Toast-only mutation

A response that is nothing but an out-of-band toast must not perform a main swap. After htmx lifts the OOB node, the remainder is empty; under outerHTML, swapping emptiness deletes hx-target — see empty-after-oob.

In a PLEYN app

import { toastOnly } from "../lib/http.ts";

return toastOnly(c, "That item no longer exists", 422);

toastOnly() sets HX-Reswap: none and returns the toast via the registered #toast OOB target. Used from CSRF failures, 404 handlers, and other error paths that should not touch the triggering element.

Without the helper

Send the same header yourself:

HX-Reswap: none

Fixture: TOAST_ONLY_422 / TOAST_ONLY_422_FIXED_HEADERS in Fixtures.