Will Binns-Smith 62393b0402 Turbopack: enable server HMR for app route handlers (#91466) ...

App router handlers are already built with the Turbopack runtime, so
they can use server HMR. **We also already get subscription events for
their chunks.** However, unlike app pages which use
`__next_app__.require()` for dynamic devModuleCache lookup, route
handlers capture userland exports statically in AppRouteRouteModule at
construction time. This change makes routes behave a lot like pages,
dynamically loading the user's code when requests are made. This way, we
can freely invalidate and reload it when changes are made without
evicting the entire require cache.

Only `next dev` uses this lazy evaluation, as `next start` continues to
eagerly import route handlers.

This change removes the `isAppPage` restriction from `usesServerHmr`,
extending server HMR coverage to all App Router entries (pages and route
handlers) built with the Node.js runtime.

For route handlers, we also clear the entry chunk from Node.js
`require.cache` on each rebuild so the next `requirePage()` call
re-executes the entry and obtains fresh module exports from
`devModuleCache` (which HMR updates in-place).

Test Plan: Added an additional e2e test, `with-dep`

2026-03-19 03:57:41 +00:00

..

hello

…

with-dep

Turbopack: enable server HMR for app route handlers (#91466)

2026-03-19 03:57:41 +00:00