I've been thinking about something along these lines, but coupled with deterministic inference. At each "macro" invocation you'd also include hash-of-model, and hash-of-generated-text. (Note, determinism doesn't require temperature 0, so long as you can control the rng seed. But there are a lot of other things that make determinism hard)

You could take it a step further and have a deterministic agent inside a deterministic VM, and you can share a whole project as {model hash, vm image hash, prompt, source tree hash} and have someone else deterministically reproduce it.

Is this useful? Not sure. One use case I had in mind as a mechanism for distributing "forbidden software". You can't distribute software that violates DMCA, for example, but can you distribute a prompt?