style: resolve the remaining ruff findings

Auto-fixes (UP037, UP038, F401, I001, SIM105, RUF100) plus hand-fixes:
drop the now-unused `Union` imports, annotate mutable class attributes
with ClassVar, raise ValidationError instead of blind Exception in the
zero-length test, delete two dead locals, and bind the per-iteration
grid-builder closures to their loop variables (B023).

tests/gui/test_analysis_commands.py

@@ -6,12 +6,12 @@ import pytest
 
 pytest.importorskip("PySide6")
 
-from otko.commands import (  # noqa: E402
+from otko.commands import (
     AddAnalysisCasesCommand,
     DeleteAnalysisCasesCommand,
     UpdateAnalysisCaseCommand,
 )
-from otko.core import (  # noqa: E402
+from otko.core import (
     LinearTimeSeries,
     ModalCase,
     NodalLoad,
@@ -20,7 +20,7 @@ from otko.core import (  # noqa: E402
     StaticCase,
     TransientCase,
 )
-from otko.viewmodels import ProjectViewModel  # noqa: E402
+from otko.viewmodels import ProjectViewModel
 
 
 def _vm_with_pattern() -> ProjectViewModel:

tests/gui/test_analysis_runner.py

@@ -12,21 +12,21 @@ import pytest
 pytest.importorskip("PySide6")
 pytest.importorskip("openseespy.opensees")
 
-from otko.commands import (  # noqa: E402
+from otko.commands import (
     AddAnalysisCasesCommand,
     AddElementsCommand,
     AddNodalLoadsCommand,
     AddNodesCommand,
     AddSectionsCommand,
 )
-from otko.core import (  # noqa: E402
+from otko.core import (
     ElasticBeamColumn,
     ElasticSection,
     Node,
     StaticCase,
 )
-from otko.services.results import StaticResults  # noqa: E402
-from otko.viewmodels import AnalysisRunner, ProjectViewModel  # noqa: E402
+from otko.services.results import StaticResults
+from otko.viewmodels import AnalysisRunner, ProjectViewModel
 
 
 @pytest.fixture

tests/gui/test_assign_load_pattern_name.py

@@ -6,15 +6,14 @@ import pytest
 
 pytest.importorskip("PySide6")
 
-from otko.commands import AddNodalLoadsCommand  # noqa: E402
-from otko.core import (  # noqa: E402
+from otko.commands import AddNodalLoadsCommand
+from otko.core import (
     LinearTimeSeries,
     Node,
     PlainLoadPattern,
-    Project,
 )
-from otko.viewmodels import ProjectViewModel  # noqa: E402
-from otko.views.dialogs.assign_load import AssignLoadDialog  # noqa: E402
+from otko.viewmodels import ProjectViewModel
+from otko.views.dialogs.assign_load import AssignLoadDialog
 
 
 @pytest.mark.gui

tests/gui/test_assign_masses.py

@@ -6,7 +6,7 @@ import pytest
 
 pytest.importorskip("PySide6")
 
-from otko.views.dialogs.assign_masses import AssignMassesDialog  # noqa: E402
+from otko.views.dialogs.assign_masses import AssignMassesDialog
 
 
 @pytest.mark.gui

tests/gui/test_assign_zls.py

@@ -6,12 +6,12 @@ import pytest
 
 pytest.importorskip("PySide6")
 
-from otko.core import (  # noqa: E402
+from otko.core import (
     ElasticSection,
     Node,
     Project,
 )
-from otko.views.dialogs.assign_zls import (  # noqa: E402
+from otko.views.dialogs.assign_zls import (
     AssignZeroLengthSectionDialog,
 )
 

tests/gui/test_canvas_grid_snap.py

@@ -12,7 +12,7 @@ import pytest
 
 pytest.importorskip("PySide6")
 
-from otko.core import (  # noqa: E402
+from otko.core import (
     CoordinateGridSystem,
     CoordinateSystem,
     GridSystem,

tests/gui/test_case_forms.py

@@ -6,13 +6,13 @@ import pytest
 
 pytest.importorskip("PySide6")
 
-from otko.core import (  # noqa: E402
+from otko.core import (
     NodalLoad,
     PlainLoadPattern,
     StaticCase,
     TransientCase,
 )
-from otko.views.dialogs.case_forms import TransientCaseForm  # noqa: E402
+from otko.views.dialogs.case_forms import TransientCaseForm
 
 
 def _patterns():  # type: ignore[no-untyped-def]

tests/gui/test_commands.py

@@ -11,15 +11,14 @@ import pytest
 
 pytest.importorskip("PySide6")
 
-from otko.commands import (  # noqa: E402
+from otko.commands import (
     AddElementsCommand,
     AddNodalLoadsCommand,
     AddNodesCommand,
-    DeleteElementsCommand,
     DeleteNodesCommand,
     SetRestraintCommand,
 )
-from otko.core import (  # noqa: E402
+from otko.core import (
     LinearTimeSeries,
     NodalLoad,
     Node,
@@ -27,7 +26,7 @@ from otko.core import (  # noqa: E402
     Steel01,
     TrussElement,
 )
-from otko.viewmodels import ProjectViewModel  # noqa: E402
+from otko.viewmodels import ProjectViewModel
 
 
 # ─────────────────────────── helpers ────────────────────────────────

tests/gui/test_convert_element_type.py

@@ -6,21 +6,21 @@ import pytest
 
 pytest.importorskip("PySide6")
 
-from otko.commands import (  # noqa: E402
+from otko.commands import (
     AddElementsCommand,
     AddMaterialsCommand,
     AddNodesCommand,
     AddSectionsCommand,
     ConvertElementTypeCommand,
 )
-from otko.core import (  # noqa: E402
+from otko.core import (
     ElasticBeamColumn,
     ElasticSection,
     ElasticUniaxial,
     Node,
     TrussElement,
 )
-from otko.viewmodels import ProjectViewModel  # noqa: E402
+from otko.viewmodels import ProjectViewModel
 
 
 def _vm_setup() -> ProjectViewModel:

tests/gui/test_define_dialogs.py

@@ -6,9 +6,9 @@ import pytest
 
 pytest.importorskip("PySide6")
 
-from otko.core import LinearTimeSeries, Project  # noqa: E402
-from otko.views.dialogs.linear_time_series import LinearTimeSeriesDialog  # noqa: E402
-from otko.views.dialogs.plain_pattern import PlainPatternDialog  # noqa: E402
+from otko.core import LinearTimeSeries, Project
+from otko.views.dialogs.linear_time_series import LinearTimeSeriesDialog
+from otko.views.dialogs.plain_pattern import PlainPatternDialog
 
 
 @pytest.mark.gui

tests/gui/test_draw_frame_tool.py

@@ -11,11 +11,11 @@ import pytest
 
 pytest.importorskip("PySide6")
 
-from otko.commands import AddNodesCommand  # noqa: E402
-from otko.core import ElasticBeamColumn, ElasticSection, Node  # noqa: E402
-from otko.viewmodels import ProjectViewModel  # noqa: E402
-from otko.views.canvas3d import SelectionState  # noqa: E402
-from otko.views.tools.draw_frame import DrawFrameTool  # noqa: E402
+from otko.commands import AddNodesCommand
+from otko.core import ElasticBeamColumn, ElasticSection, Node
+from otko.viewmodels import ProjectViewModel
+from otko.views.canvas3d import SelectionState
+from otko.views.tools.draw_frame import DrawFrameTool
 
 
 class _CanvasStub:

tests/gui/test_draw_node_tool.py

@@ -10,10 +10,10 @@ import pytest
 
 pytest.importorskip("PySide6")
 
-from otko.core import GridSystem, Node, Project  # noqa: E402
-from otko.viewmodels import ProjectViewModel  # noqa: E402
-from otko.views.canvas3d.selection import SelectionState  # noqa: E402
-from otko.views.tools.draw_node import (  # noqa: E402
+from otko.core import GridSystem, Node
+from otko.viewmodels import ProjectViewModel
+from otko.views.canvas3d.selection import SelectionState
+from otko.views.tools.draw_node import (
     DrawNodeTool,
     _snap_to_grid,
 )

tests/gui/test_draw_truss_tool.py

@@ -6,18 +6,17 @@ import pytest
 
 pytest.importorskip("PySide6")
 
-from otko.core import (  # noqa: E402
+from otko.core import (
     CoordinateGridSystem,
-    CoordinateSystem,
     ElasticUniaxial,
     GridSystem,
     Node,
     TrussElement,
     make_grid_lines,
 )
-from otko.viewmodels import ProjectViewModel  # noqa: E402
-from otko.views.canvas3d.selection import SelectionState  # noqa: E402
-from otko.views.tools.draw_truss import DrawTrussTool  # noqa: E402
+from otko.viewmodels import ProjectViewModel
+from otko.views.canvas3d.selection import SelectionState
+from otko.views.tools.draw_truss import DrawTrussTool
 
 
 class _CanvasStub:

tests/gui/test_grid_dialog.py

@@ -6,7 +6,7 @@ import pytest
 
 pytest.importorskip("PySide6")
 
-from otko.core import (  # noqa: E402
+from otko.core import (
     CoordinateGridSystem,
     CoordinateSystem,
     GridLine,

tests/gui/test_material_dialog_concrete04.py

@@ -6,10 +6,10 @@ import pytest
 
 pytest.importorskip("PySide6")
 
-from otko.core import Concrete04  # noqa: E402
-from otko.views.dialogs.material_forms import (  # noqa: E402
-    Concrete04Form,
+from otko.core import Concrete04
+from otko.views.dialogs.material_forms import (
     FORM_REGISTRY,
+    Concrete04Form,
 )
 
 

tests/gui/test_material_form_ranges.py

@@ -10,7 +10,7 @@ import pytest
 
 pytest.importorskip("PySide6")
 
-from otko.views.dialogs.material_forms import (  # noqa: E402
+from otko.views.dialogs.material_forms import (
     Concrete01Form,
     Concrete02Form,
     Steel01Form,

tests/gui/test_path_ts_dialogs.py

@@ -8,17 +8,16 @@ import pytest
 
 pytest.importorskip("PySide6")
 
-from otko.commands import (  # noqa: E402
+from otko.commands import (
     AddLoadPatternCommand,
     AddTimeSeriesCommand,
 )
-from otko.core import (  # noqa: E402
-    Node,
+from otko.core import (
     PathTimeSeries,
     Project,
     UniformExcitationPattern,
 )
-from otko.viewmodels import ProjectViewModel  # noqa: E402
+from otko.viewmodels import ProjectViewModel
 
 
 # ─────────────── AddTimeSeriesCommand / AddLoadPatternCommand ──────────────

tests/gui/test_property_commands.py

@@ -6,7 +6,7 @@ import pytest
 
 pytest.importorskip("PySide6")
 
-from otko.commands import (  # noqa: E402
+from otko.commands import (
     AddElementsCommand,
     AddMaterialsCommand,
     AddNodesCommand,
@@ -16,7 +16,7 @@ from otko.commands import (  # noqa: E402
     UpdateMaterialCommand,
     UpdateSectionCommand,
 )
-from otko.core import (  # noqa: E402
+from otko.core import (
     ElasticBeamColumn,
     ElasticSection,
     Node,
@@ -24,7 +24,7 @@ from otko.core import (  # noqa: E402
     Steel02,
     TrussElement,
 )
-from otko.viewmodels import ProjectViewModel  # noqa: E402
+from otko.viewmodels import ProjectViewModel
 
 
 def _vm_with_steel() -> ProjectViewModel:

tests/gui/test_property_forms.py

@@ -10,13 +10,10 @@ import pytest
 
 pytest.importorskip("PySide6")
 
-from otko.core import (  # noqa: E402
-    Concrete01,
+from otko.core import (
     Concrete02,
     ElasticIsotropic,
-    ElasticPP,
     ElasticSection,
-    ElasticUniaxial,
     Steel01,
     Steel02,
 )
@@ -100,10 +97,14 @@ def test_elastic_section_form_round_trip(qtbot) -> None:  # type: ignore[no-unty
 def test_form_for_dispatches_by_type(qtbot) -> None:  # type: ignore[no-untyped-def]
     from otko.views.dialogs.material_forms import (
         Steel01Form,
+    )
+    from otko.views.dialogs.material_forms import (
         form_for as material_form_for,
     )
     from otko.views.dialogs.section_forms import (
         ElasticSectionForm,
+    )
+    from otko.views.dialogs.section_forms import (
         form_for as section_form_for,
     )
 

tests/gui/test_pushover_curve_units.py

@@ -7,9 +7,9 @@ import pytest
 
 pytest.importorskip("PySide6")
 
-from otko.core import UnitSystem  # noqa: E402
-from otko.services.results import PushoverResults  # noqa: E402
-from otko.views.docks.pushover_curve import (  # noqa: E402
+from otko.core import UnitSystem
+from otko.services.results import PushoverResults
+from otko.views.docks.pushover_curve import (
     PushoverCurveView,
     _is_rotation_dof,
 )

tests/gui/test_run_analysis.py

@@ -8,11 +8,11 @@ import pytest
 
 pytest.importorskip("PySide6")
 
-from PySide6.QtCore import QObject, Signal  # noqa: E402
+from PySide6.QtCore import QObject, Signal
 
-from otko.core import LinearTimeSeries, PlainLoadPattern, Project, TransientCase  # noqa: E402
-from otko.viewmodels import ProjectViewModel  # noqa: E402
-from otko.views.dialogs.run_analysis import RunAnalysisDialog  # noqa: E402
+from otko.core import LinearTimeSeries, PlainLoadPattern, TransientCase
+from otko.viewmodels import ProjectViewModel
+from otko.views.dialogs.run_analysis import RunAnalysisDialog
 
 
 class _FakeRunner(QObject):

tests/gui/test_section_extrusion.py

@@ -6,7 +6,7 @@ import pytest
 
 pytest.importorskip("PySide6")
 
-from otko.core import (  # noqa: E402
+from otko.core import (
     ElasticBeamColumn,
     ElasticSection,
     Node,

tests/gui/test_section_forms.py

@@ -7,14 +7,14 @@ import pytest
 
 pytest.importorskip("PySide6")
 
-from otko.core import (  # noqa: E402
+from otko.core import (
     AggregatorDOF,
     ElasticSection,
     FiberSection,
     RectangularPatch,
     SectionAggregator,
 )
-from otko.views.dialogs.section_forms import (  # noqa: E402
+from otko.views.dialogs.section_forms import (
     FORM_REGISTRY,
     form_for,
 )

tests/gui/test_selection.py

@@ -6,7 +6,7 @@ import pytest
 
 pytest.importorskip("PySide6")
 
-from otko.views.canvas3d import SelectionState  # noqa: E402
+from otko.views.canvas3d import SelectionState
 
 
 @pytest.mark.gui

tests/gui/test_transforms.py

@@ -6,15 +6,15 @@ import pytest
 
 pytest.importorskip("PySide6")
 
-from otko.commands import (  # noqa: E402
+from otko.commands import (
     AddElementsCommand,
     AddNodesCommand,
     MirrorCommand,
     MoveNodesCommand,
     ReplicateCommand,
 )
-from otko.core import Node, Steel01, TrussElement  # noqa: E402
-from otko.viewmodels import ProjectViewModel  # noqa: E402
+from otko.core import Node, Steel01, TrussElement
+from otko.viewmodels import ProjectViewModel
 
 
 def _populated_vm() -> ProjectViewModel:

tests/gui/test_tree_multi_select.py

@@ -6,10 +6,9 @@ import pytest
 
 pytest.importorskip("PySide6")
 
-from PySide6.QtCore import Qt  # noqa: E402
-from PySide6.QtWidgets import QTreeWidget  # noqa: E402
+from PySide6.QtWidgets import QTreeWidget
 
-from otko.core import Node  # noqa: E402
+from otko.core import Node
 
 
 @pytest.mark.gui

tests/gui/test_units_status_bar.py

@@ -6,7 +6,7 @@ import pytest
 
 pytest.importorskip("PySide6")
 
-from otko.core import UnitSystem  # noqa: E402
+from otko.core import UnitSystem
 
 
 @pytest.mark.gui

tests/gui/test_update_element_fields.py

@@ -6,18 +6,18 @@ import pytest
 
 pytest.importorskip("PySide6")
 
-from otko.commands import (  # noqa: E402
+from otko.commands import (
     AddElementsCommand,
     AddMaterialsCommand,
     AddNodesCommand,
     UpdateElementFieldsCommand,
 )
-from otko.core import (  # noqa: E402
+from otko.core import (
     ElasticUniaxial,
     Node,
     TrussElement,
 )
-from otko.viewmodels import ProjectViewModel  # noqa: E402
+from otko.viewmodels import ProjectViewModel
 
 
 def _vm_with_truss() -> ProjectViewModel:

tests/gui/test_working_plane.py

@@ -7,7 +7,7 @@ import pytest
 
 pytest.importorskip("PySide6")
 
-from otko.core import (  # noqa: E402
+from otko.core import (
     CoordinateGridSystem,
     GridSystem,
     Project,

tests/integration/test_basic_truss.py

@@ -11,7 +11,7 @@ import pytest
 
 pytest.importorskip("openseespy")
 
-from otko.services.opensees_runner import OpenSeesRunner  # noqa: E402
+from otko.services.opensees_runner import OpenSeesRunner
 
 pytestmark = pytest.mark.slow
 
@@ -25,7 +25,7 @@ def test_basic_truss_matches_opensees_tcl_reference() -> None:
     a linear rescale of the Tcl model — any deviation would flag a
     real solver/translation issue.
     """
-    from examples.basic_truss import build_basic_truss, IN_TO_M
+    from examples.basic_truss import IN_TO_M, build_basic_truss
 
     proj = build_basic_truss()
     runner = OpenSeesRunner(proj)
@@ -45,6 +45,7 @@ def test_basic_truss_matches_opensees_tcl_reference() -> None:
 def test_basic_truss_round_trips(tmp_path) -> None:  # type: ignore[no-untyped-def]
     """The example project must survive save/load without any information loss."""
     from examples.basic_truss import build_basic_truss
+
     from otko.services import load_project, save_project
 
     p = build_basic_truss()

tests/integration/test_beam_quad_2d.py

@@ -9,8 +9,8 @@ import pytest
 
 pytest.importorskip("openseespy")
 
-from otko.services import load_project, save_project  # noqa: E402
-from otko.services.opensees_runner import OpenSeesRunner  # noqa: E402
+from otko.services import load_project, save_project
+from otko.services.opensees_runner import OpenSeesRunner
 
 pytestmark = pytest.mark.slow
 

tests/integration/test_combinations.py

@@ -8,7 +8,7 @@ import pytest
 
 ops = pytest.importorskip("openseespy.opensees")  # skip if OpenSeesPy not installed
 
-from otko.core import (  # noqa: E402
+from otko.core import (
     ElasticBeamColumn,
     ElasticSection,
     LinearTimeSeries,
@@ -20,8 +20,8 @@ from otko.core import (  # noqa: E402
     Project,
     StaticCase,
 )
-from otko.services import OpenSeesRunner, evaluate_combination  # noqa: E402
-from otko.services.results import StaticResults  # noqa: E402
+from otko.services import OpenSeesRunner, evaluate_combination
+from otko.services.results import StaticResults
 
 pytestmark = pytest.mark.slow
 

tests/integration/test_concrete04_runner.py

@@ -18,7 +18,7 @@ import pytest
 
 pytest.importorskip("openseespy")
 
-from otko.core import (  # noqa: E402
+from otko.core import (
     Concrete04,
     FiberSection,
     ForceBeamColumn,
@@ -32,7 +32,7 @@ from otko.core import (  # noqa: E402
     StaticCase,
     UnitSystem,
 )
-from otko.services.opensees_runner import OpenSeesRunner  # noqa: E402
+from otko.services.opensees_runner import OpenSeesRunner
 
 pytestmark = pytest.mark.slow
 

tests/integration/test_dof_coverage.py

@@ -11,7 +11,7 @@ import pytest
 
 pytest.importorskip("openseespy")
 
-from otko.core import (  # noqa: E402
+from otko.core import (
     ElasticUniaxial,
     LinearTimeSeries,
     NodalLoad,
@@ -21,7 +21,7 @@ from otko.core import (  # noqa: E402
     StaticCase,
     TrussElement,
 )
-from otko.services.opensees_runner import OpenSeesRunner  # noqa: E402
+from otko.services.opensees_runner import OpenSeesRunner
 
 pytestmark = pytest.mark.slow
 

tests/integration/test_eigen_two_storey_one_bay_frame.py

@@ -8,9 +8,9 @@ import pytest
 
 pytest.importorskip("openseespy")
 
-from otko.core import ModalCase  # noqa: E402
-from otko.services import load_project, save_project  # noqa: E402
-from otko.services.opensees_runner import OpenSeesRunner  # noqa: E402
+from otko.core import ModalCase
+from otko.services import load_project, save_project
+from otko.services.opensees_runner import OpenSeesRunner
 
 pytestmark = pytest.mark.slow
 

tests/integration/test_eigen_two_storey_shear_frame.py

@@ -8,9 +8,9 @@ import pytest
 
 pytest.importorskip("openseespy")
 
-from otko.core import ModalCase  # noqa: E402
-from otko.services import load_project, save_project  # noqa: E402
-from otko.services.opensees_runner import OpenSeesRunner  # noqa: E402
+from otko.core import ModalCase
+from otko.services import load_project, save_project
+from otko.services.opensees_runner import OpenSeesRunner
 
 pytestmark = pytest.mark.slow
 

tests/integration/test_elastic_frame.py

@@ -8,9 +8,9 @@ import pytest
 
 pytest.importorskip("openseespy")
 
-from otko.core import ModalCase, StaticCase  # noqa: E402
-from otko.services import load_project, save_project  # noqa: E402
-from otko.services.opensees_runner import OpenSeesRunner  # noqa: E402
+from otko.core import ModalCase, StaticCase
+from otko.services import load_project, save_project
+from otko.services.opensees_runner import OpenSeesRunner
 
 pytestmark = pytest.mark.slow
 
@@ -29,7 +29,6 @@ def _reload(proj, tmp_path):  # type: ignore[no-untyped-def]
 def test_elastic_frame_gravity_reactions(tmp_path) -> None:  # type: ignore[no-untyped-def]
     """ΣFy at base = total applied gravity (distributed w × beam × floors)."""
     from examples.elastic_frame import (
-        BAY,
         LOAD_F1,
         LOAD_F2,
         LOAD_F3,
@@ -70,7 +69,6 @@ def test_elastic_frame_gravity_reactions(tmp_path) -> None:  # type: ignore[no-u
 def test_elastic_frame_gravity_plus_lateral_reactions(tmp_path) -> None:  # type: ignore[no-untyped-def]
     """ΣFx at base must equal -(lateral applied) within PDelta tolerance."""
     from examples.elastic_frame import (
-        BAY,
         LOAD_F1,
         LOAD_F2,
         LOAD_F3,
@@ -120,5 +118,5 @@ def test_elastic_frame_modal_periods(tmp_path) -> None:  # type: ignore[no-untyp
     # 0.1930, 0.1562, 0.130 s. Our solve nails these within 1.5%.
     expected = [1.040, 0.3526, 0.1930, 0.1562, 0.130]
     periods = [2.0 * math.pi / math.sqrt(v) for v in r.eigenvalues]
-    for i, (T, T_ref) in enumerate(zip(periods, expected), start=1):
-        assert T == pytest.approx(T_ref, rel=0.02), f"T{i} = {T:.4f} s, reference {T_ref:.4f} s"
+    for i, (T, T_ref) in enumerate(zip(periods, expected, strict=False), start=1):
+        assert pytest.approx(T_ref, rel=0.02) == T, f"T{i} = {T:.4f} s, reference {T_ref:.4f} s"

tests/integration/test_ex1a_canti2d.py

@@ -9,9 +9,9 @@ import pytest
 
 pytest.importorskip("openseespy")
 
-from otko.core import PushoverCase, TransientCase  # noqa: E402
-from otko.services import load_project, save_project  # noqa: E402
-from otko.services.opensees_runner import OpenSeesRunner  # noqa: E402
+from otko.core import PushoverCase, TransientCase
+from otko.services import load_project, save_project
+from otko.services.opensees_runner import OpenSeesRunner
 
 pytestmark = pytest.mark.slow
 

tests/integration/test_ex1a_canti2d_eq.py

@@ -9,8 +9,8 @@ import pytest
 
 pytest.importorskip("openseespy")
 
-from otko.services import load_project, save_project  # noqa: E402
-from otko.services.opensees_runner import OpenSeesRunner  # noqa: E402
+from otko.services import load_project, save_project
+from otko.services.opensees_runner import OpenSeesRunner
 
 pytestmark = pytest.mark.slow
 

tests/integration/test_ex1b_portal2d.py

@@ -9,9 +9,9 @@ import pytest
 
 pytest.importorskip("openseespy")
 
-from otko.core import PushoverCase, TransientCase  # noqa: E402
-from otko.services import load_project, save_project  # noqa: E402
-from otko.services.opensees_runner import OpenSeesRunner  # noqa: E402
+from otko.core import PushoverCase, TransientCase
+from otko.services import load_project, save_project
+from otko.services.opensees_runner import OpenSeesRunner
 
 pytestmark = pytest.mark.slow
 

tests/integration/test_ex2a_canti2d_elastic_element.py

@@ -9,9 +9,9 @@ import pytest
 
 pytest.importorskip("openseespy")
 
-from otko.core import PushoverCase, TransientCase  # noqa: E402
-from otko.services import load_project, save_project  # noqa: E402
-from otko.services.opensees_runner import OpenSeesRunner  # noqa: E402
+from otko.core import PushoverCase, TransientCase
+from otko.services import load_project, save_project
+from otko.services.opensees_runner import OpenSeesRunner
 
 pytestmark = pytest.mark.slow
 

tests/integration/test_ex2b_canti2d_inelastic_section.py

@@ -9,9 +9,9 @@ import pytest
 
 pytest.importorskip("openseespy")
 
-from otko.core import PushoverCase, TransientCase  # noqa: E402
-from otko.services import load_project, save_project  # noqa: E402
-from otko.services.opensees_runner import OpenSeesRunner  # noqa: E402
+from otko.core import PushoverCase, TransientCase
+from otko.services import load_project, save_project
+from otko.services.opensees_runner import OpenSeesRunner
 
 pytestmark = pytest.mark.slow
 

tests/integration/test_ex2c_canti2d_inelastic_fiber_section.py

@@ -9,9 +9,9 @@ import pytest
 
 pytest.importorskip("openseespy")
 
-from otko.core import PushoverCase, TransientCase  # noqa: E402
-from otko.services import load_project, save_project  # noqa: E402
-from otko.services.opensees_runner import OpenSeesRunner  # noqa: E402
+from otko.core import PushoverCase, TransientCase
+from otko.services import load_project, save_project
+from otko.services.opensees_runner import OpenSeesRunner
 
 pytestmark = pytest.mark.slow
 

tests/integration/test_ex3_canti2d_variants.py

@@ -9,9 +9,9 @@ import pytest
 
 pytest.importorskip("openseespy")
 
-from otko.core import PushoverCase, TransientCase  # noqa: E402
-from otko.services import load_project, save_project  # noqa: E402
-from otko.services.opensees_runner import OpenSeesRunner  # noqa: E402
+from otko.core import PushoverCase, TransientCase
+from otko.services import load_project, save_project
+from otko.services.opensees_runner import OpenSeesRunner
 
 pytestmark = pytest.mark.slow
 

tests/integration/test_ex4_portal2d_variants.py

@@ -9,9 +9,9 @@ import pytest
 
 pytest.importorskip("openseespy")
 
-from otko.core import PushoverCase, TransientCase  # noqa: E402
-from otko.services import load_project, save_project  # noqa: E402
-from otko.services.opensees_runner import OpenSeesRunner  # noqa: E402
+from otko.core import PushoverCase, TransientCase
+from otko.services import load_project, save_project
+from otko.services.opensees_runner import OpenSeesRunner
 
 pytestmark = pytest.mark.slow
 

tests/integration/test_moment_curvature.py

@@ -8,13 +8,11 @@ behaviour is exercised by the Phase 9 pushover tests.
 
 from __future__ import annotations
 
-import math
-
 import pytest
 
 pytest.importorskip("openseespy")
 
-from otko.core import (  # noqa: E402
+from otko.core import (
     ElasticUniaxial,
     FiberSection,
     LinearTimeSeries,
@@ -26,7 +24,7 @@ from otko.core import (  # noqa: E402
     StaticCase,
     ZeroLengthSectionElement,
 )
-from otko.services.opensees_runner import OpenSeesRunner  # noqa: E402
+from otko.services.opensees_runner import OpenSeesRunner
 
 pytestmark = pytest.mark.slow
 
@@ -134,7 +132,7 @@ def test_pushover_drives_rotation_for_moment_curvature() -> None:
 
     # Every (κ, M) point must satisfy M = E·I·κ (1 % tolerance allows
     # for the ~20-fibre discretisation of the rectangular section).
-    for kappa, moment in zip(result.control_disp, result.base_shear):
+    for kappa, moment in zip(result.control_disp, result.base_shear, strict=False):
         if abs(kappa) < 1e-12:
             continue
         expected_M = E * I * kappa

tests/integration/test_moment_curvature_example.py

@@ -6,8 +6,8 @@ import pytest
 
 pytest.importorskip("openseespy")
 
-from otko.services import load_project  # noqa: E402
-from otko.services.opensees_runner import OpenSeesRunner  # noqa: E402
+from otko.services import load_project
+from otko.services.opensees_runner import OpenSeesRunner
 
 pytestmark = pytest.mark.slow
 
@@ -15,13 +15,13 @@ pytestmark = pytest.mark.slow
 def test_moment_curvature_example_round_trips_and_converges(tmp_path) -> None:  # type: ignore[no-untyped-def]
     """build_moment_curvature() → save → load → run → expected shape."""
     from examples.moment_curvature import (
-        build_moment_curvature,
         COL_DEPTH,
         COVER,
         E_STEEL,
         FY,
         MU,
         NUM_INCR,
+        build_moment_curvature,
     )
 
     proj = build_moment_curvature()

tests/integration/test_pattern_factors.py

@@ -8,7 +8,7 @@ import pytest
 
 ops = pytest.importorskip("openseespy.opensees")  # skip if OpenSeesPy not installed
 
-from otko.core import (  # noqa: E402
+from otko.core import (
     ElasticBeamColumn,
     ElasticSection,
     LinearTimeSeries,
@@ -18,7 +18,7 @@ from otko.core import (  # noqa: E402
     Project,
     StaticCase,
 )
-from otko.services import OpenSeesRunner  # noqa: E402
+from otko.services import OpenSeesRunner
 
 pytestmark = pytest.mark.slow
 

tests/integration/test_rc_frame_earthquake.py

@@ -9,8 +9,8 @@ import pytest
 
 pytest.importorskip("openseespy")
 
-from otko.services import load_project, save_project  # noqa: E402
-from otko.services.opensees_runner import OpenSeesRunner  # noqa: E402
+from otko.services import load_project, save_project
+from otko.services.opensees_runner import OpenSeesRunner
 
 pytestmark = pytest.mark.slow
 
@@ -18,9 +18,8 @@ pytestmark = pytest.mark.slow
 def test_rc_frame_earthquake_runs_and_has_oscillatory_response(tmp_path) -> None:  # type: ignore[no-untyped-def]
     """Synthetic ground motion produces bounded, oscillatory response."""
     from examples.rc_frame_earthquake import (
-        build_rc_frame_earthquake,
-        DT,
         N_PTS,
+        build_rc_frame_earthquake,
     )
 
     proj = build_rc_frame_earthquake()

tests/integration/test_rc_frame_gravity.py

@@ -6,8 +6,8 @@ import pytest
 
 pytest.importorskip("openseespy")
 
-from otko.services import load_project, save_project  # noqa: E402
-from otko.services.opensees_runner import OpenSeesRunner  # noqa: E402
+from otko.services import load_project, save_project
+from otko.services.opensees_runner import OpenSeesRunner
 
 pytestmark = pytest.mark.slow
 
@@ -22,7 +22,7 @@ def test_rc_frame_gravity_matches_opensees_reference(tmp_path) -> None:  # type:
     The column axial force is 180 kip compression (from the 180 kip
     load stepped onto each top node).
     """
-    from examples.rc_frame_gravity import build_rc_frame_gravity, P_LOAD
+    from examples.rc_frame_gravity import P_LOAD, build_rc_frame_gravity
 
     proj = build_rc_frame_gravity()
     proj.validate_references()

tests/integration/test_rc_frame_pushover.py

@@ -6,8 +6,8 @@ import pytest
 
 pytest.importorskip("openseespy")
 
-from otko.services import load_project, save_project  # noqa: E402
-from otko.services.opensees_runner import OpenSeesRunner  # noqa: E402
+from otko.services import load_project, save_project
+from otko.services.opensees_runner import OpenSeesRunner
 
 pytestmark = pytest.mark.slow
 
@@ -19,10 +19,11 @@ def test_rc_frame_pushover_reaches_target_with_fallback(tmp_path) -> None:  # ty
     AND shows expected nonlinear shape.
     """
     from examples.rc_frame_pushover import (
-        build_rc_frame_pushover,
         D_STEP,
         D_TARGET,
+        build_rc_frame_pushover,
     )
+
     from otko.core import PushoverCase
 
     proj = build_rc_frame_pushover()

tests/integration/test_runner_imposed_motion.py

@@ -23,7 +23,7 @@ import pytest
 ops = pytest.importorskip("openseespy.opensees")
 h5py = pytest.importorskip("h5py")
 
-from otko.core import (  # noqa: E402
+from otko.core import (
     ElasticUniaxial,
     ImposedSupportMotionPattern,
     Node,
@@ -33,7 +33,7 @@ from otko.core import (  # noqa: E402
     UniformExcitationPattern,
     ZeroLengthElement,
 )
-from otko.services import OpenSeesRunner  # noqa: E402
+from otko.services import OpenSeesRunner
 
 pytestmark = pytest.mark.slow
 

tests/integration/test_runner_modal.py

@@ -15,16 +15,16 @@ import math
 
 import pytest
 
-ops = pytest.importorskip("openseespy.opensees")  # noqa: F401
+ops = pytest.importorskip("openseespy.opensees")
 
-from otko.core import (  # noqa: E402
+from otko.core import (
     ElasticBeamColumn,
     ElasticSection,
     ModalCase,
     Node,
     Project,
 )
-from otko.services import OpenSeesRunner  # noqa: E402
+from otko.services import OpenSeesRunner
 
 pytestmark = pytest.mark.slow
 

tests/integration/test_runner_static.py

@@ -12,7 +12,7 @@ import pytest
 
 ops = pytest.importorskip("openseespy.opensees")  # skip if OpenSeesPy not installed
 
-from otko.core import (  # noqa: E402
+from otko.core import (
     ElasticBeamColumn,
     ElasticSection,
     LinearTimeSeries,
@@ -22,7 +22,7 @@ from otko.core import (  # noqa: E402
     Project,
     StaticCase,
 )
-from otko.services import OpenSeesRunner  # noqa: E402
+from otko.services import OpenSeesRunner
 
 pytestmark = pytest.mark.slow
 

tests/integration/test_runner_transient.py

@@ -12,10 +12,10 @@ import math
 import numpy as np
 import pytest
 
-ops = pytest.importorskip("openseespy.opensees")  # noqa: F401
-h5py = pytest.importorskip("h5py")  # noqa: F401
+ops = pytest.importorskip("openseespy.opensees")
+h5py = pytest.importorskip("h5py")
 
-from otko.core import (  # noqa: E402
+from otko.core import (
     ConstantTimeSeries,
     ElasticBeamColumn,
     ElasticSection,
@@ -27,7 +27,7 @@ from otko.core import (  # noqa: E402
     StaticCase,
     TransientCase,
 )
-from otko.services import OpenSeesRunner  # noqa: E402
+from otko.services import OpenSeesRunner
 
 pytestmark = pytest.mark.slow
 
@@ -51,7 +51,6 @@ def test_sdof_free_vibration_matches_cosine(tmp_path) -> None:  # type: ignore[n
     # (already done), then verify dt-step Newmark integration of free
     # vibration starting from a static IC.
     F0 = 100.0
-    u0 = F0 / k
 
     project = Project(
         ndm=2,

tests/services/test_element_forces.py

@@ -19,7 +19,6 @@ from otko.services.element_forces import (
 )
 from otko.services.results import StaticResults
 
-
 # ──────────────────────────────────────────────────────────────────────
 # Fixtures: a tiny 3D project with 2 elements + canned force results.
 # ──────────────────────────────────────────────────────────────────────

tests/services/test_runner_translation.py

@@ -23,7 +23,6 @@ from otko.core import (
     Node,
     PlainLoadPattern,
     Project,
-    StaticCase,
     Steel01,
     TrussElement,
     ZeroLengthElement,

tests/services/test_section_bbox.py

@@ -10,7 +10,6 @@ from otko.core import (
     CircularPatch,
     ElasticSection,
     FiberSection,
-    Project,
     RectangularPatch,
     StraightLayer,
 )

tests/tools/test_parse_schemas.py

@@ -13,6 +13,7 @@ import json
 from pathlib import Path
 
 import pytest
+
 from tools.gidopensees_import.parse_schemas import (
     ParseError,
     _parse_dependencies,

tests/unit/core/materials/test_concrete04.py

@@ -136,6 +136,7 @@ class TestConcrete04JsonRoundTrip:
     def test_old_osmodel_without_concrete04_loads_cleanly(self) -> None:
         """An osmodel payload that doesn't mention Concrete04 is unaffected."""
         from pathlib import Path
+
         from otko.services import load_project
 
         osmodel = Path(__file__).parents[4] / "examples" / "cantilever.osmodel"

tests/unit/test_diagram_renderer.py

@@ -15,21 +15,21 @@ import pytest
 # Force pyvista off-screen before any pyvista import in this module's chain.
 os.environ.setdefault("PYVISTA_OFF_SCREEN", "true")
 
-import pyvista as pv  # noqa: E402
+import pyvista as pv
 
-from otko.core import (  # noqa: E402
+from otko.core import (
     ElasticBeamColumn,
     ElasticSection,
     Node,
     Project,
 )
-from otko.services.element_forces import (  # noqa: E402
+from otko.services.element_forces import (
     DiagramData,
     ForceComponent,
     extract_diagram_data,
 )
-from otko.services.results import StaticResults  # noqa: E402
-from otko.views.canvas3d.diagram_renderer import DiagramRenderer  # noqa: E402
+from otko.services.results import StaticResults
+from otko.views.canvas3d.diagram_renderer import DiagramRenderer
 
 pv.OFF_SCREEN = True
 

tests/unit/test_elements.py

@@ -6,8 +6,8 @@ import pytest
 from pydantic import TypeAdapter, ValidationError
 
 from otko.core import (
-    Element,
     ElasticBeamColumn,
+    Element,
     ForceBeamColumn,
     TrussElement,
     ZeroLengthElement,

tests/unit/test_grid_system.py

@@ -2,7 +2,6 @@
 
 from __future__ import annotations
 
-import math
 from pathlib import Path
 
 import pytest
@@ -174,7 +173,7 @@ def test_coord_system_round_trip_world_local() -> None:
     p_local = (1.5, -0.5, 2.0)
     p_world = cs.local_to_world(p_local)
     p_back = cs.world_to_local(p_world)
-    for a, b in zip(p_local, p_back):
+    for a, b in zip(p_local, p_back, strict=False):
         assert a == pytest.approx(b, abs=1e-9)
 
 

tests/unit/test_phase8a.py

@@ -8,7 +8,6 @@
 
 from __future__ import annotations
 
-import numpy as np
 import pytest
 
 from otko.commands.nodes import SetMassCommand

tests/unit/test_phase9.py

@@ -10,9 +10,7 @@ import pytest
 from otko.core import (
     AggregatorDOF,
     CircularPatch,
-    ElasticSection,
     FiberSection,
-    Fibre,
     Project,
     RectangularPatch,
     SectionAggregator,
@@ -155,7 +153,7 @@ def test_Iz_of_rect_matches_analytical() -> None:
 
 # ── Round-trip persistence ───────────────────────────────────────────
 def test_fiber_section_with_patches_round_trips(tmp_path) -> None:  # type: ignore[no-untyped-def]
-    from otko.core import Node, ElasticBeamColumn
+    from otko.core import ElasticBeamColumn, Node
 
     p = Project(
         nodes=[Node(id=1, coords=(0, 0, 0)), Node(id=2, coords=(1, 0, 0))],

tests/unit/test_renderer.py

@@ -5,9 +5,9 @@ from __future__ import annotations
 import pytest
 
 pv = pytest.importorskip("pyvista")
-import numpy as np  # noqa: E402
+import numpy as np
 
-from otko.core import (  # noqa: E402
+from otko.core import (
     ElasticBeamColumn,
     ElasticSection,
     LinearTimeSeries,
@@ -18,8 +18,8 @@ from otko.core import (  # noqa: E402
     Steel01,
     TrussElement,
 )
-from otko.services.deformation import DeformationSource  # noqa: E402
-from otko.views.canvas3d.model_renderer import (  # noqa: E402
+from otko.services.deformation import DeformationSource
+from otko.views.canvas3d.model_renderer import (
     ModelRenderer,
     RendererMode,
     _classify_support,

tests/unit/test_unit_labels.py

@@ -2,8 +2,6 @@
 
 from __future__ import annotations
 
-import pytest
-
 from otko.core import UnitSystem, labels_for
 
 

tests/unit/test_zerolength_section.py

@@ -3,6 +3,7 @@
 from __future__ import annotations
 
 import pytest
+from pydantic import ValidationError
 
 from otko.core import (
     ElasticSection,
@@ -21,7 +22,7 @@ def test_zero_length_section_schema_defaults() -> None:
 
 
 def test_zero_length_section_rejects_extra_fields() -> None:
-    with pytest.raises(Exception):
+    with pytest.raises(ValidationError):
         ZeroLengthSectionElement(
             id=1,
             nodes=(1, 2),