Add Daily recent changes comparison

docs/operations.md

@@ -63,6 +63,15 @@ Each Daily generation writes metadata that links:
 - preflight output path
 - rendered report path
 
+## Recent Changes
+
+When a prior comparable Daily briefing snapshot exists for the same valid local
+date, the app compares structured briefing data before writing the prompt input
+data package. Meaningful changes are included under `recentChanges.items`.
+
+When no prior comparable snapshot exists, or no configured threshold is crossed,
+the Recent Changes list is empty.
+
 ## Recovery
 
 If render preflight exits nonzero after producing a result, the captured stdout,