21.1 Interop overview
Language-meta interop domain and how profiles bind primitives.
Interop overview
Start at Interop. Profiles (C ABI, Rust ABI) define how primitive data crosses boundaries; higher-level mapping rules live under Interop contracts.
User extern is not “link any Rust crate you found on crates.io”—read the Rust ABI profile before you @extern a dependency into production.