feat(RMASTER-WP-0026): declare Taxonomy layer and consume NetKingdom §20

Add layer.yaml, RMASTER-ADR-0009, the consumption contract, and a tracked
non-answer for the five §20.3 questions. Split admission, exposure, and
authorization without renaming schema fields. Finish the workplan.

Assistant: grok
Assistant-Session: 01a04c9f-cd6b-7741-bce0-f1d9d1b3c3bc

docs/netkingdom-security-consumption-contract.md

@@ -0,0 +1,87 @@
+# NetKingdom Security Consumption Contract
+
+Date: 2026-08-29
+Status: Adopted under ADR-0009 / RMASTER-WP-0026-T03
+
+## Purpose
+
+Say what every Railiance rail, rapp, and reef owes when it consumes
+NetKingdom security, without copying engine schemas or turning this
+repository into a second decision point.
+
+The statute is `net-kingdom/canon/standards/security-layer-model_v0.7.md`
+§20.2 and §6.4. The working companion is `net-kingdom/SECURITY-COMPANION.md`
+v0.2 §9. On disagreement the statute governs.
+
+This contract does **not** decide:
+
+- whether a binding may run in production — that is [ADR-0006](adr/ADR-0006-reef-production-admission.md);
+- who may reach a listener we control — that is [ADR-0008](adr/ADR-0008-private-by-default-exposure.md);
+- how the four Railiance axes map onto Taxonomy, Tooling, Engine, and Staff
+  — that remains unset in [the open-questions record](netkingdom-axis-layer-open-questions.md).
+
+## Three distinct questions
+
+| Question | Owner | Must not be read as |
+| --- | --- | --- |
+| May this binding run in production? | Railiance admission (ADR-0006) | permission for an actor to act |
+| Who may reach the listener we control? | Railiance exposure (ADR-0008) | an authorization decision |
+| May this actor perform this action on this resource? | `access-engine` | admission or exposure |
+
+`production-approved` and `exposure: public` MUST NOT be treated as
+authorization decisions. Compiled admission or exposure data that resolved
+whether an actor may act would be statute §6.1 — deciding early.
+
+## Consumption rules
+
+For any Railiance consumer of NetKingdom security, without exception:
+
+1. **Authorization decisions come from `access-engine` and from nowhere
+   else.** No rail, rapp, reef, or ownership repo may render or cache an
+   authorization verdict. A registry, schema, or cache that resolves a
+   result before the engine runs has decided early (statute §6.1).
+2. **Approvals are objects in `approval-engine`, consumed as claims.**
+   They are not a Railiance axis and not an audit-core verdict. Callers
+   needing current approval state ask `approval-engine`.
+3. **Credentials are materialized by `secrets-engine` after a decision,
+   never as a substitute for one.** A lease or certificate is an artifact
+   of authority, not its source.
+4. **Evidence goes to `audit-core` under the bound in statute §9.6.** An
+   archive proves records were not altered or truncated after arrival. It
+   does not prove an event was sent. Absence of a record is not
+   non-occurrence.
+5. **A runtime that causes a protected side effect is PEP-shaped** and
+   owes statute §6.4 **in its own repository**: no side effect without a
+   decision record or a recorded unreachable-engine stance; no replay
+   outside the decision's binding and lifetime; a published stance map
+   inventoried in statute §13.1; reconstructability within the evidence
+   bound.
+
+This repository is not PEP-shaped. `layer.yaml` records that. Implementation
+rails, rapps, and reefs that do cause protected side effects inherit these
+obligations themselves. This contract does not publish a stance map.
+
+## What this repository does not host
+
+- a policy decision point
+- an approval store
+- a credential lifecycle API
+- an evidence archive
+- an actuation or containment surface
+
+Observation-in-production and automatic containment are estate-wide zeros
+(companion §10). Do not plan Railiance operations as if they existed.
+
+## Engine schemas stay with their owners
+
+This file names the engines and the rules. It does not restate their
+request, decision, approval, credential, or evidence schemas. Those
+contracts live in the owning repositories and, for shared claim
+vocabulary, in Taxonomy artifacts statute §17 still requires.
+
+## Related
+
+- [ADR-0009](adr/ADR-0009-netkingdom-security-layer-interaction.md) — assent
+- [ADR-0006](adr/ADR-0006-reef-production-admission.md) — admission
+- [ADR-0008](adr/ADR-0008-private-by-default-exposure.md) — exposure
+- [Open questions](netkingdom-axis-layer-open-questions.md) — §20.3, unset