Record the public facade compatibility baseline

docs/roadmap/implementation.md

@@ -95,6 +95,17 @@ coverage passes, and no production ownership or behavior has changed. If the
 existing tests already cover these risks, do not add tests solely to fill this
 stage; record the coverage reviewed and proceed.
 
+### Completion
+
+- [x] Pre-refactor baseline commit: `7a858c2365e1a3625de67a46f5c488e0fe31856b`.
+- [x] Captured the exported API inventory outside the tracked repository for
+  the final comparison.
+- [x] Reviewed existing public coverage for source replacement, backend
+  accumulation, option error and capture timing, injected-value and profile
+  ownership, nil and zero facade behavior, prepared execution, and typed error
+  translation. The existing tests cover these relocation risks without a
+  duplicate matrix.
+
 ## Stage 2: Relocate The Memory Profile Repository
 
 Purpose: move a self-contained repository before changing engine assembly.