Custom Provider

import { MCPServer } from "mcp-use";
import {
  oauthCustomProvider,
  type OAuthAuthInfo,
  type OAuthMetadata,
} from "mcp-use/oauth";
import { createRemoteJWKSet, jwtVerify } from "jose";

const issuer = "https://auth.example.com";
const jwks = createRemoteJWKSet(new URL(`${issuer}/.well-known/jwks.json`));

const oauthMetadata = {
  issuer,
  authorization_endpoint: `${issuer}/oauth/authorize`,
  token_endpoint: `${issuer}/oauth/token`,
  registration_endpoint: `${issuer}/oauth/register`,
  response_types_supported: ["code"],
  grant_types_supported: ["authorization_code", "refresh_token"],
  code_challenge_methods_supported: ["S256"],
} satisfies OAuthMetadata;

type AppUser = {
  id: string;
  email?: string;
  organizationId?: string;
};

const server = new MCPServer({
  name: "custom-auth-server",
  version: "1.0.0",
  oauth: oauthCustomProvider<AppUser>({
    oauthMetadata,

    createTokenVerifier(resource) {
      return {
        async verifyAccessToken(token) {
          const { payload } = await jwtVerify(token, jwks, {
            issuer,
            audience: resource.href,
          });

          if (!payload.sub || !payload.exp) {
            throw new Error("Token is missing sub or exp");
          }

          const scopes =
            typeof payload.scope === "string"
              ? payload.scope.split(/\s+/).filter(Boolean)
              : [];

          return {
            token,
            clientId:
              typeof payload.client_id === "string"
                ? payload.client_id
                : typeof payload.azp === "string"
                  ? payload.azp
                  : "",
            scopes,
            expiresAt: payload.exp,
            resource,
            extra: { payload: payload as Record<string, unknown> },
          };
        },
      };
    },

    mapAuthInfo(authInfo: OAuthAuthInfo) {
      const payload = authInfo.extra?.payload as Record<string, unknown>;
      if (typeof payload.sub !== "string") {
        throw new Error("Verified token is missing sub");
      }

      return {
        user: {
          id: payload.sub,
          email: typeof payload.email === "string" ? payload.email : undefined,
          organizationId:
            typeof payload.organization_id === "string"
              ? payload.organization_id
              : undefined,
        },
        payload,
        permissions: Array.isArray(payload.permissions)
          ? payload.permissions.filter(
              (value): value is string => typeof value === "string",
            )
          : [],
      };
    },
  }),
});

export default server;