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Recipe: Async stand-up update writer

Build a non-blocking update pipeline that writes stand-up snapshots to Upstash KV without blocking the request path.

Overview

When a user submits a daily stand-up, the write must land in KV before the next read. Blocking the HTTP response on that write adds latency the user feels. This recipe offloads the KVSETto a background queue drained by a single async worker, so the API returns instantly.

Architecture

  • In-memory ring buffer holds pending writes (max 256 entries).
  • Single worker goroutine drains the buffer every 50 ms.
  • Exponential backoff with jitter on KV failures.
  • Circuit breaker opens after 5 consecutive errors, auto-resets after 30 s.

Key decisions

At-most-once delivery is acceptable because the next stand-up submission overwrites the same key. No need for a persistent outbox.

No Vercel Edge — the worker runs in the Node.js runtime where Upstash Redis client keepalive works reliably.

Graceful shutdown drains the buffer on SIGTERM before the process exits.

Quick start

  1. Create lib/update-writer.ts.
  2. Import and call enqueue(standup) from your API route.
  3. Start the worker in instrumentation.ts.