Toast & Toaster

Transient notifications, created imperatively — exactly what a “Downloaded” or “Added to favourites” handler wants, rather than threading open-state through the view tree. Mount a single Toaster() once anywhere in the tree, then call the toast API from anywhere:

// Once, near the root:
div(App(), Toaster())

// Anywhere, imperatively:
toast.success("Downloaded")
toast.error("Upload failed", description = Some(span("Check your connection.")))
val id = toast.loading("Processing…")     // sticky spinner; dismiss when done
toast.dismiss(id)

toast.info/success/warning/error each take a message, optional description, and duration (ms; defaults to 4000). toast.loading is a sticky spinner with no auto-dismiss until you dismiss(id) or clear(). The general form toast.show(message, kind, …) also takes a placement (ToastPlacement — six corners/edges; each toast carries its own, so one Toaster can show several stacks), closable, a custom icon, and an onClick. Each toast auto-dismisses after its duration, pauses on hover, and animates out before leaving; urgent kinds (Error/Warning) announce assertively (role="alert"), the rest politely. The store behind it (ToastStore) is a plain external store bridged in through useSyncExternalStore.