The 2026-08-21 prod 500 on POST /api/v1/blogacl was caused by the
PostIt client sending { circleId } only — the server deserialised
into CircleAuthorizationToBlogPost with BlogPostId = default(long) = 0,
and EF Core refused the INSERT with InvalidOperationException.
The PostIt-side fix lives in b82b6722 (enrich the payload with
blogPostId). This commit is the server-side guard: validate
BlogPostId > 0 in the controller and return 400 BadRequest instead
of letting the request reach SaveChangesAsync. The same shape that
crashed on 2026-08-21 now fails fast at the validation layer.
Verified by BlogAclApiTests.PostCircleAuthorization_dosent_return_500:
sentinel that asserts 'never 500' on a payload with BlogPostId = -1.
Previously red (500 from EF Core), now green (400 from the new guard).
Paul Schneider
d2a0c263dd