D-137 tier 3 (VALIDITY) BUILT: cross-copy sha256 provenance ...

Closes the gap the plan names: creds-audit PARSES declared provenance and
never verifies it, so SEC-020's stale-trap warning has been unchecked prose
and its sha256 equality was a ONE-TIME manual act on 2026-07-25.

sha256sum runs as an EXTERNAL command on both sides so only a 64-hex digest
enters the checker -- hashing bytes in Python would meet the letter of "never
transfer content" and not the spirit.

RESULT: 4 groups compared, all byte-identical, INCLUDING the SEC-020 pair
(maas-region-admin, region source-of-record vs jumphost copy). Now
machine-verified instead of remembered. The [ok] line names the groups.

TWO FALSE POSITIVES IN MY OWN DRAFT, caught by verifying before reporting.
Keying digests by (role, site) let an identity's DISTINCT artifacts at one
scope overwrite each other, so it compared unrelated files and reported drift
on maas-region-admin and dc1-svc-key. Manual sha256sum showed both IDENTICAL.
Reporting that would have raised a false credential-rotation alarm.

Root cause was a schema gap: nothing expressed which rows are byte-copies.
custody gains `verbatim-copy` [OPS]. V1 now compares only rows sharing
(id, filename) across scopes, or a source-of-record row against declared
verbatim-copy rows -- SEC-020's exact shape. Everything else is skipped with
a reason: a pair we cannot justify comparing is not a pair we may report
drift on. verbatim-copy is manifest-bearing; it asserts byte-identity, it
does not move the file.

Harness 44 -> 52: T47/T48 regression-lock both false positives; T49 keeps
SEC-020's case from falling into T48's skip; T51 asserts the digest path uses
sha256sum and that no content-transfer verb exists anywhere in the checker.

NOT built: tier 3's behavioural probes. Liveness, expiry, revocation state
and grant/scope drift remain unverified.

Gauntlet ALL GREEN (80), repo-lint 0-fail, finding-class baseline unchanged.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01HvCyrwvYTTcDYnRErfMsNf