eythaann/Seelen-UI · error · Error

Missing widget id on webview label

Error message

Missing widget id on webview label

What it means

Seelen UI encodes each widget webview's identity as a base64url label of the form '<widgetId>?<query>'. getDecodedWebviewLabel() decodes the current webview's label and splits it; if the decoded label has no part before the '?', there is no widget id, meaning the label was not produced by the widget spawn machinery, so the library cannot determine which widget is running.

Source

Thrown at libs/core/src/state/widget/mod.ts:419

type ExtendedGlobalThis = typeof globalThis & {
  __SLU_WIDGET?: IWidget;
  __SLU_WIDGET_INSTANCE?: Widget;
};

export const SeelenSettingsWidgetId: WidgetId = "@seelen/settings" as WidgetId;
export const SeelenPopupWidgetId: WidgetId = "@seelen/dialog" as WidgetId;
export const SeelenWegWidgetId: WidgetId = "@seelen/weg" as WidgetId;
export const SeelenToolbarWidgetId: WidgetId = "@seelen/fancy-toolbar" as WidgetId;
export const SeelenWindowManagerWidgetId: WidgetId = "@seelen/window-manager" as WidgetId;
export const SeelenWallWidgetId: WidgetId = "@seelen/wallpaper-manager" as WidgetId;

function getDecodedWebviewLabel(): [WidgetId, string | undefined] {
  const encondedLabel = getCurrentWebview().label;
  const decodedLabel = new TextDecoder().decode(decodeBase64Url(encondedLabel));
  const [id, query] = decodedLabel.split("?");
  if (!id) {
    throw new Error("Missing widget id on webview label");
  }
  return [id as WidgetId, query];
}

function getDefinitionDefaultValues(definition: WidgetConfigDefinition): Record<string, unknown> {
  const config: Record<string, unknown> = {};

  // Check if it's a group (has "group" property)
  if ("group" in definition) {
    // Recursively process all items in the group
    for (const item of definition.group.items) {
      Object.assign(config, getDefinitionDefaultValues(item));
    }
  } else {
    // It's a setting item, extract key and defaultValue
    const item = definition as WidgetSettingItem;
    if ("key" in item && "defaultValue" in item) {
      config[item.key] = item.defaultValue;

View on GitHub (pinned to dee4aaa940)

Solutions

1. Load the widget through Seelen UI's standard widget creation path so its label is the encoded id?query form.
2. If mocking in tests, set the label to the correct base64url encoding of '<widgetId>'.
3. Verify the current webview's label decodes to a non-empty widget id before use.
4. Align @seelen-ui/lib and Seelen UI versions to avoid label-format mismatches.

Example fix

// before (test mock): getCurrentWebview: () => ({ label: 'main' })
// after: getCurrentWebview: () => ({ label: toBase64Url('my-widget@example') }) // decodes to a real widget id

const label = getCurrentWebview().label; const decoded = new TextDecoder().decode(decodeBase64Url(label)); if (!decoded.split('?')[0]) throw new Error('webview label has no widget id');

function hasWidgetIdLabel(label: string): boolean { try { return Boolean(new TextDecoder().decode(decodeBase64Url(label)).split('?')[0]); } catch { return false; } }

let id: WidgetId | undefined; try { [id] = getDecodedWebviewLabel(); } catch (e) { if (e instanceof Error && e.message.includes('Missing widget id')) { id = undefined; } else { throw e; } }

When it happens

Trigger: Accessing [id, query] or the query getter on a webview whose label is not a base64url-encoded 'id?query' string — a webview created manually in Tauri, a label that decodes to an empty string, or a Seelen UI/lib version mismatch where label encoding changed; tests mocking getCurrentWebview() with a plain label like 'main'.

Common situations: Running widget code in a webview registered outside the Seelen UI widget factory; hand-crafting webview labels in custom tooling; upgrading Seelen UI or the lib so the label format differs; test mocks using unencoded labels.

Related errors

• Missing webview label

AI-assisted analysis of eythaann/Seelen-UI@dee4aaa940 (2026-09-03). Data as JSON: /api/errors/d2a813b5afb0a89d. Report an issue: GitHub.