Add native configuration display

docs/cli.md

@@ -125,6 +125,28 @@ empty value was explicitly supplied, so a scope callback can map those inputs to
 its own ConfigKit load policy. Help and invalid syntax do not call scope
 providers.
 
+### Show effective configuration
+
+`config show` writes the provider's native effective YAML for one scope. Its
+default scope is `app`; `--format yaml` is accepted and YAML is the only initial
+format. Single-scope output is passed through unchanged, without a CommandKit
+header or document marker.
+
+```text
+example config show
+example config show --scope promptkit
+example config show --scope all
+```
+
+`--scope all` acquires every selected scope and checks each effective writer
+before writing output. It then emits one YAML document per scope in discovery
+order, with a `# scope: NAME` comment after each document marker. Existing native
+markers and leading comments are retained; documents without a marker receive
+one. Scope labels containing line control characters are quoted to keep them on
+one comment line. A provider failure leaves the output stream empty. A rendering
+or output failure may leave an aggregate prefix, and the outcome reports
+incomplete report delivery.
+
 ## Outcome status
 
 CommandKit usage failures use status `2`; operational failures use status `1`.

docs/development.md

@@ -4,9 +4,9 @@ CommandKit currently contains adopted repository policies, accepted architectura
 decisions, implementation plans, identity and outcome primitives, typed command
 declarations, an instance-owned registry, a Cobra-backed routing and parsing
 adapter, public `App.Execute` coordination, and generated help/version commands.
-Configuration suite registration, scope discovery, ConfigKit integration, and
-validation are implemented; other configuration and PromptKit operations remain
-pending. The
+Configuration suite registration, scope discovery, ConfigKit integration,
+validation, and native effective YAML display are implemented; other
+configuration and PromptKit operations remain pending. The
 [README](../README.md) provides project orientation; the
 [documentation policy](policy/documentation.md#canonical-ownership) assigns
 canonical documentation owners.

docs/roadmap/implementation.md

@@ -1,6 +1,6 @@
 # Initial CommandKit implementation plan
 
-Status: implementation underway; Stages 1-8 complete and Stages 9-14 pending.
+Status: implementation underway; Stages 1-9 complete and Stages 10-14 pending.
 
 Date: 2026-10-07.
 
@@ -606,7 +606,7 @@ development orientation, and CLI reference describe the implemented boundary.
 
 ## Stage 9: implement native effective YAML display
 
-**Status:** pending. **Prerequisite:** Stage 8.
+**Status:** complete. **Prerequisite:** Stage 8.
 
 1. Implement `config show`; its only initial format is yaml (default and explicit).
    Single scope writes Effective.WriteEffective directly to Out with no envelope,
@@ -633,6 +633,16 @@ labels and native values. Cover an already marked native document, missing/null/
 empty structures, a second acquisition failure with no prefix, and a writer failure
 after output begins. These protect selected behavior, not encoder whitespace.
 
+**Completion evidence:** installed `config show` when a scope declares it, with
+YAML as its only format. Single-scope output passes through the native effective
+writer; aggregate output acquires and checks every view before emitting framed
+native documents in scope order. Existing markers, leading comments and YAML
+directives are retained, including explicit document termination where needed
+between directive-bearing documents. Checks cover native single-scope bytes,
+aggregate document decoding and values, invalid formats, acquisition failure with
+empty output, and incomplete delivery after a writer failure. `go test ./...`
+passes; README, development orientation, and CLI reference describe the feature.
+
 ## Stage 10: implement source inventory reports
 
 **Status:** pending. **Prerequisite:** Stage 9.