Appendix A — Atlas Crate Dependency Map

Figure A.1 — A. Atlas Crate Dependency Map Figure A.1 — A. Atlas Crate Dependency Map

A CFDrs-centric view of the Atlas stack — which crate owns which surface and which CFDrs crate consumes it.

Crate Map

Atlas crate	Surface	CFDrs consumer
`eunomia`	`RealField`, `ComplexField`, `FloatElement`, `IntElement`	every CFDrs crate
`leto`	`NdArray<T,D>`, `CowArray`, geometry types	`cfd-math`, `cfd-1d`, `cfd-2d`, `cfd-3d`, `cfd-schematics`
`leto-ops`	dense/sparse linear algebra, Krylov solvers, sparse LU	`cfd-math`
`hermes-simd`	`SimdLane`, vectorized kernels	`cfd-2d::stencil`, `cfd-3d::fem`, `cfd-1d::kernel`
`mnemosyne`	`Arena`, `ScratchArena`	every CFDrs crate
`themis`	`Placement`, NUMA bindings	`cfd-3d`, `cfd-2d`
`moirai`	`Executor`, `TaskGraph`, channels	`cfd-2d::parallel`, `cfd-3d::parallel`, `cfd-optim`
`apollo`	`FftPlan`	`cfd-3d::spectral`, `cfd-2d::spectral`
`aequitas`	dimensioned quantities for public physical contracts	`cfd-core`, `cfd-1d`, `cfd-2d`, `cfd-3d`, `cfd-validation`
`hephaestus`	`Backend`, GPU kernels	opt-in via the `cfd-3d` GPU feature
`coeus`	`Tensor`, autodiff	not consumed — CFDrs runs no autodiff
`ritk`	image I/O	not consumed — CFDrs holds no image data
`consus`	persistent storage	`cfd-io` (planned)

The dependency direction is one-way — foundation crates never depend on CFDrs — and these properties are enforced rather than asserted:

cargo tree resolves no ndarray, nalgebra, rayon, tokio, or rustfft in the CFDrs graph; the Atlas crates above are the sole providers of those roles.
unsafe SIMD intrinsics live only in hermes-simd, and raw buffer reconstruction only in mnemosyne.
cfd-validation parity passes on every canonical scenario.