CodePen embed iframe and host page lifecycle cancellation signals

Integration between a CodePen Pen preview iframe and an embedding host page raises questions about cancellation and timeout propagation across the boundary. The goal is to clarify what control, if any, exists for aborting user code execution or in-flight network requests when the host page lifecycle changes.

CodePen runs pen code in a sandboxed preview iframe. The platform does not document a built-in cancellation or timeout API exposed to pen authors, and external asset loading follows standard browser semantics within the iframe. Execution limits appear delegated to browser policies and CodePen resource policies, with no documented programmatic abort mechanism provided to the pen.

The unresolved behavior concerns hard execution timeouts for long-running scripts or network requests and how such enforcement would interact with author-managed AbortController. Documented boundaries between the iframe runtime and the parent page are needed.

Does CodePen document a message channel for a host page to request abort of operations inside the preview iframe? Is there a documented hard execution timeout for user JavaScript in the preview, and how does it interact with AbortController used by the pen author? When a host page unloads an embedded pen, are pending network requests in the iframe treated as terminated by browser teardown or can they persist independently?