# pmoutils - Agent Guidelines

## Build & Test Commands

```bash
# Build the library
cargo build

# Run all tests (unit + doctests)
cargo test

# Run a single unit test
cargo test --lib ip_utils::tests::test_guess_local_ip

# Run tests for a specific module
cargo test --lib ip_utils::tests

# Run only doctests
cargo test --doc

# Lint with clippy
cargo clippy --all-targets -- -D warnings

# Format code
cargo fmt
```

## Code Style Guidelines

### General
- Rust 2024 edition
- Follow official Rust style guide and Clippy recommendations
- All code must be documented with Rustdoc comments
- Prefer `&str` over `String` for function parameters when possible

### Imports
- Group imports by source: std → external crates → crate modules
- Use `use` statements at the top of each module
- Import specific items, not glob imports (`use std::net::IpAddr`, not `use std::net::*`)

### Naming Conventions
- Types: `PascalCase` (e.g., `ProcessPortInfo`, `TransportProtocol`)
- Functions/methods: `snake_case` (e.g., `guess_local_ip`, `find_process_using_port`)
- Constants: `SCREAMING_SNAKE_CASE`
- Traits: prefix with `To` or descriptive noun (e.g., `ToXmlElement`)
- Tests: `test_functionality_what_it_does` format

### Error Handling
- Use `Option` for operations that may not return a value (e.g., `find_process_using_port` returns `Option<ProcessPortInfo>`)
- Use `?` operator for propagating errors
- Return default values (like `"127.0.0.1"`) only when appropriate fallback exists
- Document error conditions in function documentation

### Types
- Prefer concrete types over generics unless abstraction is needed
- Use `u32` for PIDs, `u16` for ports
- Use `String` for process names and owners (owned, mutable)
- Derive `Debug` and `Clone` for data structures

### Documentation
- All public items require Rustdoc comments
- Include `# Examples` section when useful
- Document return values and error conditions
- Use triple slashes `///` for module-level documentation

### Formatting
- Run `cargo fmt` before committing
- Use 4 spaces for indentation (default Rust formatter)
- Keep lines under 100 characters when possible

### Testing
- Unit tests in same file as code (in `mod tests {}` block)
- Test names follow pattern: `test_<function>_<condition>`
- Include tests for edge cases (e.g., fallback to localhost)
- Verify return value formats and constraints
- Test filtering: `cargo test --lib ip_utils::tests::test_list_all_ips_no_loopback`