Expand description
Persistent cache for latent-coordinate REML design evaluations.
This follows the same invalidation shape as the design-revision pattern in
src/terms/smooth.rs’s SpatialLogKappa path (around the
SpatialLogKappa cache near line 12805) and the EvalShared rho-keyed
cache in src/solver/reml/mod.rs (around line 3525). REML’s outer
evaluator is reentrant for each theta: the rho component is already covered
by EvalShared, while the design-moving component is fully determined by
the latent fingerprint. Together, (rho, latent_fingerprint) is sufficient
to reuse the realized surface until the caller bumps the design revision or
explicitly invalidates this cache.