sparsax : A jax-native interface to SuiteSparse

JAX & PyTensor-native sparse direct solvers backed by SuiteSparse. solve, logdet, and friends are XLA FFI custom calls into CHOLMOD (Cholesky, for symmetric positive definite matrices) and KLU (LU, for general non-symmetric matrices), so sparse factorizations run at full native speed inside @jax.jit (and lax.scan / lax.fori_loop) — no Python callback overhead.