Eject

Replace MainSDK calls for one interface, or all of them, with the provider's own SDK. mainsdk eject keeps your tests passing, writes a report of the guarantees you give up, runs offline and sends nothing anywhere. No lock-in, by design.

Before you start:

• A clean git working tree, so you can review and revert the change.
• Your test suite passing, so you can compare the count after eject.

1. See the plan

Eject always plans first. --dry-run lists every file it would change and changes none.

npx mainsdk eject email --dry-run

$ npx mainsdk eject email --dry-run
eject email · driver resend
  app/lib/receipts.ts      email.send() → resend.emails.send()
  app/lib/newsletter.ts    email.marketing() → resend.emails.send()
  tests/receipts.test.ts   @mainsdk/testing fake → plain mock
  main.yaml                email.key secret:RESEND_API_KEY → process.env.RESEND_API_KEY
no files changed (dry run)

2. Eject one interface

npx mainsdk eject email

Before:

import { email } from "mainsdk";

export async function sendReceipt(to: string, orderId: string) {
  await email.send({ to, template: "receipt", data: { orderId } });
}

After, with the Resend driver:

import { Resend } from "resend";
const resend = new Resend(process.env.RESEND_API_KEY);

export async function sendReceipt(to: string, orderId: string) {
  await resend.emails.send({
    from: "orders@pinecart.dev",
    to,
    subject: "Your receipt",
    html: renderReceipt({ orderId }),
  });
}

How the template is rendered (renderReceipt here) depends on each driver's recipe.

What eject changes:

• Every call to that interface becomes idiomatic code for the provider SDK named by the driver in main.yaml.
• secret: references become plain environment variable reads.
• Tests that used @mainsdk/testing fakes are rewritten to the provider's test mode or a plain mock. They are never deleted.
• EJECT-REPORT.md lists each guarantee that no longer holds.

A partial eject keeps every other interface working.

3. Verify it worked

Run your tests. They pass, with the same test count as before.

node --test

Then read the report and decide how you replace each guarantee:

# Eject report: email (resend)

No longer enforced by MainSDK:
- Unsubscribe link on marketing email (was enforced by types)
- Suppression list checked before every send
- Idempotency keys on sends (retries may send twice)

Eject everything

npx mainsdk eject --all --dry-run
npx mainsdk eject --all

After the last interface, main.yaml, the gates and every mainsdk and @mainsdk/* dependency are removed from the project. Interfaces with a built-in driver, such as Cedar for policy or built-in webhooks, eject to the open-source library code they use.

Next

• Swap a driver
• Interfaces and drivers
• CLI reference