nestrs-saml covers the SP-initiated login redirect (AuthnRequest via HTTP-Redirect). Assertion consumption (XML signature, crypto) stays in your app or a dedicated XML stack. Implement SamlResponseValidator at the ACS route.
Install
Redirect to the IdP
redirect_url appends SAMLRequest, RelayState, spEntityId, and acs on the IdP SSO URL. A full IdP integration typically deflates and base64-encodes a real AuthnRequest XML; this adapter sends a relay-friendly request id the ACS can correlate.
Validate at the ACS
POST the SAMLResponse form field to /acs, call validate, then issue your own session.
This crate does not verify XML signatures. Do not accept a SAMLResponse in production without a real validator implementation.