Follow-up to fix-auth-bypass Brief 2 (commit 258e479). Brief 2 made
getUserFromRequest return null for unauthenticated requests. POST, PUT,
and DELETE branches of pages/api/collections/[identifier]/cards.js
were dereferencing user.userId without a guard → NPE → HTTP 500.
Security side was already fixed by Brief 2 (no more
anonymous-write-as-admin on collections owned by userId: 1). This patch
adds the cosmetic 500 → 401 cleanup the Brief 2 reviewer flagged.
Three identical 'if (!user) return 401' guards added, one per write
branch. GET branch was already guarded via the ternary pattern.
Sibling endpoints under pages/api/collections/** were re-audited by the
implementer and confirmed correctly guarded (thumbnails, permissions,
activity all have early null checks; [identifier].js uses optional
chaining throughout). No further hotfixes needed for that route group.
Convoy: fix-auth-bypass / Brief 6 (post-architect hotfix)
Co-authored-by: Cursor <cursoragent@cursor.com>