Rust modules (no mod.rs)

Rule

For a module named foo:

• Preferred: foo.rs (module root) and foo/ (child modules live here as foo/bar.rs, etc.).
• Avoid: foo/mod.rs as the root of foo. Do not introduce new mod.rs files; migrate away when touching that area.

lib.rs / main.rs follow the same idea: mod foo; resolves to foo.rs or foo/mod.rs — choose foo.rs + foo/.

Layout sketch