D-136 step 6: the chain audit -- R9's drift gate built, three refusals, two dead cases ...

Three read-only lenses over data source -> renderer -> deployment mechanism,
the ruled final step of D-136 option (D). Lens 3 was adversarial and made
the chain produce wrong-but-green THREE times, all executed.

All three converged on one root cause: dc1's overlay was byte-gated and
dc0's was gated by nothing. render/values/ was referenced by zero scripts
and zero harnesses, while preflight P2 feeds the deploy gate dc0's overlay.
R9's render-drift check had been RULED and never built.

Executed wrong-but-green:
- transposing two apps' octets in the dc0 overlay (consistent, in-band,
  correct prefixes) -> PASS
- changing ONE WORD, family: dual -> v4, silently reverting dc0 to IPv4-only
  against R2's ruling -> PASS, because dropping prefer-ipv6 and the v6 legs
  together satisfies invariant 9, and vip_dual is printed but never asserted

tests/render-drift/ is R9's gate, built. It iterates render/values/*.yaml,
reads each file's own output: field (inert until now), renders and
byte-compares. A new per-DC values file is gated the moment it is committed.
Non-zero floor plus a proof-of-teeth case that mutates a copy and requires
red.

Three refusals where the chain took the last writer silently:
- duplicate (role, kind) in the apex, in BOTH readers. Appending one spare
  prefix -- routine IPAM work -- re-homed every dc0 VIP into a different /64
  and went green, because the gate checks overlay-vs-apex agreement and both
  sides read the same wrong value. The winner depended on JSON array order.
- duplicate app name / duplicate octet / out-of-band octet in APP_OCTET. A
  duplicate name emitted two YAML blocks, safe_load kept the last, and one
  app's ruled octet vanished with nothing red.

Two harness cases that could not fail:
- T3b's byte-compare was CIRCULAR -- header derived --from-overlay $LIVE
  then compared --against $LIVE, so a third of the bytes were self-copied.
  Proven by rewriting a header line to a false claim and still matching.
- T29's own fixture was inert; its assertion held from the overlay alone.

OWNED: my first T29 re-point asserted a --show-legs flag THAT DOES NOT
EXIST. I invented an interface instead of reading one. The harness caught it
immediately; replaced with real behaviour and recorded rather than quietly
fixed.

Gauntlet ALL GREEN (86) on vcloud; repo-lint 0 fail / 612 files. The larger
deploy-path half is logged not actioned -- see the changelog, items 16-25.

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