the built-in archetypes come with a default prompt

docs/4-implementation/swarm/archetypes.md

@@ -48,3 +48,10 @@ The stored value:
   "refused": { "broken": "limits: …" }
 }
 ```
+
+## The built-in prompts
+
+Each built-in archetype's `meta.prompt` is `builtins.readFile` of
+`nix/archetypes/prompts/<name>.md`. The file read gives a plain string, so
+`meta` stays plain data and the `nix eval` above prints it as JSON. The
+controller's check holds the prompt to 64 KiB.