rust-lang/rustlings

src/main.rs + src/cli.rs

Entry point that parses CLI arguments (init/dev/run/check-all/reset/hint/watch) and dispatches to subsystems.

src/app_state.rs

Holds exercise list, done/pending progress, current-exercise index, and reads/writes the `.rustlings-state.txt` state file; also resets exercises (embedded dump or `git stash`).

src/watch.rs

Interactive watch mode that recompiles/re-runs exercises on file changes using notify events.

src/cmd.rs

CmdRunner abstraction for invoking cargo/clippy/test subprocesses on exercises.

src/info_file.rs + rustlings-macros

Parses the exercise manifest (info.toml) and provides proc macros embedding exercise metadata/files into the binary.

src/embedded.rs

Embedded copies of official exercise/solution files used by init and reset.

src/init.rs

Scaffolds a new rustlings project directory (exercises/, solutions/, generated Cargo.toml).

src/dev.rs

Developer/maintainer commands for managing exercise lists and regenerating dev-Cargo.toml bins.