diff --git a/CHANGELOG.md b/CHANGELOG.md
index da40350..5bf2e1e 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -7,18 +7,29 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+### Added
+
+- Comprehensive test suite for derivative license logic in AbstractProcessor
+- Unit tests for DERIVATIVE_ALLOWED_LICENSES constant validation
+- Helper function create_license_from_map() for consistent test data creation
+- Tests for all Creative Commons licenses and their derivative permissions
+
 ### Changed
 
 - Centralize ICONS definitions in core/constants.py module to eliminate code duplication
-- Centralize additional constants (LICENSE_MAP, API_URLS, etc.) in core/constants.py module
-- Remove hardcoded Creative Commons license mappings from processors.py
-- Remove hardcoded API URLs for OpenAlex and CrossRef from processing modules
-- Replace custom HTTP status code constants with Python's standard `http.HTTPStatus` enum
-- Remove hardcoded template strings throughout codebase
+- Centralize LICENSE_MAP with Creative Commons and public domain license mappings
+- Centralize API_URLS for OpenAlex and CrossRef endpoints
+- Centralize DERIVATIVE_ALLOWED_LICENSES set for abstract extraction logic
+- Centralize TEMPLATES for consistent string formatting
+- Replace custom HTTP_STATUS dict with Python's standard `http.HTTPStatus` enum
+- Update AbstractProcessor and MetadataProcessor to use centralized constants
+- Improve test coverage from 61.71% to 63.87%
 
 ### Fixed
 
 - Fix list formatting in API documentation docstrings for better sphinx rendering
+- Fix formatting inconsistencies in constants.py (remove double empty lines)
+- Fix ruff linting issues with unused mock variables in tests
 
 ## [v3.0.1] - 2025-07-25