Parent: #461 Blocks: #734 Related: #775
Problem
The schema-v3 exact-parent validator requires both one-commit binary overlays to report every path in the fixed shared-measurement inventory as changed. That rejects a logically valid historical pair when some measurement blobs were already inherited unchanged by both logical revisions: #734 already contains three of the twelve frozen V24 files, so applying the identical audited overlay changes only nine paths. Fabricating no-op content changes would corrupt provenance.
Scope
- Validate that binary revisions remain one-commit children of their logical revisions.
- Reject every changed path outside the frozen shared-measurement inventory.
- Require the effective overlay blob for every inventoried path to be identical between parent and candidate, whether newly changed or already inherited.
- Require both sides to change the same non-empty subset and retain the full measurement-surface inventory in artifact metadata.
- Add fail-closed fixtures for partially inherited, asymmetric, undeclared, and blob-divergent overlays.
- Version the representative matrix and keep historical artifacts unchanged.
No-workaround rules
No dummy edits, weakened binary ancestry, omitted paths, normalized blobs, source transforms, benchmark recognizers, or reuse of whole-process occupancy as invocation-boundary CPU evidence.
Acceptance
- The exact #734 parent/candidate overlay validates with nine real changes and three already-inherited identical measurement blobs.
- Undeclared, asymmetric, empty, ancestry, and blob mutations fail closed.
- Exact-parent self-tests, representative matrix mutations, benchmark harness, docs/link gates, and Test262 flip accounting pass.