Document catalog profile compatibility

docs/policy/architecture.md

@@ -30,7 +30,8 @@ The implemented internal components consist of:
 - `internal/filecatalog`, which discovers YAML files and provides source-path
   helpers for filesystem and `fs.FS` consumers;
 - `internal/catalog`, which validates immutable external maintained-catalog
-  assets before they are eligible for engine assembly;
+  assets and their reserved profile namespace before they are eligible for
+  engine assembly;
 - `internal/jsonvalue`, which validates and defensively copies JSON-compatible
   extra-parameter trees;
 - `internal/promptdef`, which loads and validates prompt definitions from
@@ -63,11 +64,11 @@ policy snapshot, wraps the selected built-in or injected model client, and
 supplies bounded admission to the runner. The defaults and renderer depend on
 the domain model. Prompt-definition and profile repositories use the domain
 model, file catalog, and YAML decoder. The catalog adapter validates imported
-immutable maintained data before internal engine assembly supplies it to the profile
-package. Artifact reading uses the domain
-model and application-neutral defaults. Validation uses the domain model, file
-catalog, and JSON Schema implementation. The model client uses the domain
-model, application-neutral defaults, and an injected or standard-library HTTP
+immutable maintained data, including its reserved namespace, before internal
+engine assembly supplies it to the profile package. Artifact reading uses the
+domain model and application-neutral defaults. Validation uses the domain model,
+file catalog, and JSON Schema implementation. The model client uses the domain
+model and application-neutral defaults, and an injected or standard-library HTTP
 client. The use-case runner depends on the narrow interfaces owned by each
 internal component, including backend lookup and run admission.