REG-043 — after (zk_proof stub surface boundary published in the register)
===========================================================================

Row: REG-043 [CLM-019][TRACK-B5] ARCH P1 'zk_proof public surface' — SEED -> DOCUMENTED

Why the row was open: the boundary was true and disclosed elsewhere, but absent here.
  $ grep -in "stub" docs/institutional/UNSUPPORTED_CLAIMS.md     # before the edit
    (no output — zero hits, case-insensitive)
  $ grep -in "zk" docs/BOUNDARIES.md
    (one hit, real-circuit row only: the unconfigurable max_forensic_bytes / CLM-089)

The stub, verified against source this session:
  $ sed -n '35p;115,118p;174,178p;217,220p;249,256p' aegis/core/zk_proof.py
    HAS_ZK_NATIVE: bool = False  # True when bellman/halo2 Rust extension loaded
    def _derive_proof_bytes(
        audit_node_hash: str,
        chain_root: str,
        proof_system: ProofSystem,
        def __init__(self, *, require_real: bool = False) -> None:
            if require_real and not HAS_ZK_NATIVE:
                raise ZKProofUnavailableError(
                    "real ZK backend (bellman/halo2/winterfell) is not integrated; "
                    "refusing to operate with require_real=True (stub proofs are not sound)"
        @property
        def is_stub(self) -> bool:
            """Always True until real ZK library is integrated."""
            return True
            expected = _derive_proof_bytes(audit_node_hash, chain_root, result.proof_system)
            if result.proof_bytes == expected:
                return ZKVerificationResult(
                    valid=True,
                    proof_system=result.proof_system,
                    verified_at=now,
                    reason="stub verification passed",
                )

  $ sed -n '53,61p' aegis/crypto/__init__.py      # public re-export
    from aegis.core.zk_proof import (
        ProofSystem,
        ZKProofRequest,
        ZKProofResult,
        ZKProofUnavailableError,
        ZKProver,
        ZKVerificationResult,
        ZKVerifier,
    )

Fix: UC-043 added (doc-only edit).
  docs/institutional/UNSUPPORTED_CLAIMS.md — new UC-043 row after UC-042 + an
  'Amended:' line dated 2026-09-21. The row states the digest construction, that
  valid=True carries no soundness, that fail-closed needs require_real=True, the
  seven exported symbols, and the separation from UC-039/CLM-089/DOC-08.

  $ grep -in "stub" docs/institutional/UNSUPPORTED_CLAIMS.md     # after the edit
    5:**Amended:** 2026-09-21 UTC — `UC-043` added for the exported `zk_proof` stub surface, whose boundary lived only in 
    63:| `UC-043` | Aegis provides zero-knowledge audit proofs through its public API, or a `ZKVerificationResult(valid=True

No code change. Nothing retracted: CLM-019, DOC-08 §5/§6.6 and ROADMAP.md:110 all stand.

Gates re-run after the edit:
verify_docs: verify_docs: PASS (0 findings)
verify_claims: verify_claims: PASS (102 claims, 0 findings)
verify_links: verify_links: PASS (1285 relative links and anchors resolved)
verify_documentation --strict: status=PASS errors=0 warnings=0 required_files=27
