How do you manage auth for Google add-ons? This is how I solved authentication for Google editor addons.

Step by step:

1. User installs the add-on

2. Google already knows who the user is

3. The add-on requests the user’s Google identity token (ScriptApp.getIdentityToken();)

4. That token is verified on the backend (nextjs, fastapi, etc)

5. A backend session is created (eg: Supabase)

6. The user is now authenticated across:

   1. the add-on UI

   2. the backend API

   3. Stripe (for billing)

The scope require to get the id token is:

"oauthScopes": [ "openid"

Check out the details -> https://www.shipaddons.com/docs/features/authentication