Prisma transaction with retries for serialization errors

                  import { PrismaClient } from '@prisma/client';

const prisma = new PrismaClient();

export async function withTxRetry<T>(fn: (tx: PrismaClient) => Promise<T>, attempts = 3): Promise<T> {
  for (let i = 0; i < attempts; i++) {
    try {
      return await prisma.$transaction((tx) => fn(tx as any));
    } catch (e: any) {
      const msg = String(e?.message ?? '');
      const transient = msg.includes('Serialization') || msg.includes('deadlock');
      if (!transient || i === attempts - 1) throw e;
      await new Promise((r) => setTimeout(r, 50 + Math.random() * 150));
    }
  }
  throw new Error('unreachable');
}