Review counts and ratings updated near-real-time on submission

Rating counts and averages that update on a nightly batch job rather than in real time allow the displayed schema-org aggregateRating to diverge from the database truth for hours after a review is submitted. A listing that receives 10 new 1-star reviews after a service failure continues displaying its pre-incident 4.5-star average until the batch runs — actively misleading users making decisions based on the structured data. Data-integrity is the core taxon: the JSON-LD reviewCount fed to Google must match the actual review count at page-render time. Delayed updates also suppress Google's trust in your rating freshness, reducing the likelihood of rich-result display.

Recalculate averageRating and reviewCount synchronously in the same transaction that writes the review. Avoid recomputing from a full table scan on every submit — maintain running aggregates on the listing row.

// src/app/api/listings/[id]/reviews/route.ts
export async function POST(request: Request, { params }: { params: { id: string } }) {
  const { rating, text } = await request.json();

  await db.$transaction(async (tx) => {
    await tx.review.create({ data: { listingId: params.id, rating, text } });

    // Recompute aggregate from all reviews in the same transaction
    const { _avg, _count } = await tx.review.aggregate({
      where: { listingId: params.id },
      _avg: { rating: true },
      _count: { rating: true },
    });

    await tx.listing.update({
      where: { id: params.id },
      data: {
        averageRating: parseFloat((_avg.rating ?? 0).toFixed(2)),
        reviewCount: _count.rating,
        dateModified: new Date(),
      },
    });
  });

  return Response.json({ ok: true });
}

The dateModified update in the same transaction ensures the JSON-LD timestamp stays current.