Add governed test plane and close T04/T08

Encode fail-closed admission, target registrations, and a credential
broker that never returns secret values. Calibrate audit-core shaped
probes in-process. Send no packets and request no live credentials.

Assistant: grok
Assistant-Session: 01a02670-3345-76f2-a014-70fde8e2a2bb

SCOPE.md

@@ -69,17 +69,20 @@ boundary always holds.
 - `T01` is complete: the rules of engagement were accepted on 2026-08-21.
 - `T02` is complete: the per-axis attacker model is recorded in
   `docs/attacker-model.md`.
-- `T03` is in progress: the differential core and audit-core/tenant-engine
-  target packs exist, but target run records are still gated.
-- `T04` is in progress: all generic read/write operations detect the
-  known-bad fixture; target-specific calibration follows executable adapters.
+- `T03` is in progress: the differential core, audit-core adapter and test
+  plane admission exist. `tenant-engine` is registered `not_applicable` for
+  E2. Live audit-core still needs a new engagement and a provisioned plane.
+- `T04` is complete for every applicable E2 probe: generic and audit-core
+  shaped fixtures fail known-bad and pass known-good in-process.
 - `T05` is in progress with a 24-hour E3 cadence and offline evaluator.
 - `T06` is in progress with a bounded characterization evaluator; no shared
   substrate window is approved.
-- `T07` is in progress with a report schema and risk-nexus message formatter;
-  the first target report has not yet been produced.
+- `T07` is in progress: reports can be queued to `outbox/`; the first target
+  report has not been produced.
+- `T08` is the governed test plane contract. Cluster provisioning is outside
+  this repository.
 - No live probe traffic is authorized; each target still requires its own
-  engagement record and approvals.
+  engagement record, plane admission and approvals.
 
 ## Relationships