project-principleslisted

# Project Principles Skill This skill defines the fundamental design principles and coding standards for the edda project. These principles are MANDATORY for all code written in this project and should guide every development decision. ## The Four Core Principles ### 1. YAGNI (You Aren't Gonna Need It) - CORE PRINCIPLE **Don't add functionality until it's actually needed.** Quick rules: - Start with the simplest solution that works - Avoid premature abstractions - Delete unused code aggressively - No "just in case" features **When coding:** Ask "Do we need this NOW?" If not, don't add it. > For detailed guidelines and examples, read `yagni.md` ### 2. Proper Error Handling (Not Defensive Programming) **Use `Result`/`Option` and `?` propagation. Don't panic or swallow errors.** Quick rules: - Only handle errors when you can meaningfully recover - Let errors propagate with `?` to where they can be properly addressed - Avoid `.unwrap()` in library code - use `?` or `.expect("reason")` - Trust the type system and Rust's ownership model **When coding:** Only add explicit error handling when you have specific recovery logic. > For detailed guidelines and examples, read `no-defensive.md` ### 3. Leverage Rust's Type System **Use the type system to enforce correctness at compile time.** Quick rules: - Use newtypes for domain concepts (`SessionId(Uuid)` not raw `Uuid`) - Make invalid states unrepresentable with enums - Use `thiserror` for library errors, `anyhow` for appl