Show HN: S2-lite, an open source Stream Store

S2 was on HN for our intro blog post a year ago (https://s2.dev/blog/agent-sessions#landscape). Kafka and NATS Jetstream treat streams as provisioned resources, and the protocols/implementations are oriented around such assumptions. Redis Streams and NATS allow for larger numbers of streams, but without proper durability.

The cloud service is completely elastic, but you can also get pretty far with lite despite it being a single-node binary that needs to be scaled vertically. Streams in lite are "just keys" in SlateDB, and cloud object storage is bottomless – although of course there is metadata overhead.

One thing I am excited to improve in s2-lite is pipelining of writes for performance (already supported behind a knob, but needs upstream interface changes for safety). It's a technique we use extensively in s2.dev. Essentially when you are dealing with high latencies like S3, you want to keep data flowing throughout the pipe between client and storage, rather than go lock-step where you first wait for an acknowledgment and then issue another write. This is why S2 has a session protocol over HTTP/2, in addition to stateless REST.

You can test throughput/latency for lite yourself using the `s2 bench` CLI command. The main factors are: your network quality to the storage bucket region, the latency characteristics of the remote store, SlateDB's flush interval (`SL8_FLUSH_INTERVAL=..ms`), and whether pipelining is enabled (`S2LITE_PIPELINE=true` to taste the future).

I'll be here to get thoughts and feedback, and answer any questions!