docs: declare policy publication reuse scope

Assistant: codex
Assistant-Model: gpt-6-astra
Assistant-Session: 01a15374-f59f-7a31-86d2-d23b5d2ed181

SCOPE.md

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+---
+domain: capabilities
+repo: policy-nexus
+updated: "2026-10-19"
+---
+
+# Scope
+
+Policy Nexus publishes estate policy from its owning repositories at stable,
+versioned addresses. It owns publication and currency; policy content and
+ratification remain with the source owners (see `INTENT.md`).
+
+## Provided capabilities
+
+- Generate policy pages and indexes from `publication.json`, retaining source
+  revision, review status, superseded versions and immutable publication paths.
+- Inventory canon and ADR sources and detect unpublished or changed source
+  documents with `tools/source_inventory.py` and `tools/check_currency.py`.
+- Build and verify release artifacts with `make build` and `make release-check`;
+  verify source provenance before publishing a release.
+- Extract the build-mode authorization rule from the Custodian canon YAML block
+  into `/guardrails/build-mode-change-authorization.json`, with visible lifetime
+  on the generated policy page. `tools/guardrails.py` validates and evaluates the
+  restricted rule format, failing closed for unknown categories and malformed
+  inputs. This is local lane classification, not a runtime authorization token.
+
+The discovery declaration is
+`registry/capabilities/capability.security.policy-publication.md`, indexed by
+`registry/indexes/capabilities.yaml` for reuse-surface consumption. Consumers
+should use the publication contract in `docs/publication-contract.md` rather
+than copy policy into this repository.
+
+## Boundaries and current acceptance
+
+Policy Nexus does not author or ratify policy, interpret external regulations,
+implement identity or credential custody, or enforce downstream authorization.
+Workplans, evidence, runbooks and general documentation are not publication
+content. Source owners retain control of publication disposition.
+
+The build-mode guardrail implementation is available as source; public release
+acceptance remains tracked in `PNEX-WP-0006`. That record requires founder batch
+publication disposition and resolution of the source inventory gate. Source
+availability and passing local checks do not establish live publication.