"""Process-model data structures for :mod:`pidtune`.

This subpackage defines the model abstractions described in
``docs/design/02_data_models.md``:

* :class:`~pidtune.models.base.ProcessModel` — the abstract interface
  every model implements (step/frequency response, parameter access,
  validation, serialisation).
* :class:`~pidtune.models.fopdt.FOPDTModel` — first-order plus dead time
  (gain ``K``, time constant ``tau``, dead time ``theta``); the workhorse
  model for classical tuning rules.
* :class:`~pidtune.models.sopdt.SOPDTModel` — second-order plus dead time
  (gain, two time constants or natural frequency/damping, dead time).
* :class:`~pidtune.models.transfer_function.TransferFunctionModel` —
  arbitrary rational transfer functions given as numerator/denominator
  polynomial coefficients, with optional dead time.

All models are immutable after construction and validate their
parameters eagerly, raising
:class:`~pidtune.exceptions.ModelValidationError` on bad input.
"""

from __future__ import annotations

from pidtune.models.base import ProcessModel
from pidtune.models.fopdt import FOPDTModel
from pidtune.models.sopdt import SOPDTModel
from pidtune.models.transfer_function import TransferFunctionModel

__all__ = [
    "ProcessModel",
    "FOPDTModel",
    "SOPDTModel",
    "TransferFunctionModel",
]