Rivet launches open-source agent orchestrator on S3-backed actors

Rivet (YC W23) launched an open-source actor orchestrator for agent workloads, aimed as a self-hostable alternative to heavy sandboxes and Cloudflare Durable Objects. Its README cites 4.99 ms p99 cold starts, about 72 KB RAM per actor versus 512 MiB for a typical sandbox, and S3-backed SQLite with roughly 1.07 ms p99 durable writes. Amp reportedly migrated from Durable Objects to Rivet and deploys on-prem. HN Launch (71 points, 38 comments): No consensus. Some self-hosters praise the Durable Objects alternative; others say the product pitch is unclear and question whether orchestration latency is the real agent bottleneck. Sorted take: worth a look if you are drowning in idle sandboxes, but validate cold-start and isolation claims on your own workload first.