feat: sync autumn customer after signup

src/auth.ts

@@ -1,4 +1,5 @@
 import { betterAuth } from "better-auth";
+import { syncAutumnCustomerOnRegistration } from "./autumn";
 import { buildAuthEmail, sendEmail } from "./email";
 import { trustedOrigins, type Env } from "./env";
 import { createSocialProviders } from "./oauth";
@@ -19,6 +20,21 @@ export function createAuth(env: Env, runtime: AuthRuntime = {}) {
     secret: env.BETTER_AUTH_SECRET ?? "development-secret-change-before-production",
     baseURL: env.BETTER_AUTH_URL,
     trustedOrigins: trustedOrigins(env, runtime.requestOrigin),
+    databaseHooks: {
+      user: {
+        create: {
+          after: async (user) => {
+            const sync = syncAutumnCustomerOnRegistration(env, user);
+            if (runtime.waitUntil) {
+              runtime.waitUntil(sync);
+              return;
+            }
+
+            await sync;
+          },
+        },
+      },
+    },
     session: {
       cookieCache: {
         enabled: true,

tests/auth-config.test.ts

@@ -1,5 +1,5 @@
 import { readFileSync } from "node:fs";
-import { describe, expect, it } from "vitest";
+import { describe, expect, it, vi } from "vitest";
 import { createAuth } from "../src/auth";
 import {
   booleanEnv,
@@ -89,6 +89,52 @@ describe("auth env helpers", () => {
   });
 });
 
+describe("Autumn registration hook", () => {
+  it("schedules Autumn sync after Better Auth creates a user", async () => {
+    const waitUntil = vi.fn();
+    const auth = createAuth(
+      {
+        ...env,
+        AUTUMN_SECRET_KEY: "autumn-secret",
+        AUTUMN_FREE_PLAN_ID: "free",
+      },
+      {
+        waitUntil,
+      },
+    );
+
+    const hook = (
+      auth as unknown as {
+        options: {
+          databaseHooks?: {
+            user?: {
+              create?: {
+                after?: (
+                  user: { id: string; email?: string | null; name?: string | null },
+                  context?: unknown,
+                ) => Promise<void>;
+              };
+            };
+          };
+        };
+      }
+    ).options.databaseHooks?.user?.create?.after;
+    expect(hook).toEqual(expect.any(Function));
+
+    await hook?.(
+      {
+        id: "user_123",
+        email: "user@example.com",
+        name: "Example User",
+      },
+      undefined,
+    );
+
+    expect(waitUntil).toHaveBeenCalledTimes(1);
+    expect(waitUntil.mock.calls[0]?.[0]).toBeInstanceOf(Promise);
+  });
+});
+
 describe("production auth config", () => {
   it("allows the Web Shell origin in Wrangler trusted origins", () => {
     const config = JSON.parse(readFileSync("wrangler.jsonc", "utf8")) as {