Record completion of the Promptkit migration

docs/roadmap/implementation.md

@@ -2,7 +2,28 @@
 
 ## Status
 
-Ready for implementation.
+Complete as of 2026-07-28.
+
+## Completion Summary
+
+Promptkit's annotated `v0.1.0` tag remains published at commit
+`9e68a2bbf779545995270c47842048a3bc6c85dc`. Scriptorium's annotated
+`v0.12.0` tag object `734632371773bb7620ce9f18e79ae179a2a2b44b`
+resolves to independently validated commit
+`2f42bdde3957563cb9b7a1e27fdd4ab2516f621a`. The
+[hosted release](https://gitea.maximumdirect.net/eric/scriptorium/releases/tag/v0.12.0)
+succeeded with release notes matching the checked-in source, exactly the Linux
+`amd64` and `arm64` binaries, and verified SHA-256 checksums.
+
+Fresh remote module resolution and independent repository validation passed
+without sibling-repository state. The downloaded `amd64` binary completed an
+offline render; its existing command interface treated `--help` as an unknown
+command and printed usage. The `arm64` binary could not be executed on the
+`amd64` host, so its checksum, format, and target architecture were verified.
+Notarius at commit `de046a8f13e227676d79c3aa3b685b049902038d`
+remains migrated and verified, and no other downstream Go consumer was
+identified. All three repositories were clean and synchronized after
+validation.
 
 This plan implements the target state and policy decisions in
 [Step 9](step9.md). Execute the stages in order. A later stage may begin only