Middleware

Middleware runs before every navigation and server render — the middleware.ts equivalent. It can redirect, rewrite, raise a 404, or simply observe.

Global Middleware

import { createApp, redirect, rewrite } from "@domphy/app"

const app = createApp(routes, {
  middleware: [
    (context) => {
      // Auth gate: redirect interrupts the navigation
      if (context.pathname.startsWith("/admin") && !isLoggedIn()) {
        redirect("/login")
      }
    },
    (context) => {
      // Rewrite: render another route, keep the URL
      if (context.pathname === "/home") return rewrite("/")
    },
  ],
})

The MiddlewareContext carries url, pathname, searchParams and (on the server) headers. Middleware may be async.

Results

Action	Effect
return nothing	continue to the next middleware
`return rewrite(path)`	match and render `path`, address bar keeps the original URL
`redirect(path)` / `permanentRedirect(path)` (throws)	restart navigation at `path`; SSR reports 307/308 + `result.redirect`
`notFound()` (throws)	render the not-found boundary; SSR reports 404

Per-Route Middleware

Routes can attach middleware that runs only when their subtree matches — runs for the whole chain, root first:

{
  path: "(admin)",
  middleware: [requireAdminSession],
  children: [
    { path: "dashboard", page: DashboardPage },
    { path: "settings", page: SettingsPage },
  ],
}

Global middleware runs before matching (so it can rewrite the path); per-route middleware runs after matching, before loaders.