Fixed minor inconsistencies and ambiguities in the implementation roadmap

docs/roadmap/implementation.md

@@ -82,6 +82,8 @@ Implementation scope:
 - introduce `pkg/bundle` with the public source manifest model, schema version,
   digest logic, parsing, validation, explicit file-list building, scan-based
   building, and zero-`Created` defaulting to current UTC;
+- implement the locked Stage 2 exported API symbols defined in
+  `docs/roadmap/public_bundle_package.md`;
 - update internal validation to consume the shared implementation without
   behavior drift;
 - keep destination state, publish planning, storage backends, transforms,
@@ -111,8 +113,10 @@ Goal: implement the local bundle writer portion of
 
 Implementation scope:
 
-- add producer-side local bundle writing with staging and atomic promotion where
-  practical;
+- add producer-side local bundle writing with staging, atomic filesystem
+  operations where practical, and best-effort restore on overwrite failure;
+- implement the locked Stage 3 exported API symbols defined in
+  `docs/roadmap/public_bundle_package.md`;
 - keep the writer filesystem-local and producer-focused;
 - do not expose distributor storage backends or publication behavior through
   the public package.
@@ -124,7 +128,7 @@ Documentation updates after implementation:
 
 Tests:
 
-- writer creates a complete valid local bundle;
+- writer creates a complete valid local bundle through staged promotion;
 - writer output validates through distributor's normal validation path;
 - overwrite and failure behavior avoid leaving a completed bundle path without
   a valid manifest where practical.