Record public facade boundary

docs/roadmap/implementation.md

@@ -181,6 +181,35 @@ distinguish decision from implementation, and documentation links pass.
 Run `go test . -run 'LocalDocumentationLinks|DependencyImportBoundary|Example|Facade'`
 and the everyday check. No engine migration in this stage.
 
+### Completion
+
+Status: complete (2026-09-12).
+
+Baseline behavior was verified at `28e7fc5f690b36c60e4d03586afcff00fb1dee90`;
+this plan was introduced by `eb7de8e40ab944f022a2b6984f4d4e0086f1484d`. The
+complete root surface was inventoried with `go doc -all .`: lifecycle and generic
+entry points; root value/input types (`Path`, `Source`, `Secret`); callback and
+option records; metadata, provenance, diagnostics, history, and rendering
+records; typed errors and bootstrap reports; and the scalar enum families. The
+inventory also covered receiver methods, generic instantiations, and relevant
+interfaces (`error`, `fmt.Formatter`, `fmt.Stringer`, `json.Marshaler`, and
+`io.WriterTo`). Existing behavioral tests remain the source of detailed API
+semantics; `facade_compatibility_test.go` supplies compact external-package
+coverage for the migration boundary.
+
+Added ADR 0006 and the architecture rule for root-owned public wrappers and
+inward-only implementation dependencies. They describe the accepted target, not
+an already-completed extraction. Repaired the development guide, source-origins
+record, and remediation record to identify the old provenance plan by its Git
+revision instead of linking to this plan. No engine or lifecycle migration was
+introduced.
+
+Validation on Linux with Go 1.26.7 passed: the focused documentation,
+import-boundary, executable-example, and facade checks, followed by
+`./scripts/check.sh`. There were no deviations. The next handoff copies the
+unchanged root implementation into the bounded internal relocation candidate;
+it must retain the documented public behavior while proving engine independence.
+
 ## Stage 2 — Establish the internal relocation candidate
 
 Status: not started.