mr boxington
A shared cache. A tidier target/.
Reuse Cargo builds across worktrees, keep disk use in check, and run builds together.
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mbx is a build cache for Rust projects. Cargo still resolves dependencies,
plans builds, and runs your tools. mbx restores matching compiler outputs from
one shared store and compiles the rest. Each command starts its own cache
agent and stops it when the build ends; there is no daemon to manage.
Get started
With mise:
mise use --global --tool-option mr_boxington=true rust mr-boxington
Or with Cargo:
cargo install mbx --locked
mbx setup
With mise 2026.9.2 or newer, the Rust option enables wrapping without an
mbx setup hook. Open a shell with mise activation or shims on PATH,
check Cargo's path,
and use Cargo normally:
cargo build
cargo test --workspace --all-features
cargo clippy --workspace --all-targets -- -D warnings
To try mbx without automatic wrapping, install it and run mbx build directly.
For coding agents and other non-interactive tools, use mise exec -- cargo build
or put mise's shims on their PATH. The
setup guide covers desktop applications,
older mise versions, and standalone shims.
Verified release archives are available for Linux, macOS, and Windows.
All installation options →
What you get
- Reuse across worktrees. Equivalent compilations share cache keys even
when checkout paths differ. Building one worktree warms the next.
- Automatic cleanup. The store has a disk budget. Managed targets are
collected when their checkout disappears, they go unused, or they exceed
their budget. Preview collection with
mbx gc --dry-run.
- Parallel builds with a shared budget. Independent Cargo commands share
CPU and memory permits and deduplicate identical compilations in flight.
Give each command its own target directory to avoid Cargo's directory lock.
- Faster local edits. mbx keeps private incremental state for crates you
are changing while sharing eligible work across the rest of the build.
- CI reuse. Use GitHub Actions cache, a compatible cache server, or an
S3-compatible bucket. Pull request builds restore remote work without
publishing new objects through mbx.
- An explanation for each result. Hits, misses, unavailable lookups, and
bypasses are counted separately.
mbx explain --last helps diagnose a build.
A cold store needs a build to fill it. Unsupported invocations run normally
without caching, and restored debug information can retain the original
checkout's paths. See how it works
and the caching limits.
Use it in GitHub Actions
permissions:
contents: read
jobs:
test:
runs-on: ubuntu-latest
steps:
- uses: actions/checkout@v7
- uses: jdx/mr-boxington-action@v1
- run: mbx test --workspace
Install your chosen Rust toolchain before the cache action. The default backend
restores a pruned Cargo target and registry archive; pull requests are
restore-only. See the GitHub Action guide
for complete workflows, parallel builds, remote servers, and release policy.
Inspect and maintain the cache
mbx doctor # check tools, setup, and cache access
mbx tui # watch builds across the machine
mbx stats # report lifetime savings and workspace sharing
mbx explain --last # explain the last recorded build
mbx cache stats # inspect storage
mbx gc --dry-run # preview collection
mbx clean # remove this workspace's managed target
On a filesystem that supports reflinks, restored outputs share data blocks
with the store until modified. Elsewhere, mbx copies bytes. An existing real
target/ is only replaced after you accept a prompt.
Understand managed targets →
Find your next step
Contribute
See CONTRIBUTING.md for development setup, documentation
checks, tests, and pull request conventions. Ask questions in
Discussions; report suspected
vulnerabilities through the private process in SECURITY.md.
mbx builds on Cargo and was informed by sccache and kache, which directly
inspired its design. Acknowledgements.
License
MIT
mbx 是一个 Rust 项目的构建缓存。Cargo 仍然负责解析依赖、规划构建并运行你的各种工具；mbx 则从一份共享存储中恢复匹配的编译产物，只重新编译剩下的部分。