diff --git a/CHANGELOG.md b/CHANGELOG.md
index cd88320e..52d397a5 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,4 +1,36 @@
 # Changelog
+## [0.5.0] - 2025-10-26
+
+### Added
+- **Clean TDD-Driven Editor Architecture**: Complete rewrite with object-oriented JavaScript architecture featuring Section, SectionManager, and DOMRenderer classes
+- **Enhanced Test Framework**: Comprehensive testing framework with clean separation of concerns for robust development
+- **Multiple Concurrent Section Editing**: Support for editing multiple sections simultaneously with intelligent management
+- **Intelligent Section Splitting**: Advanced heading detection and section management capabilities
+- **Four-Layer Content Management**: Sophisticated content state management (original, current, pending, editing layers)
+- **Enhanced Status Dialog**: Repository info display showing version, git commit status, and actual save filename
+- **Elegant Slide-in Control Panel**: Floating control panel for edit mode with improved UX
+- **Intelligent Auto-sizing Textarea**: Optimal editing experience with smart textarea resizing
+- **Enhanced Empty Line Preservation**: Better markdown structure preservation with automatic paragraph separation
+
+### Fixed
+- **Textarea Sizing and Font Preservation**: Resolved sizing issues and maintained consistent font rendering
+- **Markdown Structure Preservation**: Fixed roundtrip formatting issues in save functionality
+- **Section Duplication Prevention**: Eliminated duplicate sections when saving edited content
+- **Section Position Preservation**: Prevented unwanted section jumping during editing
+- **CSS Embedding Issues**: Resolved import errors in HTML template generation
+- **Control Panel UX**: Hidden control ribbon when panel is expanded for cleaner interface
+
+### Changed
+- **Action Semantics**: Proper implementation of Accept, Cancel, and Reset operations
+- **Global Reset Functionality**: Enhanced reset capabilities across the editor
+- **Makefile Organization**: Reorganized installation targets for better user experience
+
+### Technical Improvements
+- Complete legacy editor system replacement
+- Test-driven development approach implementation
+- Enhanced UI/UX with better section positioning
+- Improved content management workflow
+
 ## [0.4.0] - 2025-10-25
 
 ### Added
diff --git a/markitect/__version__.py b/markitect/__version__.py
index 83b81887..ad576394 100644
--- a/markitect/__version__.py
+++ b/markitect/__version__.py
@@ -11,7 +11,7 @@ from pathlib import Path
 from typing import Optional
 
 # Base version from pyproject.toml
-__version__ = "0.4.0"
+__version__ = "0.5.0"
 
 def get_git_commit_hash() -> Optional[str]:
     """Get the current git commit hash if available."""
diff --git a/pyproject.toml b/pyproject.toml
index ba6b4f43..b7dabb24 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -4,7 +4,7 @@ build-backend = "setuptools.build_meta"
 
 [project]
 name = "markitect"
-version = "0.4.0"
+version = "0.5.0"
 description = "Advanced Markdown engine for structured content"
 readme = "README.md"
 requires-python = ">=3.8"