feat: MCP plugin (#2666)

* chore: wip

* wip

* feat: mcp plugin

* wip

* chore: fix lock file

* clean up

* schema

* docs

* chore: lint

* chore: release v1.2.9-beta.1

* blog

* chore: lint

demo/nextjs/app/.well-known/oauth-authorization-server/route.ts

@@ -0,0 +1,4 @@
+import { oAuthDiscoveryMetadata } from "better-auth/plugins";
+import { auth } from "../../../lib/auth";
+
+export const GET = oAuthDiscoveryMetadata(auth);

demo/nextjs/app/api/[transport]/route.ts

@@ -0,0 +1,38 @@
+import { createMcpHandler } from "@vercel/mcp-adapter";
+import { withMcpAuth } from "better-auth/plugins";
+import { z } from "zod";
+import { auth } from "@/lib/auth";
+
+const handler = withMcpAuth(auth, (req, session) => {
+	return createMcpHandler(
+		(server) => {
+			server.tool(
+				"echo",
+				"Echo a message",
+				{ message: z.string() },
+				async ({ message }) => {
+					return {
+						content: [{ type: "text", text: `Tool echo: ${message}` }],
+					};
+				},
+			);
+		},
+		{
+			capabilities: {
+				tools: {
+					echo: {
+						description: "Echo a message",
+					},
+				},
+			},
+		},
+		{
+			redisUrl: process.env.REDIS_URL,
+			basePath: "/api",
+			verboseLogs: true,
+			maxDuration: 60,
+		},
+	)(req);
+});
+
+export { handler as GET, handler as POST, handler as DELETE };

demo/nextjs/app/api/auth/[...all]/route.ts

@@ -1,10 +1,4 @@
 import { auth } from "@/lib/auth";
 import { toNextJsHandler } from "better-auth/next-js";
-import { NextRequest } from "next/server";
 
-export const { GET } = toNextJsHandler(auth);
-
-export const POST = async (req: NextRequest) => {
-	const res = await auth.handler(req);
-	return res;
-};
+export const { GET, POST } = toNextJsHandler(auth);

demo/nextjs/lib/auth.ts

@@ -8,8 +8,8 @@ import {
 	oneTap,
 	oAuthProxy,
 	openAPI,
-	oidcProvider,
 	customSession,
+	mcp,
 } from "better-auth/plugins";
 import { reactInvitationEmail } from "./email/invitation";
 import { LibsqlDialect } from "@libsql/kysely-libsql";
@@ -19,9 +19,9 @@ import { MysqlDialect } from "kysely";
 import { createPool } from "mysql2/promise";
 import { nextCookies } from "better-auth/next-js";
 import { passkey } from "better-auth/plugins/passkey";
-import { expo } from "@better-auth/expo";
 import { stripe } from "@better-auth/stripe";
 import { Stripe } from "stripe";
+import Database from "better-sqlite3";
 
 const from = process.env.BETTER_AUTH_EMAIL || "delivered@resend.dev";
 const to = process.env.TEST_EMAIL || "";
@@ -52,10 +52,7 @@ const STARTER_PRICE_ID = {
 
 export const auth = betterAuth({
 	appName: "Better Auth Demo",
-	database: {
-		dialect,
-		type: process.env.USE_MYSQL ? "mysql" : "sqlite",
-	},
+	database: new Database("auth.db"),
 	emailVerification: {
 		async sendVerificationEmail({ user, url }) {
 			const res = await resend.emails.send({
@@ -117,6 +114,9 @@ export const auth = betterAuth({
 		},
 	},
 	plugins: [
+		mcp({
+			loginPage: "/sign-in",
+		}),
 		organization({
 			async sendInvitationEmail(data) {
 				await resend.emails.send({
@@ -160,9 +160,7 @@ export const auth = betterAuth({
 		multiSession(),
 		oAuthProxy(),
 		nextCookies(),
-		oidcProvider({
-			loginPage: "/sign-in",
-		}),
+
 		oneTap(),
 		customSession(async (session) => {
 			return {
@@ -198,7 +196,6 @@ export const auth = betterAuth({
 				],
 			},
 		}),
-		expo(),
 	],
 	trustedOrigins: ["exp://"],
 });