Helpful vote or "was this helpful?" mechanism is displayed

Helpful-vote mechanisms surface the reviews with the highest signal-to-noise ratio, so shoppers reach useful content faster and conversion climbs. Without votes, long-form detailed reviews sit next to one-line "love it" posts with no way to distinguish quality; community ranking is the cheapest moderation layer that exists. Vote data also feeds the "Most Helpful" sort (WCAG-adjacent discoverability) and trains future review-ranking models.

Add a helpful_votes integer column to the reviews table, expose a POST route at api/reviews/[id]/helpful that increments the counter (rate-limited per user), and render a components/HelpfulVote.tsx button beneath each review displaying the current count:

const handleHelpful = async () => {
  await fetch(`/api/reviews/${reviewId}/helpful`, { method: 'POST' })
  setVotes(v => v + 1)
}

Block duplicate votes from the same user by storing a (user_id, review_id) join row.

• ID: helpful-votes

• Severity: low

• What to look for: Enumerate all interactive elements in the review display component. Classify whether any element functions as a helpful-vote mechanism (thumbs up/down, "Was this helpful?" button, upvote counter). Count the number of vote-related database fields or API endpoints.

• Pass criteria: At least 1 helpful-vote mechanism (button, thumbs up/down, or "Was this helpful?" prompt) is visible on each review, backed by at least 1 database field (e.g., helpful_votes column) and at least 1 API endpoint that records the vote.

• Fail criteria: No helpful-vote mechanism exists in the review display component, or a vote button renders but has no backend support (no API endpoint or database field).

• Skip (N/A) when: The project has fewer than 5 total reviews or no review display component exists.

• Detail on fail: "No helpful-vote button or mechanism found in ReviewItem component. 0 vote-related API endpoints. Users cannot indicate which reviews are useful."

• Remediation: Add helpful voting in components/HelpfulVote.tsx with an API route at api/reviews/[id]/helpful:

  // components/HelpfulVote.tsx
  export function HelpfulVote({ reviewId, initialVotes }) {
    const [votes, setVotes] = useState(initialVotes)
  
    const handleHelpful = async () => {
      await fetch(`/api/reviews/${reviewId}/helpful`, { method: 'POST' })
      setVotes(votes + 1)
    }
  
    return (
      <button onClick={handleHelpful} className="helpful-btn">
        👍 Helpful ({votes})
      </button>
    )
  }