Rust Module Organization & Public API Design

Structure Rust modules by grouping code into logical directories based on domain and features, then control visibility using `pub`, `pub(crate)`, and `pub(super)` keywords to separate internal details from the public API.

The best way to define a public API in Rust is by using re-export patterns in your `lib.rs` file, which aggregates exposed items from internal modules into a single stable interface for library consumers.

You can conditionally expose API elements in Cargo by using feature gates, which allow you to compile specific code paths and modules only when certain Cargo features are explicitly enabled by the user.

The `cargo-public-api` tool prevents breaking changes by tracking your library's exposed API surface and validating it against previous versions to ensure no unintended modifications or removals occur during refactoring.

Use `pub(crate)` instead of `pub` in Rust when an item needs to be accessible across multiple modules within the same crate but must remain hidden from external users, preventing accidental API exposure.

Document a Rust public API effectively by applying best practices alongside module organization principles, ensuring re-exported items in `lib.rs` have clear documentation that explains their intended usage and stability.