fix(#205)#247
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…CTOU bypass Closes Coder-s-OG-s#205 claimRecommendation enforced the 3-active-claim limit using a COUNT query followed by a separate UPDATE. Two concurrent requests from the same user could both pass the pre-check count before either write committed, allowing the user to hold more than 3 active claims (TOCTOU race condition). The existing UPDATE WHERE status='open' is already atomic at the row level so two concurrent requests cannot claim the same rec twice. The race only applies to claims on different recs near the limit. Added a post-claim count verification immediately after the successful UPDATE. If the post-write count exceeds 3, the newly claimed rec is immediately reverted to 'open' and the caller receives a claim_limit error. This eliminates the window between check and write without requiring a database schema change: the worst case is an extra write on the rare concurrent edge case, not a permanent limit bypass.
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Summary
Adds post-claim count verification with automatic rollback to close a TOCTOU race condition that allowed concurrent requests to bypass the 3-active-claim limit.
Related Issue
Closes #205
Type of Change
Root Cause
`claimRecommendation` used COUNT then UPDATE as two separate round-trips. Concurrent requests could both read a count below the limit, both proceed with the claim INSERT, and both return success - leaving the user with more than 3 active claims.
What Changed
Testing
Checklist