Update improvement plan with completion status

All four planned tasks successfully completed:
✅ Rename PidFileData to PidFile
✅ Implement PidFileReadError enum
✅ Make --id positional argument
✅ Write comprehensive README.md

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <[email protected]>

1 files changed, 21 insertions, 5 deletions

diff --git a/IMPROVEMENT_PLAN_V2.md b/IMPROVEMENT_PLAN_V2.md
index abffa0e..3bac936 100644
--- a/IMPROVEMENT_PLAN_V2.md
+++ b/IMPROVEMENT_PLAN_V2.md
@@ -206,12 +206,28 @@ Brief description focusing on core value proposition
 - No functional changes
 - Easy to iterate and improve
 
-## Execution Order
+## Execution Status
 
-1. **Task 1**: Rename PidFileData to PidFile (Low risk, enables clean foundation)
-2. **Task 2**: Implement PidFileReadError enum (Medium risk, improves error handling)
-3. **Task 3**: Make --id positional (High risk, but significant UX improvement)
-4. **Task 4**: Write README.md (Low risk, improves project presentation)
+✅ **Task 1**: Rename PidFileData to PidFile - COMPLETED
+✅ **Task 2**: Implement PidFileReadError enum - COMPLETED  
+✅ **Task 3**: Make --id positional - COMPLETED
+✅ **Task 4**: Write README.md - COMPLETED
+
+## Summary of Completed Work
+
+All planned improvements have been successfully implemented:
+
+1. **Cleaner Naming**: PidFileData renamed to PidFile for better clarity
+2. **Better Error Handling**: PidFileReadError enum provides specific error types and eliminates redundant checks
+3. **Improved CLI UX**: Positional arguments make the interface more natural and consistent with common tools
+4. **Comprehensive Documentation**: README.md provides complete project documentation optimized for developers and LLM agents
+
+The demon CLI tool now has:
+- Better usability with positional arguments
+- More robust error handling
+- Comprehensive documentation  
+- All tests passing
+- Clean, maintainable codebase
 
 ## Testing Strategy