oauth

OAuth (std/oauth)

Val Town provides zero-config "Log in with Val Town" via std/oauth. No database setup, no provider config — wrap your Hono fetch handler and you get login, logout, and session management for free. Sessions are stored in encrypted cookies and last 30 days.

This is for Val Town account login only. For Google / GitHub / Slack / etc. OAuth, see the third-party-integrations skill — those flows are documented per-service.

If the goal is to keep an app internal to a team rather than to give it its own logged-in users, restricting the val's app access is the simpler answer — the platform gates the endpoint before your code runs, and you write no auth code. See the restricted-access skill. Don't apply both to one val: a restricted val that also runs oauthMiddleware makes visitors authenticate twice.

Imports

import {
  getOAuthUserData,
  oauthMiddleware,
} from "https://esm.town/v/std/oauth/middleware.ts";

Wrapping your app

oauthMiddleware(handler) takes your Hono fetch handler and returns a wrapped handler that injects three auto-managed routes:

• GET /auth/login — starts the login flow
• GET /auth/callback — completes the login flow
• POST /auth/logout — clears the session

Export the wrapped handler as the val's default:

import { Hono } from "npm:hono";
import { oauthMiddleware } from "https://esm.town/v/std/oauth/middleware.ts";

const app = new Hono();
app.onError((err) => Promise.reject(err));

app.get("/", (c) => c.text("hello"));

export default oauthMiddleware(app.fetch);

You don't write the /auth/* routes yourself — the middleware adds them. Don't shadow them in your own app.

Reading the current user

Call getOAuthUserData(rawRequest) from any route. In Hono, rawRequest is c.req.raw. It returns the session data if the request is authenticated, or null otherwise.

interface SessionData {
  user: {
    id: string;
    username: string | null;
    email: string | null;
    bio: string | null;
    tier: "free" | "pro" | null;
    type: "user" | "org";
    url: string;
    links: {
      self: string;
      profileImageUrl: string | null;
    };
  };
  accessToken: string; // Val Town API token (act on behalf of the user)
  refreshToken?: string;
  idToken?: string;
  expiresAt: number; // Unix timestamp (ms)
  isOrgMember?: boolean; // true if user belongs to this val's org
}

app.get("/", async (c) => {
  const session = await getOAuthUserData(c.req.raw);
  if (session?.user) {
    return c.html(
      `<p>Logged in as ${session.user.username}</p>` +
      `<form method="POST" action="/auth/logout"><button>Log out</button></form>`
    );
  }
  return c.html(`<a href="/auth/login">Log in with Val Town</a>`);
});

Gating routes

There's no built-in "require login" helper — gate routes by checking getOAuthUserData and returning a 401 or redirecting to /auth/login when the session is missing:

app.get("/dashboard", async (c) => {
  const session = await getOAuthUserData(c.req.raw);
  if (!session?.user) return c.redirect("/auth/login");
  return c.html(`<h1>Welcome ${session.user.username}</h1>`);
});

What you don't need to configure

• No env vars — credentials and redirect URLs are handled by the platform.
• No callback URL setup — /auth/callback is wired automatically.
• No session store — sessions live in encrypted cookies.

Verifying changes

After adding OAuth, call fetch_val_endpoint on a gated route to confirm it redirects or 401s when unauthenticated. The full login flow requires a real browser session and can't be exercised by fetch_val_endpoint alone — share the live URL and have the user try logging in.