Rust Cursor Rules Template

---
description: "Ownership & Borrowing"
alwaysApply: false
---
- Prefer borrowing (&T, &mut T) over taking ownership when possible.
- Use snake_case for variables, functions, and methods.
- Use PascalCase for types, traits, and enums.
- Use SCREAMING_SNAKE_CASE for constants and statics.
- Clone only when ownership transfer is unavoidable.
- Use references with explicit lifetimes only when the compiler requires them.

---
description: "Error Handling"
alwaysApply: false
---
- Use Result<T, E> for fallible operations — no exceptions.
- Use the ? operator for error propagation.
- Use thiserror for custom error types with derive macros.
- Use anyhow for application-level error handling.
- Use Option<T> instead of null — never use unwrap() in production code.
- Use expect() with descriptive messages during development only.

---
description: "Modules & Crates"
alwaysApply: false
---
- Use mod declarations to organize code into modules.
- Use pub to control visibility — keep internals private by default.
- Use use statements for imports at the top of each file.
- Use pub(crate) for internal visibility within the crate.
- Use workspace for multi-crate projects.
- Keep module files focused: one primary concern per module.

---
description: "Idiomatic Patterns"
alwaysApply: false
---
- Use match for exhaustive pattern matching.
- Use if let for single-pattern matching when fallback isn't needed.
- Use iterators (map, filter, collect) over explicit loops.
- Use derive macros (Debug, Clone, PartialEq) for boilerplate.
- Use impl Trait for return types when the concrete type is complex.
- Use trait bounds with where clauses for readability.