---
title: "@dualmark/deno"
description: Deno Deploy edge adapter -- wraps any upstream Deno fetch handler.
---

Deno-native edge adapter. Published to npm with the `"deno"` export condition first, so it works under `Deno.serve()` via `npm:` specifiers in `deno.json`.

## Install

### Deno (Deno Deploy and local `deno run`)

```jsonc title="deno.json"
{
  "imports": {
    "@dualmark/deno": "npm:@dualmark/deno@^0.1.0",
    "@dualmark/core": "npm:@dualmark/core@^0.7.0"
  }
}
```

<Callout type="info">
  The `"deno"` export condition is only consulted by Deno when you pass `--conditions=deno`. For everyday use, the `npm:` specifier above is what you want -- Deno resolves it through npm and uses the ESM build.
</Callout>

### Node / Bun (for tooling and tests)

<Tabs items={["bun", "npm", "yarn"]}>
<Tab value="bun">
```bash
bun add @dualmark/deno @dualmark/core
```
</Tab>
<Tab value="npm">
```bash
npm install @dualmark/deno @dualmark/core
```
</Tab>
<Tab value="yarn">
```bash
yarn add @dualmark/deno @dualmark/core
```
</Tab>
</Tabs>

## `createAEOHandler(options)`

```ts
import { createAEOHandler } from "@dualmark/deno";

const handler = createAEOHandler({
  upstream: existingHandler,
  trailingSlash: "never",
  enableLinkHeader: true,

  redirects: {
    internal: { "/old": "/new" },
    external: { "/login": "https://app.example.com" },
  },

  skip: {
    prefixes: ["/admin", "/api/"],
    extensions: [".js", ".css", ".png"],
  },

  headers: { cacheControl: "public, max-age=3600" },

  hooks: {
    onAIRequest: (info) => console.log(info.botName, info.pathname),
    onMiss: (info) => console.warn("miss:", info.pathname),
  },
});

Deno.serve(handler);
```

## Options

| Option | Type | Default | Notes |
| --- | --- | --- | --- |
| `upstream` | `(req: Request, info: DenoServeHandlerInfo) => Response \| Promise<Response>` | required | Serves both your HTML and the underlying `.md` twins |
| `trailingSlash` | `"never" \| "always" \| "preserve"` | `"never"` | Redirect policy |
| `enableLinkHeader` | `boolean` | `true` | Inject `Link rel="alternate"` on HTML responses |
| `redirects.internal` | `Record<string, string>` | `{}` | Path -> path |
| `redirects.external` | `Record<string, string>` | `{}` | Path -> URL |
| `skip.prefixes` | `readonly string[]` | `["/admin", "/api/", "/_"]` | Skip negotiation entirely; matched as exact segments |
| `skip.extensions` | `readonly string[]` | common assets | Skip negotiation for these extensions |
| `headers.cacheControl` | `string` | `"public, max-age=3600"` | For markdown responses |
| `hooks.onAIRequest` | `(info: AIRequestInfo) => void \| Promise<void>` | `undefined` | Scheduled on `info.completed` |
| `hooks.onMiss` | `(info: MissInfo) => void \| Promise<void>` | `undefined` | Scheduled on `info.completed` |

## Types

```ts
interface AIRequestInfo {
  url: URL;
  botName: string | null;
  botVendor: string | null;
  acceptHeader: string;
  pathname: string;
  cacheStatus: "hit" | "miss";
  tokens: number;
}

interface MissInfo {
  url: URL;
  botName: string | null;
  pathname: string;
  acceptHeader: string;
}

interface DenoServeHandlerInfo {
  remoteAddr: { transport: "tcp" | "udp" | "unix" | "unixpacket"; hostname: string; port: number };
  completed: Promise<void>;
}
```

## Hook scheduling

Hooks are scheduled on `info.completed` so they never block the response but are guaranteed to flush before the runtime suspends the isolate (on Deno Deploy). When `info.completed` is not present -- for example in a custom mock or non-Deploy `Deno.serve` setup -- the adapter falls back to scheduling the hook on a resolved microtask (`Promise.resolve().then(...)`), which is fire-and-forget. Hook errors are caught and logged via `console.error` so a throwing hook never takes down the request pipeline.

## Safe-method semantics

Only `GET` and `HEAD` requests are intercepted for negotiation, trailing-slash normalization, and `.md` lookups. `POST`, `PUT`, `PATCH`, `DELETE`, and `OPTIONS` flow through to `upstream` unchanged so request bodies and methods are preserved end-to-end.

## Skip rules

The `skip.prefixes` array uses exact-or-segment matching:

- `"/api"` matches `/api` and `/api/foo` -- but **not** `/api-docs`
- `"/admin/"` matches anything under `/admin/`
- `"/_"` matches anything starting with `/_` (Astro-style internal routes)

This is stricter than a raw `startsWith` and avoids over-matching neighboring paths.