The three sets

set_manifest_sha256 is the SHA-256 of the RFC 8785 (JCS) canonical form of the manifest's parsed JSON. It is recorded here and never inside the manifest — a document cannot carry its own digest.

These are exactly the three spaces verd.embed.MODEL_CHAIN can load — the §6.2 fallback chain, in its own order: primary, fallback, last resort. The third is a different, smaller space whose vectors are not comparable with the first two's, which is why it has a set of its own rather than a footnote in theirs.

Recompute all three from the repository root:

PYTHONPATH=services/verd/src .venv/bin/python - <<'PY'
import hashlib, json, pathlib, rfc8785
for path in sorted(pathlib.Path("standards/reference-sets").glob("*/manifest.json")):
    document = json.loads(path.read_text(encoding="utf-8"))
    print(hashlib.sha256(rfc8785.dumps(document)).hexdigest(), document["space_id"])
PY