diff --git a/CLAUDE.md b/CLAUDE.md
index e48c817..9e8db6d 100644
--- a/CLAUDE.md
+++ b/CLAUDE.md
@@ -11,7 +11,8 @@ This is a personal agenda web application built with Flask that tracks various e
 
 ## Python Environment
 - Always use `python3` directly, never `python`
-- Run `black` code formatter after creating or modifying Python files
+- Run `black` code formatter on modified code after creating or modifying Python files
+- Avoid running `black .`
 - Main entry point: `python3 web_view.py` (Flask app on port 5000)
 - Tests: Use `pytest` (tests in `/tests/` directory)
 
@@ -26,4 +27,4 @@ This is a personal agenda web application built with Flask that tracks various e
 ## Git Workflow
 - Avoid committing unrelated untracked files (e.g., `node_modules/`, build artifacts)
 - Only commit relevant project files
-- Personal data directory (`personal-data/`) is excluded from git
\ No newline at end of file
+- Personal data directory (`personal-data/`) is excluded from git