For agents, on top of README.md, which they read first.

• No std::fs, std::net, std::time::Instant, threads or windowing in console/, alttp/ or panels/. The browser build has none of them; a crate that reaches for one stops the WASM target compiling, and nothing else will tell you. The native-only crates are zbanks/ (C and a signal handler; src/outcomes.rs writes a file), decisions/ (a socket through jev-http, and its history log), replay/ (a run's log and keyframes are files) and mcp/ (sockets, threads, files — see its own CLAUDE.md). None of those four may become a dependency of a portable crate.
• Third-party crates are named in ../third-party/rust/Cargo.toml and turned into buck targets by reindeer. Never hand-edit ../third-party/rust/BUCK.