I need concurrent access to the post id and the full rendering output, e.g. to fully cache it in cases where there is significant content modification being done to it by an addon.
That class has access to post id via $cache. But the XenForo_BbCode_Parser render() doesn't receive that (so no point trying to extend there). So currently I can't see a way to do this without directly editing the class, which of course isn't addon packageable.
Or is there a way to override pathing in XenForo so it uses a class from a different location to usual?