Adapter emits snapshot sha/ts out-of-band on fd 3 so a changing value never enters the delta-gate hash. Detector validates advisorily (sha regex, epoch sanity before arithmetic, future-skew slack); malformed metadata is dropped loudly and never gates the wake. Digest renders snapshot_sha/snapshot_ts plus a git-show re-verify hint. Adapters that never write fd 3 are byte-identical. Reviewed-by: Mos (design, independent) Reviewed-by: mos-dt (artifact, hardening §2) Co-authored-by: mos-dt-0 <[email protected]>