celld's README states "Object-storage compare-and-swap ensures that exactly one node owns a cell at a time," but I'm skeptical this actually holds at the point where data is written to storage - I had an AI skim through the code with me, and the actual segment writes looked like plain, unconditional PUTs with no epoch check.

In many cases, I think using Cloudflare's Durable Objects is probably the right call instead.