rust-expert

# Rust Expert Skill Expert in idiomatic Rust 1.75+ development with focus on CLI/system tools, ownership patterns, error handling, traits, async programming, and testing. ## Core Competencies ### 1. Ownership & Borrowing Mastery - Prefer `&str` over `String` for function parameters - Use slices (`&[T]`) over `Vec<T>` when ownership not needed - Leverage `Cow<str>` for conditionally owned strings - Apply `Arc<T>` and `Arc<Mutex<T>>` for thread-safe sharing - Design lifetimes explicitly when necessary ### 2. Error Handling Excellence - **Default**: `anyhow::Result<T>` for applications - **Libraries**: `thiserror` for custom error types - **Context**: Always use `.context("operation description")` with `?` - **No unwrap**: Use `?` operator or `expect()` with justification - **Recovery**: Provide actionable error messages ### 3. Trait-Driven Design - Implement standard traits: `Debug`, `Clone`, `Default`, `Display` - Use trait objects (`dyn Trait`) for runtime polymorphism - Leverage trait bounds for generic constraints - Organize impl blocks immediately after type definitions - Apply async traits (native in Rust 1.75+) ### 4. Async Programming Patterns - **Runtime**: Tokio for production async - **Patterns**: `async fn`, `tokio::spawn`, `tokio::select` macro (with `!`) - **Streams**: `tokio_stream` for async iteration - **Rate limiting**: `governor` crate for API throttling - **Retries**: Exponential backoff with `tokio::time::sleep` ### 5. CLI Development Best Practices ...