Record Notarius upgrade validation

docs/roadmap/implementation.md

@@ -1,6 +1,6 @@
 # Implementation Plan 0020: Adopt Notarius v0.8.1
 
-Status: ready
+Status: implemented — independent review pending
 
 Target executor: GPT-5.6-Terra
 
@@ -151,6 +151,8 @@ Notarius transport retries`.
 
 ## Stage 3: Document Compatibility and Prepare Independent Review
 
+Completion: complete (2026-09-28).
+
 ### Required Policy Review
 
 Read workspace `AGENTS.md`, `docs/orientation.md`, `docs/conventions.md`,
@@ -228,6 +230,11 @@ Plan approved.
   cases. Existing v0.7.0 selection, supplied-Go recovery, imports, pipelines,
   cache behavior, and clean immediate repeats passed. Role `git diff --check`
   passed.
+- Stage 3: role commits `b1b922c`, `380b6a3`, and `6aef48b` provide the
+  implementation and documentation. The README was checked against tagged
+  v0.8.0/v0.8.1 upstream guidance. Documentation-only changes reused Stage 2
+  integration evidence; role and workspace `git diff --check` and
+  `scripts/status` passed. F0020 remains open for independent review.
 
 ## Open Questions