Extract prompt sources and rendering internals

docs/policy/architecture.md

@@ -16,19 +16,27 @@ The module root contains package `promptkit`, which is the public facade. It
 declares the module's public package boundary but does not yet provide a usable
 exported framework API.
 
-The implemented internal foundation consists of:
+The implemented internal components consist of:
 
 - `internal/domain`, which owns framework data values shared by later internal
   components;
 - `internal/defaults`, which owns application-neutral framework defaults and
   constructs the default execution target; and
 - `internal/filecatalog`, which discovers YAML files and provides source-path
-  helpers for filesystem and `fs.FS` consumers.
+  helpers for filesystem and `fs.FS` consumers;
+- `internal/promptdef`, which loads and validates prompt definitions from
+  filesystem and `fs.FS` sources;
+- `internal/profile`, which loads, validates, and overlays execution profiles
+  from filesystem and `fs.FS` sources;
+- `internal/profile/builtin`, which embeds the built-in execution profile
+  catalog; and
+- `internal/prompt`, which renders prompt messages from Go templates.
 
-`internal/defaults` depends on `internal/domain`; the file catalog is
-independent and uses only the standard library. Prompt and profile sources,
-rendering, artifact reading, validation, model clients, orchestration, and the
-public engine have not yet been extracted.
+The defaults and renderer depend on the domain model. Prompt-definition and
+profile repositories use the domain model, file catalog, and YAML decoder. The
+built-in profile repository supplies an embedded `fs.FS` to the profile
+package. Artifact reading, output validation, model clients, orchestration, and
+the public engine have not yet been extracted.
 
 Future framework extraction must follow this dependency direction: