diff --git a/CLAUDE.md b/CLAUDE.md
index 7ac4f01d0..4303582c2 100644
--- a/CLAUDE.md
+++ b/CLAUDE.md
@@ -427,10 +427,12 @@ git checkout -b feature/your-feature-name
 
 ## Code Style
 
-- Ruff for linting and formatting (configured in `pyproject.toml`)
-- Line length: 100 characters
-- Pre-commit hooks run ruff automatically
-- Type hints encouraged (mypy checks enabled)
+- **Formatter**: Ruff (configured in `pyproject.toml`)
+- **Line length**: 100 characters
+- **String quotes**: Use double quotes `"` not single quotes `'` (enforced by ruff-format)
+- **Pre-commit hooks**: Run ruff linting and formatting automatically
+- **Type hints**: Encouraged (mypy checks enabled)
+- **Important**: Always run `pre-commit run --all-files` before committing to catch formatting issues
 
 ## Testing Strategy