Fix: handle concurrent vote race condition gracefully#26
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The vote handler uses SELECT to check for duplicates, then INSERT. Two concurrent requests can both pass the SELECT check. The UNIQUE constraint on (coupon_id, voter_did) catches this at the DB level, but the resulting constraint violation error returns a generic 500 instead of the expected 409 response. Use INSERT OR IGNORE so concurrent duplicate inserts are silently ignored instead of throwing errors, while keeping the SELECT check for user-friendly feedback on normal duplicate attempts. Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
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Summary
Fixes #25
The vote endpoint's SELECT+INSERT pattern can throw a UNIQUE constraint error on concurrent requests, returning 500 instead of 409.
Changes
apps/web/app/api/coupons/vote/route.ts: UseINSERT OR IGNOREto handle concurrent duplicates gracefully; keep SELECT check for normal duplicate feedbackTest plan
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