## Summary
Refactors the monolithic `run.rs` file into a clean modular structure to
improve maintainability and code organization.
### Changes
- **Split `run.rs` into focused modules:**
- `run/environment.rs` - TestEnvironment and file operations
- `run/params.rs` - RunParams configuration and conditions
- `run/commands.rs` - Built-in command implementations
- `run/execution.rs` - Command dispatch and execution logic
- `run/mod.rs` - Public API coordination
### Benefits
- **Better maintainability** - Each file has clear responsibility
- **Easier navigation** - Find specific functionality quickly
- **Separation of concerns** - Commands, config, environment isolated
- **Prepares for future features** - Clean foundation for WorkdirRoot
and other enhancements
### Test Plan
- [x] All 37 tests still pass
- [x] No functionality changes
- [x] Clean compilation with no warnings
- [x] Pre-commit hooks pass (formatting, linting, compilation)
This is a pure refactoring with no behavior changes - just improved code
organization.
🤖 Generated with [Claude Code](https://claude.ai/code)
Co-authored-by: Claude <noreply@anthropic.com>
