Add configuration path explanations

docs/roadmap/implementation.md

@@ -1,6 +1,6 @@
 # Initial CommandKit implementation plan
 
-Status: implementation underway; Stages 1-10 complete and Stages 11-14 pending.
+Status: implementation underway; Stages 1-11 complete and Stages 12-14 pending.
 
 Date: 2026-10-07.
 
@@ -676,7 +676,7 @@ describe the report.
 
 ## Stage 11: implement path explanation reports
 
-**Status:** pending. **Prerequisite:** Stage 10.
+**Status:** complete. **Prerequisite:** Stage 10.
 
 1. Implement single-scope `config explain --path POINTER`. Presence is required;
    explicitly empty is the root. Parse with public `configkit.ParsePath` before
@@ -704,6 +704,16 @@ inherited values; malformed versus unknown outcomes; redacted before/after and
 reference-name preservation; YAML snapshot strings and inheritance pointers;
 native text equivalence; writer failure. Update explanation CLI documentation.
 
+**Completion evidence:** installed single-scope `config explain` with required
+JSON Pointer `--path`, text as the native writer output, and explicit YAML DTOs
+for snapshots, origins, history, inheritance, and secret references. Malformed
+pointers return usage before context creation or acquisition; unknown paths are
+operational failures checked before native writing. Checks cover root and escaped
+paths, inherited and historical values, ordered resolution dependencies, secret
+redaction and name-only references, exact native text, missing/invalid/unknown
+paths, and writer failure. `go test ./...` passes; README, development orientation,
+and CLI reference describe the feature.
+
 ## Stage 12: integrate the PromptKit configuration scope
 
 **Status:** pending. **Prerequisite:** Stage 11.