I've identified an issue in the isTextNodeVisible function where we need to handle the special case when viewportExpansion is set to -1, which should bypass the viewport check entirely.

function isTextNodeVisible(textNode) {
    // ... existing code ...

    // Simple viewport check without scroll calculations
    const isInViewport = !(
      rect.bottom < -viewportExpansion ||
      rect.top > window.innerHeight + viewportExpansion ||
      rect.right < -viewportExpansion ||
      rect.left > window.innerWidth + viewportExpansion
    ) || viewportExpansion === -1; // here

    // ... existing code ...
}

This change ensures that when viewportExpansion is set to -1, the text node will be considered in the viewport regardless of its actual position. This matches the behavior in other parts of the code where a value of -1 for viewportExpansion means "consider all elements regardless of viewport position."