Know what changed
Action keys cover sources, dependency artifacts, toolchain, target, features, flags, configuration and environment.
Rust first · reads your existing Cargo.toml
Build work,
accounted for.
Mitts identifies every eligible compile action by its full set of inputs, stores the output once as an immutable object, and restores it into an isolated workspace target. If an input can't be accounted for, the action stays uncached.
action / rlibinputs tracked
- src
source set · Cargo.toml - deps
dependency artifacts - tool
rustc · target triple - cfg
features · profile · flags - env
declared environment
action key
sha256(inputs)shared store
cas/ab/3f…immutableworkspace
.mitts/target/isolatedReuse follows the inputs.
A cache hit counts only when the effective compile inputs match exactly. Correctness comes before hit rate.
Objects never mutate
Content-addressed artifacts are verified before use. A corrupt object is rejected and rebuilt, never trusted.
State stays local
Mutable outputs live in each workspace's target, apart from shared objects. No unsafe hardlinks, no timestamp tricks.
A deliberate cache boundary.
Mitts caches the actions it can describe completely. Everything else runs normally and is reported as uncached.
- Rust library and binary actions with matching keys
- Concurrent builds coordinate with single-flight locks
- C/C++ adapter shares the same store
- Build scripts, proc macros, and mixed native outputs bypass the initial cache
Unknown inputs are never treated as unchanged. If Mitts can't prove an action is compatible, it builds it.
A small CLI.
No new manifest and no second lockfile. Point it at a Cargo workspace.
- mitts build
- Compile the package and its dependencies into the isolated Mitts target
- mitts run
- Run a binary of the local package
- mitts explain
- Show the build plan, compilation units, and cache eligibility
- mitts fetch
- Fetch dependencies into the global source store
- mitts gc
- Prune old or unreferenced objects within storage quotas
- mitts clean
- Remove workspace artifacts, and optionally the shared cache
Where it stands.
Milestones M0–M6 are complete and verified by the workspace test suite. The repository is still private.
- M1Uncached build correctness
- M2Content-addressed store & action cache
- M3Parallel fetcher & lockfile resolution
- M4Native parallel DAG runner
- M5Pilot, deduplication & conservative GC
- M6Second adapter: C/C++