@molecule/api-external-auth

External authentication interface for molecule.dev.

Verifies a user token issued by an imported app's own auth platform (Supabase, Firebase, Clerk, ...). Apps imported into molecule.dev usually arrive with a working frontend auth flow — their users already hold session tokens from that platform. This core is the server-side capability for accepting those tokens: verifyUserToken() turns the token the frontend already sends into a verified { userId, email }, or null when it is invalid or expired.

Use setProvider() to wire the concrete implementation from the provider bond matching the app's platform, such as @molecule/api-external-auth-supabase.

Auto-generated, AI-first package reference for the molecule.dev ecosystem. It is written to be read by coding agents as much as by people, and is generated from this package's source — edit src/index.ts JSDoc, not this file.

Quick Start

// bonds.ts — wire the provider matching the imported app's auth platform:
import { setProvider } from '@molecule/api-external-auth'
import { provider } from '@molecule/api-external-auth-supabase'

setProvider(provider)

// A protected server route — verify the token the frontend already sends:
import { verifyUserToken } from '@molecule/api-external-auth'

app.get('/api/me', async (req, res) => {
  const token = req.headers.authorization?.replace(/^Bearer /, '') ?? ''
  const user = await verifyUserToken(token)
  if (!user) {
    res.status(401).json({ error: 'Invalid or expired session.' })
    return
  }
  res.json({ userId: user.userId, email: user.email })
})

Type

core

Installation

npm install @molecule/api-external-auth @molecule/api-bond

API

Interfaces

ExternalAuthUser

The verified identity extracted from an external auth platform's user token by ExternalAuthProvider.verifyUserToken.

interface ExternalAuthUser {
  /**
   * The platform's stable user id (e.g. Supabase `auth.users.id`, a Firebase
   * UID, a Clerk user id).
   */
  userId: string

  /**
   * The user's email address, when present on the token's user record.
   */
  email?: string
}

ExternalAuthProvider

Contract implemented by external-auth provider bonds (e.g. @molecule/api-external-auth-supabase).

interface ExternalAuthProvider {
  /**
   * Verifies a user token issued by the external auth platform and returns
   * the verified identity, or `null` when the token is invalid, expired, or
   * empty. Never throws on a bad token — a bad token is a normal runtime
   * condition, not an error.
   *
   * @param token - The raw token the app's frontend already sends (typically
   *   the `Authorization: Bearer <token>` value).
   * @returns The verified user, or `null` if the token cannot be verified.
   */
  verifyUserToken(token: string): Promise<ExternalAuthUser | null>
}

Functions

setProvider(provider)

Registers an external-auth provider as the active singleton. Called by bond packages (matched to the imported app's auth platform) during application startup.

function setProvider(provider: ExternalAuthProvider): void

• provider — The external-auth provider implementation to bond.

getProvider()

Retrieves the bonded external-auth provider, throwing if none is configured.

function getProvider(): ExternalAuthProvider

Returns: The bonded external-auth provider.

hasProvider()

Checks whether an external-auth provider is currently bonded.

function hasProvider(): boolean

Returns: true if an external-auth provider is bonded.

verifyUserToken(token)

Verifies a user token issued by the imported app's own auth platform using the bonded provider, returning the verified identity or null when the token is invalid, expired, or empty (never throws on a bad token).

function verifyUserToken(token: string): Promise<ExternalAuthUser | null>

• token — The raw token the app's frontend already sends (typically the Authorization: Bearer <token> value).

Returns: The verified user, or null if the token cannot be verified.

Available Providers

Provider	Package
Supabase	@molecule/api-external-auth-supabase

Injection Notes

Requirements

Peer dependencies:

• @molecule/api-bond ^1.0.1

Runtime Dependencies

• @molecule/api-bond

This is how you authenticate an IMPORTED app's existing users server-side. Do not hand-roll JWT verification against the vendor's API or rebuild the app's auth from scratch — the provider bond matching the app's platform does the vendor-specific work, and the app's frontend keeps the login flow it already has.

• A bad token is a normal runtime condition: verifyUserToken() resolves null for invalid/expired/empty tokens — map that to a 401, never a 500.
• verifyUserToken() THROWS only when no provider is bonded — that is a wiring bug: call setProvider() from the matching bond at startup.
• The verified userId is the external platform's stable user id — key your server-side records on it.

E2E Tests

Integration checklist — drive the real UI (live preview, no mocks), adapt each item to this app's actual screens/flows, and check every box off one by one. A box you can't check is an integration bug to fix — not a skip:

• The provider bond matching the app's auth platform is wired with setProvider() at startup — no "No external-auth provider bonded" errors appear in server logs when hitting protected routes.
• Log in through the app's existing auth UI, then hit a protected API route: verifyUserToken() accepts the live session token and the route returns that user's data.
• The counterparty is the auth platform itself: obtain a REAL user token by signing up / logging in through the app's own UI (interact_preview) and exercise verifyUserToken() with the token the frontend sends — never fabricate, hand-mint, or replay a made-up token as a "valid" case.
• A garbage or expired Bearer token gets a clean 401 from protected routes (verifyUserToken() → null) — never a 500 or a crash.
• A request with no Authorization header is rejected as unauthenticated (401), not treated as a server error.
• Server-side records created for the logged-in user are keyed on the verified userId, and another user's token never reads them back.