Sprwt keeps the old address alive automatically. On save it creates a 301 (permanent) redirect from /pages/<old-slug> to /pages/<new-slug> (or /blog/... for posts) with the note "Auto-created: page URL changed", re-points any existing redirect that targeted the old address, removes a stale rule whose source was the new address (to avoid loops), and updates any navigation menu links (header/footer menus and menu groups) that pointed to the old address so they follow the page to its new one. You can see and edit the auto-created rule under Website > Redirects. Bookmarks, external links and search rankings therefore keep working.