[nodamage]

> And people are telling you that this is not possible with the Google public OAuth API.

Yes I understand, however it is possible to integrate Slack and Google SSO in such a way that it checks that the user belongs to the correct workspace, correct? Either via the SAML integration (https://support.google.com/a/answer/6357481) or an internal Google OAuth integration? The purpose of the public Google OAuth API as opposed to the previous two options is to allow logins from non-workspace or cross-workspace Google accounts, correct?

[SAI_Peregrinus]

No, there's no way to check which workspace is in use, just that the domain matches. That's the problem.

[nodamage]

Only if you use the Google public OAuth integration. If you instead use the SAML integration with Slack as described in the link above you don’t have this problem.