Working with mbx

Overview

mbx (Mr. Boxington) is a shared compiler cache for Cargo, plus automatic management of target/ directories. Cargo still resolves dependencies and decides what needs building; mbx restores matching compilations and runs the compiler for everything else.

Use this skill when:

• Installing mbx or enabling it for plain cargo commands
• A build reports few cache hits and you need to know why
• Deciding whether an mbx result (hit / miss / bypass) is expected
• Reclaiming disk from the cache store or managed target directories
• Adding mbx caching to CI, or migrating off sccache / rust-cache

The Iron Rules