Method copyToClipboard

lib/selection-manager.ts:845–892

* Copy text to clipboard

(text: string)

   * Copy text to clipboard
   */
  private async copyToClipboard(text: string): Promise<void> {
    // First try: modern async clipboard API
    if (navigator.clipboard && navigator.clipboard.writeText) {
      try {
        await navigator.clipboard.writeText(text);
        return;
      } catch (err) {
        // Clipboard API failed (common in non-HTTPS or non-focused contexts)
        // Fall through to legacy method
      }
    }

    // Second try: legacy execCommand method via textarea
    const previouslyFocused = document.activeElement as HTMLElement;
    try {
      // Position textarea offscreen but in a way that allows selection
      const textarea = this.textarea;
      textarea.value = text;
      textarea.style.position = 'fixed'; // Avoid scrolling to bottom
      textarea.style.left = '-9999px';
      textarea.style.top = '0';
      textarea.style.width = '1px';
      textarea.style.height = '1px';
      textarea.style.opacity = '0';

      // Select all text and copy
      textarea.focus();
      textarea.select();
      textarea.setSelectionRange(0, text.length);

      const success = document.execCommand('copy');

      // Restore focus
      if (previouslyFocused) {
        previouslyFocused.focus();
      }

      if (!success) {
        console.error('❌ execCommand copy failed');
      }
    } catch (err) {
      console.error('❌ Fallback copy failed:', err);
      // Still try to restore focus even on error
      if (previouslyFocused) {
        previouslyFocused.focus();
      }
    }
  }

  /**
   * Request a render update (triggers selection overlay redraw)