@021.is/spine-cache

TTL + tag-invalidation cache with single-flight dedupe. Fixes the classic N+1: 10 components asking for the same user concurrently → 1 backend call.

Use

import { makeMemoryCache, makeKey } from "@021.is/spine-cache";

const cache = makeMemoryCache();

async function getUser(id: string) {
  return cache.fetch(
    makeKey("user", id),
    async () => db.user.findUniqueOrThrow({ where: { id } }),
    { ttlMs: 60_000, tags: ["user", `user:${id}`] },
  );
}

// Invalidate by key or by tag
cache.invalidate(makeKey("user", id));
cache.invalidateTag("user"); // wipes ALL user entries

Why single-flight matters

Without dedupe: 10 concurrent components each call getUser("u_1") → 10 DB hits. With dedupe: 1 promise shared → 1 DB hit.

Helpers

• makeKey("user", id, "lang", "en") → "user:u_1:lang:en" (readable in dashboards)
• cache.size() for observability
• cache.clear() for tests

Why not Next.js unstable_cache directly

You can combine them — unstable_cache for cross-request, spine-cache for in-request dedupe. spine-cache is process-local (no Redis), zero deps.