Record release tooling validation

docs/roadmap/implementation.md

@@ -1,6 +1,6 @@
 # Release tooling implementation plan
 
-Status: Stages 1–4 complete; Stages 5–6 pending.
+Status: Stages 1–5 complete; Stage 6 pending.
 
 Follow the stages in integer order. This is one end-to-end sprint: intermediate
 stages may temporarily leave scripts, tests, and documentation inconsistent.
@@ -249,6 +249,21 @@ selected checks, separate outcomes, and recovery without obsolete scaffolding.
 
 ## Stage 5: Verify the final source and record validation boundaries
 
+**Completed.** With Go 1.26.8 and local toolchain selection, shell syntax,
+executable modes, JSON parsing, ignored/untracked token path, and whitespace
+checks passed. The real helper reported ReleaseKit v0.8.0 under foreign target
+settings and an inherited workspace; a disposable copy with missing tool sums
+failed under inherited `-mod=mod` without changing its sums.
+
+The staged tree was archived and committed in a disposable repository. The
+pinned ReleaseKit core check passed, including the root suite and selected
+committed-file checks. Both integration checks passed using the documented
+temporary workspace shim, including their current-source suites and selected
+file checks. Independent workspace-off tests for both integrations failed on
+missing core symbols including `CompletionHint` and `Explanation`, consistent
+with the baseline dependency-version mismatch. The shimmed checks do not prove
+published dependency alignment or integration release readiness.
+
 Use Go 1.26.8 on `PATH`, `GOTOOLCHAIN=local`, and prepared dependency caches.
 Reuse checks for unchanged final content instead of repeating them for each
 stage. Preserve the existing ignored `go.work` (currently declaring Go 1.26.10);