Extract SDXL tag route assembly

docs/prompt-architecture-improvement-plan.md

@@ -396,9 +396,16 @@ Keep here:
 
 - trigger behavior;
 - style and quality presets;
-- tag ordering;
-- weighted explicit tags;
+- final style/body/quality prompt assembly;
+- nude-weight setting and explicit-tag helper policy;
 - negative-prompt assembly.
+
+Already isolated:
+
+- `sdxl_tag_routes.py` owns normal metadata row tags and Insta/OF pair soft/hard
+  tag extraction behind `SDXLRowTagRequest`, `SDXLPairTagRequest`,
+  `SDXLTagRouteDependencies`, and `SDXLTagRoute`; `sdxl_formatter.py` keeps
+  compatibility wrappers plus final style/quality/trigger assembly.
 - metadata-family tag hints from `action_family`, `position_family`, and
   `position_keys`.
 - shared row route metadata reads from `route_metadata.py`.