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,