oauth.sx routes the PKCE check through pkce_ok: an S256 challenge carried as
{s256, Hash} compares crypto:hash(sha256, Verifier) =:= Hash; a bare
challenge stays plain (§4.1), so both methods coexist with no change to
existing flows (the bare path is the old =:= behaviour). Raw sha256 digests
are compared (base64url is wire encoding, omitted). New tests/pkce.sx (6,
incl. S256 through PAR). Verified pkce 6/6; substrate fix is in the
preceding commit. 239 total.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
giles
37b7d1635c