mastra-ai/mastra · error · Error

Keyboard event injection not supported by this provider

Error message

Keyboard event injection not supported by this provider

What it means

injectKeyboardEvent is a base-class stub that providers override when they support text/key event injection (e.g. CDP Input.dispatchKeyEvent). The default implementation always throws for providers without keyboard input support.

Source

Thrown at packages/core/src/browser/browser.ts:1512

  // Event Injection (optional - for Studio live view)
  // ---------------------------------------------------------------------------

  /**
   * Inject a mouse event. Override in subclass if supported.
   * @param event - Mouse event parameters
   * @param threadId - Optional thread ID for thread-isolated sessions
   */
  async injectMouseEvent(_event: MouseEventParams, _threadId?: string): Promise<void> {
    throw new Error('Mouse event injection not supported by this provider');
  }

  /**
   * Inject a keyboard event. Override in subclass if supported.
   * @param event - Keyboard event parameters
   * @param threadId - Optional thread ID for thread-isolated sessions
   */
  async injectKeyboardEvent(_event: KeyboardEventParams, _threadId?: string): Promise<void> {
    throw new Error('Keyboard event injection not supported by this provider');
  }

  // ---------------------------------------------------------------------------
  // Abstract Methods (providers must implement)
  // ---------------------------------------------------------------------------

  /**
   * Get the active page for a thread.
   * Used by screencast reconnection to emit the current URL.
   *
   * @param threadId - Optional thread ID (uses current thread if not provided)
   * @returns The active Playwright Page, or null if not available
   */
  protected abstract getActivePage(threadId?: string): Promise<{ url(): string } | null>;

  /**
   * Get the current browser state for a thread.
   * Used to persist and restore browser state across sessions.

View on GitHub (pinned to 75dd419e61)

Solutions

Use a provider that implements injectKeyboardEvent.
Check capability before calling and fall back to higher-level typing APIs.
Implement the override in a custom provider subclass.
Inject input directly on the page/session object the provider exposes.

Example fix

// before
await browser.injectKeyboardEvent({ type: 'keyDown', key: 'Enter' });
// after
await page.keyboard.press('Enter'); // via provider-exposed page handle

Defensive patterns

Strategy: validation

Validate before calling

if (browser.injectKeyboardEvent === MastraBrowser.prototype.injectKeyboardEvent) {
  throw new Error(`Provider ${browser.provider} cannot inject keyboard events`);
}

Type guard

function supportsKeyboardInput(b: object): boolean {
  return b.injectKeyboardEvent !== MastraBrowser.prototype.injectKeyboardEvent;
}

Try / catch

try {
  await browser.injectKeyboardEvent(ev, threadId);
} catch (err) {
  if (err instanceof Error && err.message.includes('Keyboard event injection not supported')) {
    await page.keyboard.type(ev.key); // fallback via page handle
  } else throw err;
}

Prevention

Feature-detect input injection before enabling form-filling flows.
Bundle mouse/keyboard capability checks together since they usually co-vary.
Prefer providers that expose a page/session handle as a fallback path.
Add capability assertions to integration tests.

When it happens

Trigger: Calling browser.injectKeyboardEvent(event, threadId?) on a provider that has not overridden the method.

Common situations: Typing into forms during agent automation against a provider lacking input injection; shared tooling that sends both mouse and keyboard events but runs on a launch-only provider.

Related errors

AI-assisted analysis of mastra-ai/mastra@75dd419e61 (2026-08-30). Data as JSON: /api/errors/1576aadf2832c922. Report an issue: GitHub.