Configuration files require careful validation to ensure they work as intended and don't introduce unintended side effects. This includes verifying ignore patterns don't create parent-child conflicts, understanding rule severity implications, and confirming dependency changes are expected. For ignore patterns, ensure re-inclusion rules don't conflict with parent directory exclusions: ``` # Bad: Can't re-include files in ignored parent directories /tests/format/**/*.* !/tests/format/**/format.test.js # Good: Re-include parent directories first /tests/format/**/*.* !/tests/format/**/*.*/ !/tests/format/**/format.test.js ``` For rule configurations, understand the difference between "error" and "warn" severity levels and use appropriate tooling flags like `--max-warnings=0` to enforce standards consistently. For dependency changes, use tools like `yarn why` to understand why specific versions exist and `yarn-deduplicate` to clean up duplicate dependencies before merging. Always test configuration changes locally and verify they produce the expected behavior across different scenarios.