---
title: "Routing · Affordances"
description: "How the same URL answers people with HTML and agents with a graph, how agents discover it, and why graphs are never cached."
url: "https://affordances.vercel.app/docs/guides/nextjs/routing"
image: "https://affordances.vercel.app/og/docs/guides/nextjs/routing"
lang: "en"
---

# Routing

How the same URL answers people with HTML and agents with a graph, how agents discover it, and why graphs are never cached.

The same URL answers people and agents. `withAffordances` adds rewrites that run before Next's filesystem routes, and send a request to the route handler when it has any of:

- `Accept: application/vnd.affordances+json` (reading a graph);
- `Content-Type: application/vnd.affordances+json` (calling an action);
- the query parameter `affordances=1`, for clients that can't set headers.

`/.well-known/affordances.json`, the [site index](https://affordances.vercel.app/docs/reference/protocol), is rewritten to the handler too.

## What's left alone

- Every browser request for HTML reaches your pages as before.
- Requests to `/api/` routes, the handler's own included, and to `/_next` are never rewritten.
- Your own rewrites are kept. `withAffordances` puts its rules first in `beforeFiles` and leaves the rest where they were.

## Discovery

For each route in the manifest, `withAffordances` adds a header to the HTML response, so a client that loaded the page can find its graph:

```http
Link: <?affordances=1>; rel="affordances"
```

## Caching

Graphs and deltas are sent with `Cache-Control: private, no-store` and `Vary: Accept`. HTML responses keep whatever caching they had.

Agent requests are rewritten to the handler before the filesystem and before any cached page. So a cached HTML page is never served to an agent, and a graph is never cached at all.