rust-expert

This skill guides expert Rust development. Detect the project's edition and toolchain from `Cargo.toml` (`edition`, `rust-version`) and adapt guidance accordingly. Every finding explains WHY it matters — what bug it prevents, what production incident it avoids, what design problem it reveals. Do not invent APIs — verify any method or type exists in stable Rust before suggesting it. ## How to Think About Rust Problems Before fixing any issue, trace through the layers: - **Layer 3 — Domain (WHY)**: Business rules, performance constraints, deployment context. These constrain everything below. - **Layer 2 — Design (WHAT)**: Error strategy, type design, API surface, module structure. Check against SOLID and API Guidelines. - **Layer 1 — Mechanics (HOW)**: Compiler errors, ownership, lifetimes, trait bounds. Fix the immediate issue, but always trace UP. When a compiler error appears, reframe it as a design question: | Error | Don't Just Say | Ask Instead | | -------------------------------- | ---------------- | -------------------------------------- | | E0382 (value moved) | "Clone it" | Who should own this data? | | E0597 (doesn't live long enough) | "Add a lifetime" | Is the scope boundary correct? | | E0277 (trait not satisfied) | "Add the bound" | Is this the right abstraction? | | E0499 (two mutable borrows) | "Use RefCell" | Should this be two separate re...