Add immutable namespace views

docs/consumers/pkg-promptkit.md

@@ -63,6 +63,33 @@ new engine to observe configuration edits. See the [constructor GoDoc](../../eng
 for the exact public contract and the [framework format reference](../formats.md)
 for definition fields.
 
+### Use Scoped Engine Views
+
+Create a view when an application wants short request IDs to resolve within a
+selected collection:
+
+```go
+scoped, err := engine.WithNamespaces(promptkit.Namespaces{
+	Prompt:  "support",
+	Profile: "support",
+})
+if err != nil { return err }
+
+prepared, err := scoped.Prepare(ctx, promptkit.RunRequest{
+	PromptID:  "answer",
+	ProfileID: "concise",
+})
+```
+
+Ordinary execution and preparation qualify slashless caller selections with
+their respective namespace. Already-qualified IDs pass through unchanged;
+configured defaults and references are not rewritten. Each call replaces the
+view's scope defaults, including clearing a scope with an empty field, without
+changing the receiver or rebuilding its captured configuration and execution
+collaborators. Namespace syntax is checked when creating the view; resource
+existence is checked when selected. See [`WithNamespaces`](../../namespaces.go)
+for the exact public contract.
+
 ## Supply Embedded Application Defaults
 
 Use `FilesystemInputs` for embedded defaults and `DirectoryInputs` for an