The primary purpose of this PR appears to be:
1. Simplifying the change notification API by removing the redundant value parameter from callbacks
2. Improving the reactive system's handling of specialized types (Text and Boxed) in flat data
3. Adding better test coverage for text handling in the flat data model
The new code should be more efficient as it:
- Avoids unnecessary iterations when objects aren't empty
- Has clearer path management
- Reduces redundant object traversals