v4.10.0

# Release Notes

Hono v4.10.0 is now available!

This release brings improved TypeScript support and new utilities.

The main highlight is the enhanced middleware type definitions that solve a long-standing issue with type safety for RPC clients.

## Middleware Type Improvements

Imagine the following app:

```ts
import { Hono } from 'hono'

const app = new Hono()

const routes = app.get(
  '/',
  (c) => {
    return c.json({ errorMessage: 'Error!' }, 500)
  },
  (c) => {
    return c.json({ message: 'Success!' }, 200)
  }
)
```

The client with RPC:

```ts
import { hc } from 'hono/client'

const client = hc<typeof routes>('/')

const res = await client.index.$get()

if (res.status === 500) {
}

if (res.status === 200) {
}
```

Previously, it couldn't infer the responses from middleware, so a type error was thrown.

<img width="1538" height="724" alt="CleanShot 2025-10-17 at 06 51 48@2x" src="https://github.com/user-attachments/assets/7e660db0-6c52-4249-9a3d-2932614bbace" />

Now the responses are correctly typed.

<img width="1586" height="876" alt="CleanShot 2025-10-17 at 06 54 13@2x" src="https://github.com/user-attachments/assets/ef6136f1-bc26-4625-9238-0aec25110efc" />

---

This was a long-standing issue and we were thinking it was super difficult to resolve it. But now come true.

Thank you for the great work @slawekkolodziej!

## cloneRawRequest Utility

The new `cloneRawRequest` utility allows you to clone the raw Request object after it has been consumed by validators or middleware.

```ts
import { cloneRawRequest } from 'hono/request'

app.post('/api', async (c) => {
  const body = await c.req.json()

  // Clone the consumed request
  const clonedRequest = cloneRawRequest(c.req)
  await externalLibrary.process(clonedRequest)
})
```

Thanks @kamaal111!

## New features

- feat(types): passing middleware types https://github.com/honojs/hono/pull/4393
- feat(ssg): add default plugin that defines the recommended behavior https://github.com/honojs/hono/pull/4394
- feat(request): add cloneRawRequest utility for request cloning https://github.com/honojs/hono/pull/4382

## All changes

- feat(types): passing middleware types by @slawekkolodziej in https://github.com/honojs/hono/pull/4393
- feat(ssg): add default plugin that defines the recommended behavior by @3w36zj6 in https://github.com/honojs/hono/pull/4394
- feat(request): add cloneRawRequest utility for request cloning by @kamaal111 in https://github.com/honojs/hono/pull/4382
- fix(proxy): Correct hop-by-hop header handling per RFC 9110 by @sugar-cat7 in https://github.com/honojs/hono/pull/4459

## New Contributors

- @slawekkolodziej made their first contribution in https://github.com/honojs/hono/pull/4393
- @kamaal111 made their first contribution in https://github.com/honojs/hono/pull/4382

**Full Changelog**: https://github.com/honojs/hono/compare/v4.9.12...v4.10.0