docs: declare institutional architecture boundary

AGENTS.md

@@ -1,5 +1,11 @@
 # govoplan-search Codex Guide
 
+## Documentation Contract
+
+- Treat documentation as part of every behavior change. Update this module's manifest-driven `DocumentationTopic` contributions for affected user and administrator behavior.
+- Keep feature content here; `govoplan-docs` projects it without importing Search internals.
+- Maintain a static user/admin baseline and run `/mnt/DATA/git/govoplan/tools/checks/check-manifest-shapes.py` after behavior or manifest changes.
+
 ## Scope
 
 This module owns global and contextual search aggregation, the built-in

src/govoplan_search/backend/manifest.py

@@ -21,6 +21,7 @@ from govoplan_core.core.modules import (
     PermissionDefinition,
     RoleTemplate,
 )
+from govoplan_core.core.provider_governance import declared_module_architecture
 from govoplan_core.core.search import (
     CAPABILITY_SEARCH_INDEX_WRITER,
     SearchProviderRegistration,
@@ -209,6 +210,20 @@ manifest = ModuleManifest(
             order=12,
         ),
     ),
+    architecture=declared_module_architecture(
+        layer="governance_accountability",
+        kind="runtime",
+        maturity="vertical_slice",
+        documentation_ref="README.md",
+        test_ref="tests/test_postgres_search.py",
+        known_limits=("The built-in PostgreSQL index is implemented; optional OpenSearch target evidence is not.",),
+        supported_authority_modes=("external_mirror",),
+        owned_concepts=("derived search index", "search ACL projection", "index change queue"),
+        non_owned_concepts=("source object", "source authorization", "external search engine"),
+        recovery_docs=("README.md",),
+        security_docs=("README.md",),
+        operations_docs=("README.md",),
+    ),
 )