Rivet Launches Open-Source Agent Orchestrator on S3 With 5ms Cold Starts and 72KB Per Actor

YC W23 alum Rivet launched an open-source actor orchestrator aimed at agent workloads, claiming 4.99ms p99 cold starts, 72KB RAM per actor, and billions-of-actors scale. It pairs long-lived in-memory state with SQLite databases backed by S3, ships TypeScript/Rust/Python/Swift SDKs, and positions itself as a lower-overhead alternative to sandbox-based approaches and Cloudflare Durable Objects.