Backlog item 2. CreateSuggestedJob, RelinkThread, and UnlinkThread each
upserted exactly one GmailReviewDecision by ThreadId but loaded every review
decision for the owner (GmailReviewDecisions.Where(OwnerUserId == x).ToList())
just to linear-scan for the one match. Replaced with FirstOrDefaultAsync
filtered on both OwnerUserId and ThreadId, and added a single-row
UpsertReviewDecision overload alongside the existing dictionary-based one
(still used by the review-queue endpoints, which genuinely need every
decision at once to render the queue).
169/169 green.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>