Auditor found this via hybrid fixture 2026-04-22. Blocks the serde-tag-newtype shape by converting to struct-like variants. See PR #2 body for full context.
Manual merge: auditor commit status was failure due to 1 false-positive inference finding on a commit-message reference; underlying fix is verified (curl against live gateway confirmed all 3 upsert paths return valid JSON). Proceeding per human review.