Viewport-aware insertion

The canvas editor automatically adjusts how new nodes are placed when inserting or pasting. This behaviour has two parts:

Altered position

When the bounding box of the content to insert lies entirely outside the current viewport, the editor shifts the content so that its centre aligns with the viewport centre. This guarantees that newly inserted nodes are immediately visible without requiring the user to pan the canvas.

Hit-tested nested placement

If there is no explicit selection to determine the insertion target, the editor performs a hit test at the insertion point. If the insertion rectangle is fully contained within a container node discovered by the hit test, the content is inserted as a child of that container. The search is limited by a configurable maximum depth to avoid traversing excessively deep hierarchies.

When a container is selected, insertion respects the selection: the new content is placed under the selected container, or alongside the selection if it is not itself a container.