+					continue
+				}
+
+				role := resp.Role
+				if role == "" {
+					role = "(none)"
+				}
+
+				fmt.Printf("- %s (tier=%s, role=%s)\n", resp.Hostname, resp.Tier, role)
+				for _, subj := range resp.DeploySubjects {
+					fmt.Printf("    %s\n", subj)
+				}
+			}
+
+			return nil
+		},
+	}
+}