make enthalpy_units required in Python API

.gitignore

@@ -37,4 +37,5 @@ __pycache__/
 source/bind/excel/~$*.xlsm
 source/bind/excel/*.lib
 source/bind/python/samples
-source/bind/python/cea/samples/intro.py
+source/bind/python/cea/samples/intro.py
+AGENTS.local.md

CHANGELOG.md

@@ -4,20 +4,27 @@ All notable user-visible changes to this project are documented here.
 
 ## [Unreleased]
 
+### Changed
+
+### Fixed
+
+### Added
+
+## [3.2.0] - 2026-05-12
+
 ### Changed
 - Python `cea.Reactant` now supports explicit `enthalpy_units` for custom reactant enthalpy input (`J/kg`, `kJ/kg`, `cal/kg`, `kcal/kg`, `J/mol`, `kJ/mol`, `cal/mol`, `kcal/mol`; `/mol` and `/mole` spellings accepted).
-- Backward-compatible behavior is preserved when `Reactant.enthalpy` is provided without `enthalpy_units`: the legacy default (`J/kg`) is still used, but this now emits a `FutureWarning` directing users to pass `enthalpy_units` explicitly.
+- Python `cea.Reactant` now requires explicit `enthalpy_units` whenever `enthalpy` is provided; omitting the units now raises `ValueError` instead of falling back to the legacy implicit `J/kg` default.
 - Weight-based enthalpy units (`*/kg`) now require `Reactant.molecular_weight` for conversion, while molar units (`*/mol`) do not require molecular weight for enthalpy interpretation.
 - Python docs and examples were updated to pass explicit `enthalpy_units` for custom reactants (including RP-1311 Example 5) instead of relying on implicit defaults.
-- **Compatibility notice:** a future **minor** version increment will require `enthalpy_units` whenever `Reactant.enthalpy` is defined. Code that currently relies on implicit enthalpy units may break until updated.
 - Smooth-truncation derivative assembly in the equilibrium solver now uses an effective Jacobian/chain-rule formulation across TP/HP/SP/TV/UV/SV solves so reported sensitivities track the smoothed species-activity model more consistently near truncation thresholds.
 
 ### Fixed
 - Smooth-truncation total derivatives for reported gas species and derived thermodynamic outputs were aligned with the final reported-species mapping, improving behavior for trace-species sensitivities near truncation cutoffs.
 - Corrected user-facing viscosity unit labels in the equilibrium core comments and Python bindings to report millipoise consistently.
 
 ### Added
-- Added Python regression coverage for `Reactant` enthalpy-unit handling, including omitted-units warning behavior, explicit molar/weight units, molecular-weight requirements for weight units, and accepted unit spellings.
+- Added Python regression coverage for `Reactant` enthalpy-unit handling, including required explicit units, explicit molar/weight units, molecular-weight requirements for weight units, and accepted unit spellings.
 - Added pfunit regression coverage for smooth-truncation derivative chain-rule behavior, targeted finite-difference agreement across TP/HP/SP/TV/UV/SV constraints, and reported-entropy consistency checks.
 
 ## [3.1.2] - 2026-03-23

CMakeLists.txt

@@ -8,7 +8,7 @@ set(CMAKE_MSVC_RUNTIME_LIBRARY "MultiThreaded$<$<CONFIG:Debug>:Debug>")
 set(CMAKE_DISABLE_SOURCE_CHANGES ON)
 set(CMAKE_DISABLE_IN_SOURCE_BUILD ON)
 project(CEA
-    VERSION 3.1.2
+    VERSION 3.2.0
     LANGUAGES Fortran
 )
 

docs/source/conf.py

@@ -21,8 +21,8 @@
 project = 'CEA'
 copyright = ''
 author = 'Mark Leader'
-version = '3.1'
-release = '3.1.2'
+version = '3.2'
+release = '3.2.0'
 
 # -- General configuration ---------------------------------------------------
 # https://www.sphinx-doc.org/en/master/usage/configuration.html#general-configuration

docs/source/examples/equilibrium/example5.rst

@@ -22,8 +22,7 @@ Define the pressure schedule and reactant composition by weight fraction:
     T_reac = np.array([298.15, 298.15, 298.15, 298.15, 298.15], dtype=np.float64)
 
 Create a :class:`~cea.Reactant` for ``CHOS-Binder`` using explicit enthalpy units.
-For backward compatibility, omitting ``enthalpy_units`` still defaults to ``J/kg`` for now,
-but that implicit behavior is deprecated and emits a warning.
+When ``enthalpy`` is provided, ``enthalpy_units`` is required.
 
 .. code-block:: python
 

docs/source/interfaces/python_api.rst

@@ -11,10 +11,8 @@ The :class:`~cea.Mixture` class is used to define a mixture of product or reacta
 The instances of this class are then passed as inputs to the available solver classes (e.g., :class:`~cea.EqSolver`, :class:`~cea.RocketSolver`, :class:`~cea.ShockSolver`, or :class:`~cea.DetonationSolver`).
 Custom reactants can be provided through :class:`~cea.Reactant` objects (including mixed lists of strings and Reactant objects).
 For :class:`~cea.Reactant`, ``temperature`` is in K, and ``enthalpy`` must be paired with explicit
-``enthalpy_units`` (for example ``"J/kg"`` or ``"kJ/mol"``). Omitting ``enthalpy_units`` while
-providing ``enthalpy`` preserves the legacy default (``J/kg``) for backward compatibility, but this
-is deprecated and emits a ``FutureWarning``. A future minor version will require explicit
-``enthalpy_units``.
+``enthalpy_units`` (for example ``"J/kg"`` or ``"kJ/mol"``). Weight-based enthalpy units require
+``molecular_weight`` for conversion, while molar enthalpy units do not.
 
 .. autoclass:: cea.Reactant
    :members:

source/bind/python/CEA.pyx

@@ -546,9 +546,7 @@ cdef class Reactant:
         Units for ``enthalpy``. Supported values (case-insensitive):
         ``J/kg``, ``kJ/kg``, ``cal/kg``, ``kcal/kg``, ``J/mol``, ``kJ/mol``,
         ``cal/mol``, ``kcal/mol`` (``/mole`` spellings are also accepted).
-        If omitted while ``enthalpy`` is provided, the legacy default ``J/kg``
-        is used for backward compatibility and a ``FutureWarning`` is emitted.
-        Future minor versions will require explicit ``enthalpy_units``.
+        Required whenever ``enthalpy`` is provided.
     temperature : float, optional
         Reference temperature in SI units (K).
 
@@ -612,16 +610,10 @@ cdef class Reactant:
 
         if enthalpy is not None:
             if enthalpy_units is None:
-                warnings.warn(
-                    "Reactant enthalpy without explicit enthalpy_units is deprecated; "
-                    "using legacy default J/kg for backward compatibility. "
-                    "Future minor versions will require explicit enthalpy_units. "
-                    "Pass enthalpy_units='J/kg' or enthalpy_units='kJ/mol'.",
-                    FutureWarning,
+                raise ValueError(
+                    "Reactant enthalpy requires explicit enthalpy_units; "
+                    "pass enthalpy_units='J/kg' or enthalpy_units='kJ/mol'"
                 )
-                normalized_enthalpy_units = "j/kg"
-                enthalpy_core_units = "j/mole"
-                enthalpy_is_weight_units = True
             else:
                 (
                     normalized_enthalpy_units,

source/bind/python/cea/__init__.py

@@ -1,4 +1,4 @@
-__version__ = "3.1.2"
+__version__ = "3.2.0"
 
 # initialize libcea, loading in the default data files
 from cea.lib.libcea import init as libcea_init

source/bind/python/cea/lib/libcea.pyi

@@ -198,9 +198,20 @@ class Reactant:
         self,
         name: str,
         formula: Mapping[str, SupportsFloat] | None = None,
-        molecular_weight: SupportsFloat = ...,
-        enthalpy: SupportsFloat = ...,
-        enthalpy_units: WeightEnthalpyUnits = ...,
+        molecular_weight: SupportsFloat | None = None,
+        enthalpy: None = None,
+        enthalpy_units: None = None,
+        temperature: SupportsFloat | None = None,
+    ) -> None: ...
+
+    @overload
+    def __init__(
+        self,
+        name: str,
+        formula: Mapping[str, SupportsFloat] | None = None,
+        molecular_weight: SupportsFloat,
+        enthalpy: SupportsFloat,
+        enthalpy_units: WeightEnthalpyUnits,
         temperature: SupportsFloat | None = None,
     ) -> None: ...
 
@@ -210,8 +221,8 @@ class Reactant:
         name: str,
         formula: Mapping[str, SupportsFloat] | None = None,
         molecular_weight: SupportsFloat | None = None,
-        enthalpy: SupportsFloat | None = None,
-        enthalpy_units: MolarEnthalpyUnits | None = None,
+        enthalpy: SupportsFloat,
+        enthalpy_units: MolarEnthalpyUnits,
         temperature: SupportsFloat | None = None,
     ) -> None: ...
 

source/bind/python/tests/test_rp1311_samples.py

@@ -240,40 +240,21 @@ def test_example5_hp_custom_reactant(cea_module):
     assert soln.mole_fractions["CO"] == pytest.approx(0.25896, rel=1e-4)
 
 
-def test_reactant_enthalpy_implicit_units_warn_and_match_explicit(cea_module):
+def test_reactant_enthalpy_requires_explicit_units(cea_module):
     cea = cea_module
     mw = 14.6652984484
     h_cal_per_mol = -2999.082
     h_j_per_kg = cea.units.cal_to_joule(h_cal_per_mol) / (mw * 1.0e-3)
     formula = {"C": 1.0, "H": 1.86955, "O": 0.031256, "S": 0.008415}
 
-    with pytest.warns(FutureWarning, match="legacy default J/kg"):
-        legacy = cea.Reactant(
+    with pytest.raises(ValueError, match="requires explicit enthalpy_units"):
+        cea.Reactant(
             name="CHOS-Binder",
             formula=formula,
             molecular_weight=mw,
             enthalpy=h_j_per_kg,
             temperature=298.15,
         )
-    explicit = cea.Reactant(
-        name="CHOS-Binder",
-        formula=formula,
-        molecular_weight=mw,
-        enthalpy=h_j_per_kg,
-        enthalpy_units="J/kg",
-        temperature=298.15,
-    )
-
-    assert legacy.enthalpy_units == "j/kg"
-    assert explicit.enthalpy_units == "j/kg"
-
-    mix_legacy = cea.Mixture([legacy])
-    mix_explicit = cea.Mixture([explicit])
-    weights = np.array([1.0], dtype=np.float64)
-    T_reac = np.array([298.15], dtype=np.float64)
-    h_legacy = mix_legacy.calc_property(cea.ENTHALPY, weights, T_reac)
-    h_explicit = mix_explicit.calc_property(cea.ENTHALPY, weights, T_reac)
-    assert h_legacy == pytest.approx(h_explicit, rel=1e-12)
 
 
 def test_reactant_molar_enthalpy_units_do_not_require_molecular_weight(cea_module):