Docs bug: const total = 0 mutated in "Metrics removed" example (Upgrade to v7)

[serhii-sierov-crest]

Summary

The totalQueries counter example in the "Metrics removed" section of the Upgrade to Prisma ORM v7 guide declares total with const but then attempts to reassign it, which will throw a TypeError: Assignment to constant variable at runtime (and fail to compile under TypeScript).

Location

• Page: https://www.prisma.io/docs/guides/upgrade-prisma-orm/v7#metrics-removed
• Source file: apps/docs/content/docs/guides/upgrade-prisma-orm/v7.mdx

Current (broken) code

const total = 0;
const prisma = new PrismaClient().$extends({
  client: {
    $log: (s: string) => console.log(s),
    async $totalQueries() {
      return total;
    },
  },
  query: {
    $allModels: {
      async $allOperations({ query, args }) {
        total += 1;          // ❌ Cannot assign to `total` because it is a constant
        return query(args);
      },
    },
  },
});

Expected fix

Change const to let:

let total = 0;

​

Why this matters

This is the example users are directed to when replacing the removed Metrics preview feature, so anyone copy-pasting it as a starting point will hit an immediate runtime/compile error. It also undermines confidence in the migration guide at exactly the moment users are doing a major version upgrade.

Additional notes

• The snippet also uses $allModels, which scopes the counter to model operations only - raw queries ($queryRaw, $executeRaw) won't be counted. Worth a brief note if the intent is a true "total queries" counter.