Evaluate the Jacobian

Numeric values at a point, and prepared evaluators and ODE pieces that fill a fixed sparse prototype.

Operation	Kind	Bindings	Summary
`assemble_jacobian`	function	Julia, Python, Rust	One-shot convenience over `prepare_jacobian`: evaluate the analytical Jacobian at a point (defaults: the document’s initial state and parameters).
`jac_prototype`	function	Julia	A freshly zeroed sparse prototype on the structural pattern — the object to pass as `ODEFunction(f!; jac_prototype = …)`.
`ode_components`	function	Julia	Everything a stiff ODE solver needs, with no solver dependency:
`prepare_jacobian`	function	Julia	Build the analytical Jacobian evaluator once: differentiates the system, compiles the derived band-field model through the ordinary `EarthSciAST.build_evaluator`, and precomputes…
`scatter_plan`	function	Julia	Build the scatter plan of a model’s state Jacobian for `layout`.
`jacobian_evaluator`	type	Julia	Prepared analytical Jacobian: call as `jac!(J, u, p, t)` where `J` is (a copy of) `jac.prototype`.
`scatter_plan`	type	Julia, Rust	Band fields → storage positions for one (band list, layout).