Add shell completion support

toolkit/cmd/gsp/main.go

@@ -36,6 +36,8 @@ func run(args []string) error {
 		return runAIInit(args[1:])
 	case "version":
 		return runVersion(args[1:])
+	case "completion":
+		return runCompletion(args[1:])
 	case "validate":
 		return runValidate(args[1:])
 	case "index":
@@ -65,6 +67,8 @@ Usage:
   gsp init [path] [--name project-name] [--entry project.entry] [--force]
   gsp ai-init [--root .] [--agents] [--skill generic|codex] [--all] [--force]
   gsp version [--json]
+  gsp completion powershell|bash|zsh|fish
+  gsp completion install powershell
   gsp validate [--root .] [--out report.json]
   gsp index [--root .] [--out index.json]
   gsp trace <id> [--root .] [--depth 3] [--out trace.json]
@@ -75,6 +79,79 @@ Usage:
 `)
 }
 
+func runCompletion(args []string) error {
+	if len(args) == 0 {
+		return fmt.Errorf("completion requires powershell, bash, zsh, fish, or install powershell")
+	}
+	if args[0] == "install" {
+		if len(args) != 2 {
+			return fmt.Errorf("completion install requires one shell")
+		}
+		if args[1] != "powershell" {
+			return fmt.Errorf("completion install currently supports powershell")
+		}
+		return installPowerShellCompletion()
+	}
+	if len(args) != 1 {
+		return fmt.Errorf("completion accepts one shell")
+	}
+	switch args[0] {
+	case "powershell":
+		return writeText("", powerShellCompletionScript())
+	case "bash":
+		return writeText("", bashCompletionScript())
+	case "zsh":
+		return writeText("", zshCompletionScript())
+	case "fish":
+		return writeText("", fishCompletionScript())
+	default:
+		return fmt.Errorf("unsupported completion shell %q", args[0])
+	}
+}
+
+func installPowerShellCompletion() error {
+	home, err := os.UserHomeDir()
+	if err != nil {
+		return err
+	}
+	completionDir := filepath.Join(home, ".gsp", "completion")
+	completionFile := filepath.Join(completionDir, "gsp.ps1")
+	if err := os.MkdirAll(completionDir, 0755); err != nil {
+		return err
+	}
+	if err := os.WriteFile(completionFile, []byte(powerShellCompletionScript()), 0644); err != nil {
+		return err
+	}
+
+	profilePath := filepath.Join(home, "Documents", "PowerShell", "Microsoft.PowerShell_profile.ps1")
+	if err := os.MkdirAll(filepath.Dir(profilePath), 0755); err != nil {
+		return err
+	}
+	sourceLine := fmt.Sprintf(". '%s'", strings.ReplaceAll(completionFile, "'", "''"))
+	existing, err := os.ReadFile(profilePath)
+	if err != nil && !os.IsNotExist(err) {
+		return err
+	}
+	if !strings.Contains(string(existing), sourceLine) {
+		var builder strings.Builder
+		if len(existing) > 0 {
+			builder.Write(existing)
+			if !strings.HasSuffix(string(existing), "\n") {
+				builder.WriteString("\n")
+			}
+		}
+		builder.WriteString(sourceLine)
+		builder.WriteString("\n")
+		if err := os.WriteFile(profilePath, []byte(builder.String()), 0644); err != nil {
+			return err
+		}
+	}
+	fmt.Printf("Installed PowerShell completion to %s\n", completionFile)
+	fmt.Printf("Updated PowerShell profile %s\n", profilePath)
+	fmt.Println("Open a new PowerShell terminal or run the profile file to enable completion.")
+	return nil
+}
+
 func runAIInit(args []string) error {
 	fs := flag.NewFlagSet("ai-init", flag.ContinueOnError)
 	root := commonRoot(fs)