OptionalexpiresOptional token lifetime in seconds, as reported by the auth server (its expires_in).
PopClip records it with the sign-in time; once it elapses the app treats the extension
as signed out and prompts the user to sign in again.
OptionallabelOptional account identifier to display, e.g. an email or username ("Signed in as …").
The secret to store (e.g. an access token). Saved as the extension's authsecret.
Object form of the value returned by Extension.auth, for when the extension has more than just the secret to hand back. Returning a bare string is equivalent to returning
{ secret: theString }.