# Rust Project Guidance
## Project Layout
- Prefer a workspace for multi-crate projects.
- Binary crate: `src/main.rs` thin; logic in `src/lib.rs` or modules.
- Library crate: `src/lib.rs` public API; internal modules private.
- Tests: `tests/` integration; unit tests co-located.
## Error Handling
- Libraries: define `enum Error` with `thiserror`.
- Applications: use `anyhow::Result` at boundaries.
- Avoid `unwrap()`/`expect()` in production.
## Design Patterns
- Newtype, Builder, trait objects, From/Into, Default, enum state machines, RAII/Drop, interior mutability.
## Async
- Use tokio; avoid blocking in async; use spawn_blocking; channels for message passing.
## Testing
- Unit + integration; property tests with proptest.
## Tooling
- cargo fmt, clippy, test, doc, audit, deny.
## Common Crates
- CLI: clap, dialoguer, indicatif, console, tracing.
- Web: axum, actix-web, reqwest, tower, tower-http.
- DB: sqlx, diesel, sea-orm.
- Errors: thiserror, anyhow, miette.
- Testing: proptest, mockall, wiremock, assert_cmd.