- Basic operations

- Change from RenderCanvas to RenderWidget for embedded Qt widget
- Add _animate() callback for canvas.request_draw()
- Update render() to use request_draw() for continuous rendering
- This enables OrbitController to work properly with mouse events

.gitignore

@@ -1,3 +1,38 @@
 *.xml
 *.iml
-.idea
+.idea
+
+# Python
+__pycache__/
+*.py[cod]
+*$py.class
+*.so
+.Python
+build/
+develop-eggs/
+dist/
+downloads/
+eggs/
+.eggs/
+lib/
+lib64/
+parts/
+sdist/
+var/
+wheels/
+*.egg-info/
+.installed.cfg
+*.egg
+
+# Virtual environments
+.venv/
+venv/
+ENV/
+
+# Lock files
+uv.lock
+
+# IDE
+.vscode/
+*.swp
+*.swo

.idea/fluency.iml

@@ -1,11 +0,0 @@
-<?xml version="1.0" encoding="UTF-8"?>
-<module type="PYTHON_MODULE" version="4">
-  <component name="NewModuleRootManager">
-    <content url="file://$MODULE_DIR$">
-      <sourceFolder url="file://$MODULE_DIR$/sdfcad" isTestSource="false" />
-      <excludeFolder url="file://$MODULE_DIR$/.venv" />
-    </content>
-    <orderEntry type="jdk" jdkName="Python 3.12 (fluency)" jdkType="Python SDK" />
-    <orderEntry type="sourceFolder" forTests="false" />
-  </component>
-</module>

.idea/modules.xml

@@ -2,7 +2,7 @@
 <project version="4">
   <component name="ProjectModuleManager">
     <modules>
-      <module fileurl="file://$PROJECT_DIR$/.idea/fluency.iml" filepath="$PROJECT_DIR$/.idea/fluency.iml" />
+      <module fileurl="file://$PROJECT_DIR$/.idea/fluency-cad.iml" filepath="$PROJECT_DIR$/.idea/fluency-cad.iml" />
     </modules>
   </component>
 </project>

.idea/workspace.xml

@@ -4,31 +4,13 @@
     <option name="autoReloadType" value="SELECTIVE" />
   </component>
   <component name="ChangeListManager">
-    <list default="true" id="8f0bafd6-58a0-4b20-aa2b-ddc3ba278873" name="Changes" comment="- Improved sketching">
+    <list default="true" id="8f0bafd6-58a0-4b20-aa2b-ddc3ba278873" name="Changes" comment="- Tons of addtions">
-      <change afterPath="$PROJECT_DIR$/README.md" afterDir="false" />
-      <change afterPath="$PROJECT_DIR$/doc/BUGFIX_DRAWING_ISSUES.md" afterDir="false" />
-      <change afterPath="$PROJECT_DIR$/doc/IMPLEMENTATION_SUMMARY.md" afterDir="false" />
-      <change afterPath="$PROJECT_DIR$/doc/PHASE1_COMPLETE.md" afterDir="false" />
-      <change afterPath="$PROJECT_DIR$/doc/PHASE2_COMPLETE.md" afterDir="false" />
-      <change afterPath="$PROJECT_DIR$/doc/SELECTION_DELETION.md" afterDir="false" />
-      <change afterPath="$PROJECT_DIR$/doc/SINGLE_WINDOW_MIGRATION_PLAN.md" afterDir="false" />
-      <change afterPath="$PROJECT_DIR$/doc/TEST_REPORT_PHASE1.md" afterDir="false" />
-      <change afterPath="$PROJECT_DIR$/doc/changes_log.md" afterDir="false" />
-      <change afterPath="$PROJECT_DIR$/doc/current_state.md" afterDir="false" />
-      <change afterPath="$PROJECT_DIR$/doc/technical_documentation.md" afterDir="false" />
-      <change afterPath="$PROJECT_DIR$/drawing_modules/constraints_3d.py" afterDir="false" />
-      <change afterPath="$PROJECT_DIR$/drawing_modules/vtk_sketch_widget.py" afterDir="false" />
-      <change afterPath="$PROJECT_DIR$/drawing_modules/workplane.py" afterDir="false" />
-      <change afterPath="$PROJECT_DIR$/minimal_main.py" afterDir="false" />
-      <change afterPath="$PROJECT_DIR$/ouput_test.md" afterDir="false" />
-      <change afterPath="$PROJECT_DIR$/state.png" afterDir="false" />
-      <change afterPath="$PROJECT_DIR$/test_delete_functionality.py" afterDir="false" />
-      <change afterPath="$PROJECT_DIR$/test_minimal_vtk.py" afterDir="false" />
-      <change afterPath="$PROJECT_DIR$/test_projection.py" afterDir="false" />
-      <change afterPath="$PROJECT_DIR$/test_selection.py" afterDir="false" />
-      <change afterPath="$PROJECT_DIR$/test_vtk_sketch_widget.py" afterDir="false" />
       <change beforePath="$PROJECT_DIR$/.idea/workspace.xml" beforeDir="false" afterPath="$PROJECT_DIR$/.idea/workspace.xml" afterDir="false" />
-      <change beforePath="$PROJECT_DIR$/main.py" beforeDir="false" afterPath="$PROJECT_DIR$/main.py" afterDir="false" />
+      <change beforePath="$PROJECT_DIR$/src/fluency/geometry_occ/kernel.py" beforeDir="false" afterPath="$PROJECT_DIR$/src/fluency/geometry_occ/kernel.py" afterDir="false" />
+      <change beforePath="$PROJECT_DIR$/src/fluency/geometry_occ/sketch.py" beforeDir="false" afterPath="$PROJECT_DIR$/src/fluency/geometry_occ/sketch.py" afterDir="false" />
+      <change beforePath="$PROJECT_DIR$/src/fluency/main.py" beforeDir="false" afterPath="$PROJECT_DIR$/src/fluency/main.py" afterDir="false" />
+      <change beforePath="$PROJECT_DIR$/src/fluency/rendering/occ_renderer.py" beforeDir="false" afterPath="$PROJECT_DIR$/src/fluency/rendering/occ_renderer.py" afterDir="false" />
+      <change beforePath="$PROJECT_DIR$/tests/test_geometry.py" beforeDir="false" afterPath="$PROJECT_DIR$/tests/test_geometry.py" afterDir="false" />
     </list>
     <option name="SHOW_DIALOG" value="false" />
     <option name="HIGHLIGHT_CONFLICTS" value="true" />
@@ -45,7 +27,7 @@
   <component name="Git.Settings">
     <option name="RECENT_BRANCH_BY_REPOSITORY">
       <map>
-        <entry key="$PROJECT_DIR$" value="master" />
+        <entry key="$PROJECT_DIR$" value="single_window" />
       </map>
     </option>
     <option name="RECENT_GIT_ROOT_PATH" value="$PROJECT_DIR$" />
@@ -65,32 +47,39 @@
     <option name="hideEmptyMiddlePackages" value="true" />
     <option name="showLibraryContents" value="true" />
   </component>
-  <component name="PropertiesComponent"><![CDATA[{
+  <component name="PropertiesComponent">{
-  "keyToString": {
+  &quot;keyToString&quot;: {
-    "Python.2dtest.executor": "Run",
+    &quot;Python.2dtest.executor&quot;: &quot;Run&quot;,
-    "Python.3d_windows.executor": "Run",
+    &quot;Python.3d_windows.executor&quot;: &quot;Run&quot;,
-    "Python.Unnamed.executor": "Run",
+    &quot;Python.Unnamed.executor&quot;: &quot;Run&quot;,
-    "Python.draw_widget2d.executor": "Run",
+    &quot;Python.draw_widget2d.executor&quot;: &quot;Run&quot;,
-    "Python.draw_widget_solve.executor": "Run",
+    &quot;Python.draw_widget_solve.executor&quot;: &quot;Run&quot;,
-    "Python.fluency.executor": "Run",
+    &quot;Python.fluency.executor&quot;: &quot;Run&quot;,
-    "Python.fluencyb.executor": "Run",
+    &quot;Python.fluencyb.executor&quot;: &quot;Run&quot;,
-    "Python.gl_widget.executor": "Run",
+    &quot;Python.gl_widget.executor&quot;: &quot;Run&quot;,
-    "Python.main.executor": "Run",
+    &quot;Python.kernel.executor&quot;: &quot;Run&quot;,
-    "Python.meshtest.executor": "Run",
+    &quot;Python.main.executor&quot;: &quot;Run&quot;,
-    "Python.side_fluency.executor": "Run",
+    &quot;Python.meshtest.executor&quot;: &quot;Run&quot;,
-    "Python.simple_mesh.executor": "Run",
+    &quot;Python.occ_renderer.executor&quot;: &quot;Run&quot;,
-    "Python.test_vtk_sketch_widget.executor": "Run",
+    &quot;Python.side_fluency.executor&quot;: &quot;Run&quot;,
-    "Python.vtk_sketch_widget.executor": "Run",
+    &quot;Python.simple_mesh.executor&quot;: &quot;Run&quot;,
-    "Python.vtk_widget.executor": "Run",
+    &quot;Python.vtk_widget.executor&quot;: &quot;Run&quot;,
-    "Python.vulkan.executor": "Run",
+    &quot;Python.vulkan.executor&quot;: &quot;Run&quot;,
-    "RunOnceActivity.OpenProjectViewOnStart": "true",
+    &quot;RunOnceActivity.OpenProjectViewOnStart&quot;: &quot;true&quot;,
-    "RunOnceActivity.ShowReadmeOnStart": "true",
+    &quot;RunOnceActivity.ShowReadmeOnStart&quot;: &quot;true&quot;,
-    "RunOnceActivity.git.unshallow": "true",
+    &quot;RunOnceActivity.TerminalTabsStorage.copyFrom.TerminalArrangementManager.252&quot;: &quot;true&quot;,
-    "git-widget-placeholder": "single__window",
+    &quot;RunOnceActivity.git.unshallow&quot;: &quot;true&quot;,
-    "last_opened_file_path": "/Volumes/Data_drive/Programming/fluency",
+    &quot;RunOnceActivity.typescript.service.memoryLimit.init&quot;: &quot;true&quot;,
-    "settings.editor.selected.configurable": "project.propVCSSupport.DirectoryMappings"
+    &quot;codeWithMe.voiceChat.enabledByDefault&quot;: &quot;false&quot;,
+    &quot;git-widget-placeholder&quot;: &quot;feature/occ-migration&quot;,
+    &quot;last_opened_file_path&quot;: &quot;/Volumes/Data_drive/Programming/fluency/src/fluency&quot;,
+    &quot;node.js.detected.package.eslint&quot;: &quot;true&quot;,
+    &quot;node.js.selected.package.eslint&quot;: &quot;(autodetect)&quot;,
+    &quot;node.js.selected.package.tslint&quot;: &quot;(autodetect)&quot;,
+    &quot;nodejs_package_manager_path&quot;: &quot;npm&quot;,
+    &quot;settings.editor.selected.configurable&quot;: &quot;project.propVCSSupport.DirectoryMappings&quot;
   }
-}]]></component>
+}</component>
   <component name="QodanaReportsService">
     <option name="descriptions">
       <ReportDescription localRun="true" path="/private/var/folders/kg/zm48w_r96yb68mlbzvb9gtq40000gn/T/qodana_output/qodana.sarif.json" reportGuid="5f5b823c-c594-48c5-ae1f-062e30303918" reportId="fluency/qodana/2024-02-04" />
@@ -98,19 +87,19 @@
   </component>
   <component name="RecentsManager">
     <key name="CopyFile.RECENT_KEYS">
+      <recent name="$PROJECT_DIR$/src/fluency" />
       <recent name="$PROJECT_DIR$" />
       <recent name="$PROJECT_DIR$/drawing_modules" />
       <recent name="$PROJECT_DIR$/modules" />
     </key>
     <key name="MoveFile.RECENT_KEYS">
-      <recent name="$PROJECT_DIR$/doc" />
       <recent name="$PROJECT_DIR$" />
     </key>
   </component>
   <component name="SharedIndexes">
     <attachedChunks>
       <set>
-        <option value="bundled-python-sdk-4762d8aabb82-6d6dccd035ac-com.jetbrains.pycharm.pro.sharedIndexes.bundled-PY-253.30387.173" />
+        <option value="bundled-python-sdk-c59985aa861c-c2ffad84badb-com.jetbrains.pycharm.pro.sharedIndexes.bundled-PY-261.24374.152" />
       </set>
     </attachedChunks>
   </component>
@@ -275,17 +264,28 @@
       <option name="project" value="LOCAL" />
       <updated>1755369224187</updated>
     </task>
-    <task id="LOCAL-00020" summary="- Improved sketching">
+    <task id="LOCAL-00020" summary="- Tons of addtions">
       <option name="closed" value="true" />
-      <created>1763311700335</created>
+      <created>1782673954850</created>
       <option name="number" value="00020" />
       <option name="presentableId" value="LOCAL-00020" />
       <option name="project" value="LOCAL" />
-      <updated>1763311700335</updated>
+      <updated>1782673954850</updated>
     </task>
-    <option name="localTasksCounter" value="21" />
+    <task id="LOCAL-00021" summary="- Tons of addtions">
+      <option name="closed" value="true" />
+      <created>1782679912834</created>
+      <option name="number" value="00021" />
+      <option name="presentableId" value="LOCAL-00021" />
+      <option name="project" value="LOCAL" />
+      <updated>1782679912834</updated>
+    </task>
+    <option name="localTasksCounter" value="22" />
     <servers />
   </component>
+  <component name="TypeScriptGeneratedFilesManager">
+    <option name="version" value="3" />
+  </component>
   <component name="Vcs.Log.Tabs.Properties">
     <option name="TAB_STATES">
       <map>
@@ -318,7 +318,7 @@
     <MESSAGE value="- added MIT license" />
     <MESSAGE value="- added screenshot" />
     <MESSAGE value="- added sdf folder ( doesnt work via pip or git=)" />
-    <MESSAGE value="- Improved sketching" />
+    <MESSAGE value="- Tons of addtions" />
-    <option name="LAST_COMMIT_MESSAGE" value="- Improved sketching" />
+    <option name="LAST_COMMIT_MESSAGE" value="- Tons of addtions" />
   </component>
 </project>

pyproject.toml

@@ -33,6 +33,7 @@ dependencies = [
     "numpy>=1.24.0",
     "scipy>=1.10.0",
     "pillow>=10.0.0",
+    "python_solvespace>=3.0.0",
 ]
 
 [project.optional-dependencies]

src/fluency/geometry_occ/kernel.py

@@ -46,7 +46,11 @@ class OCGeometryKernel(GeometryKernel):
         self._mesh_tolerance: float = 0.1
 
     def _get_shape(self, obj: GeometryObject) -> Any:
-        """Extract the underlying OCC shape from a GeometryObject."""
+        """Extract the underlying OCC shape from a GeometryObject.
+
+        Returns *None* if the object carries no shape (e.g. an empty sketch) —
+        callers should check for None before using the result.
+        """
         import cadquery as cq
 
         if isinstance(obj, OCCGeometryObject):
@@ -64,7 +68,13 @@ class OCGeometryKernel(GeometryKernel):
                 if hasattr(obj.shape, "wrapped"):
                     return obj.shape.wrapped
                 return obj.shape
-        return obj.shape if obj.shape else obj
+            # No cadquery obj and no raw shape → genuinely empty.
+            return None
+        # Non-OCCGeometryObject: return its shape if present, else None.
+        # (Use explicit identity/truth checks — some OCP TopoDS objects have a
+        # falsy __bool__, so ``obj.shape if obj.shape`` is unsafe.)
+        shape = getattr(obj, "shape", None)
+        return shape if shape is not None else None
 
     def _get_cq_obj(self, obj: GeometryObject) -> Any:
         """Get CadQuery object from GeometryObject."""
@@ -157,24 +167,113 @@ class OCGeometryKernel(GeometryKernel):
         direction: Tuple[float, float, float] = (0, 0, 1),
         symmetric: bool = False,
     ) -> GeometryObject:
-        """Extrude a 2D sketch into a 3D solid."""
+        """Extrude a sketch face into a 3D solid along the sketch plane normal.
-        import cadquery as cq
 
-        cq_obj = self._get_cq_obj(sketch)
+        The sketch's plane normal is read from ``sketch.metadata["normal"]``
+        (set by ``OCCSketch.build_face_geometry``); it defaults to +Z for
+        legacy objects that don't carry one.  *direction* is accepted for API
+        compatibility but ignored — the plane normal is authoritative.  A
+        negative *height* extrudes against the normal.
+        """
+        from OCP.gp import gp_Vec
+        from OCP.BRepPrimAPI import BRepPrimAPI_MakePrism
+        from OCP.BRepAlgoAPI import BRepAlgoAPI_Fuse
+        from OCP.TopoDS import TopoDS_Shape
 
-        if isinstance(cq_obj, cq.Workplane):
+        # Defensive: figure out the actual shape from whatever the caller
-            if symmetric:
+        # hands us, and surface a clear error if we can't get one.
-                solid = cq_obj.extrude(height / 2, both=True)
+        #  - If it's an OCCGeometryObject wrapper, unwrap via _get_shape.
-            else:
+        #  - If it's already a TopoDS_Shape (raw face/wire/etc.), use it.
-                solid = cq_obj.extrude(height)
+        #  - If it's a cadquery Workplane, unwrap that too.
+        #  - If it's a cadquery Shape (cq.Shape), unwrap to TopoDS_Shape.
+        if isinstance(sketch, OCCGeometryObject):
+            face = self._get_shape(sketch)
+        elif isinstance(sketch, TopoDS_Shape):
+            face = sketch
         else:
-            wp = cq.Workplane("XY").add(cq_obj)
+            face = self._get_shape(sketch)
-            if symmetric:
+        if face is None:
-                solid = wp.extrude(height / 2, both=True)
+            raise ValueError(
-            else:
+                "Cannot extrude: sketch has no geometry. "
-                solid = wp.extrude(height)
+                "Draw a closed profile before extruding."
+            )
+        # If the wrapper class itself leaked through somehow, surface a
+        # clear error instead of letting BRepPrimAPI_MakePrism raise an
+        # opaque TypeError.
+        if isinstance(face, OCCGeometryObject):
+            raise ValueError(
+                "Cannot extrude: sketch geometry is a wrapper, not a shape. "
+                "This is a bug — please report it."
+            )
+        # ``face`` may be a TopoDS_Face (new path) or a compound/wire from
+        # legacy cadquery objects.  If it's not already a face, build one.
+        face = self._ensure_face(face)
+        if face is None:
+            raise ValueError(
+                "Cannot extrude: sketch geometry is not a valid face. "
+                "Ensure the profile is closed (no open ends)."
+            )
 
-        return OCCGeometryObject(solid, {"type": "extrusion"})
+        normal = self._sketch_normal(sketch)
+        nx, ny, nz = normal
+
+        def _prism(h: float):
+            vec = gp_Vec(nx * h, ny * h, nz * h)
+            maker = BRepPrimAPI_MakePrism(face, vec, False, True)
+            maker.Build()
+            return maker.Shape()
+
+        if symmetric:
+            half = height / 2.0
+            pos = _prism(half)
+            neg = _prism(-half)
+            fuse = BRepAlgoAPI_Fuse(pos, neg)
+            fuse.Build()
+            solid = fuse.Shape()
+        else:
+            solid = _prism(height)
+
+        return OCCGeometryObject(solid, {"type": "extrusion", "normal": normal})
+
+    @staticmethod
+    def _sketch_normal(obj: GeometryObject) -> Tuple[float, float, float]:
+        """Return the normal stored on a sketch-derived geometry object, else +Z."""
+        import numpy as np
+        meta = getattr(obj, "metadata", None) or {}
+        n = meta.get("normal")
+        if n is None:
+            return (0.0, 0.0, 1.0)
+        arr = np.asarray(n, dtype=float)
+        norm = float(np.linalg.norm(arr))
+        if norm < 1e-12:
+            return (0.0, 0.0, 1.0)
+        arr = arr / norm
+        return (float(arr[0]), float(arr[1]), float(arr[2]))
+
+    @staticmethod
+    def _ensure_face(shape: Any) -> Any:
+        """Return a ``TopoDS_Face`` from *shape*, or *None* if impossible.
+
+        If *shape* is already a face, return it unchanged; otherwise try to
+        build a planar face from it (wire/edge/compound).  Returns *None* for
+        empty/invalid input so callers can surface a clear error instead of
+        feeding a non-face to ``BRepPrimAPI_MakePrism``.
+        """
+        from OCP.TopoDS import TopoDS_Face
+        from OCP.BRepBuilderAPI import BRepBuilderAPI_MakeFace
+
+        if shape is None:
+            return None
+        if isinstance(shape, TopoDS_Face):
+            return shape
+        try:
+            maker = BRepBuilderAPI_MakeFace(shape, True)
+            maker.Build()
+            if maker.IsDone():
+                return maker.Face()
+        except Exception:
+            pass
+        return None
 
     def revolve(
         self,
@@ -183,20 +282,24 @@ class OCGeometryKernel(GeometryKernel):
         axis: Tuple[float, float, float] = (0, 0, 1),
         origin: Tuple[float, float, float] = (0, 0, 0),
     ) -> GeometryObject:
-        """Revolve a 2D sketch around an axis."""
+        """Revolve a sketch face around an axis."""
-        import cadquery as cq
+        import math
 
-        cq_obj = self._get_cq_obj(sketch)
+        # Get the OCC shape directly (a TopoDS_Face for new sketch geometry).
+        shape = self._get_shape(sketch)
+        face = self._ensure_face(shape)
 
-        if isinstance(cq_obj, cq.Workplane):
+        from OCP.gp import gp_Ax1, gp_Pnt, gp_Dir
-            solid = cq_obj.revolve(angle)
+        from OCP.BRepPrimAPI import BRepPrimAPI_MakeRevol
-        else:
-            face = cq.Face.makeFromWires(cq_obj)
-            axis_vec = cq.Vector(*axis)
-            origin_vec = cq.Vector(*origin)
-            solid = face.revolve(axis_vec, origin_vec, angle)
 
-        return OCCGeometryObject(solid, {"type": "revolution"})
+        # Revolve the face around the axis
+        revolve_axis = gp_Ax1(gp_Pnt(*origin), gp_Dir(*axis))
+        angle_rad = math.radians(angle)
+        revolver = BRepPrimAPI_MakeRevol(face, revolve_axis, angle_rad)
+        revolver.Build()
+        solid_shape = revolver.Shape()
+
+        return OCCGeometryObject(solid_shape, {"type": "revolution"})
 
     def loft(self, profiles: List[GeometryObject], ruled: bool = False) -> GeometryObject:
         """Create a loft between multiple profiles."""
@@ -593,7 +696,9 @@ class OCGeometryKernel(GeometryKernel):
         from OCP.BRep import BRep_Tool
         from OCP.TopLoc import TopLoc_Location
 
-        mesh = BRepMesh_IncrementalMesh(shape, tolerance, False, 0.5, False)
+        # Use finer angular deflection (0.15 rad ≈ 24 segments/circle) so
+        # curved surfaces like cylinders render smoothly instead of faceted.
+        mesh = BRepMesh_IncrementalMesh(shape, tolerance, False, 0.15, True)
         mesh.Perform()
 
         vertices_list: List[List[float]] = []
@@ -601,6 +706,7 @@ class OCGeometryKernel(GeometryKernel):
         vertex_offset = 0
 
         from OCP.TopoDS import TopoDS
+        from OCP.TopAbs import TopAbs_Orientation
 
         explorer = TopExp_Explorer(shape, TopAbs_FACE)
         while explorer.More():
@@ -615,15 +721,21 @@ class OCGeometryKernel(GeometryKernel):
                     vertices_list.append([p.X(), p.Y(), p.Z()])
 
                 n_triangles = triangulation.NbTriangles()
+                # REVERSED faces store triangle winding in the natural (surface)
+                # orientation — we must flip it so the computed normals point
+                # outward (away from solid interior).  TopAbs_REVERSED = 1.
+                reverse_winding = face.Orientation() == TopAbs_Orientation.TopAbs_REVERSED
                 for i in range(1, n_triangles + 1):
                     tri = triangulation.Triangle(i)
-                    faces_list.append(
+                    v0, v1, v2 = (
-                        [
+                        tri.Value(1) - 1 + vertex_offset,
-                            tri.Value(1) - 1 + vertex_offset,
+                        tri.Value(2) - 1 + vertex_offset,
-                            tri.Value(2) - 1 + vertex_offset,
+                        tri.Value(3) - 1 + vertex_offset,
-                            tri.Value(3) - 1 + vertex_offset,
-                        ]
                     )
+                    if reverse_winding:
+                        # Swap last two vertices to flip winding direction.
+                        v1, v2 = v2, v1
+                    faces_list.append([v0, v1, v2])
 
                 vertex_offset += n_vertices
 
@@ -673,7 +785,8 @@ class OCGeometryKernel(GeometryKernel):
 
         explorer = TopExp_Explorer(shape, TopAbs_EDGE)
         while explorer.More():
-            edge = explorer.Current()
+            from OCP.TopoDS import TopoDS
+            edge = TopoDS.Edge_s(explorer.Current())
             edge_points = discretize_edge(edge)
 
             for i, pt in enumerate(edge_points):

src/fluency/models/data_model.py

@@ -6,7 +6,7 @@ including projects, components, sketches, and bodies.
 """
 
 from dataclasses import dataclass, field
-from typing import Dict, List, Optional, Any
+from typing import Dict, List, Optional, Any, Tuple
 from datetime import datetime
 import uuid
 import numpy as np
@@ -46,6 +46,32 @@ class Sketch:
     created_at: datetime = field(default_factory=datetime.now)
     modified_at: datetime = field(default_factory=datetime.now)
 
+    def set_workplane(
+        self,
+        origin: Tuple[float, float, float],
+        normal: Tuple[float, float, float],
+        x_dir: Tuple[float, float, float],
+    ) -> None:
+        """Set this sketch's 3D workplane and sync it to the OCC sketch.
+
+        Call this when the sketch is placed on a face/datum plane.  UV
+        coordinates are unchanged; only their world mapping moves.
+        """
+        self.workplane_origin = np.asarray(origin, dtype=float)
+        self.workplane_normal = np.asarray(normal, dtype=float)
+        self.workplane_x_dir = np.asarray(x_dir, dtype=float)
+        self.apply_workplane()
+        self.modified_at = datetime.now()
+
+    def apply_workplane(self) -> None:
+        """Push the stored workplane fields into the underlying OCCSketch."""
+        if self.occ_sketch is not None:
+            self.occ_sketch.set_workplane(
+                tuple(self.workplane_origin.tolist()),
+                tuple(self.workplane_normal.tolist()),
+                tuple(self.workplane_x_dir.tolist()),
+            )
+
     def add_point(self, x: float, y: float) -> Any:
         """Add a point to the sketch."""
         self.modified_at = datetime.now()

src/fluency/rendering/__init__.py

@@ -6,6 +6,7 @@ from fluency.rendering.base import (
     RenderColor,
 )
 from fluency.rendering.pygfx_renderer import PygfxRenderer, PygfxRenderObject
+from fluency.rendering.occ_renderer import OCCRenderer, OCCRenderObject
 
 __all__ = [
     "Renderer",

src/fluency/rendering/base.py

@@ -97,7 +97,7 @@ class Renderer(ABC):
         faces: np.ndarray,
         color: Tuple[float, float, float] = (0.2, 0.4, 0.8),
         name: Optional[str] = None,
-    ) -> RenderObject:
+    ) -> str:
         """
         Add a mesh to the scene.
 
@@ -108,7 +108,7 @@ class Renderer(ABC):
             name: Optional name for the object
 
         Returns:
-            RenderObject representing the mesh
+            String ID of the mesh
         """
         pass
 
@@ -120,7 +120,7 @@ class Renderer(ABC):
         color: Tuple[float, float, float] = (1.0, 1.0, 1.0),
         line_width: float = 1.0,
         name: Optional[str] = None,
-    ) -> RenderObject:
+    ) -> str:
         """
         Add a wireframe to the scene.
 
@@ -132,7 +132,7 @@ class Renderer(ABC):
             name: Optional name for the object
 
         Returns:
-            RenderObject representing the wireframe
+            String ID of the wireframe
         """
         pass
 
@@ -143,7 +143,7 @@ class Renderer(ABC):
         color: Tuple[float, float, float] = (1.0, 0.0, 0.0),
         size: float = 5.0,
         name: Optional[str] = None,
-    ) -> RenderObject:
+    ) -> str:
         """
         Add points to the scene.
 
@@ -154,7 +154,7 @@ class Renderer(ABC):
             name: Optional name for the object
 
         Returns:
-            RenderObject representing the points
+            String ID of the points
         """
         pass
 
@@ -166,7 +166,7 @@ class Renderer(ABC):
         color: Tuple[float, float, float] = (1.0, 1.0, 1.0),
         line_width: float = 1.0,
         name: Optional[str] = None,
-    ) -> RenderObject:
+    ) -> str:
         """
         Add line segments to the scene.
 
@@ -178,7 +178,7 @@ class Renderer(ABC):
             name: Optional name for the object
 
         Returns:
-            RenderObject representing the lines
+            String ID of the lines
         """
         pass
 
@@ -312,13 +312,13 @@ class Renderer(ABC):
         size: float = 100.0,
         divisions: int = 10,
         color: Tuple[float, float, float] = (0.3, 0.3, 0.3),
-    ) -> RenderObject:
+    ) -> str:
-        """Add a reference grid."""
+        """Add a reference grid. Returns the grid ID."""
         pass
 
     @abstractmethod
-    def add_axes(self, size: float = 10.0, visible: bool = True) -> RenderObject:
+    def add_axes(self, size: float = 10.0, visible: bool = True) -> str:
-        """Add coordinate axes."""
+        """Add coordinate axes. Returns the axes ID."""
         pass
 
     @abstractmethod

src/fluency/rendering/occ_renderer.py

@@ -0,0 +1,968 @@
+"""OCC-based 3D renderer — displays BRep shapes directly on the GPU.
+
+Uses OCC's ``AIS_Shape`` and ``V3d_Viewer`` so that curved surfaces (cylinders,
+spheres, etc.) render smoothly without manual triangulation, and edges/faces are
+natively selectable.
+"""
+
+import logging
+import uuid
+from dataclasses import dataclass, field
+from typing import Any, Dict, List, Optional, Tuple
+
+import numpy as np
+
+from .base import Renderer, RenderObject, RenderColor
+
+logger = logging.getLogger(__name__)
+
+
+@dataclass
+class OCCRenderObject(RenderObject):
+    """Internal object state for the OCC renderer."""
+
+    obj_id: str = ""
+    ais_shape: Any = None  # AIS_Shape
+    ais_type: str = "shape"  # "shape" | "wireframe" | "points"
+    color: RenderColor = field(default_factory=lambda: RenderColor(0.5, 0.5, 0.5))
+
+
+class OCCRenderer(Renderer):
+    """Renderer that uses OCC's native AIS display for smooth BRep rendering."""
+
+    def __init__(self) -> None:
+        super().__init__()
+        self._viewer: Any = None
+        self._view: Any = None
+        self._context: Any = None
+        self._window: Any = None
+        self._initialized: bool = False
+        self._objects: Dict[str, OCCRenderObject] = {}
+        self._parent_widget: Any = None
+        self._last_mouse_x: int = 0
+        self._last_mouse_y: int = 0
+        self._pan_start_x: int = 0
+        self._pan_start_y: int = 0
+        self._nav_mode: Optional[str] = None  # "rotate" | "pan" | None
+        # Persistent light-blue transparent overlay marking the selected face.
+        self._highlight_ais: Any = None
+        # Temporary transparent preview AIS for the live extrude/cut dialog.
+        self._preview_ais: Any = None
+
+    def initialize(self, parent_widget: Any) -> bool:
+        """Initialise OCC viewer inside *parent_widget* (a QWidget)."""
+        self._parent_widget = parent_widget
+
+        import os as _os
+        if _os.environ.get("QT_QPA_PLATFORM") == "offscreen":
+            logger.warning("OCCRenderer skipped (QT_QPA_PLATFORM=offscreen)")
+            return False
+
+        logger.info("OCCRenderer imports starting...")
+        from OCP.Aspect import (
+            Aspect_DisplayConnection,
+            Aspect_NeutralWindow,
+            Aspect_GFM_VER,
+            Aspect_TypeOfTriedronPosition,
+        )
+        from OCP.OpenGl import OpenGl_GraphicDriver
+        from OCP.V3d import (
+            V3d_Viewer,
+            V3d_View,
+            V3d_TypeOfView,
+            V3d_DirectionalLight,
+            V3d_AmbientLight,
+            V3d_TypeOfOrientation,
+        )
+        from OCP.AIS import AIS_InteractiveContext
+        from OCP.Graphic3d import (
+            Graphic3d_Camera,
+            Graphic3d_TypeOfShadingModel,
+            Graphic3d_MaterialAspect,
+            Graphic3d_NameOfMaterial,
+        )
+        from OCP.Quantity import (
+            Quantity_Color,
+            Quantity_TOC_RGB,
+            Quantity_NameOfColor,
+        )
+        logger.info("OCCRenderer imports complete")
+
+        hwnd = int(parent_widget.winId())
+        if hwnd <= 1:
+            logger.warning("OCCRenderer skipped (no native window handle)")
+            return False
+
+        logger.info("OCCRenderer creating objects...")
+
+        try:
+            display = Aspect_DisplayConnection()
+            driver = OpenGl_GraphicDriver(display)
+            viewer = V3d_Viewer(driver)
+
+            # ── Lighting: replace defaults with a tuned 3-light rig ───────
+            # Key light (warm directional from upper-front-right) + fill
+            # (cool, softer) + ambient for base lift.  Gives proper shading
+            # on curved BRep surfaces (cylinders, spheres).
+            viewer.SetLightOff()  # clear default lights first
+            key = V3d_DirectionalLight(
+                V3d_TypeOfOrientation.V3d_XposYnegZpos,
+                Quantity_Color(1.0, 0.96, 0.88, Quantity_TOC_RGB),
+                True,
+            )
+            fill = V3d_DirectionalLight(
+                V3d_TypeOfOrientation.V3d_XnegYnegZpos,
+                Quantity_Color(0.55, 0.62, 0.78, Quantity_TOC_RGB),
+                True,
+            )
+            rim = V3d_DirectionalLight(
+                V3d_TypeOfOrientation.V3d_XposYposZneg,
+                Quantity_Color(0.5, 0.5, 0.55, Quantity_TOC_RGB),
+                True,
+            )
+            ambient = V3d_AmbientLight(
+                Quantity_Color(0.35, 0.35, 0.4, Quantity_TOC_RGB)
+            )
+            for light in (key, fill, rim, ambient):
+                viewer.SetLightOn(light)
+
+            view = V3d_View(viewer, V3d_TypeOfView.V3d_ORTHOGRAPHIC)
+
+            # ── Background gradient (dark studio look) ───────────────────
+            viewer.SetDefaultBgGradientColors(
+                Quantity_Color(0.18, 0.20, 0.24, Quantity_TOC_RGB),
+                Quantity_Color(0.08, 0.09, 0.11, Quantity_TOC_RGB),
+                Aspect_GFM_VER,
+            )
+            view.SetBgGradientColors(
+                Quantity_Color(0.18, 0.20, 0.24, Quantity_TOC_RGB),
+                Quantity_Color(0.08, 0.09, 0.11, Quantity_TOC_RGB),
+                Aspect_GFM_VER,
+                True,
+            )
+
+            # ── Rendering quality: MSAA + Phong shading + AA ─────────────
+            params = view.ChangeRenderingParams()
+            params.NbMsaaSamples = 4  # 4x MSAA for smoother edges
+            params.IsAntialiasingEnabled = True
+            params.LineFeather = 0.6
+            view.SetShadingModel(Graphic3d_TypeOfShadingModel.Graphic3d_TypeOfShadingModel_Phong)
+
+            # ── Corner orientation trihedron (axis gizmo) ────────────────
+            try:
+                view.TriedronDisplay(
+                    Aspect_TypeOfTriedronPosition.Aspect_TOTP_LEFT_LOWER,
+                    Quantity_Color(Quantity_NameOfColor.Quantity_NOC_WHITE),
+                    0.08,
+                )
+            except Exception:
+                logger.debug("TriedronDisplay unavailable", exc_info=True)
+
+            context = AIS_InteractiveContext(viewer)
+            # Default display mode = shaded (AIS_Shaded = 1)
+            context.SetDisplayMode(1, True)
+
+            # Style the dynamic (hover) highlight as light-blue so the face
+            # pick preview matches the persistent selection overlay below.
+            try:
+                from OCP.Quantity import Quantity_Color, Quantity_TOC_RGB
+                # Modify the existing dynamic-highlight drawer in place (per
+                # OCC docs this is safer than building a fresh Prs3d_Drawer).
+                hd = context.HighlightStyle()
+                hd.SetColor(Quantity_Color(0.45, 0.75, 1.0, Quantity_TOC_RGB))
+                hd.SetDisplayMode(1)
+            except Exception:
+                logger.debug("dynamic highlight style unavailable", exc_info=True)
+
+            # Attach OCC view to the Qt widget via the native window handle.
+            win = Aspect_NeutralWindow()
+            win.SetNativeHandle(hwnd)
+            w, h = parent_widget.width(), parent_widget.height()
+            win.SetSize(w, h)
+            view.SetWindow(win)
+            # Ensure the depth range follows the scene so nothing clips.
+            view.SetAutoZFitMode(True)
+
+            self._viewer = viewer
+            self._view = view
+            self._context = context
+            self._window = win
+            self._initialized = True
+
+            logger.info("OCCRenderer initialised (native OCC display)")
+            return True
+
+        except Exception as exc:
+            logger.error(f"OCCRenderer initialisation failed: {exc}")
+            self._initialized = False
+            return False
+
+    def shutdown(self) -> None:
+        """Clean up OCC viewer resources."""
+        self.clear_scene()
+        if self._view is not None:
+            self._view.Remove()
+            self._view = None
+        if self._viewer is not None:
+            self._viewer.Remove()
+            self._viewer = None
+        self._initialized = False
+
+    # ─── BRep shape display (primary entry point) ───────────────────────
+
+    def add_shape(
+        self,
+        shape: Any,
+        color: Optional[Tuple[float, float, float]] = None,
+        name: Optional[str] = None,
+    ) -> str:
+        """Display an OCC ``TopoDS_Shape`` directly via ``AIS_Shape``.
+
+        Returns a unique object ID (or *name* if provided).
+        """
+        from OCP.AIS import AIS_Shape
+        from OCP.Quantity import Quantity_Color, Quantity_TOC_RGB
+        from OCP.Prs3d import Prs3d_Drawer
+
+        obj_id = name or f"shape_{uuid.uuid4().hex[:8]}"
+
+        ais = AIS_Shape(shape)
+
+        # Order matters: set material *before* color so the per-channel color
+        # overrides only the diffuse albedo and the plastic BRDF is retained.
+        ais.SetMaterial(self._default_material())
+        if color is not None:
+            qcol = Quantity_Color(*color, Quantity_TOC_RGB)
+            ais.SetColor(qcol)
+
+        # Shaded display with boundary edges drawn on top for readability.
+        ais.SetDisplayMode(1)  # 1 = AIS_Shaded
+        drawer = ais.Attributes()
+        try:
+            # Always draw face boundaries — makes solid edges crisp.
+            drawer.SetFaceBoundaryDraw(True)
+        except Exception:
+            logger.debug("boundary-draw attrs unavailable", exc_info=True)
+        # Slight polygon offset so boundary edges don't z-fight the surface.
+        # Mode 3 = Graphic3d_POM_Fill (offset filled polygons).
+        try:
+            ais.SetPolygonOffsets(3, 1.0, 0.0)
+        except Exception:
+            logger.debug("polygon offset unavailable", exc_info=True)
+
+        self._context.Display(ais, True)
+        # Activate selection modes so the viewer can detect/pick the whole
+        # shape (mode 0) and individual faces (mode for TopAbs_FACE) — needed
+        # for sketch-on-surface face picking.  Left-click orbits the camera
+        # (see handle_mouse_press), so active selection doesn't interfere.
+        try:
+            from OCP.TopAbs import TopAbs_FACE
+            face_mode = AIS_Shape.SelectionMode_s(TopAbs_FACE)
+            self._context.Activate(ais, face_mode)
+        except Exception:
+            logger.debug("face selection mode activation failed", exc_info=True)
+
+        defcol = color or (0.5, 0.5, 0.5)
+        robj = OCCRenderObject(
+            obj_id=obj_id,
+            ais_shape=ais,
+            ais_type="shape",
+            color=RenderColor(*defcol),
+        )
+        self._objects[obj_id] = robj
+
+        # Fit camera on first shape added.
+        if len(self._objects) == 1:
+            try:
+                self.fit_camera()
+            except Exception:
+                logger.warning("fit_camera failed on first shape", exc_info=True)
+
+        return obj_id
+
+    def _default_material(self):
+        """Return a default Graphic3d_MaterialAspect for shading.
+
+        Plastic gives a clean, readable matte surface that responds well to
+        the 3-light rig set up in :meth:`initialize`.
+        """
+        from OCP.Graphic3d import Graphic3d_MaterialAspect, Graphic3d_NameOfMaterial
+
+        mat = Graphic3d_MaterialAspect(
+            Graphic3d_NameOfMaterial.Graphic3d_NOM_PLASTIC
+        )
+        return mat
+
+    # ─── Legacy mesh / wireframe (kept for backward compat) ────────────
+
+    def add_mesh(
+        self,
+        vertices: np.ndarray,
+        faces: np.ndarray,
+        color: Tuple[float, float, float] = (0.2, 0.4, 0.8),
+        name: Optional[str] = None,
+    ) -> str:
+        """Add triangulated mesh by converting it to an OCC polygonal shape.
+
+        Prefer :meth:`add_shape` for native BRep display — it avoids meshing
+        artifacts on curved surfaces.
+        """
+        from OCP.Poly import Poly_Triangulation, Poly_Triangle
+        from OCP.TopoDS import TopoDS_Face
+        from OCP.BRep import BRep_Builder
+        from OCP.gp import gp_Pnt
+
+        n_verts = len(vertices)
+        n_tris = len(faces)
+
+        # Build triangulation via (nbNodes, nbTriangles, hasUVNodes) constructor
+        tri = Poly_Triangulation(n_verts, n_tris, False)
+
+        for i, (x, y, z) in enumerate(vertices):
+            tri.SetNode(i + 1, gp_Pnt(float(x), float(y), float(z)))
+
+        for i, (a, b, cc) in enumerate(faces):
+            tri.SetTriangle(i + 1, Poly_Triangle(int(a) + 1, int(b) + 1, int(cc) + 1))
+
+        builder = BRep_Builder()
+        shape = TopoDS_Face()
+        builder.MakeFace(shape, tri)
+        return self.add_shape(shape, color, name)
+
+    def add_wireframe(
+        self,
+        vertices: np.ndarray,
+        edges: np.ndarray,
+        color: Tuple[float, float, float] = (1.0, 1.0, 1.0),
+        line_width: float = 1.0,
+        name: Optional[str] = None,
+    ) -> str:
+        """Add a wireframe from edge data (legacy, kept for compatibility).
+
+        For new code prefer :meth:`add_shape` — OCC's AIS displays the
+        shape boundary automatically.
+        """
+        obj_id = name or f"wf_{uuid.uuid4().hex[:8]}"
+        logger.debug(f"add_wireframe {obj_id} — ignored (AIS draws edges natively)")
+        # Wireframes are already provided by the AIS shaded display, so we
+        # skip explicit line geometry unless there is a specific need.
+        return obj_id
+
+    def add_points(
+        self,
+        points: np.ndarray,
+        color: Tuple[float, float, float] = (1.0, 0.0, 0.0),
+        size: float = 5.0,
+        name: Optional[str] = None,
+    ) -> str:
+        """Add point cloud (not yet implemented with OCC renderer)."""
+        obj_id = name or f"pts_{uuid.uuid4().hex[:8]}"
+        logger.debug(f"add_points {obj_id} — not implemented in OCCRenderer")
+        return obj_id
+
+    def add_lines(
+        self,
+        start_points: np.ndarray,
+        end_points: np.ndarray,
+        color: Tuple[float, float, float] = (1.0, 1.0, 1.0),
+        line_width: float = 1.0,
+        name: Optional[str] = None,
+    ) -> str:
+        """Add line segments (not yet implemented with OCC renderer)."""
+        obj_id = name or f"ln_{uuid.uuid4().hex[:8]}"
+        logger.debug(f"add_lines {obj_id} — not implemented in OCCRenderer")
+        return obj_id
+
+    # ─── Object management ─────────────────────────────────────────────
+
+    def remove_object(self, obj: OCCRenderObject) -> bool:
+        """Remove an object from the scene."""
+        if obj.ais_shape is not None:
+            self._context.Remove(obj.ais_shape, True)
+        if obj.obj_id in self._objects:
+            del self._objects[obj.obj_id]
+            return True
+        return False
+
+    def remove_mesh(self, obj_id: str) -> None:
+        """Remove an object by ID (legacy compatibility)."""
+        obj = self._objects.get(obj_id)
+        if obj is not None:
+            self.remove_object(obj)
+
+    def set_visibility(self, obj_id: str, visible: bool) -> bool:
+        """Show or hide an object by ID, preserving its place in the scene.
+
+        Unlike ``remove_mesh``, this doesn't free the object — the user can
+        toggle it back on later.  Returns True on success, False if the
+        object isn't found (e.g. it was already removed).
+        """
+        obj = self._objects.get(obj_id)
+        if obj is None:
+            return False
+        self.set_object_visible(obj, visible)
+        return True
+
+    def set_object_transparency(self, obj_id: str, transparency: float) -> bool:
+        """Set the transparency of an object by ID (0.0 opaque..1.0 invisible).
+
+        Used by the live extrude preview to dim the existing target body
+        so the user can see the previewed result through/over it.  Returns
+        True on success, False if the object isn't found.
+        """
+        obj = self._objects.get(obj_id)
+        if obj is None or obj.ais_shape is None:
+            return False
+        try:
+            obj.ais_shape.SetTransparency(transparency)
+            self._context.RecomputePrsOnly(obj.ais_shape, True)
+        except Exception:
+            logger.debug("set_object_transparency failed", exc_info=True)
+            return False
+        return True
+
+    # ─── Live preview (extrude/cut preview) ──────────────────────────────
+
+    _PREVIEW_ID = "__extrude_preview__"
+
+    def preview_shape(
+        self,
+        shape: Any,
+        color: Optional[Tuple[float, float, float]] = None,
+        transparency: float = 0.60,
+    ) -> None:
+        """Display a temporary transparent preview of *shape* (TopoDS_Shape).
+
+        The preview lives under a fixed id (``__extrude_preview__``) so a
+        subsequent call replaces the previous preview in place.  Call
+        :meth:`clear_preview` to remove it.  This is independent of the
+        tracked ``_objects`` dict — the preview is NOT a body and won't
+        be returned by ``pick_planar_face``'s owner scan.
+        """
+        if self._context is None:
+            return
+        # Clear any previous preview (uses the same id).
+        self.clear_preview()
+        from OCP.AIS import AIS_Shape
+        from OCP.Quantity import Quantity_Color, Quantity_TOC_RGB
+
+        ais = AIS_Shape(shape)
+        try:
+            ais.SetMaterial(self._default_material())
+        except Exception:
+            logger.debug("preview material set failed", exc_info=True)
+        col = color or (0.45, 0.80, 0.95)  # cyan-ish for preview
+        ais.SetColor(Quantity_Color(*col, Quantity_TOC_RGB))
+        ais.SetDisplayMode(1)  # shaded
+        try:
+            ais.SetTransparency(transparency)
+        except Exception:
+            logger.debug("preview transparency set failed", exc_info=True)
+        # Draw face boundaries so the preview shape reads cleanly.
+        try:
+            drawer = ais.Attributes()
+            drawer.SetFaceBoundaryDraw(True)
+        except Exception:
+            pass
+        self._context.Display(ais, True)
+        self._preview_ais = ais
+        if self._view is not None:
+            self._view.Repaint()
+
+    def clear_preview(self) -> None:
+        """Remove the live extrude preview shape."""
+        if self._context is None or getattr(self, "_preview_ais", None) is None:
+            return
+        try:
+            self._context.Remove(self._preview_ais, True)
+        finally:
+            self._preview_ais = None
+
+    def clear_scene(self) -> None:
+        """Remove all objects from the scene."""
+        if self._context is None:
+            return
+        self.clear_preview()
+        self.clear_face_highlight()
+        # Remove every displayed AIS object. ``RemoveAll`` is the cleanest
+        # path; fall back to iterating the displayed list if unavailable.
+        try:
+            self._context.RemoveAll(True)
+        except Exception:
+            from OCP.AIS import AIS_ListOfInteractive, AIS_KindOfInteractive
+            lst = AIS_ListOfInteractive()
+            self._context.DisplayedObjects(AIS_KindOfInteractive.AIS_KOI_None, -1, lst)
+            for ais in lst:
+                self._context.Remove(ais, True)
+        self._objects.clear()
+
+    def update_mesh(
+        self,
+        obj: OCCRenderObject,
+        vertices: np.ndarray,
+        faces: np.ndarray,
+    ) -> bool:
+        """Update mesh geometry (not supported for OCC shapes; re-add instead)."""
+        logger.warning("update_mesh not supported for OCC shapes — remove + re-add")
+        return False
+
+    # ─── Display properties ────────────────────────────────────────────
+
+    def set_object_color(
+        self,
+        obj: OCCRenderObject,
+        color: Tuple[float, float, float],
+    ) -> None:
+        """Set the colour of an object."""
+        from OCP.Quantity import Quantity_Color, Quantity_TOC_RGB
+
+        if obj.ais_shape is not None:
+            qcol = Quantity_Color(*color, Quantity_TOC_RGB)
+            obj.ais_shape.SetColor(qcol)
+            self._context.RecomputePrsOnly(obj.ais_shape, True)
+
+    def set_object_visible(self, obj: OCCRenderObject, visible: bool) -> None:
+        """Show or hide an object."""
+        if obj.ais_shape is not None:
+            if visible:
+                self._context.Display(obj.ais_shape, True)
+            else:
+                self._context.Erase(obj.ais_shape, True)
+
+    # ─── Camera ────────────────────────────────────────────────────────
+
+    def set_camera_position(
+        self,
+        position: Tuple[float, float, float],
+        target: Tuple[float, float, float] = (0, 0, 0),
+        up: Tuple[float, float, float] = (0, 0, 1),
+    ) -> None:
+        """Set camera eye, target (at) and up vectors."""
+        if self._view is None:
+            return
+        self._view.SetEye(float(position[0]), float(position[1]), float(position[2]))
+        self._view.SetAt(float(target[0]), float(target[1]), float(target[2]))
+        self._view.SetUp(float(up[0]), float(up[1]), float(up[2]))
+        self._view.ZFitAll()
+        self._view.Redraw()
+
+    def get_camera_position(self) -> Tuple[np.ndarray, np.ndarray, np.ndarray]:
+        """Get camera position, target, and up vector."""
+        if self._view is None:
+            return (
+                np.array([1, 1, 1]),
+                np.array([0, 0, 0]),
+                np.array([0, 0, 1]),
+            )
+        eye = self._view.Eye()
+        at = self._view.At()
+        up = self._view.Up()
+
+        def _xyz(v):
+            if isinstance(v, (tuple, list)):
+                return np.array([float(v[0]), float(v[1]), float(v[2])])
+            return np.array([v.X(), v.Y(), v.Z()])
+
+        return (_xyz(eye), _xyz(at), _xyz(up))
+
+    def fit_camera(self, padding: float = 0.05) -> None:
+        """Fit camera to show all displayed objects.
+
+        *padding* is the margin coefficient (0 ≤ padding < 1.0) passed to
+        OCC's ``FitAll``.  A small value like 0.05 adds 5% margin.
+        """
+        if self._view is None:
+            return
+        margin = max(0.0, min(padding, 0.99))
+        self._view.FitAll(margin)
+        self._view.ZFitAll()
+
+    def set_view_orientation(self, orientation: str = "iso") -> None:
+        """Snap the camera to a standard CAD view.
+
+        orientation ∈ {"front","back","top","bottom","left","right","iso"}.
+        Preserves the current target and distance, then refits.
+        """
+        if self._view is None:
+            return
+        from OCP.V3d import V3d_TypeOfOrientation
+
+        mapping = {
+            "front":  V3d_TypeOfOrientation.V3d_Yneg,
+            "back":   V3d_TypeOfOrientation.V3d_Ypos,
+            "top":    V3d_TypeOfOrientation.V3d_Zpos,
+            "bottom": V3d_TypeOfOrientation.V3d_Zneg,
+            "left":   V3d_TypeOfOrientation.V3d_Xneg,
+            "right":  V3d_TypeOfOrientation.V3d_Xpos,
+            "iso":    V3d_TypeOfOrientation.V3d_XposYnegZpos,
+        }
+        orient = mapping.get(orientation.lower())
+        if orient is None:
+            logger.warning(f"unknown view orientation: {orientation}")
+            return
+        self._view.SetProj(orient)
+        self.fit_camera()
+        self._view.Redraw()
+
+    def reset_camera(self) -> None:
+        """Reset to the default isometric view and fit all."""
+        self.set_view_orientation("iso")
+
+    def set_camera_perspective(
+        self, fov: float = 45.0, near: float = 0.1, far: float = 100000.0
+    ) -> None:
+        """Switch to a perspective camera with the given FOV (degrees).
+
+        Near/far planes are auto-fit by OCC (``ZFitAll``) — the *near*/*far*
+        args are accepted for API compatibility but ignored.
+        """
+        if self._view is None:
+            return
+        from OCP.Graphic3d import Graphic3d_Camera
+
+        cam = self._view.Camera()
+        cam.SetProjectionType(Graphic3d_Camera.Projection_Perspective)
+        cam.SetFOVy(fov)
+        self._view.ZFitAll()
+        self._view.Redraw()
+
+    def set_camera_orthographic(
+        self, width: float = 100.0, near: float = 0.1, far: float = 100000.0
+    ) -> None:
+        """Switch to an orthographic camera."""
+        if self._view is None:
+            return
+        from OCP.Graphic3d import Graphic3d_Camera
+
+        cam = self._view.Camera()
+        cam.SetProjectionType(Graphic3d_Camera.Projection_Orthographic)
+        self._view.ZFitAll()
+        self._view.Redraw()
+
+    # ─── Rendering ─────────────────────────────────────────────────────
+
+    def render(self) -> None:
+        """Redraw the OCC view."""
+        if self._view is None:
+            return
+        self._view.Redraw()
+
+    def screenshot(self, width: int, height: int) -> bytes:
+        """Take a screenshot."""
+        return b""
+
+    # ─── Stub implementations for remaining abstract methods ──────────
+
+    def add_axes(self, size: float = 100.0) -> None:
+        """Add coordinate axes."""
+        pass
+
+    def add_grid(self, size: float = 100.0) -> None:
+        """Add a reference grid."""
+        pass
+
+    def get_screen_size(self) -> Tuple[int, int]:
+        if self._parent_widget:
+            return self._parent_widget.width(), self._parent_widget.height()
+        return (800, 600)
+
+    def on_camera_change(self, callback: Any) -> None:
+        pass
+
+    def on_pick(self, callback: Any) -> None:
+        pass
+
+    def project_to_screen(
+        self, point: Tuple[float, float, float]
+    ) -> Tuple[float, float]:
+        return (0.0, 0.0)
+
+    def save_screenshot(self, path: str, width: int = 1920, height: int = 1080) -> None:
+        logger.warning("save_screenshot not implemented for OCCRenderer")
+
+    def set_background_color(self, color: Tuple[float, float, float]) -> None:
+        if self._view is None:
+            return
+        from OCP.Quantity import Quantity_Color, Quantity_TOC_RGB
+        qcol = Quantity_Color(*color, Quantity_TOC_RGB)
+        self._view.SetBackgroundColor(qcol)
+
+    def take_screenshot(self) -> bytes:
+        return b""
+
+    def unproject_from_screen(
+        self, x: float, y: float
+    ) -> Tuple[float, float, float]:
+        return (0.0, 0.0, 0.0)
+
+    # ─── Face picking (for sketch-on-surface) ────────────────────────────
+
+    def pick_planar_face(self, x: int, y: int) -> Optional[Dict[str, Any]]:
+        """Pick the planar face under screen pixel (x, y).
+
+        Returns a dict with ``origin``, ``normal``, ``x_dir`` (a stable
+        in-plane axis) and ``face`` (the ``TopoDS_Face``), or *None* if the
+        hit is not a planar face.  The plane is derived from the face's
+        underlying surface via ``BRepAdaptor_Surface``; *x_dir* is taken
+        from the face's first edge direction so the UV frame is aligned to
+        the face geometry.
+        """
+        if self._view is None or self._context is None:
+            return None
+
+        from OCP.BRepAdaptor import BRepAdaptor_Surface
+        from OCP.GeomAbs import GeomAbs_Plane
+        from OCP.TopoDS import TopoDS_Face, TopoDS
+        from OCP.TopExp import TopExp_Explorer
+        from OCP.TopAbs import TopAbs_EDGE, TopAbs_FACE
+        from OCP.BRep import BRep_Tool
+        from OCP.gp import gp_Pln, gp_Dir, gp_Pnt
+        import numpy as np
+
+        # Detect what's under the cursor.
+        self._context.MoveTo(x, y, self._view, True)
+        if not self._context.HasDetected():
+            return None
+
+        shape = self._context.DetectedShape()
+        if shape is None:
+            return None
+
+        # The detected sub-shape is returned as a TopoDS_Shape; with face
+        # selection mode active it downcasts to a TopoDS_Face.  Try the
+        # downcast; if it isn't a face, give up (non-planar/edge/vertex hits).
+        face = None
+        try:
+            candidate = TopoDS.Face_s(shape)
+            # Verify it really is a face by building an adaptor.
+            _ = BRepAdaptor_Surface(candidate)
+            face = candidate
+        except Exception:
+            face = None
+        if face is None:
+            return None
+
+        try:
+            adaptor = BRepAdaptor_Surface(face)
+            if adaptor.GetType() != GeomAbs_Plane:
+                return None  # non-planar faces can't host a flat UV sketch
+            pln: gp_Pln = adaptor.Plane()
+        except Exception:
+            return None
+
+        # Outward normal: the plane's geometric axis is independent of the
+        # face's orientation (TopAbs_FORWARD / TopAbs_REVERSED).  For a face
+        # on a solid the TRUE outward normal is the axis when FORWARD and its
+        # negation when REVERSED.  Without this correction a top face whose
+        # axis happens to point inward would return an inward normal, so a
+        # default (non-inverted) extrude would punch back into the body
+        # instead of building outward on top of it.
+        from OCP.TopAbs import TopAbs_REVERSED
+        n = pln.Axis().Direction()
+        if face.Orientation() == TopAbs_REVERSED:
+            n = n.Reversed()
+
+        # Plane origin: use the face's bounding-box centre projected onto the
+        # plane, so the UV frame is centred on the face (nicer for sketching).
+        from OCP.Bnd import Bnd_Box
+        from OCP.BRepBndLib import BRepBndLib
+        bbox = Bnd_Box()
+        BRepBndLib.Add_s(face, bbox)
+        xmin, ymin, zmin, xmax, ymax, zmax = bbox.Get()
+        cx, cy, cz = (xmin + xmax) / 2.0, (ymin + ymax) / 2.0, (zmin + zmax) / 2.0
+        # Project the bbox centre onto the plane.
+        pln_origin = pln.Location()  # gp_Pnt
+        nx, ny, nz = n.X(), n.Y(), n.Z()
+        # signed distance from bbox centre to plane
+        d = (cx - pln_origin.X()) * nx + (cy - pln_origin.Y()) * ny + (cz - pln_origin.Z()) * nz
+        origin = (cx - d * nx, cy - d * ny, cz - d * nz)
+
+        # x_dir: direction of the face's first edge (stable, in-plane).
+        x_dir = None
+        try:
+            from OCP.TopExp import TopExp
+            from OCP.BRep import BRep_Tool
+            expl = TopExp_Explorer(face, TopAbs_EDGE)
+            if expl.More():
+                edge = TopoDS.Edge_s(expl.Current())
+                v1 = TopExp.FirstVertex_s(edge, True)
+                v2 = TopExp.LastVertex_s(edge, True)
+                p1 = BRep_Tool.Pnt_s(v1)
+                p2 = BRep_Tool.Pnt_s(v2)
+                ex, ey, ez = p2.X() - p1.X(), p2.Y() - p1.Y(), p2.Z() - p1.Z()
+                elen = (ex * ex + ey * ey + ez * ez) ** 0.5
+                if elen > 1e-9:
+                    x_dir = (ex / elen, ey / elen, ez / elen)
+        except Exception:
+            pass
+        if x_dir is None:
+            # Fall back to the plane's own X axis.
+            px = pln.XAxis().Direction()
+            x_dir = (px.X(), px.Y(), px.Z())
+
+        # Identify the displayed body that owns this face, so the host can
+        # auto-target it as the cut/union body when the user extrudes the
+        # sketch-on-face.  ``DetectedInteractive`` returns the AIS_
+        # InteractiveObject that the picked sub-shape belongs to; we match
+        # it against the renderer's tracked objects by AIS identity.
+        owner_obj_id: Optional[str] = None
+        try:
+            owner_ais = self._context.DetectedInteractive()
+        except Exception:
+            owner_ais = None
+        if owner_ais is not None:
+            for oid, robj in self._objects.items():
+                if robj.ais_shape is owner_ais:
+                    owner_obj_id = oid
+                    break
+
+        return {
+            "origin": origin,
+            "normal": (nx, ny, nz),
+            "x_dir": x_dir,
+            "face": face,
+            "owner_obj_id": owner_obj_id,
+        }
+
+    def highlight_face(self, face: Any) -> None:
+        """Overlay a persistent, mostly-transparent light-blue tint on *face*.
+
+        Used to mark the planar face the user has selected for sketch-on-
+        surface.  The overlay is an independent ``AIS_Shape`` so it survives
+        until :meth:`clear_face_highlight` is called.
+        """
+        if self._context is None:
+            return
+        self.clear_face_highlight()
+        from OCP.AIS import AIS_Shape
+        from OCP.Quantity import Quantity_Color, Quantity_TOC_RGB
+
+        ais = AIS_Shape(face)
+        try:
+            ais.SetMaterial(self._default_material())
+        except Exception:
+            logger.debug("highlight material set failed", exc_info=True)
+        ais.SetColor(Quantity_Color(0.45, 0.75, 1.0, Quantity_TOC_RGB))
+        ais.SetDisplayMode(1)  # shaded — tint the whole face, not just edges
+        try:
+            # Mostly transparent so the underlying face stays visible.
+            ais.SetTransparency(0.78)
+        except Exception:
+            logger.debug("highlight transparency set failed", exc_info=True)
+        try:
+            # Bias the overlay slightly toward the camera so it draws on top
+            # of the coincident face surface without z-fighting.
+            # mode 3 = Graphic3d_POM_Fill; negative units pull forward.
+            ais.SetPolygonOffsets(3, 1.0, -0.5)
+        except Exception:
+            logger.debug("highlight polygon offset failed", exc_info=True)
+
+        self._context.Display(ais, True)
+        self._highlight_ais = ais
+        if self._view is not None:
+            self._view.Update()
+
+    def clear_face_highlight(self) -> None:
+        """Remove the persistent face-selection overlay, if any."""
+        if self._context is None or self._highlight_ais is None:
+            return
+        try:
+            self._context.Remove(self._highlight_ais, True)
+        except Exception:
+            logger.debug("clear_face_highlight remove failed", exc_info=True)
+        self._highlight_ais = None
+
+    # ─── Mouse / keyboard event forwarding ──────────────────────────────
+    #
+    # CAD-style navigation:
+    #   • Left button drag   → orbit (rotate around target)
+    #   • Middle button drag → pan
+    #   • Right button       → (reserved for future use)
+    #   • Wheel              → zoom toward cursor
+    #   • Double-click left  → fit all  (handled by the widget)
+
+    def _qt_buttons(self, event) -> Any:
+        """Return the PySide6 Qt enum module lazily."""
+        from PySide6.QtCore import Qt
+        return Qt
+
+    def handle_mouse_press(self, event) -> None:
+        """Begin an orbit / pan / zoom gesture based on the pressed button."""
+        if self._view is None or self._context is None:
+            return
+        Qt = self._qt_buttons(event)
+        x, y = event.x(), event.y()
+        btn = event.button()
+
+        if btn == Qt.LeftButton:
+            self._nav_mode = "rotate"
+            # zRotationThreshold=0.4 enables screen-Z spin outside the inner
+            # circle, matching the FreeCAD/OCC viewer feel.
+            self._view.StartRotation(x, y, 0.4)
+        elif btn == Qt.MiddleButton:
+            self._nav_mode = "pan"
+            # Record the gesture start; OCC's Pan(..., Start=False) expects
+            # deltas CUMULATIVE from this point, not per-frame deltas.
+            self._pan_start_x = x
+            self._pan_start_y = y
+            self._view.Pan(0, 0, 1.0, True)
+        else:
+            # Right button (and any other) is reserved — no gesture yet.
+            self._nav_mode = None
+
+        self._last_mouse_x = x
+        self._last_mouse_y = y
+
+    def handle_mouse_move(self, event) -> None:
+        """Continue the active gesture; otherwise just hover-detect."""
+        if self._view is None or self._context is None:
+            return
+        Qt = self._qt_buttons(event)
+        x, y = event.x(), event.y()
+        buttons = event.buttons()
+
+        if self._nav_mode == "rotate" and (buttons & Qt.LeftButton):
+            self._view.Rotation(x, y)
+        elif self._nav_mode == "pan" and (buttons & Qt.MiddleButton):
+            # Cumulative delta from the gesture start — OCC interprets
+            # Pan(..., Start=False) as an absolute offset from the start point.
+            dx = x - self._pan_start_x
+            dy = y - self._pan_start_y
+            # dy negated because Qt y grows downward while OCC y grows upward.
+            self._view.Pan(dx, -dy, 1.0, False)
+        else:
+            # Idle: dynamic highlighting under the cursor.
+            self._context.MoveTo(x, y, self._view, True)
+
+        self._last_mouse_x = x
+        self._last_mouse_y = y
+
+    def handle_mouse_release(self, event) -> None:
+        """End the active gesture."""
+        Qt = self._qt_buttons(event)
+        if event.button() in (Qt.LeftButton, Qt.MiddleButton, Qt.RightButton):
+            self._nav_mode = None
+
+    def handle_wheel(self, event) -> None:
+        """Zoom toward the cursor on scroll."""
+        if self._view is None:
+            return
+        # Qt6: QWheelEvent has no .x()/.y(); use position().toPoint().
+        pos = event.position().toPoint() if hasattr(event, "position") else event.pos()
+        x, y = pos.x(), pos.y()
+        delta = event.angleDelta().y()
+        if delta == 0:
+            return
+        # ZoomAtPoint(startX, startY, endX, endY): move the cursor anchor
+        # by a few pixels to drive a smooth zoom centered on the pointer.
+        step = 30 if delta > 0 else -30
+        self._view.ZoomAtPoint(x, y, x, y - step)
+        self._view.ZFitAll()
+
+    def handle_resize(self, w: int, h: int) -> None:
+        """Resize the OCC view when the widget is resized."""
+        if self._window is not None:
+            self._window.SetSize(w, h)
+        if self._view is not None:
+            self._view.MustBeResized()
+            self._view.Redraw()

src/fluency/rendering/pygfx_renderer.py

@@ -55,9 +55,17 @@ class PygfxRenderObject(RenderObject):
     geometry: Any = None
     material: Any = None
 
-    def __post_init__(self) -> None:
+    def __init__(
-        if self.scene_node is not None:
+        self,
-            self._scene_node = self.scene_node
+        scene_node: Any = None,
+        geometry: Any = None,
+        material: Any = None,
+        name: Optional[str] = None,
+    ):
+        super().__init__(name=name)
+        self.scene_node = scene_node
+        self.geometry = geometry
+        self.material = material
 
 
 class PygfxRenderer(Renderer):
@@ -84,17 +92,18 @@ class PygfxRenderer(Renderer):
         """Initialize pygfx with Qt widget."""
         try:
             import pygfx as gfx
-            from wgpu.gui.qt import WgpuCanvas
+            from rendercanvas.qt import RenderWidget
             from PySide6.QtWidgets import QVBoxLayout
 
-            self._canvas = WgpuCanvas(parent=parent_widget)
+            self._canvas = RenderWidget(parent=parent_widget)
             self._renderer = gfx.renderers.WgpuRenderer(self._canvas)
             self._scene = gfx.Scene()
 
             self._camera = gfx.PerspectiveCamera(50, 16 / 9)
-            self._camera.position.set(100, 100, 100)
+            self._camera.local.position = (100, 100, 100)
 
-            self._controller = gfx.OrbitController(self._camera, register_events=self._renderer)
+            self._controller = gfx.OrbitController(self._camera)
+            self._controller.register_events(self._renderer)
 
             self._setup_lighting()
             self._add_grid()
@@ -103,6 +112,8 @@ class PygfxRenderer(Renderer):
             layout.setContentsMargins(0, 0, 0, 0)
             layout.addWidget(self._canvas)
 
+            self._canvas.request_draw(self._animate)
+
             self._setup_picking()
             self._initialized = True
 
@@ -110,8 +121,16 @@ class PygfxRenderer(Renderer):
 
         except Exception as e:
             print(f"Failed to initialize pygfx: {e}")
+            import traceback
+
+            traceback.print_exc()
             return False
 
+    def _animate(self):
+        """Animation callback for the canvas."""
+        if self._initialized:
+            self._renderer.render(self._scene, self._camera)
+
     def _setup_lighting(self) -> None:
         """Setup scene lighting."""
         import pygfx as gfx
@@ -120,11 +139,11 @@ class PygfxRenderer(Renderer):
         self._scene.add(ambient)
 
         directional = gfx.DirectionalLight(intensity=1.0)
-        directional.position.set(100, 100, 100)
+        directional.local.position = (100, 100, 100)
         self._scene.add(directional)
 
         fill = gfx.DirectionalLight(intensity=0.5)
-        fill.position.set(-100, 50, 50)
+        fill.local.position = (-100, 50, 50)
         self._scene.add(fill)
 
     def _add_grid(self) -> None:
@@ -151,9 +170,10 @@ class PygfxRenderer(Renderer):
         faces: np.ndarray,
         color: Tuple[float, float, float] = (0.2, 0.4, 0.8),
         name: Optional[str] = None,
-    ) -> PygfxRenderObject:
+    ) -> str:
-        """Add a mesh to the scene."""
+        """Add a mesh to the scene. Returns the mesh ID."""
         import pygfx as gfx
+        import uuid
 
         vertices = np.asarray(vertices, dtype=np.float32)
         faces = np.asarray(faces, dtype=np.int32)
@@ -167,11 +187,12 @@ class PygfxRenderer(Renderer):
         mesh = gfx.Mesh(geometry, material)
         self._scene.add(mesh)
 
-        obj = PygfxRenderObject(name=name, scene_node=mesh, geometry=geometry, material=material)
+        mesh_id = name or f"mesh_{uuid.uuid4().hex[:8]}"
+        obj = PygfxRenderObject(name=mesh_id, scene_node=mesh, geometry=geometry, material=material)
         obj.color = RenderColor(*color)
         self._objects.append(obj)
 
-        return obj
+        return mesh_id
 
     def add_wireframe(
         self,
@@ -180,9 +201,10 @@ class PygfxRenderer(Renderer):
         color: Tuple[float, float, float] = (1.0, 1.0, 1.0),
         line_width: float = 1.0,
         name: Optional[str] = None,
-    ) -> PygfxRenderObject:
+    ) -> str:
-        """Add a wireframe to the scene."""
+        """Add a wireframe to the scene. Returns the wireframe ID."""
         import pygfx as gfx
+        import uuid
 
         positions: List[List[float]] = []
         for edge in edges:
@@ -197,11 +219,14 @@ class PygfxRenderer(Renderer):
         lines = gfx.Line(geometry, material)
         self._scene.add(lines)
 
-        obj = PygfxRenderObject(name=name, scene_node=lines, geometry=geometry, material=material)
+        wireframe_id = name or f"wireframe_{uuid.uuid4().hex[:8]}"
+        obj = PygfxRenderObject(
+            name=wireframe_id, scene_node=lines, geometry=geometry, material=material
+        )
         obj.color = RenderColor(*color)
         self._objects.append(obj)
 
-        return obj
+        return wireframe_id
 
     def add_points(
         self,
@@ -209,9 +234,10 @@ class PygfxRenderer(Renderer):
         color: Tuple[float, float, float] = (1.0, 0.0, 0.0),
         size: float = 5.0,
         name: Optional[str] = None,
-    ) -> PygfxRenderObject:
+    ) -> str:
-        """Add points to the scene."""
+        """Add points to the scene. Returns the points ID."""
         import pygfx as gfx
+        import uuid
 
         points_arr = np.asarray(points, dtype=np.float32)
 
@@ -221,13 +247,14 @@ class PygfxRenderer(Renderer):
         points_obj = gfx.Points(geometry, material)
         self._scene.add(points_obj)
 
+        points_id = name or f"points_{uuid.uuid4().hex[:8]}"
         obj = PygfxRenderObject(
-            name=name, scene_node=points_obj, geometry=geometry, material=material
+            name=points_id, scene_node=points_obj, geometry=geometry, material=material
         )
         obj.color = RenderColor(*color)
         self._objects.append(obj)
 
-        return obj
+        return points_id
 
     def add_lines(
         self,
@@ -236,9 +263,10 @@ class PygfxRenderer(Renderer):
         color: Tuple[float, float, float] = (1.0, 1.0, 1.0),
         line_width: float = 1.0,
         name: Optional[str] = None,
-    ) -> PygfxRenderObject:
+    ) -> str:
-        """Add line segments to the scene."""
+        """Add line segments to the scene. Returns the lines ID."""
         import pygfx as gfx
+        import uuid
 
         positions = np.hstack([start_points, end_points]).flatten()
         positions = positions.reshape(-1, 3).astype(np.float32)
@@ -249,11 +277,14 @@ class PygfxRenderer(Renderer):
         lines = gfx.Line(geometry, material)
         self._scene.add(lines)
 
-        obj = PygfxRenderObject(name=name, scene_node=lines, geometry=geometry, material=material)
+        lines_id = name or f"lines_{uuid.uuid4().hex[:8]}"
+        obj = PygfxRenderObject(
+            name=lines_id, scene_node=lines, geometry=geometry, material=material
+        )
         obj.color = RenderColor(*color)
         self._objects.append(obj)
 
-        return obj
+        return lines_id
 
     def remove_object(self, obj: RenderObject) -> bool:
         """Remove an object from the scene."""
@@ -319,15 +350,14 @@ class PygfxRenderer(Renderer):
         up: Tuple[float, float, float] = (0, 0, 1),
     ) -> None:
         """Set camera position and orientation."""
-        self._camera.position.set(*position)
+        self._camera.local.position = position
-        self._camera.look_at(*target)
+        self._camera.look_at(target)
-        self._camera.up.set(*up)
 
     def get_camera_position(self) -> Tuple[np.ndarray, np.ndarray, np.ndarray]:
         """Get camera position, target, and up vector."""
-        pos = np.array(self._camera.position.to_array())
+        pos = np.array(self._camera.local.position)
         target = np.array([0, 0, 0])
-        up = np.array(self._camera.up.to_array())
+        up = np.array(self._camera.local.up)
         return pos, target, up
 
     def fit_camera(self, padding: float = 1.1) -> None:
@@ -348,8 +378,8 @@ class PygfxRenderer(Renderer):
             center = (min_pos + max_pos) / 2
             size = np.linalg.norm(max_pos - min_pos) * padding
 
-            self._camera.position.set(center[0] + size, center[1] + size, center[2] + size)
+            self._camera.local.position = (center[0] + size, center[1] + size, center[2] + size)
-            self._camera.look_at(*center)
+            self._camera.look_at(tuple(center))
 
     def set_camera_perspective(
         self, fov: float = 50.0, near: float = 0.1, far: float = 10000.0
@@ -371,7 +401,6 @@ class PygfxRenderer(Renderer):
     def render(self) -> None:
         """Trigger a render."""
         if self._initialized:
-            self._renderer.render(self._scene, self._camera)
             self._canvas.request_draw()
 
     def on_pick(self, callback: Callable[[Any], None]) -> None:
@@ -392,8 +421,8 @@ class PygfxRenderer(Renderer):
         size: float = 100.0,
         divisions: int = 10,
         color: Tuple[float, float, float] = (0.3, 0.3, 0.3),
-    ) -> PygfxRenderObject:
+    ) -> str:
-        """Add a reference grid."""
+        """Add a reference grid. Returns the grid ID."""
         import pygfx as gfx
 
         grid = gfx.GridHelper(
@@ -402,10 +431,11 @@ class PygfxRenderer(Renderer):
         self._scene.add(grid)
 
         obj = PygfxRenderObject(name="grid", scene_node=grid)
-        return obj
+        self._objects.append(obj)
+        return "grid"
 
-    def add_axes(self, size: float = 10.0, visible: bool = True) -> PygfxRenderObject:
+    def add_axes(self, size: float = 10.0, visible: bool = True) -> str:
-        """Add coordinate axes."""
+        """Add coordinate axes. Returns the axes ID."""
         import pygfx as gfx
 
         axes = gfx.AxesHelper(size=size)
@@ -413,7 +443,8 @@ class PygfxRenderer(Renderer):
         self._scene.add(axes)
 
         obj = PygfxRenderObject(name="axes", scene_node=axes)
-        return obj
+        self._objects.append(obj)
+        return "axes"
 
     def get_screen_size(self) -> Tuple[int, int]:
         """Get the screen size in pixels."""

src/fluency/sketch_solver.py

@@ -0,0 +1,326 @@
+"""
+SolveSpace-based constraint solver for Fluency CAD.
+
+Provides integration between python-solvespace (SolverSystem) and
+the Fluency CAD sketch pipeline (OCCSketch). Drawing operations
+add entities to BOTH the OCCSketch (for OCC->render pipeline) and
+the SolverSketch (for constraint solving). After constraint solving,
+solved positions are synced back to the OCCSketch.
+"""
+
+from __future__ import annotations
+
+import math
+import re
+import uuid
+import logging
+from dataclasses import dataclass, field
+from typing import List, Optional, Tuple, Any, Dict
+
+from python_solvespace import SolverSystem, ResultFlag
+
+logger = logging.getLogger(__name__)
+
+
+# ── Data classes ──────────────────────────────────────────────────────────
+
+
+@dataclass
+class SolverPoint:
+    """A 2D point tracked by the solver system."""
+
+    x: float
+    y: float
+    handle: Any = None
+    handle_nr: int = 0
+    entity_id: int = -1  # Corresponding OCCSketch entity id
+    is_helper: bool = False
+    id: str = field(default_factory=lambda: str(uuid.uuid4()))
+
+    def to_tuple(self) -> Tuple[float, float]:
+        return (self.x, self.y)
+
+
+@dataclass
+class SolverLine:
+    """A line segment tracked by the solver system."""
+
+    start: SolverPoint
+    end: SolverPoint
+    handle: Any = None
+    handle_nr: int = 0
+    entity_ids: Tuple[int, int] = (-1, -1)  # Corresponding OCCSketch entity ids
+    is_helper: bool = False
+    constraints: List[str] = field(default_factory=list)
+    id: str = field(default_factory=lambda: str(uuid.uuid4()))
+
+    @property
+    def length(self) -> float:
+        return math.sqrt(
+            (self.end.x - self.start.x) ** 2 + (self.end.y - self.start.y) ** 2
+        )
+
+    def midpoint(self) -> Tuple[float, float]:
+        return (
+            (self.start.x + self.end.x) / 2,
+            (self.start.y + self.end.y) / 2,
+        )
+
+
+@dataclass
+class SolverCircle:
+    """A circle tracked by the solver system."""
+
+    center: SolverPoint
+    radius: float
+    handle: Any = None
+    handle_nr: int = 0
+    entity_id: int = -1  # Corresponding OCCSketch entity id
+    is_helper: bool = False
+    id: str = field(default_factory=lambda: str(uuid.uuid4()))
+
+
+# ── Solver wrapper ────────────────────────────────────────────────────────
+
+
+class SolverSketch(SolverSystem):
+    """
+    Sketch that uses python-solvespace for parametric constraint solving.
+
+    Maintains its own lists of points, lines, and circles with solve-space
+    handles. Provides methods for creating geometry, applying constraints,
+    solving, and syncing solved positions back to an OCCSketch.
+    """
+
+    def __init__(self) -> None:
+        super().__init__()
+        self.id = str(uuid.uuid4())
+        self.wp = self.create_2d_base()
+        self.points: List[SolverPoint] = []
+        self.lines: List[SolverLine] = []
+        self.circles: List[SolverCircle] = []
+        self._last_solve_result: int = 0
+
+    # ── Geometry creation ────────────────────────────────────────────────
+
+    def add_solver_point(self, x: float, y: float, is_helper: bool = False) -> SolverPoint:
+        """Add a point to the solver system and return a SolverPoint."""
+        handle = self.add_point_2d(x, y, self.wp)
+        handle_nr = _extract_handle_nr(str(handle))
+        point = SolverPoint(
+            x=x, y=y, handle=handle, handle_nr=handle_nr,
+            is_helper=is_helper,
+        )
+        self.points.append(point)
+        return point
+
+    def add_solver_line(
+        self, start: SolverPoint, end: SolverPoint, is_helper: bool = False
+    ) -> SolverLine:
+        """Add a line to the solver system and return a SolverLine."""
+        handle = self.add_line_2d(start.handle, end.handle, self.wp)
+        handle_nr = _extract_handle_nr(str(handle))
+        line = SolverLine(
+            start=start, end=end, handle=handle, handle_nr=handle_nr,
+            is_helper=is_helper,
+        )
+        self.lines.append(line)
+        return line
+
+    def add_solver_circle(
+        self, center: SolverPoint, radius: float, is_helper: bool = False
+    ) -> SolverCircle:
+        """Add a circle to the solver system and return a SolverCircle.
+
+        Note: python-solvespace handles circles via diameter, so we
+        store radius but pass 2*radius to the solver if needed.
+        """
+        # For now, circles are tracked for OCC output but the solver
+        # doesn't have a dedicated add_circle_2d in the standard API.
+        # We'll handle radius/diameter constraints through the points.
+        circle = SolverCircle(
+            center=center, radius=radius,
+            is_helper=is_helper,
+        )
+        self.circles.append(circle)
+        return circle
+
+    # ── Constraint methods ───────────────────────────────────────────────
+
+    def constrain_coincident(self, entity_a, entity_b) -> bool:
+        """Make two entities coincident (point-point or point-line)."""
+        try:
+            if isinstance(entity_a, SolverPoint) and isinstance(entity_b, SolverPoint):
+                self.coincident(entity_a.handle, entity_b.handle, self.wp)
+            elif isinstance(entity_a, SolverPoint) and isinstance(entity_b, SolverLine):
+                self.coincident(entity_a.handle, entity_b.handle, self.wp)
+
+            elif isinstance(entity_a, SolverLine) and isinstance(entity_b, SolverPoint):
+                self.coincident(entity_b.handle, entity_a.handle, self.wp)
+
+            else:
+                logger.warning(f"coincident: unsupported types {type(entity_a)}, {type(entity_b)}")
+                return False
+            return True
+        except Exception as e:
+            logger.error(f"coincident constraint failed: {e}")
+            return False
+
+    def constrain_horizontal(self, line: SolverLine) -> bool:
+        """Constrain a line to be horizontal."""
+        try:
+            self.horizontal(line.handle, self.wp)
+            return True
+        except Exception as e:
+            logger.error(f"horizontal constraint failed: {e}")
+            return False
+
+    def constrain_vertical(self, line: SolverLine) -> bool:
+        """Constrain a line to be vertical."""
+        try:
+            self.vertical(line.handle, self.wp)
+            return True
+        except Exception as e:
+            logger.error(f"vertical constraint failed: {e}")
+            return False
+
+    def constrain_distance(
+        self, entity_a, entity_b, distance: float
+    ) -> bool:
+        """Constrain distance between point-point or point-line."""
+        try:
+            handle_a = entity_a.handle if isinstance(entity_a, SolverPoint) else entity_a.handle
+            handle_b = entity_b.handle if isinstance(entity_b, SolverPoint) else entity_b.handle
+
+            if isinstance(entity_a, SolverPoint) and isinstance(entity_b, SolverLine):
+                self.distance(handle_a, handle_b, distance, self.wp)
+            elif isinstance(entity_a, SolverLine) and isinstance(entity_b, SolverPoint):
+                self.distance(handle_b, handle_a, distance, self.wp)
+            elif isinstance(entity_a, SolverPoint) and isinstance(entity_b, SolverPoint):
+                self.distance(handle_a, handle_b, distance, self.wp)
+            elif isinstance(entity_a, SolverLine) and isinstance(entity_b, SolverLine):
+                self.distance(handle_a, handle_b, distance, self.wp)
+            else:
+                logger.warning(f"distance: unsupported types {type(entity_a)}, {type(entity_b)}")
+                return False
+            return True
+        except Exception as e:
+            logger.error(f"distance constraint failed: {e}")
+            return False
+
+    def constrain_midpoint(self, point: SolverPoint, line: SolverLine) -> bool:
+        """Constrain a point to be at the midpoint of a line."""
+        try:
+            self.midpoint(point.handle, line.handle, self.wp)
+            return True
+        except Exception as e:
+            logger.error(f"midpoint constraint failed: {e}")
+            return False
+
+    def constrain_parallel(self, line_a: SolverLine, line_b: SolverLine) -> bool:
+        """Constrain two lines to be parallel."""
+        try:
+            self.parallel(line_a.handle, line_b.handle, self.wp)
+            return True
+        except Exception as e:
+            logger.error(f"parallel constraint failed: {e}")
+            return False
+
+    def constrain_perpendicular(self, line_a: SolverLine, line_b: SolverLine) -> bool:
+        """Constrain two lines to be perpendicular."""
+        try:
+            self.perpendicular(line_a.handle, line_b.handle, self.wp)
+            return True
+        except Exception as e:
+            logger.error(f"perpendicular constraint failed: {e}")
+            return False
+
+    def constrain_angle(self, line_a: SolverLine, line_b: SolverLine, angle_deg: float) -> bool:
+        """Constrain angle between two lines in degrees."""
+        try:
+            angle_rad = math.radians(angle_deg)
+            self.angle(line_a.handle, line_b.handle, angle_rad, self.wp)
+            return True
+        except Exception as e:
+            logger.error(f"angle constraint failed: {e}")
+            return False
+
+    def constrain_equal_length(self, line_a: SolverLine, line_b: SolverLine) -> bool:
+        """Constrain two lines to have equal length."""
+        try:
+            self.equal(line_a.handle, line_b.handle, self.wp)
+            return True
+        except Exception as e:
+            logger.error(f"equal length constraint failed: {e}")
+            return False
+
+    # ── Solving ──────────────────────────────────────────────────────────
+
+    def solve(self) -> int:
+        """Solve all constraints. Returns ResultFlag as int."""
+        result = super().solve()
+        self._last_solve_result = result
+
+        if result == ResultFlag.OKAY:
+            # Update our stored point positions from solver params
+            self._sync_solved_positions()
+
+        return result
+
+    def _sync_solved_positions(self) -> None:
+        """Update SolverPoint coordinates from solver's solved params."""
+        for point in self.points:
+            if point.handle and self.params(point.handle.params):
+                x, y = self.params(point.handle.params)
+                point.x = x
+                point.y = y
+
+    # ── Query ────────────────────────────────────────────────────────────
+
+    def get_solved_point_positions(self) -> Dict[int, Tuple[float, float]]:
+        """Get map of entity_id -> (x, y) after solving."""
+        positions: Dict[int, Tuple[float, float]] = {}
+        for point in self.points:
+            if point.handle and self.params(point.handle.params):
+                x, y = self.params(point.handle.params)
+                positions[point.entity_id] = (x, y)
+        return positions
+
+    def is_point_on_line(
+        self, px: float, py: float, line: SolverLine, tolerance: float = 5.0
+    ) -> bool:
+        """Check if a point lies on a solver line (in world coords)."""
+        # Vector from start to point
+        ap_x = px - line.start.x
+        ap_y = py - line.start.y
+        # Vector from start to end
+        ab_x = line.end.x - line.start.x
+        ab_y = line.end.y - line.start.y
+        ab_len_sq = ab_x**2 + ab_y**2
+        if ab_len_sq == 0:
+            return False
+        # Project point onto line
+        t = (ap_x * ab_x + ap_y * ab_y) / ab_len_sq
+        t = max(0, min(1, t))
+        closest_x = line.start.x + t * ab_x
+        closest_y = line.start.y + t * ab_y
+        dist = math.sqrt((px - closest_x) ** 2 + (py - closest_y) ** 2)
+        return dist <= tolerance
+
+    # ── Clear / reset ────────────────────────────────────────────────────
+
+    def clear(self) -> None:
+        """Clear all geometry from this solver sketch."""
+        self.points.clear()
+        self.lines.clear()
+        self.circles.clear()
+        self.wp = self.create_2d_base()
+
+
+# ── Helpers ───────────────────────────────────────────────────────────────
+
+
+def _extract_handle_nr(handle_str: str) -> int:
+    """Extract numeric handle from string like 'Entity(handle=7, ...)'."""
+    match = re.search(r"handle=(\d+)", handle_str)
+    return int(match.group(1)) if match else 0

src/fluency_cad.egg-info/PKG-INFO

@@ -1,146 +0,0 @@
-Metadata-Version: 2.4
-Name: fluency-cad
-Version: 2.0.0
-Summary: Parametric CAD application with OpenCASCADE geometry kernel
-Author: Fluency CAD Team
-License: MIT
-Project-URL: Homepage, https://github.com/fluency-cad/fluency
-Project-URL: Documentation, https://github.com/fluency-cad/fluency#readme
-Project-URL: Repository, https://github.com/fluency-cad/fluency
-Keywords: cad,parametric,opencascade,3d-modeling
-Classifier: Development Status :: 4 - Beta
-Classifier: Intended Audience :: Developers
-Classifier: Intended Audience :: End Users/Desktop
-Classifier: License :: OSI Approved :: MIT License
-Classifier: Programming Language :: Python :: 3
-Classifier: Programming Language :: Python :: 3.10
-Classifier: Programming Language :: Python :: 3.11
-Classifier: Programming Language :: Python :: 3.12
-Classifier: Topic :: Scientific/Engineering :: CAD
-Requires-Python: >=3.10
-Description-Content-Type: text/markdown
-Requires-Dist: cadquery>=2.4
-Requires-Dist: pygfx>=0.1.0
-Requires-Dist: wgpu>=0.1.0
-Requires-Dist: PySide6>=6.4.0
-Requires-Dist: numpy>=1.24.0
-Requires-Dist: scipy>=1.10.0
-Requires-Dist: pillow>=10.0.0
-Provides-Extra: dev
-Requires-Dist: pytest>=8.0; extra == "dev"
-Requires-Dist: black>=24.0; extra == "dev"
-Requires-Dist: mypy>=1.8; extra == "dev"
-Requires-Dist: ruff>=0.4.0; extra == "dev"
-
-# Fluency CAD 2.0
-
-A parametric CAD application built on OpenCASCADE Technology (OCCT) with a modern pygfx-based 3D renderer.
-
-## Features
-
-- **OpenCASCADE Geometry Kernel**: Industry-standard BRep geometry with exact precision
-- **STEP/IGES Import/Export**: Full support for industry-standard CAD file formats
-- **Parametric Sketching**: 2D sketching with constraint solving using CadQuery
-- **Boolean Operations**: Union, difference, and intersection
-- **Fillet & Chamfer**: Apply edge treatments to solid bodies
-- **Modern Renderer**: WebGPU-based rendering with pygfx (smaller footprint than VTK)
-
-## Architecture
-
-```
-fluency/
-├── src/fluency/
-│   ├── geometry/           # Geometry abstraction layer
-│   │   └── base.py         # Abstract interfaces
-│   ├── geometry_occ/       # OpenCASCADE implementation
-│   │   ├── kernel.py       # OCGeometryKernel
-│   │   └── sketch.py       # OCCSketch with constraints
-│   ├── rendering/          # Rendering abstraction
-│   │   ├── base.py         # Abstract renderer
-│   │   └── pygfx_renderer.py
-│   ├── models/             # Data models
-│   │   └── data_model.py   # Project, Component, Sketch, Body
-│   └── main.py             # Application entry point
-├── tests/
-│   └── test_geometry.py
-└── pyproject.toml
-```
-
-## Installation
-
-```bash
-# Create virtual environment
-python -m venv .venv
-source .venv/bin/activate  # On Windows: .venv\Scripts\activate
-
-# Install dependencies
-pip install -e ".[dev]"
-```
-
-## Dependencies
-
-| Package | Purpose |
-|---------|---------|
-| cadquery | High-level OpenCASCADE Python bindings |
-| ocp | Low-level OpenCASCADE Python bindings |
-| pygfx | WebGPU-based 3D renderer |
-| wgpu | WebGPU Python bindings |
-| PySide6 | Qt GUI framework |
-| numpy | Numerical computing |
-| scipy | Scientific computing |
-
-## Usage
-
-```bash
-# Run the application
-fluency-cad
-
-# Or directly
-python -m fluency.main
-```
-
-## API Example
-
-```python
-from fluency.geometry_occ.kernel import OCGeometryKernel
-from fluency.geometry.base import Point2D
-
-# Create kernel
-kernel = OCGeometryKernel()
-
-# Create a sketch
-points = [
-    Point2D(0, 0),
-    Point2D(10, 0),
-    Point2D(10, 10),
-    Point2D(0, 10),
-]
-polygon = kernel.create_polygon(points)
-
-# Extrude to 3D
-body = kernel.extrude(polygon, height=20.0)
-
-# Apply fillet
-body = kernel.fillet(body, radius=2.0)
-
-# Export to STEP
-kernel.export_step(body, "part.step")
-
-# Export to STL
-kernel.export_stl(body, "part.stl")
-```
-
-## Comparison: Before vs After
-
-| Aspect | Before (SDF + VTK) | After (OCC + pygfx) |
-|--------|-------------------|---------------------|
-| Geometry Precision | Approximate (mesh) | Exact (BRep) |
-| Export Formats | STL only | STEP, IGES, STL, BREP |
-| File Size | Large (mesh) | Small (BRep) |
-| Fillet/Chamfer | Approximate | Exact |
-| Dependency Size | ~200MB (VTK) | ~30MB (pygfx) |
-| Constraint Solver | SolveSpace (separate) | CadQuery (integrated) |
-
-## License
-
-MIT License

src/fluency_cad.egg-info/SOURCES.txt

@@ -1,23 +0,0 @@
-README.md
-pyproject.toml
-src/fluency/__init__.py
-src/fluency/main.py
-src/fluency/geometry/__init__.py
-src/fluency/geometry/base.py
-src/fluency/geometry_occ/__init__.py
-src/fluency/geometry_occ/kernel.py
-src/fluency/geometry_occ/sketch.py
-src/fluency/models/__init__.py
-src/fluency/models/data_model.py
-src/fluency/rendering/__init__.py
-src/fluency/rendering/base.py
-src/fluency/rendering/pygfx_renderer.py
-src/fluency/utils/__init__.py
-src/fluency/widgets/__init__.py
-src/fluency_cad.egg-info/PKG-INFO
-src/fluency_cad.egg-info/SOURCES.txt
-src/fluency_cad.egg-info/dependency_links.txt
-src/fluency_cad.egg-info/entry_points.txt
-src/fluency_cad.egg-info/requires.txt
-src/fluency_cad.egg-info/top_level.txt
-tests/test_geometry.py

src/fluency_cad.egg-info/dependency_links.txt

@@ -1 +0,0 @@
-

src/fluency_cad.egg-info/entry_points.txt

@@ -1,2 +0,0 @@
-[console_scripts]
-fluency-cad = fluency.main:main

src/fluency_cad.egg-info/requires.txt

@@ -1,13 +0,0 @@
-cadquery>=2.4
-pygfx>=0.1.0
-wgpu>=0.1.0
-PySide6>=6.4.0
-numpy>=1.24.0
-scipy>=1.10.0
-pillow>=10.0.0
-
-[dev]
-pytest>=8.0
-black>=24.0
-mypy>=1.8
-ruff>=0.4.0

src/fluency_cad.egg-info/top_level.txt

@@ -1 +0,0 @@
-fluency

tests/test_geometry.py

@@ -182,6 +182,951 @@ class TestOCCSketch:
         points = sketch.get_points()
         assert len(points) == 0
 
+    def test_workplane_extrude_along_normal(self):
+        """A sketch on a tilted plane extrudes along that plane's normal."""
+        import math
+        from OCP.GProp import GProp_GProps
+        from OCP.BRepGProp import BRepGProp
+
+        ang = math.radians(35)
+        normal = (math.sin(ang), 0.0, math.cos(ang))
+        x_dir = (math.cos(ang), 0.0, -math.sin(ang))
+
+        sk = OCCSketch()
+        sk.set_workplane((10.0, 0.0, 5.0), normal, x_dir)
+        # 20x20 square in UV
+        p0 = sk.add_point(-10, -10); p1 = sk.add_point(10, -10)
+        p2 = sk.add_point(10, 10);   p3 = sk.add_point(-10, 10)
+        sk.add_line(p0, p1); sk.add_line(p1, p2)
+        sk.add_line(p2, p3); sk.add_line(p3, p0)
+
+        geom = sk.get_geometry()
+        # The face must carry the plane normal for the kernel.
+        assert geom.metadata.get("normal") is not None
+
+        kernel = OCGeometryKernel()
+        solid = kernel.extrude(geom, 15.0)
+        s = kernel._get_shape(solid)
+        g = GProp_GProps()
+        BRepGProp.VolumeProperties_s(s, g)
+        # 20 * 20 * 15 = 6000 regardless of plane orientation.
+        assert abs(g.Mass() - 6000.0) < 0.1
+
+    def test_workplane_extrude_with_hole(self):
+        """A square with a circular hole on a custom plane extrudes correctly."""
+        import math
+        from OCP.GProp import GProp_GProps
+        from OCP.BRepGProp import BRepGProp
+
+        sk = OCCSketch()
+        sk.set_workplane((0, 0, 0), (0, 0, 1), (1, 0, 0))
+        a = sk.add_point(-10, -10); b = sk.add_point(10, -10)
+        c = sk.add_point(10, 10);   d = sk.add_point(-10, 10)
+        sk.add_line(a, b); sk.add_line(b, c)
+        sk.add_line(c, d); sk.add_line(d, a)
+        ctr = sk.add_point(0, 0)
+        sk.add_circle(ctr, 3.0)
+
+        geom = sk.get_geometry()
+        kernel = OCGeometryKernel()
+        solid = kernel.extrude(geom, 5.0)
+        s = kernel._get_shape(solid)
+        g = GProp_GProps()
+        BRepGProp.VolumeProperties_s(s, g)
+        expected = 20 * 20 * 5 - math.pi * 3 * 3 * 5
+        assert abs(g.Mass() - expected) < 0.1
+
+
+class TestExternalEntities:
+    """Tests for the underlay / face-projected reference entity API.
+
+    External entities live in the solver so user constraints can reference
+    them (e.g. "hole center 50 mm from the body's top edge"), but they
+    are *not* part of the sketch profile and must be excluded from
+    detect_faces / get_geometry.
+    """
+
+    def test_add_external_point_flags_and_fixes(self):
+        sk = OCCSketch()
+        ep = sk.add_external_point(5.0, 7.0)
+        assert ep is not None
+        assert ep.is_external is True
+        assert ep.is_construction is True
+        # External point is in the solver, with a non-None handle.
+        assert ep.handle is not None
+        # The point is in the entities / points dicts.
+        assert ep.id in sk._entities
+        assert ep.id in sk._points
+        # It's tracked as external.
+        assert ep.id in sk.get_external_entity_ids()
+
+    def test_add_external_line_requires_external_endpoints(self):
+        sk = OCCSketch()
+        a = sk.add_external_point(0, 0)
+        b = sk.add_external_point(10, 0)
+        line = sk.add_external_line(a, b)
+        assert line is not None
+        assert line.is_external is True
+        assert line.is_construction is True
+        assert line.handle is not None
+        assert line.id in sk._lines
+        assert line.id in sk.get_external_entity_ids()
+
+    def test_add_external_polyline_shares_corners(self):
+        sk = OCCSketch()
+        # Closed rectangle: 4 unique corners reused at the joints.
+        pts = [(0, 0), (10, 0), (10, 10), (0, 10), (0, 0)]
+        points, lines = sk.add_external_polyline(pts)
+        # 4 segments, 5 UV samples but the 1st and last are the same corner.
+        assert len(lines) == 4
+        # The 5 samples share the rectangle's 4 corners → 4 unique point entities.
+        assert len(set(p.id for p in points)) == 4
+        # All are external.
+        assert all(p.is_external for p in points)
+        assert all(ln.is_external for ln in lines)
+
+    def test_external_entities_excluded_from_detect_faces(self):
+        sk = OCCSketch()
+        # Underlay: a 20x20 square projected from a face (closed polyline).
+        sk.add_external_polyline([(0, 0), (20, 0), (20, 20), (0, 20), (0, 0)])
+        # User profile: a 5x5 square — this is what should be extruded.
+        a = sk.add_point(2, 2); b = sk.add_point(8, 2)
+        c = sk.add_point(8, 8); d = sk.add_point(2, 8)
+        sk.add_line(a, b); sk.add_line(b, c)
+        sk.add_line(c, d); sk.add_line(d, a)
+        faces = sk.detect_faces()
+        # Only the user-drawn face (5x5 square) should be detected.
+        assert len(faces) == 1
+        outer = faces[0]["outer"]
+        assert outer["type"] == "polygon"
+        # 5 vertices on the outer loop (4 corners + closing point).
+        assert len(outer["points"]) == 5
+        # It must be the user square, not the underlay.
+        xs = [p[0] for p in outer["points"][:4]]
+        ys = [p[1] for p in outer["points"][:4]]
+        assert min(xs) >= 2 and max(xs) <= 8
+        assert min(ys) >= 2 and max(ys) <= 8
+
+    def test_external_entities_excluded_from_get_polygon_points(self):
+        sk = OCCSketch()
+        sk.add_external_polyline([(0, 0), (100, 0), (100, 100), (0, 100), (0, 0)])
+        a = sk.add_point(1, 1); b = sk.add_point(2, 1)
+        c = sk.add_point(2, 2); d = sk.add_point(1, 2)
+        sk.add_line(a, b); sk.add_line(b, c)
+        sk.add_line(c, d); sk.add_line(d, a)
+        poly = sk.get_polygon_points()
+        # The user square (1..2 range) should appear, not the 0..100 underlay.
+        assert all(1.0 <= p.x <= 2.0 for p in poly)
+        assert all(1.0 <= p.y <= 2.0 for p in poly)
+
+    def test_external_entities_excluded_from_get_geometry(self):
+        """Underlay must never appear in the extruded face."""
+        from OCP.GProp import GProp_GProps
+        from OCP.BRepGProp import BRepGProp
+
+        sk = OCCSketch()
+        # Underlay (NOT to be extruded).
+        sk.add_external_polyline([(0, 0), (10, 0), (10, 10), (0, 10), (0, 0)])
+        # User profile: a 2x2 square inside the underlay.
+        a = sk.add_point(1, 1); b = sk.add_point(3, 1)
+        c = sk.add_point(3, 3); d = sk.add_point(1, 3)
+        sk.add_line(a, b); sk.add_line(b, c)
+        sk.add_line(c, d); sk.add_line(d, a)
+        geom = sk.get_geometry()
+        # Volume = 2 * 2 * 4 = 16, NOT 10 * 10 * 4 = 400.
+        kernel = OCGeometryKernel()
+        solid = kernel.extrude(geom, 4.0)
+        s = kernel._get_shape(solid)
+        g = GProp_GProps()
+        BRepGProp.VolumeProperties_s(s, g)
+        assert abs(g.Mass() - 16.0) < 0.5
+
+    def test_distance_to_external_point_constraint(self):
+        """The headline use case: hole position fixed relative to a face edge.
+
+        User draws a circle (the hole) and a distance from its centre to
+        a face-projected point.  After solve, the circle centre should be
+        exactly the requested distance from the external point.
+        """
+        sk = OCCSketch()
+        # Underlay corner: pick a known anchor on the projected face.
+        anchor = sk.add_external_point(0.0, 0.0)
+        # User geometry: a 1mm circle for the hole.
+        hole_centre = sk.add_point(7.0, 4.0)  # start position: 7 from anchor
+        sk.add_circle(hole_centre, 1.0)
+        # Constrain the hole centre 50 mm from the underlay corner.
+        ok = sk.constrain_distance(anchor, hole_centre, 50.0)
+        assert ok
+        assert sk.solve()
+        solved = sk.get_solved_point(hole_centre.id)
+        assert solved is not None
+        # The starting (7, 4) is well short of 50, so the constraint
+        # forces the centre out to a point on the 50mm circle around (0,0).
+        x, y = solved
+        assert abs(math_hypot(x, y) - 50.0) < 0.01
+
+    def test_remove_external_entities_clears_them(self):
+        sk = OCCSketch()
+        sk.add_external_polyline([(0, 0), (10, 0), (10, 10), (0, 10), (0, 0)])
+        assert len(sk.get_external_entity_ids()) > 0
+        sk.remove_external_entities()
+        assert len(sk.get_external_entity_ids()) == 0
+        # No external points/lines left in the tracking dicts.
+        for eid in sk._entities:
+            assert not getattr(sk._entities[eid], "is_external", False)
+
+    def test_remove_external_entities_prunes_related_constraints(self):
+        """Constraints referencing external entities are pruned on removal.
+
+        A distance to an external point is recorded in the constraint log
+        on the ids of both endpoints.  After remove_external_entities(),
+        those entries are gone and the solver rebuilds without them.
+        """
+        sk = OCCSketch()
+        anchor = sk.add_external_point(0.0, 0.0)
+        user = sk.add_point(20.0, 0.0)
+        sk.constrain_distance(anchor, user, 5.0)
+        sk.solve()
+        # At least one log entry references the external anchor.
+        assert any(anchor.id in entry["ids"] for entry in sk._constraint_log)
+        # Now wipe the underlay.
+        sk.remove_external_entities()
+        # The distance constraint is gone, and the user point is free.
+        assert not any(anchor.id in entry["ids"] for entry in sk._constraint_log)
+        assert sk.solve()
+
+    def test_external_polyline_dedupes_close_points(self):
+        """Co-located UV samples share a single point entity (closed loops)."""
+        sk = OCCSketch()
+        # Closed rectangle (closing point == start point).
+        pts = [(1.0, 1.0), (9.0, 1.0), (9.0, 9.0), (1.0, 9.0), (1.0, 1.0)]
+        points, lines = sk.add_external_polyline(pts)
+        # 5 samples → 4 unique points (start/end collapse).
+        assert len(set(p.id for p in points)) == 4
+        # 4 segments connect them.
+        assert len(lines) == 4
+        # Every line's endpoints are among the 4 points.
+        point_ids = {p.id for p in points}
+        for line_id, (sid, eid2) in sk._lines.items():
+            if line_id in sk.get_external_entity_ids():
+                assert sid in point_ids and eid2 in point_ids
+
+    def test_external_point_is_solver_fixed(self):
+        """An external point's solver parameters must not change on re-solve.
+
+        python_solvespace drags the first user point; external points use
+        ``dragged`` directly so dragging a user point near an external
+        reference doesn't shift the reference.
+        """
+        sk = OCCSketch()
+        ep = sk.add_external_point(3.0, 4.0)
+        # Add a user point; solve; record the external point's solved
+        # params.  Then delete the user point and add another one; the
+        # external point's params must not have moved.
+        sk.add_point(100.0, 0.0)
+        sk.solve()
+        x0, y0 = sk.solver.params(ep.handle.params)
+        for dx in range(-5, 6):
+            sk.add_point(100.0 + dx, 0.0)
+            sk.solve()
+            x1, y1 = sk.solver.params(ep.handle.params)
+            assert abs(x1 - x0) < 1e-6
+            assert abs(y1 - y0) < 1e-6
+
+    def test_horizontal_constraint_on_external_line(self):
+        """Horizontal constraint involving a partly-external line is solvable.
+
+        Both external endpoints are dragged (fixed), so a horizontal
+        constraint between them is over-determined when their y values
+        differ.  To make the system solvable we add a free user point
+        connected to one external point via a line, then constrain that
+        line horizontal — the user endpoint is dragged to a y that
+        matches the external one, satisfying the constraint.
+        """
+        sk = OCCSketch()
+        a = sk.add_external_point(0.0, 0.0)
+        # Add a free user point first (skipped auto-drag because external
+        # points exist, so this one is free).
+        free = sk.add_point(7.0, 5.0)
+        # And an external endpoint to pair with the free point in a line.
+        b = sk.add_external_point(0.0, 0.0)
+        line = sk.add_external_line(b, free)
+        # Constrain it horizontal; the free point should drop to y=0.
+        sk.constrain_horizontal(line)
+        assert sk.solve()
+        sa = sk.get_solved_point(b.id)
+        sf = sk.get_solved_point(free.id)
+        assert sa is not None and sf is not None
+        assert abs(sa[1] - sf[1]) < 1e-6
+
+    def test_cleared_sketch_drops_external_entities(self):
+        sk = OCCSketch()
+        sk.add_external_polyline([(0, 0), (1, 0), (1, 1), (0, 1), (0, 0)])
+        sk.add_point(5, 5)
+        assert len(sk.get_external_entity_ids()) > 0
+        sk.clear()
+        assert len(sk.get_external_entity_ids()) == 0
+        assert sk.get_entity_count() == 0
+
+
+class TestExtrudeCutFix:
+    """Tests for the cut/union logic in MainWindow._extrude_sketch.
+
+    The old code stored the boolean result in the *tool* (newly extruded)
+    body, leaving the *target* body untouched — so the user would see a
+    separate "cavity-shaped" body next to the original instead of a
+    cavity in the original.  After deleting that extra body, the next
+    extrude-cutter saw ``len(existing) <= 1`` and silently skipped the
+    cut, producing an unconstrained new body that looked "added without
+    cut".  The fix:
+
+    1. Apply the boolean to the *target* (existing[0]) body.
+    2. Remove the tool body from the component.
+    3. Re-render the target in place.
+
+    These tests verify the boolean operation produces the right solid and
+    that the post-extrude bookkeeping leaves exactly the right bodies
+    in the component.
+    """
+
+    def test_boolean_difference_modifies_target_not_tool(self):
+        """The fix: cut goes into the target, tool is removed.
+
+        Reproduces the cut/merge flow from ``_extrude_sketch`` without
+        spinning up the full MainWindow: build a target + tool body,
+        run boolean_difference, then verify the target's volume dropped
+        and the tool is no longer needed.
+        """
+        from OCP.BRepPrimAPI import BRepPrimAPI_MakeBox
+        from fluency.geometry_occ.kernel import OCGeometryKernel, OCCGeometryObject
+        from OCP.GProp import GProp_GProps
+        from OCP.BRepGProp import BRepGProp
+        import math
+
+        k = OCGeometryKernel()
+        target_shape = BRepPrimAPI_MakeBox(100, 100, 100).Shape()
+        target_obj = OCCGeometryObject(target_shape, {"type": "box"})
+
+        # Tool: a 20x20x200 cuboid at the corner of the box, to make the
+        # expected volume easy to compute.
+        from OCP.BRepPrimAPI import BRepPrimAPI_MakePrism
+        from OCP.gp import gp_Pnt, gp_Vec
+        # 20x20 square at (0,0,0), extruded along +Z by 200.
+        from OCP.BRepBuilderAPI import BRepBuilderAPI_MakePolygon
+        mp = BRepBuilderAPI_MakePolygon()
+        for (x, y) in [(0, 0), (20, 0), (20, 20), (0, 20)]:
+            mp.Add(gp_Pnt(x, y, 0))
+        mp.Close()
+        from OCP.BRepBuilderAPI import BRepBuilderAPI_MakeFace
+        face = BRepBuilderAPI_MakeFace(mp.Wire()).Face()
+        tool_shape = BRepPrimAPI_MakePrism(
+            face, gp_Vec(0, 0, 200)
+        ).Shape()
+        tool_obj = OCCGeometryObject(tool_shape, {"type": "prism"})
+
+        # Before cut: target is 100^3 = 1_000_000.
+        g0 = GProp_GProps()
+        BRepGProp.VolumeProperties_s(k._get_shape(target_obj), g0)
+        assert abs(g0.Mass() - 1_000_000.0) < 1.0
+
+        # Apply the fix: result goes to the target, not the tool.
+        result = k.boolean_difference(target_obj, tool_obj)
+        target_obj_geometry = result
+
+        # After cut: target is 1_000_000 - 20*20*100 = 960_000
+        # (the prism only intersects the box in z=[0,100], i.e. 100 deep).
+        g1 = GProp_GProps()
+        BRepGProp.VolumeProperties_s(
+            k._get_shape(target_obj_geometry), g1
+        )
+        assert abs(g1.Mass() - 960_000.0) < 1.0
+
+    def test_boolean_difference_does_not_leave_separate_cavity_body(self):
+        """Sanity: the cut result is a single body (not two).
+
+        The OLD bug stored the cut result in a SECOND body, so after a
+        cut the user would see the original body PLUS a "cavity-shaped"
+        body — the user thought the cut worked but it was just two
+        separate solids.  With the fix the cut is folded into the
+        target, so a single body remains.
+        """
+        from OCP.BRepPrimAPI import BRepPrimAPI_MakeBox
+        from OCP.BRepAlgoAPI import BRepAlgoAPI_Cut
+        from OCP.TopExp import TopExp_Explorer
+        from OCP.TopAbs import TopAbs_SOLID
+        from fluency.geometry_occ.kernel import OCGeometryKernel, OCCGeometryObject
+
+        k = OCGeometryKernel()
+        target_shape = BRepPrimAPI_MakeBox(100, 100, 100).Shape()
+        target_obj = OCCGeometryObject(target_shape, {})
+
+        # Tool: small box at the centre, fully inside the target.
+        from OCP.BRepPrimAPI import BRepPrimAPI_MakeBox as BBox
+        tool_shape = BBox(20, 20, 20).Shape()
+        tool_obj = OCCGeometryObject(tool_shape, {})
+
+        # The fixed cut flow:
+        #   1. Apply boolean to target.
+        #   2. Remove the tool from the component dict.
+        result = k.boolean_difference(target_obj, tool_obj)
+        target_obj.geometry = result  # the fix: result goes in target
+        # (the tool_obj is then discarded; the simulated flow above
+        # keeps it locally but doesn't use it for display).
+
+        # Count solids in the cut result.  It should be exactly 1 (the
+        # target with a cavity), not 2 (target + cavity-shaped tool).
+        shape = k._get_shape(target_obj)
+        explorer = TopExp_Explorer(shape, TopAbs_SOLID)
+        n_solids = 0
+        while explorer.More():
+            n_solids += 1
+            explorer.Next()
+        assert n_solids == 1, f"Cut result has {n_solids} solids, expected 1"
+
+
+class TestBodyVisibilityToggle:
+    """Tests for the per-body visibility toggle on the right-hand body list.
+
+    The user asked for a visibility checkbox per body so they could
+    easily verify whether an operation (e.g. cut) had actually modified
+    a body.  Hiding the second body and seeing whether the first still
+    has the cut shape is the intended workflow.
+    """
+
+    def _make_window(self):
+        import os
+        os.environ.setdefault("QT_QPA_PLATFORM", "offscreen")
+        from PySide6.QtWidgets import QApplication
+        app = QApplication.instance() or QApplication([])
+        from fluency.main import MainWindow
+        return MainWindow()
+
+    def test_body_list_uses_checkable_items(self):
+        """Each body list item must be a checkable QListWidgetItem."""
+        from PySide6.QtCore import Qt
+        win = self._make_window()
+        # Add a fake body to the current component so the list isn't empty.
+        from fluency.models.data_model import Body
+        from OCP.BRepPrimAPI import BRepPrimAPI_MakeBox
+        from fluency.geometry_occ.kernel import OCCGeometryObject
+        box = OCCGeometryObject(
+            BRepPrimAPI_MakeBox(10, 10, 10).Shape(), {}
+        )
+        win._current_component.bodies["a"] = Body(name="A", geometry=box)
+        win._refresh_lists()
+        items = win._body_list.findItems("A", Qt.MatchExactly)
+        assert len(items) == 1
+        # Item is checkable (so the user can toggle visibility).
+        assert items[0].flags() & Qt.ItemIsUserCheckable
+        # And the body id is stored on the item for the toggle handler.
+        assert items[0].data(Qt.UserRole) == "a"
+        # Default state is checked (= visible).
+        assert items[0].checkState() == Qt.Checked
+
+    def test_toggling_visibility_updates_body_model(self):
+        """Flipping the checkbox should set body.visible accordingly."""
+        from PySide6.QtCore import Qt
+        win = self._make_window()
+        from fluency.models.data_model import Body
+        from OCP.BRepPrimAPI import BRepPrimAPI_MakeBox
+        from fluency.geometry_occ.kernel import OCCGeometryObject
+        box = OCCGeometryObject(
+            BRepPrimAPI_MakeBox(10, 10, 10).Shape(), {}
+        )
+        win._current_component.bodies["a"] = Body(name="A", geometry=box)
+        win._refresh_lists()
+        item = win._body_list.findItems("A", Qt.MatchExactly)[0]
+
+        # Toggle off.
+        item.setCheckState(Qt.Unchecked)
+        win._on_body_visibility_changed(item)
+        assert win._current_component.bodies["a"].visible is False
+
+        # Toggle back on.
+        item.setCheckState(Qt.Checked)
+        win._on_body_visibility_changed(item)
+        assert win._current_component.bodies["a"].visible is True
+
+    def test_visibility_no_op_when_unchanged(self):
+        """Re-emitting the same state must not trigger a viewer call.
+
+        The set_visibility call into the viewer is cheap but not free;
+        spamming it on every selection change would be wasteful.  The
+        handler short-circuits when the new state matches the model's.
+        """
+        from PySide6.QtCore import Qt
+        win = self._make_window()
+        from fluency.models.data_model import Body
+        from OCP.BRepPrimAPI import BRepPrimAPI_MakeBox
+        from fluency.geometry_occ.kernel import OCCGeometryObject
+        box = OCCGeometryObject(
+            BRepPrimAPI_MakeBox(10, 10, 10).Shape(), {}
+        )
+        win._current_component.bodies["a"] = Body(name="A", geometry=box)
+        win._refresh_lists()
+        item = win._body_list.findItems("A", Qt.MatchExactly)[0]
+
+        # Force the model's visibility to False to mimic a desync.
+        win._current_component.bodies["a"].visible = False
+        # Set the checkbox to Unchecked — this matches the model, so the
+        # handler should short-circuit (not call set_visibility).
+        item.setCheckState(Qt.Unchecked)
+        # We can't directly assert "viewer was not called" without
+        # monkey-patching; instead assert that re-firing the handler
+        # doesn't raise and the state is consistent.
+        win._on_body_visibility_changed(item)
+        assert win._current_component.bodies["a"].visible is False
+
+
+def math_hypot(x, y):
+    import math
+    return math.hypot(x, y)
+
+
+class TestConstraintTagRendering:
+    """Tests for constraint tag rendering when a tag references a line id.
+
+    The constraint log stores entity ids.  A constraint that targets a
+    line (e.g. point-on-line coincident) puts a *line* id in the log,
+    and the tag rendering code used to naively unpack that line's
+    geometry ``((x1,y1), (x2,y2))`` as if it were a point's ``(x, y)``,
+    calling ``round()`` on a tuple and raising
+    ``TypeError: type tuple doesn't define __round__ method``.
+    These tests pin the fix in ``Sketch2DWidget._compute_constraint_tags``.
+    """
+
+    def _make_widget_with_sketch(self, sk):
+        """Build a Sketch2DWidget in offscreen mode and attach *sk* to it."""
+        import os
+        os.environ.setdefault("QT_QPA_PLATFORM", "offscreen")
+        from PySide6.QtWidgets import QApplication
+        app = QApplication.instance() or QApplication([])
+        from fluency.main import Sketch2DWidget
+        w = Sketch2DWidget()
+        w.set_sketch(sk)
+        return w
+
+    def test_point_on_line_coincident_tag_renders(self):
+        """A coincident between a point and a line must not crash the paint event.
+
+        Reproduces the user-reported error: ids[1] is a line id, the old
+        code unpacked the line's geometry ``((x1,y1), (x2,y2))`` as a
+        point and called ``round()`` on the inner tuple.
+        """
+        sk = OCCSketch()
+        a = sk.add_point(0, 0)
+        b = sk.add_point(10, 0)
+        line = sk.add_line(a, b)  # 3rd entity: the line itself
+        # Point-on-line: the line id is in the constraint log.
+        p3 = sk.add_point(5, 5)
+        sk.constrain_coincident(p3, line)
+        sk.solve()
+        w = self._make_widget_with_sketch(sk)
+        # Must not raise.
+        tags = w._compute_constraint_tags()
+        # One tag for the coincident.
+        coin_tags = [t for t in tags if "coin" in t["label"]]
+        assert len(coin_tags) == 1
+        # The tag was anchored (non-None center) and renders successfully.
+        assert coin_tags[0]["center"] is not None
+
+    def test_point_world_rejects_line_geometry(self):
+        """_point_world must return None (not crash) when given a line id."""
+        sk = OCCSketch()
+        a = sk.add_point(0, 0)
+        b = sk.add_point(10, 0)
+        line = sk.add_line(a, b)
+        w = self._make_widget_with_sketch(sk)
+        # Old behaviour: round(<tuple>) raised TypeError.
+        # New behaviour: _point_world returns None for non-point entities.
+        result = w._point_world(line.id)
+        assert result is None
+
+    def test_point_world_rejects_circle_geometry(self):
+        """_point_world must return None for circle entities too.
+
+        A circle's geometry is ``((cx, cy), radius)`` — also not a flat
+        2-tuple of numbers.  Same shape check rejects it.
+        """
+        sk = OCCSketch()
+        c = sk.add_point(0, 0)
+        circle = sk.add_circle(c, 5.0)
+        w = self._make_widget_with_sketch(sk)
+        result = w._point_world(circle.id)
+        assert result is None
+
+    def test_entity_anchor_routes_to_line_midpoint(self):
+        """_entity_anchor returns the line midpoint for line ids."""
+        sk = OCCSketch()
+        a = sk.add_point(0, 0)
+        b = sk.add_point(10, 0)
+        line = sk.add_line(a, b)
+        w = self._make_widget_with_sketch(sk)
+        anchor = w._entity_anchor(line.id)
+        assert anchor is not None
+        # Midpoint of (0,0) and (10,0) is (5, 0).
+        assert anchor.x() == 5
+        assert anchor.y() == 0
+
+    def test_distance_constraint_with_line_id(self):
+        """A distance constraint involving a line id must not crash.
+
+        Future enhancements might add a point-to-line distance; even
+        without that, the defensive routing through _entity_anchor
+        ensures the tag renders cleanly when such an entry is logged.
+        """
+        sk = OCCSketch()
+        a = sk.add_point(0, 0)
+        b = sk.add_point(10, 0)
+        line = sk.add_line(a, b)
+        p3 = sk.add_point(15, 5)
+        # Simulate a point-to-line distance by directly appending a log
+        # entry — this matches the solver's surface (it would call
+        # _record_constraint with these ids once a point-to-line
+        # distance is added to the solver wrapper).
+        sk._record_constraint("distance", (p3.id, line.id), (12.0,))
+        w = self._make_widget_with_sketch(sk)
+        tags = w._compute_constraint_tags()
+        dst_tags = [t for t in tags if "dst" in t["label"]]
+        assert len(dst_tags) == 1
+        assert dst_tags[0]["center"] is not None
+
+    def test_paint_tolerates_corrupted_entity_geometry(self):
+        """Paint must not crash if an entity's geometry is weird.
+
+        Simulates the user-reported case: after constraining many
+        points, the solver log still references an entity whose
+        geometry was corrupted (e.g. line-shape ``((x,y), r)`` on a
+        point entity, a 3-element list, or a value with a __round__
+        that raises).  _compute_constraint_tags should drop the bad
+        tag and keep rendering the rest.
+        """
+        sk = OCCSketch()
+        a = sk.add_point(0, 0)
+        b = sk.add_point(10, 0)
+        c = sk.add_point(5, 5)
+        sk.constrain_coincident(c, a)
+        sk.solve()
+        w = self._make_widget_with_sketch(sk)
+
+        # Case 1: point entity has line-shape geometry.
+        sk._entities[c.id].geometry = ((1.0, 2.0), 3.0)
+        tags = w._compute_constraint_tags()
+        # Bad entry is dropped; the good one still renders.
+        assert all(t["center"] is not None for t in tags)
+
+        # Case 2: wrong-shape geometry (3-element list).
+        sk._entities[c.id].geometry = [1.0, 2.0, 3.0]
+        tags = w._compute_constraint_tags()
+        assert all(t["center"] is not None for t in tags)
+
+        # Case 3: exotic type whose __round__ raises.
+        class _BadRound:
+            def __round__(self, ndigits=0):
+                raise TypeError("cannot round")
+        sk._entities[c.id].geometry = (_BadRound(), _BadRound())
+        tags = w._compute_constraint_tags()
+        assert all(t["center"] is not None for t in tags)
+
+    def test_paint_tolerates_dangling_constraint_ids(self):
+        """Paint must not crash if the log references an entity that was deleted.
+
+        The log can briefly reference a stale id after a delete (e.g.
+        if a constraint handler logs first and deletes second).  The
+        render path must skip such entries, not raise KeyError or
+        TypeError.
+        """
+        sk = OCCSketch()
+        a = sk.add_point(0, 0)
+        sk.constrain_fixed(a)
+        sk.solve()
+        # Simulate the entity being removed without pruning the log.
+        sk._entities.pop(a.id)
+        w = self._make_widget_with_sketch(sk)
+        tags = w._compute_constraint_tags()
+        # No crash; the dangling tag is dropped.
+        assert isinstance(tags, list)
+
+
+class TestExtrudeRedesign:
+    """Tests for the cut-through / source-body auto-target / live-preview
+    redesign (2026-06-29).
+
+    Headline workflow: a sketch projected on a face of a body, plus "Perform
+    Cut"
+    1. auto-targets the body it was projected onto,
+    2. auto-directs the cut INTO the body (the picked face's outward normal
+       points away, so a plain cut would carve nothing),
+    3. with "Through All" ticked, fully passes through the body.
+    A live transparent preview is computed from the same shared helper, and
+    a freshly-projected sketch is auto-selected in the row-left list so the
+    user can Extrude/Cut without hunting for the row.
+    """
+
+    def _make_window_with_box(self, box_side=100.0):
+        import os
+        os.environ.setdefault("QT_QPA_PLATFORM", "offscreen")
+        from PySide6.QtWidgets import QApplication
+        app = QApplication.instance() or QApplication([])
+        from fluency.main import MainWindow
+        from fluency.models.data_model import Sketch, Body
+        from fluency.geometry_occ.kernel import OCCGeometryObject
+        from fluency.geometry_occ.sketch import OCCSketch
+        from OCP.BRepPrimAPI import BRepPrimAPI_MakeBox
+
+        win = MainWindow()
+        k = win._kernel
+        box_shape = BRepPrimAPI_MakeBox(box_side, box_side, box_side).Shape()
+        box_obj = OCCGeometryObject(box_shape, {"type": "box"})
+        win._current_component.bodies["b1"] = Body(name="Box1", geometry=box_obj)
+
+        # Sketch on the TOP face of the box (normal +Z points outward).
+        sk = OCCSketch()
+        origin = (box_side / 2.0, box_side / 2.0, box_side)
+        normal = (0.0, 0.0, 1.0)
+        x_dir = (1.0, 0.0, 0.0)
+        sk.set_workplane(origin, normal, x_dir)
+        sketch = Sketch(name="S on top")
+        sketch.occ_sketch = sk
+        sketch.set_workplane(origin, normal, x_dir)
+        sketch._source_body_id = "b1"
+        win._current_component.sketches[sketch.id] = sketch
+        win._current_sketch = sketch
+        # Return all the fixtures.
+        return win, sketch, sk, box_obj
+
+    def _add_circle(self, sk, r=10.0):
+        from fluency.geometry_occ.sketch import OCCSketch
+        c = sk.add_point(0, 0)
+        sk.add_circle(c, r)
+        sk.solve()
+        return sk.get_geometry()
+
+    def _geometry_volume(self, win, geom):
+        from OCP.GProp import GProp_GProps
+        from OCP.BRepGProp import BRepGProp
+        sh = win._kernel._get_shape(geom)
+        g = GProp_GProps()
+        BRepGProp.VolumeProperties_s(sh, g)
+        return g.Mass()
+
+    def test_cut_auto_directs_into_body(self):
+        """A plain "Perform Cut" on a sketch-on-top-of-body carves a pocket.
+
+        Without the redesign a non-inverted extrude goes *outward* (up),
+        missing the box and carving nothing.  The redesign auto-flips the
+        extrusion to go *into* the body regardless of the Invert checkbox,
+        so a 5 mm cut makes a real 5 mm-deep pocket.
+        """
+        import math
+        win, sketch, sk, box_obj = self._make_window_with_box(100.0)
+        face_geom = self._add_circle(sk, r=10.0)
+        # Plain cut, length=5, NOT inverted.  Pre-redesign this would have
+        # removed nothing; post-redesign it must remove a 5 mm cylinder.
+        result = win._compute_extrude_result(
+            sketch, face_geom,
+            length=5.0, symmetric=False, invert=False,
+            cut=True, union=False, through_all=False,
+        )
+        assert result is not None
+        assert result["target_body"] is not None
+        assert result["target_body"].name == "Box1"
+        vol = self._geometry_volume(win, result["result_geom"])
+        expected = 100.0 ** 3 - math.pi * (10.0 ** 2) * 5.0
+        assert abs(vol - expected) < 1.0
+
+    def test_cut_through_all_passes_through(self):
+        """"Through All" cut fully passes through the body."""
+        import math
+        win, sketch, sk, box_obj = self._make_window_with_box(100.0)
+        face_geom = self._add_circle(sk, r=10.0)
+        result = win._compute_extrude_result(
+            sketch, face_geom,
+            length=5.0,  # ignored when through_all
+            symmetric=False, invert=False,
+            cut=True, union=False, through_all=True,
+        )
+        assert result is not None
+        vol = self._geometry_volume(win, result["result_geom"])
+        # Full through cylinder = pi * r^2 * box_depth.
+        expected = 100.0 ** 3 - math.pi * (10.0 ** 2) * 100.0
+        assert abs(vol - expected) < 1.0
+
+    def test_cut_auto_targets_source_body_not_existing_zero(self):
+        """Cut should target the source body, not the dict's first body.
+
+        Constructs a 2-body scenario where the first body in the dict is NOT
+        the source, and verifies the cut goes into the source.
+        """
+        import math
+        import os
+        os.environ.setdefault("QT_QPA_PLATFORM", "offscreen")
+        from PySide6.QtWidgets import QApplication
+        app = QApplication.instance() or QApplication([])
+        from fluency.main import MainWindow
+        from fluency.models.data_model import Sketch, Body
+        from fluency.geometry_occ.kernel import OCCGeometryObject
+        from fluency.geometry_occ.sketch import OCCSketch
+        from OCP.BRepPrimAPI import BRepPrimAPI_MakeBox
+
+        win = MainWindow()
+        # First body in the dict: a 50-millimetre box ALSO.
+        first = OCCGeometryObject(
+            BRepPrimAPI_MakeBox(50, 50, 50).Shape(), {}
+        )
+        win._current_component.bodies["first"] = Body(
+            name="First", geometry=first
+        )
+        # Source body: a 100-millimetre box (drawn over).
+        src = OCCGeometryObject(
+            BRepPrimAPI_MakeBox(100, 100, 100).Shape(), {}
+        )
+        win._current_component.bodies["src"] = Body(
+            name="Src", geometry=src
+        )
+        # Sketch circle on top of the SOURCE box (0,0 so normal +Z).
+        sk = OCCSketch()
+        sk.set_workplane((50, 50, 100), (0, 0, 1), (1, 0, 0))
+        centre = sk.add_point(0, 0)
+        sk.add_circle(centre, 10.0)
+        sk.solve()
+        sketch = Sketch(name="S")
+        sketch.occ_sketch = sk
+        sketch.set_workplane((50, 50, 100), (0, 0, 1), (1, 0, 0))
+        sketch._source_body_id = "src"  # explicitly the source box.
+        win._current_component.sketches[sketch.id] = sketch
+        win._current_sketch = sketch
+
+        face_geom = sk.get_geometry()
+        result = win._compute_extrude_result(
+            sketch, face_geom,
+            length=5.0, symmetric=False, invert=False,
+            cut=True, union=False, through_all=True,
+        )
+        assert result is not None
+        # Target is the source box, NOT the dict's first body.
+        assert result["target_body"].name == "Src"
+        vol = self._geometry_volume(win, result["result_geom"])
+        # 100^3 - pi*100*100 (through-all full-depth cut on the 100 box).
+        expected = 100.0 ** 3 - math.pi * (10.0 ** 2) * 100.0
+        assert abs(vol - expected) < 1.0
+
+    def test_union_default_builds_outward(self):
+        """Combine (Union) builds a boss OUTWARD (no auto-into-body flip).
+
+        Union semantics: the new material adds on TOP of the face, not
+        into the body.  So a 10 mm union adds a 10 mm cylinder of material
+        rather than "subtracting" from the existing box.
+        """
+        import math
+        win, sketch, sk, box_obj = self._make_window_with_box(100.0)
+        face_geom = self._add_circle(sk, r=10.0)
+        result = win._compute_extrude_result(
+            sketch, face_geom,
+            length=10.0, symmetric=False, invert=False,
+            cut=False, union=True, through_all=False,
+        )
+        assert result is not None
+        vol = self._geometry_volume(win, result["result_geom"])
+        # 100^3 + pi*100*10 — material added on top.
+        expected = 100.0 ** 3 + math.pi * (10.0 ** 2) * 10.0
+        assert abs(vol - expected) < 1.0
+
+    def test_plain_extrude_untouched_by_source_body(self):
+        """Without cut/union, the extrusion is a standalone new body."""
+        win, sketch, sk, box_obj = self._make_window_with_box(100.0)
+        face_geom = self._add_circle(sk, r=10.0)
+        result = win._compute_extrude_result(
+            sketch, face_geom,
+            length=10.0, symmetric=False, invert=False,
+            cut=False, union=False, through_all=False,
+        )
+        assert result is not None
+        # No boolean target; result is the standalone tool extrusion.
+        assert result["target_body"] is None
+        vol = self._geometry_volume(win, result["result_geom"])
+        # Standalone cylinder 10 mm tall.
+        import math
+        assert abs(vol - math.pi * (10.0 ** 2) * 10.0) < 1.0
+
+    def test_freshly_picked_sketch_is_auto_selected(self):
+        """After _on_face_picked, the new sketch is the current list row.
+
+        The user should be able to click Extrude/Cut immediately without
+        first hunting for the new sketch in the left list.
+        """
+        from fluency.geometry_occ.kernel import OCCGeometryObject
+        win, _, sk, box_obj = self._make_window_with_box(100.0)
+        # Simulate _on_face_picked by calling it through a fake face
+        # shape — but the simplest behavioural check is to call the
+        # bookkeeping directly: a new sketch matching src exists and is
+        # set as _current_sketch, and it appears (and is selected) in
+        # the list after _refresh_lists + setCurrentRow.
+        from fluency.models.data_model import Sketch
+        sketch = Sketch(name="Sketch on face 99")
+        sketch._source_body_id = "b1"
+        sketch.set_workplane((50, 50, 100), (0, 0, 1), (1, 0, 0))
+        win._current_component.sketches[sketch.id] = sketch
+        win._current_sketch = sketch
+        win._refresh_lists()
+        # The auto-select block from _on_face_picked — re-derive it
+        # here since we can't run the full pick path offscreen.
+        target_row = None
+        for row in range(win._sketch_list.count()):
+            if win._sketch_list.item(row).text() == sketch.name:
+                target_row = row
+                break
+        assert target_row is not None
+        win._sketch_list.setCurrentRow(target_row)
+        assert win._sketch_list.currentRow() == target_row
+        assert win._sketch_list.currentItem().text() == sketch.name
+
+    def test_preview_callback_invoked_on_value_change(self):
+        """The live preview callback fires on spinbox/checkbox changes."""
+        import os
+        os.environ.setdefault("QT_QPA_PLATFORM", "offscreen")
+        from PySide6.QtWidgets import QApplication
+        app = QApplication.instance() or QApplication([])
+        from fluency.main import ExtrudeDialog
+
+        calls = []
+        dialog = ExtrudeDialog()
+        dialog.set_preview_callback(lambda v: calls.append(v))
+        # set_preview_callback emits once for the initial state.
+        assert len(calls) == 1
+        # Changing the length should emit a new values tuple.
+        dialog.length_input.setValue(42.0)
+        assert len(calls) == 2
+        # Toggling "Through All" should emit again.
+        dialog.through_all_checkbox.setChecked(True)
+        assert len(calls) >= 3
+        # Passing None clears the preview (as the host does on close).
+        dialog.set_preview_callback(None)
+        # New callback None → no further emissions.
+        before = len(calls)
+        dialog.length_input.setValue(99.0)
+        assert len(calls) == before  # callback gone → no emit
+
+    def test_preview_hidden_event_sends_none(self):
+        """hideEvent should deliver None to the callback so the host clears."""
+        import os
+        os.environ.setdefault("QT_QPA_PLATFORM", "offscreen")
+        from PySide6.QtWidgets import QApplication
+        app = QApplication.instance() or QApplication([])
+        from fluency.main import ExtrudeDialog
+
+        seen = []
+        dialog = ExtrudeDialog()
+        dialog.set_preview_callback(lambda v: seen.append(v))
+        # hideEvent only fires when the dialog was previously visible, so
+        # show it first (window system / offscreen both honour this) and
+        # then hide it — which is exactly what dialog.exec() does when the
+        # user accepts or cancels.
+        dialog.show()
+        dialog.hide()
+        # The last value emitted to the callback must be None (clear).
+        assert seen and seen[-1] is None
+
 
 if __name__ == "__main__":
     pytest.main([__file__, "-v"])

uv.lock

@@ -638,6 +638,7 @@ dependencies = [
     { name = "pillow" },
     { name = "pygfx" },
     { name = "pyside6" },
+    { name = "python-solvespace" },
     { name = "scipy", version = "1.15.3", source = { registry = "https://pypi.org/simple" }, marker = "python_full_version < '3.11'" },
     { name = "scipy", version = "1.17.1", source = { registry = "https://pypi.org/simple" }, marker = "python_full_version >= '3.11'" },
     { name = "wgpu" },
@@ -661,6 +662,7 @@ requires-dist = [
     { name = "pygfx", specifier = ">=0.1.0" },
     { name = "pyside6", specifier = ">=6.4.0" },
     { name = "pytest", marker = "extra == 'dev'", specifier = ">=8.0" },
+    { name = "python-solvespace", specifier = ">=3.0.0" },
     { name = "ruff", marker = "extra == 'dev'", specifier = ">=0.4.0" },
     { name = "scipy", specifier = ">=1.10.0" },
     { name = "wgpu", specifier = ">=0.1.0" },
@@ -2107,6 +2109,18 @@ wheels = [
     { url = "https://files.pythonhosted.org/packages/ec/57/56b9bcc3c9c6a792fcbaf139543cee77261f3651ca9da0c93f5c1221264b/python_dateutil-2.9.0.post0-py2.py3-none-any.whl", hash = "sha256:a8b2bc7bffae282281c8140a97d3aa9c14da0b136dfe83f850eea9a5f7470427", size = 229892, upload-time = "2024-03-01T18:36:18.57Z" },
 ]
 
+[[package]]
+name = "python-solvespace"
+version = "3.0.8"
+source = { registry = "https://pypi.org/simple" }
+sdist = { url = "https://files.pythonhosted.org/packages/70/d9/edb532941527cfdbd22861ce574a57859952d21132f791a8706fafee9876/python_solvespace-3.0.8.tar.gz", hash = "sha256:c5c132c1151cfa4cc8719474bbbafedd109d7203317e531f9160a37aaae644b0", size = 1231985, upload-time = "2022-11-11T13:18:23.9Z" }
+wheels = [
+    { url = "https://files.pythonhosted.org/packages/1c/73/cfd7e631395b036052356517c2c8b8e7917308b4c397694da34260f7eff6/python_solvespace-3.0.8-cp310-cp310-macosx_10_15_x86_64.whl", hash = "sha256:bd3366cda1f3bac7c239c3fad98c6eee97c3d9299ee5c3a1ab3e4ea5e112b81a", size = 386490, upload-time = "2022-11-11T13:19:11.237Z" },
+    { url = "https://files.pythonhosted.org/packages/c7/28/7e8ea55da42cd9e0ab9bdc607f5d57270c553baa9c4dab63866bba7c6e40/python_solvespace-3.0.8-cp310-cp310-win_amd64.whl", hash = "sha256:33c150f68c81addf8045e28ffeb28a828fcbbe9ab84cc4a9f1e50d0847b23bfb", size = 243413, upload-time = "2022-11-11T13:19:03.064Z" },
+    { url = "https://files.pythonhosted.org/packages/e5/6a/3d3f3ffa52b4952a4d63506b20d55e23e5bf34dfd096c185cfd4b262d9a2/python_solvespace-3.0.8-cp311-cp311-macosx_10_9_universal2.whl", hash = "sha256:c899978359d95c274bbcc31405b080517af3839beca98e3342c52a37409bb916", size = 703966, upload-time = "2022-11-11T13:34:03.875Z" },
+    { url = "https://files.pythonhosted.org/packages/b1/4c/0140a197e00be797f3ee26278a9205cccfb668b8c7d7746350bb72bff3c7/python_solvespace-3.0.8-cp311-cp311-win_amd64.whl", hash = "sha256:1191b004298d57936058d9dbdd395c44c1f46d5a9c854e36c507c49c3e6b6382", size = 242810, upload-time = "2022-11-11T13:19:55.656Z" },
+]
+
 [[package]]
 name = "pytokens"
 version = "0.4.1"