fix: resolve concurrency issues in review statistics updates

[Eren-Can-Donertas]

1. Description

Concurrent review submissions update product statistics without atomic protection. Under simultaneous requests, review counts and rating averages may become inconsistent. This introduces silent data integrity issues and incorrect analytics across the application.

This work matters because inconsistent statistics degrade trust in product metrics and can propagate incorrect data to clients.

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2. Ownership, Timeline, and Effort

Owner: @utkuatasoy
Given Date: 19-02-2026
Deadline: 22-02-2026 24:00
Hours: 6
Value: 3
Week: 8

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3. Deliverables

• Concurrency-safe statistics update logic
• Atomic or transactional update mechanism
• Code merged into main branch

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4. Scope Definition

In Scope

• Protect stat calculations from race conditions
• Ensure consistent rating averages and counts

Out of Scope

• UI changes
• New analytics features

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5. Acceptance Criteria

• Concurrent submissions do not corrupt statistics
• Review counts remain accurate
• Rating averages remain correct
• Pull request merged

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6. Domain Specific Notes

Engineering: Use optimistic locking or atomic database updates.

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7. Validation and Review Requirements

• Concurrent load test executed
• Code review completed
• Pull request merged

Definition of Done:
Statistics remain consistent under concurrent load and PR is merged.