Always use stable, well-defined version constraints in configuration files to ensure reproducible builds and prevent unexpected behavior. Avoid using development branches for production dependencies. Key practices: 1. Use semantic versioning constraints: - Use `^` for minor updates: `"package": "^1.2.3"` - Use `~` for patch updates: `"package": "~1.2.3"` - Pin exact versions when needed: `"package": "1.2.3"` 2. Never use dev branches in production unless absolutely necessary. If required: ```json { "require": { "package": "1.2.*", }, "minimum-stability": "dev", "prefer-stable": true } ``` 3. Always commit lock files (e.g., composer.lock) to ensure consistent dependency versions across environments. 4. When updating versions, update all related configuration files and documentation to maintain consistency.