Add AT Protocol OAuth to SvelteKit + Cloudflare Workers#

You are adding AT Protocol OAuth authentication to an existing SvelteKit project deployed on Cloudflare Workers. This uses server-side OAuth with @atcute/oauth-node-client, Cloudflare KV for session storage, and SvelteKit remote functions.

Prerequisites#

The project must already use:

• SvelteKit with @sveltejs/adapter-cloudflare
• A wrangler.jsonc (or wrangler.toml) config

Step 0: Ask the user#

Before making any changes, ask the user these questions:

1. UI: Should I add a login UI?

   • foxui — Use @foxui/social login modal (polished, recommended)
   • basic — Simple login/logout page at /user route (uses Tailwind if available)
   • none — Backend only, no UI (you'll build your own)

2. Collections: What AT Protocol collections should your app write to? (e.g. xyz.statusphere.status, app.bsky.feed.like). Leave empty for read-only.

3. Blobs: Does the app need to upload blobs (images, video)? If yes, what types? (e.g. image/*, video/*)

Use the answers to customize settings.ts (marked with CUSTOMIZE below) and choose which UI dependencies/files to create.

Step 1: Install dependencies#

Always install:

pnpm add valibot
pnpm add -D @atcute/oauth-node-client @atcute/identity-resolver @atcute/lexicons @atcute/client @atcute/tid @cloudflare/workers-types tsx @atcute/atproto @atcute/bluesky

If UI choice is foxui:

pnpm add @foxui/social @foxui/core

Step 2: Create files#

Create all of the following files. These go into src/lib/atproto/ and src/routes/(oauth)/.

src/lib/atproto/settings.ts#

Fill in collections and blobs from the user's answers. If no collections were specified, use an empty array.

import { dev } from '$app/environment';

type Permissions = {
	collections: readonly string[];
	rpc: Record<string, string | string[]>;
	blobs: readonly string[];
};

export const permissions = {
	// CUSTOMIZE: add the user's collections
	collections: [],

	// CUSTOMIZE: add any authenticated RPC requests needed
	rpc: {},

	// CUSTOMIZE: add blob types if the user needs uploads (e.g. ['image/*'])
	blobs: []
} as const satisfies Permissions;

type ExtractCollectionBase<T extends string> = T extends `${infer Base}?${string}` ? Base : T;

export type AllowedCollection = ExtractCollectionBase<(typeof permissions.collections)[number]>;

// PDS to use for signup (change to preferred PDS)
const devPDS = 'https://bsky.social/';
const prodPDS = 'https://bsky.social/';
export const signUpPDS = dev ? devPDS : prodPDS;

export const REDIRECT_PATH = '/oauth/callback';

export const DOH_RESOLVER = 'https://mozilla.cloudflare-dns.com/dns-query';

src/lib/atproto/metadata.ts#

src/lib/atproto/auth.svelte.ts#

src/lib/atproto/methods.ts#

src/lib/atproto/index.ts#

src/lib/atproto/server/signed-cookie.ts#

src/lib/atproto/server/kv-store.ts#

src/lib/atproto/server/oauth.ts#

src/lib/atproto/server/oauth.remote.ts#

src/lib/atproto/server/repo.remote.ts#

src/lib/atproto/server/session.ts#

src/lib/atproto/server/profile.ts#

src/lib/atproto/scripts/generate-key.ts#

src/lib/atproto/scripts/generate-secret.ts#

src/lib/atproto/scripts/setup-dev.ts#

src/routes/(oauth)/oauth/callback/+server.ts#

src/routes/(oauth)/oauth/jwks.json/+server.ts#

src/routes/(oauth)/oauth-client-metadata.json/+server.ts#

.env.example#

Step 3: Modify existing files#

src/app.d.ts#

Add these to the existing App namespace. Merge with any existing Locals or Platform fields — do not remove existing fields.

import type { OAuthSession } from '@atcute/oauth-node-client';
import type { Client } from '@atcute/client';
import type { Did } from '@atcute/lexicons';

Add to App.Locals:

session: OAuthSession | null;
client: Client | null;
did: Did | null;

Add to App.Platform:

env: {
  OAUTH_SESSIONS: KVNamespace;
  OAUTH_STATES: KVNamespace;
  CLIENT_ASSERTION_KEY: string;
  COOKIE_SECRET: string;
  OAUTH_PUBLIC_URL: string;
  PROFILE_CACHE?: KVNamespace;
};

Add at the bottom of the file (for lexicon type augmentation):

import type {} from '@atcute/atproto';
import type {} from '@atcute/bluesky';

src/hooks.server.ts#

Add session restoration. If the file already has a handle export, wrap both in sequence() from @sveltejs/kit.

import type { Handle } from '@sveltejs/kit';
import { restoreSession } from '$lib/atproto/server/session';

const atprotoHandle: Handle = async ({ event, resolve }) => {
  const { session, client, did } = await restoreSession(
    event.cookies, event.platform?.env
  );
  event.locals.session = session;
  event.locals.client = client;
  event.locals.did = did;
  return resolve(event);
};

If no existing hooks: export const handle = atprotoHandle;

If existing hooks: export const handle = sequence(existingHandle, atprotoHandle); (import sequence from @sveltejs/kit)

src/routes/+layout.server.ts#

Add profile loading. Merge with any existing load function.

import type { LayoutServerLoad } from './$types';
import { loadProfile } from '$lib/atproto/server/profile';

export const load: LayoutServerLoad = async ({ locals, platform }) => {
  if (!locals.did) return { did: null, profile: null };
  const profile = await loadProfile(locals.did, platform?.env?.PROFILE_CACHE);
  return { did: locals.did, profile };
};

If a load function already exists, merge the profile data into its return value.

src/routes/+layout.svelte (foxui only)#

Only if the user chose foxui. Add the login modal to the existing layout:

<script lang="ts">
  import { AtprotoLoginModal } from '@foxui/social';
  import { login, signup } from '$lib/atproto';
</script>

<!-- keep existing layout content, add this at the bottom: -->
<AtprotoLoginModal
  login={async (handle) => {
    await login(handle);
    return true;
  }}
  signup={async () => {
    signup();
    return true;
  }}
/>

To show the modal from anywhere, use @foxui/social state and @foxui/core components:

<script lang="ts">
  import { Button } from '@foxui/core';
  import { atProtoLoginModalState } from '@foxui/social';
  import { user, logout } from '$lib/atproto';
</script>

{#if user.isLoggedIn}
  <p>Signed in as {user.profile?.handle ?? user.did}</p>
  <Button onclick={() => logout()}>Sign Out</Button>
{:else}
  <Button onclick={() => atProtoLoginModalState.show()}>Sign In</Button>
{/if}

@foxui/core also exports Avatar, Input, and other UI primitives you can use.

src/routes/user/+page.svelte (basic only)#

Only if the user chose basic. Create this file:

<script lang="ts">
  import { user, login, logout } from '$lib/atproto';

  let handle = $state('');
  let error = $state('');
  let loading = $state(false);

  async function handleLogin() {
    if (!handle.trim()) return;
    loading = true;
    error = '';
    try {
      await login(handle);
    } catch (e) {
      error = e instanceof Error ? e.message : 'Login failed';
      loading = false;
    }
  }
</script>

<div class="mx-auto max-w-sm p-8">
  {#if user.isLoggedIn}
    <p class="mb-4">Signed in as <strong>{user.profile?.handle ?? user.did}</strong></p>
    <button
      class="rounded bg-red-600 px-4 py-2 text-white hover:bg-red-700"
      onclick={() => logout()}
    >
      Sign Out
    </button>
  {:else}
    <h1 class="mb-4 text-xl font-bold">Sign in</h1>
    <form onsubmit={handleLogin} class="flex flex-col gap-3">
      <input
        type="text"
        bind:value={handle}
        placeholder="handle.bsky.social"
        class="rounded border px-3 py-2"
        disabled={loading}
      />
      {#if error}
        <p class="text-sm text-red-600">{error}</p>
      {/if}
      <button
        type="submit"
        class="rounded bg-blue-600 px-4 py-2 text-white hover:bg-blue-700 disabled:opacity-50"
        disabled={loading || !handle.trim()}
      >
        {loading ? 'Signing in...' : 'Sign In'}
      </button>
    </form>
  {/if}
</div>

If the project does not use Tailwind, replace the Tailwind classes with plain inline styles.

svelte.config.js#

Add remoteFunctions: true inside kit.experimental:

kit: {
  adapter: adapter(),
  experimental: {
    remoteFunctions: true
  }
}

If experimental already exists, merge into it. Do not remove other experimental flags.

vite.config.ts#

Add dev server config for loopback OAuth:

server: {
  host: '127.0.0.1',
  port: 5183
}

Add this inside defineConfig(). Do not remove existing plugins or config.

wrangler.jsonc#

Add or merge these fields:

• Add "nodejs_compat_v2" to compatibility_flags (create the array if it doesn't exist)
• Add "OAUTH_PUBLIC_URL": "https://your-domain.com" to vars (create vars if needed)
• Add KV namespace placeholders to kv_namespaces:

{ "binding": "OAUTH_SESSIONS", "id": "TODO" },
{ "binding": "OAUTH_STATES", "id": "TODO" }

Do not remove existing bindings or vars.

tsconfig.json#

Add "@cloudflare/workers-types" to compilerOptions.types. Create the types array if it doesn't exist.

package.json#

Add these to the scripts section:

"env:generate-key": "npx tsx src/lib/atproto/scripts/generate-key.ts",
"env:generate-secret": "npx tsx src/lib/atproto/scripts/generate-secret.ts",
"env:setup-dev": "npx tsx src/lib/atproto/scripts/setup-dev.ts"

.gitignore#

Ensure these lines are present:

.env
.env.*
!.env.example

Step 4: Run setup and verify#

1. Run pnpm env:setup-dev to generate secrets in .env
2. Run pnpm dev to start the dev server
3. Verify it starts on http://127.0.0.1:5183
4. Tell the user:
   • Dev mode uses a loopback client (no keys needed)
   • For production: create KV namespaces with npx wrangler kv namespace create OAUTH_SESSIONS and OAUTH_STATES, update the IDs in wrangler.jsonc, set OAUTH_PUBLIC_URL to their domain, and run npx wrangler secret put CLIENT_ASSERTION_KEY / COOKIE_SECRET with values from pnpm env:generate-key / pnpm env:generate-secret

Usage examples#

Login / Logout#

<script lang="ts">
  import { user, login, logout } from '$lib/atproto';
</script>

{#if user.isLoggedIn}
  <p>Signed in as {user.did}</p>
  <button onclick={() => logout()}>Sign Out</button>
{:else}
  <button onclick={() => login('user.bsky.social')}>Sign In</button>
{/if}

Write operations#

import { putRecord, deleteRecord, uploadBlob, createTID } from '$lib/atproto';

await putRecord({
  collection: 'your.collection.name',
  rkey: createTID(),
  record: { text: 'hello', createdAt: new Date().toISOString() }
});

await deleteRecord({ collection: 'your.collection.name', rkey: 'some-key' });

const blob = await uploadBlob({ blob: file });

Read operations (no auth needed)#

import { listRecords, getRecord, getDetailedProfile } from '$lib/atproto';

const records = await listRecords({ did: 'did:plc:...', collection: 'your.collection.name' });
const profile = await getDetailedProfile({ did: 'did:plc:...' });