What causes "missing xbar.title" in matryer/xbar?

Add an My Plugin Name comment block to the plugin script

missing xbar.title

Error message

missing xbar.title

What it means

Plugin.Validate enforces that a plugin's directory metadata contains a non-empty xbar.title value. The title is the plugin's display name in the xbar directory/UI, so a plugin without one is considered invalid and rejected. This is the first check in Validate, so it fires before any other missing-field errors.

Source

Thrown at pkg/metadata/plugin_metadata.go:71

	// Dependencies are a list of explicit dependencies this plugin requires to run.
	Dependencies []string `json:"dependencies"`
	// AboutURL is the public URL to learn more about the plugin, including
	// to contact the author.
	AboutURL string `json:"aboutURL"`
	// LastUpdated is when this data was last updated.
	LastUpdated time.Time `json:"lastUpdated"`
	// Vars are the configurable values for this Plugin.
	Vars []PluginVar `json:"vars"`

	// ProcessingNotes is a list of errors/warnings/notes that are set during
	// the processing of this plugin.
	ProcessingNotes []string `json:"processingNotes"`
}

// Validate checks the plugin data.
func (p Plugin) Validate() error {
	if p.Title == "" {
		return errors.New("missing xbar.title")
	}
	if p.Desc == "" {
		return errors.New("missing xbar.desc")
	}
	if !HasImage(p.ImageURL) {
		return errors.New("missing xbar.image")
	}
	if len(p.Authors) == 0 {
		return errors.New("missing xbar.author")
	}
	return nil // ok
}

// NiceDesc gets a nice description.
func (p Plugin) NiceDesc() string {
	if p.Desc == "" {
		return p.Title
	}

View on GitHub (pinned to d624239058)

Solutions

Add an <xbar.title>My Plugin Name</xbar.title> comment block to the plugin script
Set the Title field on the Plugin struct before calling Validate
Re-parse the plugin metadata with Parse after fixing the source so Title is populated

Example fix

// before (plugin script metadata)
// <xbar.title></xbar.title>
// after
// <xbar.title>CPU Monitor</xbar.title>

Defensive patterns

Strategy: validation

Validate before calling

func hasTitle(src string) bool {
	return regexp.MustCompile(`(?s)<xbar\.title>\s*\S.*?</xbar\.title>`).MatchString(src)
}

Type guard

func hasValidTitle(p metadata.Plugin) bool {
	return strings.TrimSpace(p.Title) != ""
}

Try / catch

if err := plugin.Validate(); err != nil {
	if err.Error() == "missing xbar.title" {
		return fmt.Errorf("plugin %s: add an <xbar.title> comment block: %w", path, err)
	}
	return err
}

Prevention

Start every plugin from a template containing all four required metadata blocks (title, desc, image, author)
Run Validate in CI for every plugin before publishing
Never leave metadata comment values empty
Lint plugin scripts for required <xbar.*> blocks

When it happens

Trigger: Calling Plugin.Validate (or code paths that call it, such as metadata parsing/validation pipelines) on a Plugin struct whose Title field is empty because the plugin source lacks an <xbar.title>...</xbar.title> comment or the field was never populated.

Common situations: Plugin authors forgetting the xbar.title metadata comment when creating a new plugin; title stripped by a template or generator; metadata parsed from a file missing the comment due to an editor or linter removal; programmatically built Plugin structs with Title left as the zero value.

Related errors

AI-assisted analysis of matryer/xbar@d624239058 (2026-09-02). Data as JSON: /api/errors/e493ef0df3edc504. Report an issue: GitHub.