Saturation Properties of Nuclear Matter
=======================================

The module always writes ``saturation.csv`` to the output directory.
It contains one row per temperature found in the input EoS, with the following 10 columns:

+-------------------------------+----------------------------+------------------+
| **Column**                    | **Description**            | **Unit**         |
+===============================+============================+==================+
| :math:`n_0`                   | Saturation density         | fm\ :sup:`-3`    |
+-------------------------------+----------------------------+------------------+
| BE                            | Binding energy             | MeV              |
+-------------------------------+----------------------------+------------------+
| :math:`K_0`                   | Incompressibility          | MeV              |
+-------------------------------+----------------------------+------------------+
| :math:`Q_0`                   | Skewness                   | MeV              |
+-------------------------------+----------------------------+------------------+
| :math:`Z_0`                   | Kurtosis                   | MeV              |
+-------------------------------+----------------------------+------------------+
| :math:`J`                     | Symmetry energy            | MeV              |
+-------------------------------+----------------------------+------------------+
| :math:`L`                     | Symmetry energy slope      | MeV              |
+-------------------------------+----------------------------+------------------+
| :math:`K_\text{sym}`          | Symmetry energy curvature  | MeV              |
+-------------------------------+----------------------------+------------------+
| :math:`Q_\text{sym}`          | Symmetry energy skewness   | MeV              |
+-------------------------------+----------------------------+------------------+
| :math:`Z_\text{sym}`          | Symmetry energy kurtosis   | MeV              |
+-------------------------------+----------------------------+------------------+

The file has no header row.  Values are written in scientific notation.

.. note::

   When ``method: derivative`` is used, columns that cannot be computed are written as
   ``nan``.  Specifically: Q\ :sub:`0` when ``isoscalar_expansion_order < 3``, and
   Z\ :sub:`0`, K\ :sub:`sym`, Q\ :sub:`sym`, Z\ :sub:`sym` always (fourth-order
   derivatives are not supported by either derivative backend).

Status File
-----------

The module also writes ``status.yaml`` with an integer code and a message string:

.. code-block:: yaml

   code: 200
   message: Successful run!

+-------+--------------------------------------------------------------+
| Code  | Meaning                                                      |
+=======+==============================================================+
| 200   | Success                                                      |
+-------+--------------------------------------------------------------+
| 100   | Warning (e.g. backward stencil fallback for J/L)            |
+-------+--------------------------------------------------------------+
| 101   | A computed parameter is outside its configured allowed range |
+-------+--------------------------------------------------------------+
| 400   | Bad input (YAML parse error, missing file, invalid config)   |
+-------+--------------------------------------------------------------+
| 500   | Internal error                                               |
+-------+--------------------------------------------------------------+

Config Echo
-----------

A validated copy of the input ``config.yaml``, with all omitted fields filled with their
defaults, is written to ``config.yaml`` in the output directory.