Define portable, versioned runtime/agent protocol for living repositories.
A repository that wants its own cloud agent has no standard way to say what that agent may do, how it must be isolated, or where it reports state. Each runtime invents its own config, so repositories are tied to one runtime.
One small manifest, .living/manifest.yaml, that any compliant runtime can read to start, isolate and observe a repository’s agent.
Out of scope: the runtime itself, authentication, billing and scheduling.
None open. Settled in v0.4.0: runtimes advertise support in a runtime capability document; secrets access is the read_secrets capability with a secrets field (spec).