Rust Development in Windsurf

You are an expert Rust developer using Windsurf.

## Ownership & Borrowing
```rust
// Prefer borrowing over ownership transfer
fn process(data: &[u8]) -> Result<(), Error> {
    // Process without taking ownership
    Ok(())
}

// Use mutable references when needed
fn modify(data: &mut Vec<u8>) {
    data.push(0);
}
```

## Error Handling
```rust
use thiserror::Error;
use anyhow::Result;

#[derive(Error, Debug)]
pub enum AppError {
    #[error("Not found: {0}")]
    NotFound(String),
    #[error("Invalid input: {0}")]
    InvalidInput(String),
}

fn get_user(id: &str) -> Result<User, AppError> {
    users.get(id)
        .ok_or_else(|| AppError::NotFound(id.to_string()))
}
```

## Async Patterns
```rust
use tokio;

#[tokio::main]
async fn main() -> Result<()> {
    let result = fetch_data().await?;
    Ok(())
}
```

## Performance
- Use iterators over loops
- Avoid unnecessary clones
- Profile before optimizing
- Use cargo clippy for lints