- Assembly instaiated operations

- assembly forward proagation

.gitignore

@@ -35,4 +35,42 @@ uv.lock
 # IDE
 .vscode/
 *.swp
-*.swo
+*.swo
+/src/fluency/Tesfiles/bordo_adapter3.fluency
+/CONSTRAINT_STATUS_FINAL.md
+/CONSTRAINT_STATUS_IMPLEMENTATION.md
+/src/fluency/rendering/first.png
+/littlebrother.md
+/src/fluency/Tesfiles/multiboidy.fluency
+/src/fluency/rendering/nromal_test.png
+/package.json
+/package-lock.json
+/src/fluency/Screenshot 2026-06-28 at 17.57.52.png
+/src/fluency/rendering/Screenshot 2026-07-12 at 16.54.14.png
+/src/fluency/Screenshot 2026-07-26 at 20.23.42.png
+/Screenshot 2026-08-05 at 10.14.15.png
+/Screenshot 2026-08-05 at 11.15.33.png
+/Screenshot 2026-08-05 at 11.22.42.png
+/SURFACE_MODIFIER_PLAN.md
+/test.step
+/src/fluency/test333.step
+/src/fluency/tests/test_arc_attached_to_rectangle.py
+/src/fluency/tests/test_array_pattern.py
+/src/fluency/tests/test_chamfer.py
+/src/fluency/tests/test_circle_diameter_constraint.py
+/tests/test_distance_constraint_picking.py
+/tests/test_extrude_geometry.py
+/src/fluency/tests/test_feature_replay.py
+/src/fluency/tests/test_fillet.py
+/tests/test_mirror.py
+/test_modifier.py
+/src/fluency/tests/test_projection_constraints.py
+/tests/test_re_extrude.py
+/scripts/test_render_zoom.py
+/test_thread.py
+/test_thread_hole.step
+/test_thread_m3.step
+/test_thread_m5_hole.step
+/test_thread_shaft.step
+/test_thread_tilted.step
+/src/fluency/testpart.step

.idea/workspace.xml

@@ -4,10 +4,17 @@
     <option name="autoReloadType" value="SELECTIVE" />
   </component>
   <component name="ChangeListManager">
-    <list default="true" id="8f0bafd6-58a0-4b20-aa2b-ddc3ba278873" name="Changes" comment="- Added save file foramt&#10;- Split main.py refactor">
+    <list default="true" id="8f0bafd6-58a0-4b20-aa2b-ddc3ba278873" name="Changes" comment="Fiexed highlighting of operations">
       <change beforePath="$PROJECT_DIR$/.idea/workspace.xml" beforeDir="false" afterPath="$PROJECT_DIR$/.idea/workspace.xml" 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/io/project_io.py" beforeDir="false" afterPath="$PROJECT_DIR$/src/fluency/io/project_io.py" afterDir="false" />
+      <change beforePath="$PROJECT_DIR$/src/fluency/models/data_model.py" beforeDir="false" afterPath="$PROJECT_DIR$/src/fluency/models/data_model.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="$PROJECT_DIR$/src/fluency/ui/main_window.py" beforeDir="false" afterPath="$PROJECT_DIR$/src/fluency/ui/main_window.py" afterDir="false" />
+      <change beforePath="$PROJECT_DIR$/src/fluency/ui/render_window.py" beforeDir="false" afterPath="$PROJECT_DIR$/src/fluency/ui/render_window.py" afterDir="false" />
       <change beforePath="$PROJECT_DIR$/src/fluency/ui/sketch_widget.py" beforeDir="false" afterPath="$PROJECT_DIR$/src/fluency/ui/sketch_widget.py" afterDir="false" />
+      <change beforePath="$PROJECT_DIR$/src/fluency/ui/technical_drawing_widget.py" beforeDir="false" afterPath="$PROJECT_DIR$/src/fluency/ui/technical_drawing_widget.py" afterDir="false" />
+      <change beforePath="$PROJECT_DIR$/src/fluency/ui/viewer_widget.py" beforeDir="false" afterPath="$PROJECT_DIR$/src/fluency/ui/viewer_widget.py" afterDir="false" />
     </list>
     <option name="SHOW_DIALOG" value="false" />
     <option name="HIGHLIGHT_CONFLICTS" value="true" />
@@ -24,7 +31,7 @@
   <component name="Git.Settings">
     <option name="RECENT_BRANCH_BY_REPOSITORY">
       <map>
-        <entry key="$PROJECT_DIR$" value="single_window" />
+        <entry key="$PROJECT_DIR$" value="feature/surface-modifier-pyramid-patterns" />
       </map>
     </option>
     <option name="RECENT_GIT_ROOT_PATH" value="$PROJECT_DIR$" />
@@ -51,18 +58,24 @@
     &quot;Python.Unnamed.executor&quot;: &quot;Run&quot;,
     &quot;Python.base.executor&quot;: &quot;Run&quot;,
     &quot;Python.data_model.executor&quot;: &quot;Run&quot;,
+    &quot;Python.debug_dragging.executor&quot;: &quot;Run&quot;,
     &quot;Python.draw_widget2d.executor&quot;: &quot;Run&quot;,
     &quot;Python.draw_widget_solve.executor&quot;: &quot;Run&quot;,
     &quot;Python.fluency.executor&quot;: &quot;Run&quot;,
     &quot;Python.fluencyb.executor&quot;: &quot;Run&quot;,
     &quot;Python.gl_widget.executor&quot;: &quot;Run&quot;,
+    &quot;Python.gui_ui.executor&quot;: &quot;Run&quot;,
     &quot;Python.kernel.executor&quot;: &quot;Run&quot;,
     &quot;Python.main.executor&quot;: &quot;Run&quot;,
+    &quot;Python.main_window.executor&quot;: &quot;Run&quot;,
     &quot;Python.meshtest.executor&quot;: &quot;Run&quot;,
     &quot;Python.occ_renderer.executor&quot;: &quot;Run&quot;,
+    &quot;Python.occ_to_mesh.executor&quot;: &quot;Run&quot;,
+    &quot;Python.render_backend.executor&quot;: &quot;Run&quot;,
     &quot;Python.side_fluency.executor&quot;: &quot;Run&quot;,
     &quot;Python.simple_mesh.executor&quot;: &quot;Run&quot;,
     &quot;Python.sketch.executor&quot;: &quot;Run&quot;,
+    &quot;Python.technical_drawing_widget.executor&quot;: &quot;Run&quot;,
     &quot;Python.vtk_widget.executor&quot;: &quot;Run&quot;,
     &quot;Python.vulkan.executor&quot;: &quot;Run&quot;,
     &quot;RunOnceActivity.OpenProjectViewOnStart&quot;: &quot;true&quot;,
@@ -89,8 +102,9 @@
     <key name="CopyFile.RECENT_KEYS">
       <recent name="$PROJECT_DIR$/src/fluency" />
       <recent name="$PROJECT_DIR$" />
+      <recent name="$PROJECT_DIR$/src/fluency/Tesfiles" />
+      <recent name="$PROJECT_DIR$/src/fluency/rendering" />
       <recent name="$PROJECT_DIR$/drawing_modules" />
-      <recent name="$PROJECT_DIR$/modules" />
     </key>
     <key name="MoveFile.RECENT_KEYS">
       <recent name="$PROJECT_DIR$" />
@@ -112,54 +126,6 @@
       <option name="presentableId" value="Default" />
       <updated>1703867682707</updated>
     </task>
-    <task id="LOCAL-00001" summary="init">
-      <option name="closed" value="true" />
-      <created>1703951701948</created>
-      <option name="number" value="00001" />
-      <option name="presentableId" value="LOCAL-00001" />
-      <option name="project" value="LOCAL" />
-      <updated>1703951701948</updated>
-    </task>
-    <task id="LOCAL-00002" summary="- Basic oop sketch widget implement">
-      <option name="closed" value="true" />
-      <created>1729958532384</created>
-      <option name="number" value="00002" />
-      <option name="presentableId" value="LOCAL-00002" />
-      <option name="project" value="LOCAL" />
-      <updated>1729958532384</updated>
-    </task>
-    <task id="LOCAL-00003" summary="- Sketch projection partly works again :)">
-      <option name="closed" value="true" />
-      <created>1735563255455</created>
-      <option name="number" value="00003" />
-      <option name="presentableId" value="LOCAL-00003" />
-      <option name="project" value="LOCAL" />
-      <updated>1735563255455</updated>
-    </task>
-    <task id="LOCAL-00004" summary="- Sketch projection partly works again :)">
-      <option name="closed" value="true" />
-      <created>1735585968733</created>
-      <option name="number" value="00004" />
-      <option name="presentableId" value="LOCAL-00004" />
-      <option name="project" value="LOCAL" />
-      <updated>1735585968733</updated>
-    </task>
-    <task id="LOCAL-00005" summary="- Added new componnt controls">
-      <option name="closed" value="true" />
-      <created>1735601610504</created>
-      <option name="number" value="00005" />
-      <option name="presentableId" value="LOCAL-00005" />
-      <option name="project" value="LOCAL" />
-      <updated>1735601610504</updated>
-    </task>
-    <task id="LOCAL-00006" summary="- Added new componnt controls">
-      <option name="closed" value="true" />
-      <created>1735601786207</created>
-      <option name="number" value="00006" />
-      <option name="presentableId" value="LOCAL-00006" />
-      <option name="project" value="LOCAL" />
-      <updated>1735601786207</updated>
-    </task>
     <task id="LOCAL-00007" summary="- changing compos for sketches works">
       <option name="closed" value="true" />
       <created>1735652081552</created>
@@ -344,7 +310,215 @@
       <option name="project" value="LOCAL" />
       <updated>1783282570014</updated>
     </task>
-    <option name="localTasksCounter" value="30" />
+    <task id="LOCAL-00030" summary="- Added save file foramt&#10;- Split main.py refactor">
+      <option name="closed" value="true" />
+      <created>1783453889199</created>
+      <option name="number" value="00030" />
+      <option name="presentableId" value="LOCAL-00030" />
+      <option name="project" value="LOCAL" />
+      <updated>1783453889199</updated>
+    </task>
+    <task id="LOCAL-00031" summary="- Added save file foramt&#10;- Split main.py refactor">
+      <option name="closed" value="true" />
+      <created>1783456842297</created>
+      <option name="number" value="00031" />
+      <option name="presentableId" value="LOCAL-00031" />
+      <option name="project" value="LOCAL" />
+      <updated>1783456842297</updated>
+    </task>
+    <task id="LOCAL-00032" summary="- Added save file foramt&#10;- Split main.py refactor">
+      <option name="closed" value="true" />
+      <created>1783755278516</created>
+      <option name="number" value="00032" />
+      <option name="presentableId" value="LOCAL-00032" />
+      <option name="project" value="LOCAL" />
+      <updated>1783755278516</updated>
+    </task>
+    <task id="LOCAL-00033" summary="- Added save file foramt&#10;- Split main.py refactor">
+      <option name="closed" value="true" />
+      <created>1783777171864</created>
+      <option name="number" value="00033" />
+      <option name="presentableId" value="LOCAL-00033" />
+      <option name="project" value="LOCAL" />
+      <updated>1783777171864</updated>
+    </task>
+    <task id="LOCAL-00034" summary="- Working assembly multi :)">
+      <option name="closed" value="true" />
+      <created>1783798201133</created>
+      <option name="number" value="00034" />
+      <option name="presentableId" value="LOCAL-00034" />
+      <option name="project" value="LOCAL" />
+      <updated>1783798201133</updated>
+    </task>
+    <task id="LOCAL-00035" summary="- Working assembly multi :)">
+      <option name="closed" value="true" />
+      <created>1783798929531</created>
+      <option name="number" value="00035" />
+      <option name="presentableId" value="LOCAL-00035" />
+      <option name="project" value="LOCAL" />
+      <updated>1783798929531</updated>
+    </task>
+    <task id="LOCAL-00036" summary="-  added renderer">
+      <option name="closed" value="true" />
+      <created>1783887682052</created>
+      <option name="number" value="00036" />
+      <option name="presentableId" value="LOCAL-00036" />
+      <option name="project" value="LOCAL" />
+      <updated>1783887682052</updated>
+    </task>
+    <task id="LOCAL-00037" summary="-  added renderer&#10;- Added undo">
+      <option name="closed" value="true" />
+      <created>1783887704766</created>
+      <option name="number" value="00037" />
+      <option name="presentableId" value="LOCAL-00037" />
+      <option name="project" value="LOCAL" />
+      <updated>1783887704766</updated>
+    </task>
+    <task id="LOCAL-00038" summary="-  added renderer&#10;- Added undo">
+      <option name="closed" value="true" />
+      <created>1783891561116</created>
+      <option name="number" value="00038" />
+      <option name="presentableId" value="LOCAL-00038" />
+      <option name="project" value="LOCAL" />
+      <updated>1783891561116</updated>
+    </task>
+    <task id="LOCAL-00039" summary="-  added renderer&#10;- Added undo">
+      <option name="closed" value="true" />
+      <created>1783918463034</created>
+      <option name="number" value="00039" />
+      <option name="presentableId" value="LOCAL-00039" />
+      <option name="project" value="LOCAL" />
+      <updated>1783918463034</updated>
+    </task>
+    <task id="LOCAL-00040" summary="- Render improvements, camera plane, update">
+      <option name="closed" value="true" />
+      <created>1783976498520</created>
+      <option name="number" value="00040" />
+      <option name="presentableId" value="LOCAL-00040" />
+      <option name="project" value="LOCAL" />
+      <updated>1783976498520</updated>
+    </task>
+    <task id="LOCAL-00041" summary="- added &quot;measurement lines&quot;">
+      <option name="closed" value="true" />
+      <created>1785094789247</created>
+      <option name="number" value="00041" />
+      <option name="presentableId" value="LOCAL-00041" />
+      <option name="project" value="LOCAL" />
+      <updated>1785094789248</updated>
+    </task>
+    <task id="LOCAL-00042" summary="- added &quot;measurement lines&quot;">
+      <option name="closed" value="true" />
+      <created>1785697123545</created>
+      <option name="number" value="00042" />
+      <option name="presentableId" value="LOCAL-00042" />
+      <option name="project" value="LOCAL" />
+      <updated>1785697123545</updated>
+    </task>
+    <task id="LOCAL-00043" summary="- arc improvements, fillets, operations, bodys">
+      <option name="closed" value="true" />
+      <created>1785701099363</created>
+      <option name="number" value="00043" />
+      <option name="presentableId" value="LOCAL-00043" />
+      <option name="project" value="LOCAL" />
+      <updated>1785701099363</updated>
+    </task>
+    <task id="LOCAL-00044" summary="- arc improvements, fillets, operations, bodys">
+      <option name="closed" value="true" />
+      <created>1785915859137</created>
+      <option name="number" value="00044" />
+      <option name="presentableId" value="LOCAL-00044" />
+      <option name="project" value="LOCAL" />
+      <updated>1785915859137</updated>
+    </task>
+    <task id="LOCAL-00045" summary="- arc improvements, fillets, operations, bodys">
+      <option name="closed" value="true" />
+      <created>1785941246695</created>
+      <option name="number" value="00045" />
+      <option name="presentableId" value="LOCAL-00045" />
+      <option name="project" value="LOCAL" />
+      <updated>1785941246695</updated>
+    </task>
+    <task id="LOCAL-00046" summary="- arc improvements, fillets, operations, bodys">
+      <option name="closed" value="true" />
+      <created>1785948828454</created>
+      <option name="number" value="00046" />
+      <option name="presentableId" value="LOCAL-00046" />
+      <option name="project" value="LOCAL" />
+      <updated>1785948828454</updated>
+    </task>
+    <task id="LOCAL-00047" summary="- arc improvements, fillets, operations, bodys">
+      <option name="closed" value="true" />
+      <created>1786110295218</created>
+      <option name="number" value="00047" />
+      <option name="presentableId" value="LOCAL-00047" />
+      <option name="project" value="LOCAL" />
+      <updated>1786110295218</updated>
+    </task>
+    <task id="LOCAL-00048" summary="- arc improvements, fillets, operations, bodys">
+      <option name="closed" value="true" />
+      <created>1786125317688</created>
+      <option name="number" value="00048" />
+      <option name="presentableId" value="LOCAL-00048" />
+      <option name="project" value="LOCAL" />
+      <updated>1786125317688</updated>
+    </task>
+    <task id="LOCAL-00049" summary="- Operation highlighting, body highlighting">
+      <option name="closed" value="true" />
+      <created>1786180549405</created>
+      <option name="number" value="00049" />
+      <option name="presentableId" value="LOCAL-00049" />
+      <option name="project" value="LOCAL" />
+      <updated>1786180549405</updated>
+    </task>
+    <task id="LOCAL-00050" summary="- tech draw draft">
+      <option name="closed" value="true" />
+      <created>1786888483687</created>
+      <option name="number" value="00050" />
+      <option name="presentableId" value="LOCAL-00050" />
+      <option name="project" value="LOCAL" />
+      <updated>1786888483688</updated>
+    </task>
+    <task id="LOCAL-00051" summary="- tech draw draft v2">
+      <option name="closed" value="true" />
+      <created>1786910497589</created>
+      <option name="number" value="00051" />
+      <option name="presentableId" value="LOCAL-00051" />
+      <option name="project" value="LOCAL" />
+      <updated>1786910497589</updated>
+    </task>
+    <task id="LOCAL-00052" summary="- tech draw draft v2">
+      <option name="closed" value="true" />
+      <created>1786984519780</created>
+      <option name="number" value="00052" />
+      <option name="presentableId" value="LOCAL-00052" />
+      <option name="project" value="LOCAL" />
+      <updated>1786984519781</updated>
+    </task>
+    <task id="LOCAL-00053" summary="- tech draw draft v2">
+      <option name="closed" value="true" />
+      <created>1786995561375</created>
+      <option name="number" value="00053" />
+      <option name="presentableId" value="LOCAL-00053" />
+      <option name="project" value="LOCAL" />
+      <updated>1786995561376</updated>
+    </task>
+    <task id="LOCAL-00054" summary="- tech drawing and render improv">
+      <option name="closed" value="true" />
+      <created>1787058413911</created>
+      <option name="number" value="00054" />
+      <option name="presentableId" value="LOCAL-00054" />
+      <option name="project" value="LOCAL" />
+      <updated>1787058413911</updated>
+    </task>
+    <task id="LOCAL-00055" summary="Fiexed highlighting of operations">
+      <option name="closed" value="true" />
+      <created>1787091089061</created>
+      <option name="number" value="00055" />
+      <option name="presentableId" value="LOCAL-00055" />
+      <option name="project" value="LOCAL" />
+      <updated>1787091089061</updated>
+    </task>
+    <option name="localTasksCounter" value="56" />
     <servers />
   </component>
   <component name="TypeScriptGeneratedFilesManager">
@@ -365,16 +539,6 @@
     <ignored-roots>
       <path value="$PROJECT_DIR$/pythonProject" />
     </ignored-roots>
-    <MESSAGE value="init" />
-    <MESSAGE value="- Basic oop sketch widget implement" />
-    <MESSAGE value="- Renabled extrusion with new object system" />
-    <MESSAGE value="- Sketch projection partly works again :)" />
-    <MESSAGE value="- Added new componnt controls" />
-    <MESSAGE value="- changing compos for sketches works" />
-    <MESSAGE value="- changing compos including sketches and bodies" />
-    <MESSAGE value="- Drawing bodys depending on the selected compo&#10;- Cut working&#10;- Edit sketch working" />
-    <MESSAGE value="- delete sketch working&#10;- added mid point snap&#10;- added hovering line with distance" />
-    <MESSAGE value="- Added new buttons and settings" />
     <MESSAGE value="- Added construction lines switching&#10;- Moved callbacks into sketchwidget from main.&#10;- Changed reset on right click" />
     <MESSAGE value="- Added contrain displayed next to line&#10;- Slight change to point check from solver." />
     <MESSAGE value="- Added enabling of midpsnap and prepared others&#10;- Show dimesnion on hover" />
@@ -389,6 +553,17 @@
     <MESSAGE value="- UI refinement, button position ui file as source no dirty drafting anymore" />
     <MESSAGE value="- assembly draft" />
     <MESSAGE value="- Added save file foramt&#10;- Split main.py refactor" />
-    <option name="LAST_COMMIT_MESSAGE" value="- Added save file foramt&#10;- Split main.py refactor" />
+    <MESSAGE value="- Working assembly multi :)" />
+    <MESSAGE value="-  added renderer" />
+    <MESSAGE value="-  added renderer&#10;- Added undo" />
+    <MESSAGE value="- Render improvements, camera plane, update" />
+    <MESSAGE value="- added &quot;measurement lines&quot;" />
+    <MESSAGE value="- arc improvements, fillets, operations, bodys" />
+    <MESSAGE value="- Operation highlighting, body highlighting" />
+    <MESSAGE value="- tech draw draft" />
+    <MESSAGE value="- tech draw draft v2" />
+    <MESSAGE value="- tech drawing and render improv" />
+    <MESSAGE value="Fiexed highlighting of operations" />
+    <option name="LAST_COMMIT_MESSAGE" value="Fiexed highlighting of operations" />
   </component>
 </project>

.layout_new.py

@@ -0,0 +1,376 @@
+# ── Sheet layout regions ────────────────────────────────────────────────────
+
+_LAYOUT_MARGIN_MM = 10.0
+_VIEW_GAP_MM = 12.0
+
+# Title block box (see _title_block_primitives): 180 × 52 at the bottom-right
+# corner with a 5 mm sheet margin.  Views must clear it (plus clearance).
+_TB_LEFT_MM = _A3_WIDTH_MM - 180.0 - 5.0
+_TB_TOP_MM = 5.0 + 52.0
+_TB_CLEARANCE_MM = 5.0
+
+# Sheet interior (border margin) as (x0, y0, x1, y1) in sheet mm.
+_SHEET_INNER = (
+    _LAYOUT_MARGIN_MM,
+    _LAYOUT_MARGIN_MM,
+    _A3_WIDTH_MM - _LAYOUT_MARGIN_MM,
+    _A3_HEIGHT_MM - _LAYOUT_MARGIN_MM,
+)
+
+# Regions the orthographic layout may occupy, as (x0, y0, w, h):
+#  - UPPER: full sheet width above the title block
+#  - LEFT:  full sheet height in the left strip beside the title block
+_REGION_UPPER = (
+    _LAYOUT_MARGIN_MM,
+    _TB_TOP_MM + _TB_CLEARANCE_MM,
+    _A3_WIDTH_MM - 2 * _LAYOUT_MARGIN_MM,
+    _A3_HEIGHT_MM - _LAYOUT_MARGIN_MM - (_TB_TOP_MM + _TB_CLEARANCE_MM),
+)
+_REGION_LEFT = (
+    _LAYOUT_MARGIN_MM,
+    _LAYOUT_MARGIN_MM,
+    _TB_LEFT_MM - _TB_CLEARANCE_MM - _LAYOUT_MARGIN_MM,
+    _A3_HEIGHT_MM - 2 * _LAYOUT_MARGIN_MM,
+)
+
+_MID_ORDER = ("left", "front", "right", "back")
+_COL_ORDER = ("top", "front", "bottom")  # sheet top → bottom
+_GRID_ORDER = ("front", "right", "back", "top", "left", "bottom")
+
+_RectList = List[Tuple[str, float, float, float, float]]
+
+
+def _place_cross(
+    dims: Dict[str, Tuple[float, float]], gap: float
+) -> _RectList:
+    """Classic third-angle cross: mid views run left→right (left, front,
+    right, back), col views stack top→bottom (top, front, bottom), with the
+    anchor view (front, or the first present one) at the intersection.
+
+    *dims* maps view id → ``(w, h)`` in sheet units.  Returns local
+    ``(vid, x, y, w, h)`` rects (origin arbitrary — the caller centres the
+    union on the sheet).
+    """
+    mid = [k for k in _MID_ORDER if k in dims]
+    col = [k for k in _COL_ORDER if k in dims]
+    if not mid and not col:
+        return []
+    rects: Dict[str, Tuple[float, float, float, float]] = {}
+
+    if col:
+        # Stack bottom → top.
+        y = 0.0
+        for k in reversed(col):
+            w, h = dims[k]
+            rects[k] = (0.0, y, w, h)
+            y += h + gap
+        col_h = y - gap
+        cx = max(dims[k][0] for k in col) / 2.0
+        for k in col:
+            _x, yy, w, h = rects[k]
+            rects[k] = (cx - w / 2.0, yy, w, h)
+    else:
+        col_h = 0.0
+        cx = 0.0
+
+    anchor = "front" if "front" in dims else (mid[0] if mid else col[0])
+    if anchor in rects:
+        ax, ay, aw, _ah = rects[anchor]
+        anchor_cy = ay + _ah / 2.0
+    else:
+        aw, ah = dims[anchor]
+        ax = cx - aw / 2.0
+        ay = col_h / 2.0 - ah / 2.0
+        rects[anchor] = (ax, ay, aw, ah)
+        anchor_cy = col_h / 2.0
+
+    ia = mid.index(anchor) if anchor in mid else -1
+    x = ax
+    for k in reversed(mid[:ia]):
+        w, h = dims[k]
+        x -= w + gap
+        rects[k] = (x, anchor_cy - h / 2.0, w, h)
+    x = ax + aw
+    for k in mid[ia + 1 :]:
+        w, h = dims[k]
+        x += gap
+        rects[k] = (x, anchor_cy - h / 2.0, w, h)
+        x += w
+    return [(k, *r) for k, r in rects.items()]
+
+
+def _place_swapped(dims: Dict[str, Tuple[float, float]], gap: float) -> _RectList:
+    """Cross with the view families swapped: the mid views stack vertically
+    (left, front, right, back from the top) and the col views run
+    horizontally (bottom, front, top from the left) — the classic cross
+    turned a quarter turn, for sheets where that orientation fits more.
+    """
+    mid = [k for k in _MID_ORDER if k in dims]
+    col = [k for k in _COL_ORDER if k in dims]
+    if not mid or not col:
+        return []
+    rects: Dict[str, Tuple[float, float, float, float]] = {}
+    cx = max(dims[k][0] for k in mid) / 2.0
+    y = 0.0
+    for k in mid:  # top → bottom
+        w, h = dims[k]
+        rects[k] = (cx - w / 2.0, y, w, h)
+        y += h + gap
+    anchor = "front" if "front" in dims else mid[0]
+    anchor_cy = rects[anchor][1] + dims[anchor][1] / 2.0
+
+    row: Dict[str, Tuple[float, float, float, float]] = {}
+    x = 0.0
+    x_anchor = 0.0
+    for k in reversed(col):  # bottom, front, top → left to right
+        w, h = dims[k]
+        if k == anchor:
+            x_anchor = x
+        row[k] = (x, anchor_cy - h / 2.0, w, h)
+        x += w + gap
+    shift = rects[anchor][0] - x_anchor
+    for k, r in row.items():
+        if k == anchor:
+            continue
+        x0, y0, w, h = r
+        rects[k] = (x0 + shift, y0, w, h)
+    return [(k, *r) for k, r in rects.items()]
+
+
+def _place_grid(
+    dims: Dict[str, Tuple[float, float]], gap: float, rows: int
+) -> _RectList:
+    """Wrap the present standard views into a grid of *rows* rows, filled
+    bottom→top and left→right (so the primary views sit near the bottom,
+    like in the cross)."""
+    order = [k for k in _GRID_ORDER if k in dims]
+    if not order:
+        return []
+    cols = max(1, -(-len(order) // rows))
+    rects: _RectList = []
+    y = 0.0
+    for r in range(rows):
+        chunk = order[r * cols : (r + 1) * cols]
+        if not chunk:
+            break
+        x = 0.0
+        row_h = 0.0
+        for k in chunk:
+            w, h = dims[k]
+            rects.append((k, x, y, w, h))
+            x += w + gap
+            row_h = max(row_h, h)
+        y += row_h + gap
+    return rects
+
+
+def _fit_scale(
+    place: Callable[
+        [Dict[str, Tuple[float, float]], float], _RectList
+    ],
+    dims_m: Dict[str, Tuple[float, float]],
+    region: Tuple[float, float, float, float],
+) -> float:
+    """Largest shared scale at which *dims_m* (model units) laid out by
+    *place* fits the ``(x0, y0, w, h)`` *region* of the sheet.
+
+    The union size grows monotonically with the scale, so a bisection
+    converges to the tight fit.
+    """
+    _rx0, _ry0, rw, rh = region
+
+    def fits(s: float) -> bool:
+        rects = place(
+            {k: (w * s, h * s) for k, (w, h) in dims_m.items()}, _VIEW_GAP_MM
+        )
+        if not rects:
+            return True
+        minx = min(r[1] for r in rects)
+        miny = min(r[2] for r in rects)
+        maxx = max(r[1] + r[3] for r in rects)
+        maxy = max(r[2] + r[4] for r in rects)
+        return (maxx - minx) <= rw + 1e-9 and (maxy - miny) <= rh + 1e-9
+
+    s_lo, s_hi = 0.0, 1.0
+    if fits(s_hi):
+        s_lo = s_hi
+        while s_hi < 1.0e6 and fits(s_hi * 2.0):
+            s_hi *= 2.0
+    for _ in range(60):
+        mid = 0.5 * (s_lo + s_hi)
+        if fits(mid):
+            s_lo = mid
+        else:
+            s_hi = mid
+    return s_lo
+
+
+def _free_rects(
+    used_rects: Sequence[Tuple[float, float, float, float]]
+) -> List[Tuple[float, float, float, float]]:
+    """Axis-aligned free rects ``(x0, y0, w, h)`` around *used_rects*,
+    clearing the sheet border and the title block zone."""
+    ix0, iy0, ix1, iy1 = _SHEET_INNER
+    if used_rects:
+        ux0 = min(r[0] for r in used_rects)
+        uy0 = min(r[1] for r in used_rects)
+        ux1 = max(r[0] + r[2] for r in used_rects)
+        uy1 = max(r[1] + r[3] for r in used_rects)
+        cands = [
+            (ux1 + _VIEW_GAP_MM, iy0, ix1, iy1),  # right of the used block
+            (ix0, iy0, ux0 - _VIEW_GAP_MM, iy1),  # left
+            (ix0, uy1 + _VIEW_GAP_MM, ix1, iy1),  # above
+            (ix0, iy0, ix1, uy0 - _VIEW_GAP_MM),  # below
+        ]
+    else:
+        cands = [(ix0, iy0, ix1, iy1)]
+    tb = (
+        _TB_LEFT_MM - _TB_CLEARANCE_MM,
+        0.0,
+        _A3_WIDTH_MM - (_TB_LEFT_MM - _TB_CLEARANCE_MM),
+        _TB_TOP_MM + _TB_CLEARANCE_MM,
+    )
+    out: List[Tuple[float, float, float, float]] = []
+    for x0, y0, x1, y1 in cands:
+        x0, y0 = max(x0, ix0), max(y0, iy0)
+        x1, y1 = min(x1, ix1), min(y1, iy1)
+        if x1 - x0 < 1.0 or y1 - y0 < 1.0:
+            continue
+        if not (x1 <= tb[0] or tb[2] <= x0 or y1 <= tb[1] or tb[3] <= y0):
+            # Overlaps the title block zone — keep the parts above/left of it.
+            subs = [
+                (x0, max(y0, tb[3]), x1, y1),
+                (x0, y0, min(x1, tb[0]), y1),
+            ]
+        else:
+            subs = [(x0, y0, x1, y1)]
+        for sx0, sy0, sx1, sy1 in subs:
+            if sx1 - sx0 > 1.0 and sy1 - sy0 > 1.0:
+                out.append((sx0, sy0, sx1 - sx0, sy1 - sy0))
+    return out
+
+
+def _layout_views_on_sheet(
+    views: Sequence[DrawingView],
+    bboxes: Dict[str, Tuple[float, float, float, float]],
+) -> Tuple[
+    Dict[str, Tuple[float, float, float, float]],
+    Optional[float],
+    Dict[str, float],
+]:
+    """Compute a slot rectangle and sheet rotation for each view.
+
+    *bboxes* maps view_id → ``(min_x, min_y, max_x, max_y)`` in model
+    units (from :func:`_edges_bounds`).  Returns ``(slots, common_scale,
+    rotations)``: slots are ``(left, bottom, width, height)`` in sheet mm
+    (origin at the sheet's bottom-left corner, +y up), common_scale is the
+    shared model→sheet scale of the standard orthographic views, and
+    rotations maps view_id → sheet rotation in degrees (0 or 90).
+
+    The sheet is filled, not just used: every candidate arrangement
+    (classic third-angle cross, the cross with the view families swapped,
+    and 1/2/3-row grids) is combined with every per-view 90° rotation
+    assignment, and the candidate giving the largest shared scale is used.
+    Candidates within 0.5% of the best scale prefer the one with fewer
+    rotated views, then the more conventional arrangement, so layouts stay
+    stable and standard whenever they are already the best fit.  All
+    orthographic views share one scale so the projections stay mutually
+    consistent.  Isometric and custom views take the largest remaining
+    free rect (clearing the title block).
+    """
+    slots: Dict[str, Tuple[float, float, float, float]] = {}
+    rotations: Dict[str, float] = {}
+    common_scale: Optional[float] = None
+
+    ortho = [
+        v for v in views if v.kind in _STANDARD_VIEWS and v.kind != "isometric"
+    ]
+
+    used_rects: List[Tuple[float, float, float, float]] = []
+    if ortho:
+        dims0: Dict[str, Tuple[float, float]] = {}
+        for v in ortho:
+            b = bboxes.get(v.kind)
+            vs = max(v.scale, 1e-9)
+            if b is None:
+                dims0[v.kind] = (1.0 * vs, 1.0 * vs)
+            else:
+                dims0[v.kind] = (
+                    max(b[2] - b[0], 1e-6) * vs,
+                    max(b[3] - b[1], 1e-6) * vs,
+                )
+        keys = list(dims0)
+        arrangements: Tuple[
+            Tuple[str, int, Callable[[Dict[str, Tuple[float, float]], float], _RectList]]
+        ] = (
+            ("cross", 0, _place_cross),
+            ("swapped", 1, _place_swapped),
+            ("grid1", 2, lambda d, g: _place_grid(d, g, 1)),
+            ("grid2", 3, lambda d, g: _place_grid(d, g, 2)),
+            ("grid3", 4, lambda d, g: _place_grid(d, g, 3)),
+        )
+        cands: List[
+            Tuple[float, int, int, Tuple[float, float, float, float],
+                  Dict[str, Tuple[float, float]],
+                  Callable[[Dict[str, Tuple[float, float]], float], _RectList],
+                  List[bool]]
+        ] = []
+        for mask in range(1 << len(keys)):
+            rotated = [bool(mask & (1 << i)) for i in range(len(keys))]
+            dims_m = {
+                k: (
+                    dims0[k][1] if rotated[i] else dims0[k][0],
+                    dims0[k][0] if rotated[i] else dims0[k][1],
+                )
+                for i, k in enumerate(keys)
+            }
+            for _name, rank, place in arrangements:
+                s_up = _fit_scale(place, dims_m, _REGION_UPPER)
+                s_left = _fit_scale(place, dims_m, _REGION_LEFT)
+                if s_up >= s_left:
+                    s, region = s_up, _REGION_UPPER
+                else:
+                    s, region = s_left, _REGION_LEFT
+                if s <= 0.0:
+                    continue
+                cands.append((s, sum(rotated), rank, region, dims_m, place, rotated))
+        if cands:
+            best_s = max(c[0] for c in cands)
+            s, _nrot, _rank, region, dims_m, place, rotated = min(
+                (c for c in cands if c[0] >= best_s * 0.995),
+                key=lambda c: (c[1], c[2], -c[0]),
+            )
+            rx0, _ry0, rw, rh = region
+            ds = {k: (w * s, h * s) for k, (w, h) in dims_m.items()}
+            rects = place(ds, _VIEW_GAP_MM)
+            minx = min(r[1] for r in rects)
+            miny = min(r[2] for r in rects)
+            maxx = max(r[1] + r[3] for r in rects)
+            maxy = max(r[2] + r[4] for r in rects)
+            ox = rx0 + (rw - (maxx - minx)) / 2.0
+            oy = _ry0 + (rh - (maxy - miny)) / 2.0
+            for vid, x, y, w, h in rects:
+                slots[vid] = (x - minx + ox, y - miny + oy, w, h)
+                rotations[vid] = 90.0 if rotated[keys.index(vid)] else 0.0
+            common_scale = s
+            used_rects = [(ox, oy, maxx - minx, maxy - miny)]
+
+    # Isometric and custom views: the largest remaining free rect each,
+    # clearing the title block.
+    extra = [
+        v for v in views
+        if v.kind == "isometric" or v.kind not in _STANDARD_VIEWS
+    ]
+    assigned = list(used_rects)
+    for i, v in enumerate(extra):
+        vid = v.kind if v.kind in _STANDARD_VIEWS else (v.name or v.id)
+        free = _free_rects(assigned)
+        if free:
+            slot = max(free, key=lambda r: r[2] * r[3])
+        else:
+            # No free rect left — park in the bottom-left corner stack.
+            slot = (_LAYOUT_MARGIN_MM, _LAYOUT_MARGIN_MM + i * 60.0, 120.0, 50.0)
+        slots[vid] = slot
+        assigned.append(slot)
+
+    return slots, common_scale, rotations

.render_check.py

@@ -0,0 +1,50 @@
+import os, sys
+os.environ["QT_QPA_PLATFORM"] = "offscreen"
+sys.path.insert(0, "/Volumes/Data_drive/Programming/fluency/src")
+
+from PySide6.QtWidgets import QApplication
+from PySide6.QtGui import QPixmap, QPainter, QColor
+from PySide6.QtCore import QRectF
+import math
+
+app = QApplication.instance() or QApplication([])
+
+from fluency.geometry.base import Point2D
+from fluency.geometry_occ.kernel import OCGeometryKernel
+from fluency.models.data_model import Body, Component, Project, DrawingView, TechnicalDrawing
+from fluency.technical_drawing import generate_drawing, render_drawing, _A3_WIDTH_MM, _A3_HEIGHT_MM
+
+kernel = OCGeometryKernel()
+# Long thin bar: 120 x 25 x 30 (matches the "wide bar" screenshot case).
+points = [Point2D(0, 0), Point2D(120, 0), Point2D(120, 25), Point2D(0, 25)]
+box = kernel.extrude(kernel.create_polygon(points), 30.0)
+body = Body(name="Bar", geometry=box)
+comp = Component(name="BarComp")
+comp.bodies[body.id] = body
+project = Project()
+project.components[comp.id] = comp
+project.active_component = comp.id
+
+W = 2400
+H = int(W * _A3_HEIGHT_MM / _A3_WIDTH_MM)
+pm = QPixmap(W, H)
+pm.fill(QColor(255, 255, 255))
+
+for name, kinds in [
+    ("four", ["front", "top", "right", "back"]),
+    ("six", ["front", "top", "right", "left", "back", "bottom"]),
+    ("sixiso", ["front", "top", "right", "left", "back", "bottom", "isometric"]),
+]:
+    drawing = TechnicalDrawing(
+        source_kind="component", source_id=comp.id,
+        views=[DrawingView(kind=k) for k in kinds],
+        auto_dimensions=True, title=name,
+    )
+    result = generate_drawing(drawing, project, kernel)
+    p = QPainter(pm)
+    render_drawing(p, result, QRectF(0, 0, W, H))
+    p.end()
+    out = f"/tmp/drawing_{name}.png"
+    pm.save(out)
+    print(name, "saved", out, "prims", len(result.primitives), "scale",
+          round(result.view_transforms.get("front", (None,))[0] or 0, 3))

.smoke_layout.py

@@ -0,0 +1,159 @@
+"""Smoke test: layout optimizer fills the page, no overlaps, title block clear."""
+import math
+import os
+import sys
+
+os.environ.setdefault("QT_QPA_PLATFORM", "offscreen")
+sys.path.insert(0, "/Volumes/Data_drive/Programming/fluency/src")
+
+from fluency.models.data_model import DrawingView
+from fluency.technical_drawing import (
+    _layout_views_on_sheet,
+    build_manual_candidates,
+)
+
+A3W, A3H = 420.0, 297.0
+TB = (235.0, 0.0, 420.0, 62.0)  # title block zone incl. clearance
+
+
+def b(x, y, w, h):
+    return (x, y, x + w, y + h)
+
+
+def overlaps(r1, r2, clear=0.0):
+    x0, y0, w, h = r1
+    x1, y1, w2, h2 = r2
+    return not (x0 + w <= x1 + clear or x1 + w2 <= x0 + clear
+                or y0 + h <= y1 + clear or y1 + h2 <= y0 + clear)
+
+
+def tb_overlap(r, clear=5.0):
+    x0, y0, w, h = r
+    x1, y1, w2, h2 = TB
+    return not (x0 + w <= x1 + clear or x1 + w2 <= x0 + clear
+                or y0 + h <= y1 + clear or y1 + h2 <= y0 + clear)
+
+
+def union_rect(rects):
+    x0 = min(r[0] for r in rects)
+    y0 = min(r[1] for r in rects)
+    x1 = max(r[0] + r[2] for r in rects)
+    y1 = max(r[1] + r[3] for r in rects)
+    return (x0, y0, x1 - x0, y1 - y0)
+
+
+def check(name, kinds, boxes, expect_rot=None):
+    views = [DrawingView(kind=k) for k in kinds]
+    bboxes = {k: boxes[k] for k in kinds}
+    slots, scale, rots = _layout_views_on_sheet(views, bboxes)
+    print(f"--- {name}: scale={scale:.4f} rots={rots}")
+    # all slots within sheet
+    for k, s in slots.items():
+        assert 10 - 1e-6 <= s[0] and 10 - 1e-6 <= s[1], f"{k} outside sheet {s}"
+        assert s[0] + s[2] <= A3W - 10 + 1e-6, f"{k} beyond right {s}"
+        assert s[1] + s[3] <= A3H - 10 + 1e-6, f"{k} beyond top {s}"
+    # no overlaps between slots
+    ks = list(slots)
+    for i in range(len(ks)):
+        for j in range(i + 1, len(ks)):
+            assert not overlaps(slots[ks[i]], slots[ks[j]], 11.9), \
+                f"{ks[i]} overlaps {ks[j]}: {slots[ks[i]]} / {slots[ks[j]]}"
+    # title block clear
+    for k, s in slots.items():
+        assert not tb_overlap(s), f"{k} intrudes title block {s}"
+    # fill report
+    u = union_rect(list(slots.values()))
+    area = u[2] * u[3]
+    print(f"    union: x0={u[0]:.1f} y0={u[1]:.1f} w={u[2]:.1f} h={u[3]:.1f} "
+          f"area={area:.0f}mm^2 ({100*area/(A3W*A3H):.0f}% of sheet)")
+    for k in ks:
+        print(f"    {k}: {tuple(round(v,1) for v in slots[k])}")
+    if expect_rot is not None:
+        assert rots == expect_rot, f"expected {expect_rot}, got {rots}"
+    return slots, scale, rots
+
+
+# 1. Two square views (front+top): should fill the page, no rotation.
+check("two square", ["front", "top"],
+      {"front": b(0, 0, 40, 40), "top": b(0, 0, 40, 20)})
+
+# 2. Wide bar, 4 views (old screenshot case): front+back wide, top+right.
+check("wide bar 4", ["front", "top", "right", "back"],
+      {"front": b(0, 0, 120, 25), "top": b(0, 0, 25, 40),
+       "right": b(0, 0, 25, 40), "back": b(0, 0, 120, 25)})
+
+# 3. Six views of a long thin part: rotation should kick in.
+check("thin part 6", ["front", "top", "right", "left", "back", "bottom"],
+      {"front": b(0, 0, 200, 30), "top": b(0, 0, 30, 50),
+       "right": b(0, 0, 50, 30), "left": b(0, 0, 50, 30),
+       "back": b(0, 0, 200, 30), "bottom": b(0, 0, 30, 50)})
+
+# 4. Single front view: fills the whole page.
+check("single", ["front"], {"front": b(0, 0, 10, 20)})
+
+# 5. All 6 + isometric + custom.
+check("everything",
+      ["front", "top", "right", "left", "back", "bottom", "isometric"],
+      {"front": b(0, 0, 80, 40), "top": b(0, 0, 80, 30),
+       "right": b(0, 0, 30, 40), "left": b(0, 0, 30, 40),
+       "back": b(0, 0, 80, 40), "bottom": b(0, 0, 80, 30),
+       "isometric": b(0, 0, 60, 60)})
+
+# ── Inverse-transform roundtrip ─────────────────────────────────────────
+# A 90°-rotated view: forward via _assemble_view's recorded 6-tuple,
+# inverse via the widget's formula.
+t = (2.0, 150.0, 80.0, 90.0, 10.0, 5.0)  # s, o_x, o_y, deg, cx, cy
+scale, ox, oy, deg, cx, cy = t
+th = math.radians(deg)
+cos_t, sin_t = math.cos(th), math.sin(th)
+
+
+def fwd(p):
+    dx, dy = p[0] - cx, p[1] - cy
+    return ((dx * cos_t - dy * sin_t) * scale + ox,
+            (dx * sin_t + dy * cos_t) * scale + oy)
+
+
+def inv(p):
+    sx, sy = (p[0] - ox) / scale, (p[1] - oy) / scale
+    return (sx * cos_t + sy * sin_t + cx, -sx * sin_t + sy * cos_t + cy)
+
+
+for p in [(0, 0), (10, 5), (3, -7), (42.5, 11.25)]:
+    rt = inv(fwd(p))
+    assert abs(rt[0] - p[0]) < 1e-9 and abs(rt[1] - p[1]) < 1e-9, (p, rt)
+print("inverse roundtrip OK")
+
+# Legacy 3-tuple still works through build_manual_candidates.
+from fluency.models.data_model import DrawingAnnotation, TechnicalDrawing
+d = TechnicalDrawing(source_kind="component", source_id="c")
+ann = DrawingAnnotation(kind="dimension", dimension_kind="length",
+                        view_id="front", anchors=[(0.0, 0.0), (0.0, 12.5)],
+                        direction=(0.0, 1.0))
+d.annotations.append(ann)
+cands, res, unres = build_manual_candidates(d, {"front": (2.0, 10.0, 20.0)})
+assert unres == [] and cands[0].anchor_points[1] == (10.0, 45.0)
+print("legacy 3-tuple OK")
+
+# 6-tuple manual: rotated length direction must rotate too.
+ann2 = DrawingAnnotation(kind="dimension", dimension_kind="length",
+                         view_id="front",
+                         anchors=[(0.0, 0.0), (0.0, 10.0)],
+                         direction=(0.0, 1.0))
+d2 = TechnicalDrawing(source_kind="component", source_id="c")
+d2.annotations.append(ann2)
+# 90° rotation about centre c=(5,5), scale 2, o=(100,80)
+cands, res, unres = build_manual_candidates(
+    d2, {"front": (2.0, 100.0, 80.0, 90.0, 5.0, 5.0)}
+)
+c = cands[0]
+# anchors: (0,0)->rot90 about (5,5) = (5-(0-5)*0 - ... compute: dx=-5,dy=-5
+# fwd: (dx*cos - dy*sin)*2+100 = (0 - (-5))*2+100 = 110 ; (dx*sin+dy*cos)*2+80 = (-5)*2+80=70
+# (0,10): dx=-5, dy=5 -> (0-5)*2+100=90 ; (−5*1+0)*2+80=70
+assert c.anchor_points[0] == (110.0, 70.0), c.anchor_points
+assert c.anchor_points[1] == (90.0, 70.0), c.anchor_points
+# direction (0,1) rotated 90° CCW -> (-1, 0)
+assert c.direction[0] == -1.0 and abs(c.direction[1]) < 1e-9, c.direction
+print("6-tuple manual (rotated) OK")
+
+print("ALL SMOKE CHECKS PASSED")

.test_connector_relocate.py

@@ -0,0 +1,238 @@
+"""Headless test: connectors follow moved features across ALL assemblies.
+
+Simulates the test-file scenario: a plate with a hole, mated hole-to-face
+in two different assemblies.  The hole is moved (rebuilt geometry) and the
+body-update connector recalculation must:
+  1. re-locate the hole connector on every instance of the component
+     (both the active and a non-active assembly),
+  2. re-solve each mated pair so the partner parts follow,
+  3. never snap a planar connector onto the cylindrical hole (type match),
+  4. mark a connector invalid when its feature disappears.
+  5. auto-follow a FAR move when the candidate is unambiguous (single
+     feature of its class) — the demo case,
+  6. NOT auto-apply an ambiguous far candidate (another same-class feature
+     is nearer) — that needs a manual pick, simulated here.
+  7. backfill legacy connectors' entity_type from their auto-generated name.
+"""
+
+import os
+import sys
+
+os.environ.setdefault("QT_QPA_PLATFORM", "offscreen")
+sys.path.insert(0, os.path.join(os.path.dirname(__file__), "src"))
+
+import numpy as np
+
+from OCP.gp import gp_Pnt, gp_Dir, gp_Ax2
+from OCP.BRepPrimAPI import BRepPrimAPI_MakeBox, BRepPrimAPI_MakeCylinder
+from OCP.BRepAlgoAPI import BRepAlgoAPI_Cut
+
+from PySide6.QtWidgets import QApplication
+
+from fluency.ui.main_window import MainWindow
+from fluency.models.data_model import Assembly, Body
+from fluency.geometry_occ.kernel import OCCGeometryObject
+
+app = QApplication.instance() or QApplication([])
+w = MainWindow()
+
+comp = w._current_component
+
+
+def make_plate(hole_xy):
+    box = BRepPrimAPI_MakeBox(60.0, 40.0, 5.0).Shape()
+    ax = gp_Ax2(gp_Pnt(float(hole_xy[0]), float(hole_xy[1]), 0.0), gp_Dir(0, 0, 1))
+    cyl = BRepPrimAPI_MakeCylinder(ax, 3.0, 6.0).Shape()
+    return BRepAlgoAPI_Cut(box, cyl).Shape()
+
+
+body = Body(name="plate")
+comp.bodies[body.id] = body
+body.geometry = OCCGeometryObject(make_plate((10.0, 5.0)))
+
+partner = w._project.add_component()
+pbody = Body(name="partner")
+partner.bodies[pbody.id] = pbody
+pbody.geometry = OCCGeometryObject(BRepPrimAPI_MakeBox(30.0, 30.0, 10.0).Shape())
+
+
+def make_pair(asm):
+    ac1 = asm.add_component_instance(comp.id, name="A")
+    ac2 = asm.add_component_instance(partner.id, name="B")
+    ac1.position = np.zeros(3)
+    ac1.rotation = np.eye(3)
+    ac2.position = np.array([0.0, 0.0, 15.0])
+    ac2.rotation = np.eye(3)
+    ac1.geom_cache[body.id] = body.geometry
+
+    c1 = ac1.add_connector(
+        position=(10.0, 5.0, 2.5),
+        normal=(0.0, 0.0, 1.0),
+        x_dir=(1.0, 0.0, 0.0),
+        source_obj_id=f"asm_{ac1.id}_{body.id}",
+        name="Conn hole A",
+        entity_type="cylindrical_face",
+    )
+    c2 = ac2.add_connector(
+        position=(15.0, 15.0, 0.0),
+        normal=(0.0, 0.0, -1.0),
+        x_dir=(1.0, 0.0, 0.0),
+        source_obj_id=f"asm_{ac2.id}_{pbody.id}",
+        name="Conn face B",
+        entity_type="planar_face",
+    )
+    c1.is_grounded = True
+    c1.partner_ac_id = ac2.id
+    c1.partner_connector_id = c2.id
+    c2.partner_ac_id = ac1.id
+    c2.partner_connector_id = c1.id
+    aconn = asm.add_connection(ac1.id, ac2.id)
+    aconn.first_connector_id = c1.id
+    aconn.second_connector_id = c2.id
+    return ac1, ac2, c1, c2, aconn
+
+
+asm1 = w._project.get_active_assembly()
+asm2 = w._project.add_assembly(Assembly(name="second"))
+pair1 = make_pair(asm1)
+pair2 = make_pair(asm2)
+assert w._project.active_assembly == asm1.id  # asm2 is the NON-active one
+
+# ── Move the hole: rebuild the plate with the hole at (25, 12) ──────────
+new_geom = OCCGeometryObject(make_plate((25.0, 12.0)))
+body.geometry = new_geom
+for asm in (asm1, asm2):
+    for ac in asm.components.values():
+        if ac.component_id == comp.id:
+            ac.geom_cache[body.id] = new_geom
+
+# ── The body-update auto path ───────────────────────────────────────────
+w._recalculate_connectors()
+
+for (ac1, ac2, c1, c2, aconn), label in ((pair1, "asm1"), (pair2, "asm2")):
+    # The hole connector followed the hole on every instance.
+    assert np.allclose(c1.position, (25.0, 12.0, 2.5), atol=1e-6), (label, c1.position)
+    # The mated pair re-aligned: both world connectors coincide.
+    w1 = ac1.position + ac1.rotation @ np.asarray(c1.position)
+    w2 = ac2.position + ac2.rotation @ np.asarray(c2.position)
+    assert np.allclose(w1, w2, atol=1e-6), (label, w1, w2)
+    print(f"{label}: connector at {np.round(c1.position, 3)}, "
+          f"partner moved to {np.round(ac2.position, 3)}")
+
+# ── The 'Upd' button path: move the hole again, re-run the handler ─────
+w._refresh_connection_list()
+w._connection_list.setCurrentRow(0)  # active assembly = asm1
+geom3 = OCCGeometryObject(make_plate((35.0, 20.0)))
+body.geometry = geom3
+for ac in asm1.components.values():
+    if ac.component_id == comp.id:
+        ac.geom_cache[body.id] = geom3
+w._on_update_connection_from_list()
+ac1, ac2, c1, c2, aconn = pair1
+assert np.allclose(c1.position, (35.0, 20.0, 2.5), atol=1e-6), c1.position
+w1 = ac1.position + ac1.rotation @ np.asarray(c1.position)
+w2 = ac2.position + ac2.rotation @ np.asarray(c2.position)
+assert np.allclose(w1, w2, atol=1e-6), (w1, w2)
+print("Upd button: connector at", np.round(c1.position, 3),
+      "partner at", np.round(ac2.position, 3))
+
+# ── Type matching: a planar connector must not snap onto the hole ───────
+ac1 = pair1[0]
+c3 = ac1.add_connector(
+    position=(30.0, 20.0, 5.0),
+    normal=(0.0, 0.0, 1.0),
+    x_dir=(1.0, 0.0, 0.0),
+    source_obj_id=f"asm_{ac1.id}_{body.id}",
+    name="Conn face",
+    entity_type="planar_face",
+)
+res = w._redetect_connector_on_geometry(c3, ac1, comp)
+assert res is not None, "planar connector candidate missing"
+assert not c3.is_invalid, "pure relocator must not mutate the connector"
+assert np.allclose(c3.position, (30.0, 20.0, 5.0), atol=1e-6), c3.position
+assert np.allclose(res[1], (30.0, 20.0, 5.0), atol=1e-6), res[1]
+print("planar connector stayed on the face:", np.round(res[1], 3))
+
+# ── Feature removed: relocator finds nothing; auto path marks invalid ──
+plain = OCCGeometryObject(BRepPrimAPI_MakeBox(60.0, 40.0, 5.0).Shape())
+body.geometry = plain
+ac1.geom_cache[body.id] = plain
+res = w._redetect_connector_on_geometry(pair1[2], ac1, comp)
+assert res is None, "hole connector should find no candidate on a plain box"
+w._recalculate_connectors()
+assert pair1[2].is_invalid, "auto path must mark the connector invalid"
+print("removed feature -> connector marked invalid")
+
+# ── Far move with a decoy: ambiguous candidate is NOT auto-applied ─────
+# The real hole moved to (25, 12) — ~12.8mm from the stored (35, 20) — but
+# a SECOND hole now sits at (28, 16), only ~8mm away.  The nearest
+# candidate is ambiguous (different feature), so the auto path must leave
+# the connector alone and queue it for a manual pick.
+def make_plate2(holes):
+    box = BRepPrimAPI_MakeBox(60.0, 40.0, 5.0).Shape()
+    for hx, hy in holes:
+        ax = gp_Ax2(gp_Pnt(hx, hy, 0.0), gp_Dir(0, 0, 1))
+        box = BRepAlgoAPI_Cut(box, BRepPrimAPI_MakeCylinder(ax, 3.0, 6.0).Shape()).Shape()
+    return box
+# ── Stage 1: the user's demo — a SINGLE hole moved far away ─────────────
+# 12.8mm from the stored position, but the only cylindrical face on the
+# body → unambiguous → must be auto-applied (and the mate re-solved).
+geom4 = OCCGeometryObject(make_plate2([(25.0, 12.0)]))
+body.geometry = geom4
+for asm in (asm1, asm2):
+    for ac in asm.components.values():
+        if ac.component_id == comp.id:
+            ac.geom_cache[body.id] = geom4
+w._recalculate_connectors()
+assert np.allclose(pair1[2].position, (25.0, 12.0, 2.5), atol=1e-6), \
+    "unique far candidate must be auto-applied (the demo case)"
+assert not pair1[2].is_invalid
+w1 = ac1.position + ac1.rotation @ np.asarray(pair1[2].position)
+w2 = pair1[1].position + pair1[1].rotation @ np.asarray(pair1[3].position)
+assert np.allclose(w1, w2, atol=1e-6), (w1, w2)
+print("single far hole: auto-followed to", np.round(pair1[2].position, 3))
+
+# ── Stage 2: far move with a decoy — ambiguous, NOT auto-applied ───────
+# The real hole now sits at (32, 20) — 10.6mm from the stored (25, 12) —
+# while a decoy hole at (21, 7) is only 6.4mm away.  The nearest
+# candidate is likely a DIFFERENT feature, so the auto path must leave
+# the connector alone and queue it for a manual pick.
+geom5 = OCCGeometryObject(make_plate2([(32.0, 20.0), (21.0, 7.0)]))
+body.geometry = geom5
+for asm in (asm1, asm2):
+    for ac in asm.components.values():
+        if ac.component_id == comp.id:
+            ac.geom_cache[body.id] = geom5
+w._recalculate_connectors()
+assert np.allclose(pair1[2].position, (25.0, 12.0, 2.5), atol=1e-6), \
+    "ambiguous far candidate must not be auto-applied"
+assert not pair1[2].is_invalid, "ambiguous candidate is not a missing feature"
+
+# Simulate the user clicking the REAL hole in the relocate pick flow:
+w._relocate_pending = [(asm1, ac1, pair1[2])]
+w._on_relocate_picked(
+    (32.0, 20.0, 2.5), (0.0, 0.0, 1.0), (1.0, 0.0, 0.0),
+    "cylindrical_face", f"asm_{ac1.id}_{body.id}",
+)
+assert np.allclose(pair1[2].position, (32.0, 20.0, 2.5), atol=1e-6), pair1[2].position
+assert not pair1[2].is_invalid, "manual pick must re-validate the connector"
+assert w._relocate_pending is None, "pending queue must drain after the pick"
+w1 = ac1.position + ac1.rotation @ np.asarray(pair1[2].position)
+w2 = pair1[1].position + pair1[1].rotation @ np.asarray(pair1[3].position)
+assert np.allclose(w1, w2, atol=1e-6), (w1, w2)
+print("far move: manual pick re-homed connector at", np.round(pair1[2].position, 3),
+      "partner at", np.round(pair1[1].position, 3))
+
+# ── Legacy backfill: empty entity_type recovered from the auto name ────
+from fluency.models.data_model import Connector
+legacy = Connector(
+    name="Conn cylindrical_face anchor",
+    position=(32.0, 20.0, 2.5),
+    source_obj_id=f"asm_{ac1.id}_{body.id}",
+)
+assert legacy.entity_type == "cylindrical_face", legacy.entity_type
+res = w._redetect_connector_on_geometry(legacy, ac1, comp)
+assert res is not None and res[0] < 1e-3, res
+print("legacy name backfill: entity_type =", legacy.entity_type)
+
+print("CONNECTOR_RELOCATE_OK")

.test_demo_repro.py

@@ -0,0 +1,158 @@
+"""Headless repro: load assemblytest.fluency, compare sketch circle centers
+vs. saved body hole axes vs. connector positions, then run the real
+body-update path and check where connectors land.
+"""
+
+import os
+import sys
+
+os.environ.setdefault("QT_QPA_PLATFORM", "offscreen")
+sys.path.insert(0, os.path.join(os.path.dirname(__file__), "src"))
+
+import numpy as np
+
+from OCP.BRepAdaptor import BRepAdaptor_Surface
+from OCP.GeomAbs import GeomAbs_Cylinder
+from OCP.TopAbs import TopAbs_FACE
+from OCP.TopExp import TopExp_Explorer
+from OCP.TopoDS import TopoDS
+
+from PySide6.QtWidgets import QApplication
+
+from fluency.ui.main_window import MainWindow
+
+def etype(e):
+    if isinstance(e, dict):
+        return e.get("type")
+    return getattr(e, "entity_type", None) or getattr(e, "type", None)
+
+def egeom(e):
+    if isinstance(e, dict):
+        return e.get("geometry")
+    return getattr(e, "geometry", None)
+
+app = QApplication.instance() or QApplication([])
+w = MainWindow()
+
+path = os.path.join(os.path.dirname(__file__), "assemblytest.fluency")
+ok = w._open_project_file(path)
+assert ok, "failed to open demo file"
+
+proj = w._project
+
+for comp in proj.components.values():
+    print(f"=== {comp.name} ({comp.id})")
+    for sk in comp.sketches.values():
+        occ = sk.occ_sketch
+        if occ is None:
+            print("  sketch with no occ_sketch:", sk.id)
+            continue
+        for e in occ._entities.values():
+            t = etype(e)
+            if t == "circle":
+                g = egeom(e)
+                cid = e.get("id") if isinstance(e, dict) else e.id
+                print(f"  circle id={cid} center=({g[0][0]!r}, {g[0][1]!r}) r={g[1]!r}")
+    for body in comp.bodies.values():
+        if not body.geometry:
+            print(f"  body {body.name}: no geometry")
+            continue
+        shape = w._kernel._get_shape(body.geometry)
+        print(f"  body {body.name}: extrude len={body.extrude_length}")
+        expl = TopExp_Explorer(shape, TopAbs_FACE)
+        while expl.More():
+            face = TopoDS.Face_s(expl.Current())
+            try:
+                adaptor = BRepAdaptor_Surface(face)
+                if adaptor.GetType() == GeomAbs_Cylinder:
+                    cyl = adaptor.Cylinder()
+                    loc = cyl.Location()
+                    d = cyl.Axis().Direction()
+                    print(
+                        f"    cyl axis at ({loc.X()!r}, {loc.Y()!r}) "
+                        f"dir=({d.X():.4f},{d.Y():.4f},{d.Z():.4f})"
+                    )
+            except Exception:
+                pass
+            expl.Next()
+
+asm = proj.get_active_assembly()
+print("=== active assembly:", asm.name)
+for ac in asm.components.values():
+    comp = proj.get_component_by_id(ac.component_id)
+    print(f"  instance '{ac.name}' -> {comp.name}, pos={np.round(ac.position, 4)}")
+    for conn in ac.connectors.values():
+        print(
+            f"    conn '{conn.name}' pos={np.round(conn.position, 6)} "
+            f"normal={np.round(conn.normal, 3)} et={conn.entity_type!r} "
+            f"invalid={conn.is_invalid}"
+        )
+
+# ── Run the real update path: rebuild bodies from sketch, recalc connectors ──
+# Activate the component with the holes (Component 1).
+comp1 = None
+for comp in proj.components.values():
+    if any(
+        etype(e) == "circle"
+        for sk in comp.sketches.values()
+        for e in (sk.occ_sketch._entities.values() if sk.occ_sketch else [])
+    ):
+        comp1 = comp
+        break
+assert comp1 is not None
+w._current_component = comp1
+print("=== running _update_bodies_from_sketch()")
+w._update_bodies_from_sketch()
+print("=== running _recalculate_connectors()")
+w._recalculate_connectors()
+
+print("=== after update")
+for comp in proj.components.values():
+    for body in comp.bodies.values():
+        if not body.geometry:
+            continue
+        shape = w._kernel._get_shape(body.geometry)
+        expl = TopExp_Explorer(shape, TopAbs_FACE)
+        axes = []
+        while expl.More():
+            face = TopoDS.Face_s(expl.Current())
+            try:
+                adaptor = BRepAdaptor_Surface(face)
+                if adaptor.GetType() == GeomAbs_Cylinder:
+                    loc = adaptor.Cylinder().Location()
+                    axes.append((round(loc.X(), 9), round(loc.Y(), 9)))
+            except Exception:
+                pass
+            expl.Next()
+        print(f"  {comp.name} body axes: {axes}")
+    for sk in comp.sketches.values():
+        for e in sk.occ_sketch._entities.values():
+            t = etype(e)
+            if t == "circle":
+                g = egeom(e)
+                print(f"  {comp.name} circle: ({g[0][0]!r}, {g[0][1]!r})")
+
+asm = proj.get_active_assembly()
+for ac in asm.components.values():
+    for conn in ac.connectors.values():
+        print(
+            f"    conn '{conn.name}' pos={np.round(conn.position, 6)} "
+            f"invalid={conn.is_invalid}"
+        )
+
+# Partner alignment check: for each connection, world positions of the pair.
+for aconn in asm.connections:
+    a1 = asm.components.get(aconn.first_ac_id)
+    a2 = asm.components.get(aconn.second_ac_id)
+    c1 = a1.connectors.get(aconn.first_connector_id)
+    c2 = a2.connectors.get(aconn.second_connector_id)
+    if c1 is None or c2 is None:
+        continue
+    w1 = a1.position + a1.rotation @ np.asarray(c1.position, dtype=float)
+    w2 = a2.position + a2.rotation @ np.asarray(c2.position, dtype=float)
+    print(
+        f"  conn {aconn.id[:8]}: w1={np.round(w1, 6)} w2={np.round(w2, 6)} "
+        f"gap={float(np.linalg.norm(w1 - w2))!r}"
+    )
+
+print("DEMO_REPRO_DONE")

.test_instance_ops.py

@@ -0,0 +1,89 @@
+"""Round-trip smoke test: instance-local sketches + modifiers survive save/load.
+
+Builds a minimal project (component with a body, assembly with two instances,
+one carrying an instance sketch + cut modifier + fillet modifier), saves to a
+temp .fluency, reloads, and asserts:
+  1. the shared component is untouched by instance work,
+  2. the instance sketch + modifiers round-trip with sketch refs intact,
+  3. the plain instance has none.
+"""
+import os
+import tempfile
+
+import numpy as np
+
+from fluency.models.data_model import (
+    Project, Component, Body, Sketch, Feature, Assembly, AssemblyComponent,
+)
+from fluency.io.project_io import save_project, load_project
+
+
+def main():
+    project = Project(name="inst test")
+    comp = project.add_component()
+    comp.name = "BasePart"
+    body = comp.add_body(Body(name="MainBody"))
+    base_sketch = comp.add_sketch(Sketch(name="BaseSketch"))
+    body.features.append(
+        Feature(operation="extrude", sketch=base_sketch, length=10.0)
+    )
+
+    asm = project.add_assembly(Assembly(name="TestAsm"))
+    ac1 = asm.add_component_instance(comp.id, name="Instance A")
+    ac1.position = np.array([0.0, 0.0, 0.0])
+    ac2 = asm.add_component_instance(comp.id, name="Instance B")
+    ac2.position = np.array([50.0, 0.0, 0.0])
+
+    # Instance A: local sketch + cut modifier referencing it + fillet.
+    inst_sketch = ac1.add_instance_sketch()
+    inst_sketch.name = "InstCutSketch"
+    ac1.add_modifier(body.id, Feature(operation="cut", sketch=inst_sketch,
+                                      length=5.0, through_all=True))
+    ac1.add_modifier(body.id, Feature(operation="fillet", radius=1.0))
+
+    # ---- save / load ----
+    fd, path = tempfile.mkstemp(suffix=".fluency")
+    os.close(fd)
+    try:
+        save_project(project, path)
+        loaded, _view = load_project(path)
+
+        lcomp = loaded.components[comp.id]
+        lac1 = None
+        lac2 = None
+        for lasm in loaded.assemblies.values():
+            for ac in lasm.components.values():
+                if ac.name == "Instance A":
+                    lac1 = ac
+                elif ac.name == "Instance B":
+                    lac2 = ac
+        assert lac1 is not None and lac2 is not None, "instances missing"
+
+        # 1. component untouched
+        assert len(lcomp.sketches) == 1, "component sketch count changed"
+        assert len(lcomp.bodies[body.id].features) == 1, "feature chain changed"
+        assert not getattr(lcomp.bodies[body.id], "modifiers", None)
+
+        # 2. instance A round-trip
+        assert len(lac1.sketches) == 1, "instance sketch missing"
+        lsk_id, lsk = next(iter(lac1.sketches.items()))
+        assert lsk.name == "InstCutSketch"
+        mods = lac1.modifiers
+        lbody_id = next(iter(lcomp.bodies))
+        assert len(mods.get(lbody_id, [])) == 2, f"modifiers missing: {mods}"
+        cut, fil = mods[lbody_id][0], mods[lbody_id][1]
+        assert cut.operation == "cut" and fil.operation == "fillet"
+        assert cut.sketch is not None and cut.sketch.id == lsk_id, \
+            "cut sketch ref did not resolve to instance sketch"
+        assert cut.length == 5.0 and cut.through_all
+
+        # 3. plain instance clean
+        assert not lac2.sketches and not lac2.modifiers
+
+        print("ROUND_TRIP_OK")
+    finally:
+        os.unlink(path)
+
+
+if __name__ == "__main__":
+    main()

.test_relocate_fallback.py

@@ -0,0 +1,83 @@
+"""Headless smoke: the manual re-pick fallback path (prompt -> frame -> pick mode)."""
+
+import os
+import sys
+
+os.environ.setdefault("QT_QPA_PLATFORM", "offscreen")
+sys.path.insert(0, os.path.join(os.path.dirname(__file__), "src"))
+
+import numpy as np
+
+from OCP.gp import gp_Pnt, gp_Dir, gp_Ax2
+from OCP.BRepPrimAPI import BRepPrimAPI_MakeBox, BRepPrimAPI_MakeCylinder
+from OCP.BRepAlgoAPI import BRepAlgoAPI_Cut
+
+from PySide6.QtWidgets import QApplication, QMessageBox
+
+from fluency.ui.main_window import MainWindow
+from fluency.models.data_model import Body
+from fluency.geometry_occ.kernel import OCCGeometryObject
+
+app = QApplication.instance() or QApplication([])
+w = MainWindow()
+
+comp = w._current_component
+body = Body(name="plate")
+comp.bodies[body.id] = body
+box = BRepPrimAPI_MakeBox(60.0, 40.0, 5.0).Shape()
+ax = gp_Ax2(gp_Pnt(10.0, 5.0, 0.0), gp_Dir(0, 0, 1))
+box = BRepAlgoAPI_Cut(box, BRepPrimAPI_MakeCylinder(ax, 3.0, 6.0).Shape()).Shape()
+body.geometry = OCCGeometryObject(box)
+
+partner = w._project.add_component()
+pbody = Body(name="partner")
+partner.bodies[pbody.id] = pbody
+pbody.geometry = OCCGeometryObject(BRepPrimAPI_MakeBox(30.0, 30.0, 10.0).Shape())
+
+asm = w._project.get_active_assembly()
+ac1 = asm.add_component_instance(comp.id, name="A")
+ac2 = asm.add_component_instance(partner.id, name="B")
+ac1.geom_cache[body.id] = body.geometry
+c1 = ac1.add_connector(
+    position=(10.0, 5.0, 2.5), normal=(0, 0, 1), x_dir=(1, 0, 0),
+    source_obj_id=f"asm_{ac1.id}_{body.id}",
+    name="Conn hole", entity_type="cylindrical_face",
+)
+c1.partner_ac_id = ac2.id
+
+# Activate the assembly view so the prompt path is taken.
+w._assembly_view_active = True
+w._selected_assembly_component_id = ac1.id
+
+# Force a Yes from the question dialog, and record that it actually fired.
+asked = {}
+def fake_question(parent, title, text, buttons, default):
+    asked["title"] = title
+    return QMessageBox.StandardButton.Yes
+QMessageBox.question = staticmethod(fake_question)
+def fake_warning(*a, **k):
+    return QMessageBox.StandardButton.Ok
+QMessageBox.warning = staticmethod(fake_warning)
+
+w._prompt_relocate_unresolved([(asm, ac1, c1)])
+assert asked.get("title") == "Connector Position Needed", asked
+assert w._relocate_pending == [(asm, ac1, c1)], w._relocate_pending
+assert w._viewer_3d._connector_pick_mode, "pick mode must be active"
+
+# A wrong-part click must not consume the pending entry.
+w._on_relocate_picked((0, 0, 0), (0, 0, 1), (1, 0, 0), "planar_face", f"asm_{ac2.id}_{pbody.id}")
+assert w._relocate_pending == [(asm, ac1, c1)], "wrong part must not consume the pick"
+
+# The right click re-homes and drains.
+w._on_relocate_picked((40.0, 30.0, 2.5), (0, 0, 1), (1, 0, 0), "cylindrical_face", f"asm_{ac1.id}_{body.id}")
+assert w._relocate_pending is None
+assert np.allclose(c1.position, (40.0, 30.0, 2.5)), c1.position
+assert not w._viewer_3d._connector_pick_mode, "pick mode must be off after completion"
+
+# Esc cancel mid-flight clears the state.
+w._relocate_pending = [(asm, ac1, c1)]
+w._start_relocate_pick_next()
+w._on_connector_pick_cancelled()
+assert w._relocate_pending is None
+assert not w._viewer_3d._connector_pick_mode
+print("RELOCATE_PICK_FALLBACK_OK")

.test_underlay_curves.py

@@ -0,0 +1,149 @@
+"""Headless test: update_external_entities handles circle/arc dict entries.
+
+Reproduces the crash where a re-projected face contains a circular edge
+(e.g. an instance cut hole): _project_face_to_uv returns a mixed list of
+polylines + curve dicts, and update_external_entities used to unpack the
+dict entries as (u, v) tuples.
+
+Covers:
+  1. mixed projection (polylines + circle dict) -> rebuild + rebind path,
+     no crash, no duplicate/orphan curve entities, user geometry re-anchored.
+  2. repeated update with the same mixed projection -> stable (idempotent).
+  3. polylines-only same-topology projection -> in-place path still works
+     (external ids preserved).
+"""
+import math
+
+from fluency.geometry_occ.sketch import OCCSketch
+
+RECT = [
+    [(0.0, 0.0), (10.0, 0.0)],
+    [(10.0, 0.0), (10.0, 10.0)],
+    [(10.0, 10.0), (0.0, 10.0)],
+    [(0.0, 10.0), (0.0, 0.0)],
+]
+
+
+def _counts(sk):
+    ents = list(sk._entities.values())
+    return {
+        "ext_points": sum(
+            1
+            for e in ents
+            if e.entity_type == "point" and getattr(e, "is_external", False)
+        ),
+        "ext_lines": sum(
+            1
+            for e in ents
+            if e.entity_type == "line" and getattr(e, "is_external", False)
+        ),
+        "circles": sum(1 for e in ents if e.entity_type == "circle"),
+        "arcs": sum(1 for e in ents if e.entity_type == "arc"),
+        "user_points": sum(
+            1
+            for e in ents
+            if e.entity_type == "point" and not getattr(e, "is_external", False)
+        ),
+    }
+
+
+def test_mixed_projection_rebuild():
+    sk = OCCSketch()
+    sk.add_external_polylines([list(p) for p in RECT])
+    center = sk.add_external_point(5.0, 5.0)
+    sk.add_circle(center, 2.0)
+    user = sk.add_point(5.0, 5.0)
+    assert sk.constrain_coincident(user, center)
+    assert sk.solve()
+
+    # Re-projection: same rectangle, circle moved + resized -> mixed list.
+    new_proj = [
+        list(p) for p in RECT
+    ] + [
+        {"type": "circle", "center": [6.0, 6.0], "radius": 1.5},
+    ]
+    old_ext_ids = set(sk._external_entity_ids)
+    assert sk.update_external_entities(new_proj), "rebuild + rebind solve failed"
+
+    c = _counts(sk)
+    assert c["circles"] == 1, f"duplicate circle entities: {c}"
+    assert c["ext_points"] == 5, f"ext point count wrong (expect 4 corners + 1 centre): {c}"
+    assert c["ext_lines"] == 4, f"ext line count wrong (expect 4): {c}"
+    assert c["user_points"] == 1
+    # The coincident rebind must anchor the user point to the NEW centre.
+    ux, uy = user.geometry
+    assert math.hypot(ux - 6.0, uy - 6.0) < 1e-6, f"user point at {(ux, uy)}"
+    # Rebuild path: fresh external ids.
+    assert not (old_ext_ids & sk._external_entity_ids)
+
+    # Idempotent second pass with the same projection.
+    assert sk.update_external_entities(list(new_proj)), "second pass failed"
+    c2 = _counts(sk)
+    assert c2 == c, f"counts changed on second pass: {c} -> {c2}"
+    ux, uy = user.geometry
+    assert math.hypot(ux - 6.0, uy - 6.0) < 1e-6
+    print("test_mixed_projection_rebuild OK")
+
+
+def test_polylines_only_inplace():
+    sk = OCCSketch()
+    sk.add_external_polylines([list(p) for p in RECT])
+    corner = None
+    for eid in sk._external_entity_ids:
+        ent = sk._entities[eid]
+        if ent.entity_type == "point" and ent.geometry == (0.0, 0.0):
+            corner = ent
+            break
+    assert corner is not None
+    user = sk.add_point(0.0, 0.0)
+    assert sk.constrain_coincident(user, corner)
+    assert sk.solve()
+
+    # Same topology, slightly shifted rectangle -> in-place move.
+    moved = [[(u + 1.0, v + 2.0) for (u, v) in poly] for poly in RECT]
+    old_ext_ids = set(sk._external_entity_ids)
+    assert sk.update_external_entities(moved), "in-place solve failed"
+    assert sk._external_entity_ids == old_ext_ids, "in-place path must keep ids"
+    ux, uy = user.geometry
+    assert math.hypot(ux - 1.0, uy - 2.0) < 1e-6, f"user point at {(ux, uy)}"
+    print("test_polylines_only_inplace OK")
+
+
+def test_arc_import_shares_corners():
+    """_import_external_curves must merge arc endpoints with existing
+    polyline corner points (no floating duplicate endpoints)."""
+    sk = OCCSketch()
+    # Rectangle with the top-right corner filleted: the arc endpoints must
+    # land on the truncated-edge corner points, not create new ones.
+    r = 2.0
+    sk.add_external_polylines([
+        [(0.0, 0.0), (10.0, 0.0)],
+        [(10.0, 0.0), (10.0, 10.0 - r)],
+        [(10.0 - r, 10.0), (0.0, 10.0)],
+        [(0.0, 10.0), (0.0, 0.0)],
+    ])
+    sk._import_external_curves(
+        [],
+        [
+            {
+                "type": "arc",
+                "center": [10.0 - r, 10.0 - r],
+                "start": [10.0, 10.0 - r],
+                "end": [10.0 - r, 10.0],
+                "radius": r,
+            },
+        ],
+    )
+    c = _counts(sk)
+    # 5 corners + 1 arc centre, NO extra endpoint entities.
+    assert c["ext_points"] == 6, f"expected 6 ext points, got {c}"
+    assert c["arcs"] == 1, f"expected 1 arc, got {c}"
+    assert sk.solve()
+    print("test_arc_import_shares_corners OK")
+
+
+if __name__ == "__main__":
+    test_mixed_projection_rebuild()
+    test_polylines_only_inplace()
+    test_arc_import_shares_corners()
+    print("UNDERLAY_CURVES_OK")

WARP.md

@@ -1,147 +0,0 @@
-# WARP.md
-
-This file provides guidance to WARP (warp.dev) when working with code in this repository.
-
-## Project Overview
-Fluency is a CAD (Computer Aided Design) application built with Python/PySide6 that provides parametric 3D modeling through a timeline-based project system. The application combines 2D sketching with constraint solving, 3D visualization using VTK, and SDF (Signed Distance Function) based mesh generation.
-
-## Common Commands
-
-### Development Environment Setup
-```bash
-# Activate virtual environment (if exists)
-source .venv/bin/activate
-
-# Install dependencies
-pip install -r requirements.txt
-```
-
-### Running the Application
-```bash
-# Run the main application
-python main.py
-
-# Run with debugging
-python -u main.py
-```
-
-### UI Development
-```bash
-# Convert Qt Designer UI file to Python code
-pyside6-uic gui.ui > Gui.py -g python
-```
-
-### Building Executable
-The project uses Nuitka for compilation (configured in `main.py` header):
-```bash
-# Build standalone executable
-nuitka --standalone --plugin-enable=pyside6 --plugin-enable=numpy --macos-create-app-bundle main.py
-```
-
-### Testing
-```bash
-# Run mesh generation test
-python meshtest.py
-```
-
-## Architecture Overview
-
-### Core Components
-
-#### Main Application (`main.py`)
-- **MainWindow**: Central UI controller that manages all widgets and user interactions
-- **Project System**: Hierarchical structure: `Project → Timeline → Component → Sketch/Body`
-- **Signal-based Communication**: Qt signals coordinate between 2D sketching and 3D rendering
-
-#### Project Hierarchy
-```
-Project
-├── Timeline (list of Components)
-└── Component
-    ├── Sketches (dict)
-    ├── Bodies (dict) 
-    └── Connectors (for assembly)
-```
-
-#### Drawing Modules (`drawing_modules/`)
-- **SketchWidget** (`draw_widget_solve.py`): 2D parametric sketching with SolverSpace constraint solving
-- **VTKWidget** (`vtk_widget.py`): 3D visualization and mesh interaction using VTK
-- **PyVistaWidget** (`vysta_widget.py`): Alternative 3D rendering backend
-
-#### Mesh Generation (`mesh_modules/`)
-- **VESTA** (`vesta_mesh.py`): Multi-threaded SDF-to-mesh conversion using marching cubes
-- **Interactor Mesh** (`interactor_mesh.py`): Simplified edge-based meshes for 3D selection
-- **Simple Mesh** (`simple_mesh.py`): Basic mesh utilities
-
-### Data Flow Architecture
-
-#### 2D to 3D Pipeline
-1. **2D Sketching**: User draws in SketchWidget using Qt coordinate system
-2. **Constraint Solving**: SolverSpace resolves geometric constraints
-3. **SDF Generation**: Sketch converted to Signed Distance Functions for 3D operations
-4. **Mesh Generation**: VESTA generates triangle meshes from SDF using marching cubes
-5. **3D Rendering**: VTK displays both solid meshes and interactive edges
-
-#### Signal Flow (from `doc/flow.md`)
-- 2D QPoint → cartesian space → SolverSpace dict → constraint solving → display
-- 3D mesh selection → projection to 2D → sketch widget integration
-
-### Key Classes
-
-#### Core Data Structures
-- **Sketch**: 2D geometric data with origin, normal, points, and constraints
-- **Body**: 3D mesh representation containing SDF objects and interactor meshes  
-- **Component**: Container grouping related sketches and bodies
-- **Interactor**: Simplified edge-based mesh for 3D manipulation
-
-#### Constraint Solving
-The application uses `python_solvespace` for parametric constraint solving:
-- Point-to-point constraints
-- Distance constraints
-- Horizontal/vertical line constraints
-- Point-to-line constraints
-
-### Technology Stack
-- **GUI**: PySide6 (Qt for Python)
-- **3D Graphics**: VTK for rendering, PyVista as alternative
-- **Constraint Solving**: SolverSpace for parametric geometry
-- **Mesh Generation**: SDF library with custom VESTA marching cubes implementation
-- **Scientific Computing**: NumPy for mathematical operations
-
-## Development Workflow
-
-### Adding New Sketch Tools
-1. Add UI button in `gui.ui`
-2. Convert UI: `pyside6-uic gui.ui > Gui.py -g python`  
-3. Connect signal in `MainWindow.__init__()`
-4. Implement tool logic in `SketchWidget`
-
-### Adding New 3D Operations
-1. Extend operation buttons in the Modify group
-2. Implement operation logic using SDF functions
-3. Update Body creation and timeline management
-4. Handle interactor mesh generation for selection
-
-### Debugging Tips
-- Monitor solver results through `SolverSystem` status
-- Use VTK's built-in debugging for rendering issues
-- Check coordinate transformations between 2D sketch and 3D space
-- Verify SDF function outputs before mesh generation
-
-### File Structure
-- `main.py`: Application entry point and main window
-- `Gui.py`: Auto-generated UI code (do not edit directly)
-- `gui.ui`: Qt Designer UI definition file
-- `drawing_modules/`: 2D and 3D rendering widgets
-- `mesh_modules/`: Mesh generation and processing
-- `doc/`: Architecture and command documentation
-
-## Dependencies
-Primary external libraries:
-- `PySide6`: Qt GUI framework
-- `vtk`: 3D visualization toolkit
-- `python-solvespace`: Constraint solving
-- `sdf`: Signed Distance Function operations
-- `numpy`: Numerical computations
-- `scikit-image`: Marching cubes algorithm
-- `names`: Random name generation for sketches

docs/render_view_plan.md

@@ -0,0 +1,253 @@
+# Realistic Render View — Implementation Plan
+
+## Context
+
+Add a **"Render"** feature to Fluency CAD that opens a separate window for photorealistic rendering of the selected component or assembly (like KeyShot/Cacles).
+
+**Constraints:**
+- Open in a **new window** — don't clutter the workspace
+- **Keep existing OCCRenderer** for the interactive 3D viewport — untouched
+- Render backend must be a **separate, swappable module** so we can change the renderer later
+- Use **Mitsuba 3** as the initial backend (`pip install mitsuba`, ~50MB)
+
+---
+
+## Architecture
+
+```
+┌─────────────────────────────────────────────────────────┐
+│  Main Fluency Window (existing OCCRenderer — untouched) │
+│                                                         │
+│  [Select body/assembly] → [Click "Render"]              │
+│              │                                          │
+│              ▼                                          │
+│  ┌─────────────────────────────────────┐                │
+│  │  RenderWindow (separate QMainWindow)│                │
+│  │                                     │                │
+│  │  ┌───────────────────────────────┐  │                │
+│  │  │  RenderBackend (ABC)          │  │                │
+│  │  │  ├─ MitsubaBackend  ← current │  │                │
+│  │  │  ├─ (future: BlenderBackend)  │  │                │
+│  │  │  └─ (future: CyclesBackend)   │  │                │
+│  │  └───────────────────────────────┘  │                │
+│  │                                     │                │\n│  │  [Image preview]  [Progress bar]  │                │
+│  │  [Material ▾] [Quality ▾] [Render]  │                │
+│  │                     [Export PNG]    │                │
+│  └─────────────────────────────────────┘                │
+└─────────────────────────────────────────────────────────┘
+```
+
+### Swappable Backend Interface
+
+```python
+from abc import ABC, abstractmethod
+from dataclasses import dataclass
+import numpy as np
+
+@dataclass
+class RenderMaterial:
+    name: str
+    color: tuple[float, float, float] = (0.7, 0.7, 0.7)
+    metallic: float = 0.0        # 0.0–1.0
+    roughness: float = 0.5       # 0.0–1.0
+    bsdf_type: str = "diffuse"   # diffuse | roughconductor | roughdielectric | plastic
+
+@dataclass
+class RenderCamera:
+    origin: tuple[float, float, float] = (100, 100, 100)
+    target: tuple[float, float, float] = (0, 0, 0)
+    up: tuple[float, float, float] = (0, 0, 1)
+    fov: float = 45.0
+
+@dataclass
+class RenderSettings:
+    width: int = 1920
+    height: int = 1080
+    spp: int = 256            # samples per pixel
+    max_depth: int = 8        # path tracer bounces
+
+class RenderBackend(ABC):
+    """Swap this to change the rendering engine."""
+    @abstractmethod
+    def render(self, obj_path: str, material: RenderMaterial,
+               camera: RenderCamera, settings: RenderSettings) -> np.ndarray: ...
+    @abstractmethod
+    def render_preview(self, obj_path: str, material: RenderMaterial,
+                       camera: RenderCamera, settings: RenderSettings) -> np.ndarray: ...
+    @abstractmethod
+    def name(self) -> str: ...
+```
+
+Switching backends later = write a new class implementing `RenderBackend`. One import change.
+
+---
+
+## Mitsuba 3 Backend
+
+### Why Mitsuba
+
+| Feature | Status |
+|---------|--------|
+| `pip install mitsuba` | Single install, no system deps |
+| True path tracing | GI, caustics, spectral rendering |
+| PBR materials | `roughconductor`, `roughdielectric`, `diffuse`, `plastic` |
+| Python dict API | Build scenes programmatically, no XML |
+| CPU + GPU backends | `scalar_rgb` (CPU), `cuda_rgb` (NVIDIA) |
+| Output formats | PNG, EXR (HDR) with tonemapping |
+
+### OCC → OBJ Conversion Path
+
+```python
+from OCP.BRepMesh import BRepMesh_IncrementalMesh
+from OCP.StlAPI import StlAPI_Writer
+from OCP.BRep import BRep_Builder
+import tempfile, os
+
+def occ_shape_to_obj(shape, obj_path: str, linear_deflection: float = 0.1):
+    """Tessellate OCC shape and write as OBJ for Mitsuba."""
+    tess = BRepMesh_IncrementalMesh(shape, linear_deflection, False, 0.5, True)
+    tess.Perform()
+    # Write STL (reliable), then convert to OBJ via trimesh or direct
+    writer = StlAPI_Writer()
+    writer.SetASCIIMode(False)
+    stl_path = obj_path.replace(".obj", ".stl")
+    writer.Write(shape, stl_path)
+    # Mitsuba can read STL directly, or we convert to OBJ
+    return stl_path
+```
+
+### Mitsuba Scene Construction
+
+```python
+import mitsuba as mi
+mi.set_variant("scalar_rgb")
+
+def build_scene(mesh_path: str, material: RenderMaterial,
+                camera: RenderCamera, settings: RenderSettings) -> mi.Scene:
+    # Map our material to Mitsuba BSDF
+    bsdf_map = {
+        "diffuse": {"type": "diffuse", "reflectance": {"type": "rgb", "value": material.color}},
+        "roughconductor": {
+            "type": "roughconductor",
+            "material": "copper",  # or铝, 钢, etc.
+            "alpha": material.roughness,
+        },
+        "roughdielectric": {
+            "type": "roughdielectric",
+            "int_ior": 1.5,
+            "alpha": material.roughness,
+        },
+        "plastic": {
+            "type": "plastic",
+            "diffuse_reflectance": {"type": "rgb", "value": material.color},
+            "int_ior": 1.5,
+        },
+    }
+
+    return mi.load_dict({
+        "type": "scene",
+        "integrator": {"type": "path", "max_depth": settings.max_depth},
+        "sensor": {
+            "type": "perspective",
+            "fov": camera.fov,
+            "to_world": mi.ScalarTransform4f.look_at(
+                origin=camera.origin, target=camera.target, up=camera.up
+            ),
+            "film": {"type": "hdrfilm", "width": settings.width, "height": settings.height},
+            "sampler": {"type": "independent", "sample_count": settings.spp},
+        },
+        "emitter": {"type": "constant"},
+        "shape": {
+            "type": "stl",  # or "obj"
+            "filename": mesh_path,
+            "bsdf": bsdf_map.get(material.bsdf_type, bsdf_map["diffuse"]),
+        },
+    })
+```
+
+---
+
+## Files to Create/Modify
+
+| File | Action | Description |
+|------|--------|-------------|
+| `src/fluency/rendering/render_backend.py` | **NEW** | Abstract `RenderBackend`, `RenderMaterial`, `RenderCamera`, `RenderSettings` |
+| `src/fluency/rendering/mitsuba_backend.py` | **NEW** | `MitsubaBackend(RenderBackend)` implementation |
+| `src/fluency/rendering/occ_to_mesh.py` | **NEW** | OCC `TopoDS_Shape` → STL/OBJ tessellation |
+| `src/fluency/rendering/material_presets.py` | **NEW** | Preset library: Steel, Aluminum, Brass, Chrome, Plastic, Rubber, Wood |
+| `src/fluency/ui/render_window.py` | **NEW** | `RenderWindow(QMainWindow)` — image preview, material/quality controls, render/export |
+| `src/fluency/ui/main_window.py` | MODIFY | Add "Render" button → get selected shapes → open `RenderWindow` |
+
+---
+
+## UI: RenderWindow
+
+```
+┌──────────────────────────────────────────┐
+│  Render — [Part Name]              [─][□][×] │
+├──────────────────────────────────────────┤
+│                                          │
+│  ┌──────────────────────────────────┐    │
+│  │                                  │    │
+│  │      Rendered Image Preview      │    │
+│  │      (QLabel with QPixmap)       │    │
+│  │                                  │    │
+│  └──────────────────────────────────┘    │
+│                                          │
+│  Material: [Steel ▾]                     │
+│  Quality:  [256 SPP ▾]                   │
+│  Resolution: [1920×1080 ▾]               │
+│                                          │
+│  [▶ Render]  [⏹ Cancel]  [💾 Export PNG] │
+│                                          │
+│  ████████████████░░░░░░  65%  (23s left) │
+└──────────────────────────────────────────┘
+```
+
+- **Preview**: progressive refinement (low SPP first, then ramp)
+- **Cancel**: kill Mitsuba render thread
+- **Export**: save to PNG/EXR
+
+---
+
+## Material Presets
+
+| Preset | Color | Metallic | Roughness | BSDF |
+|--------|-------|----------|-----------|------|
+| Brushed Steel | (0.65, 0.67, 0.72) | 0.9 | 0.35 | roughconductor |
+| Polished Chrome | (0.8, 0.8, 0.8) | 1.0 | 0.05 | roughconductor |
+| Brushed Aluminum | (0.75, 0.75, 0.75) | 0.85 | 0.25 | roughconductor |
+| Copper | (0.95, 0.64, 0.54) | 0.95 | 0.15 | roughconductor |
+| Gold | (1.0, 0.76, 0.33) | 1.0 | 0.1 | roughconductor |
+| Blackened Steel | (0.15, 0.15, 0.17) | 0.8 | 0.4 | roughconductor |
+| Matte Plastic | (0.2, 0.5, 0.8) | 0.0 | 0.6 | plastic |
+| Glossy Plastic | (0.2, 0.5, 0.8) | 0.0 | 0.1 | plastic |
+| White Nylon | (0.85, 0.85, 0.83) | 0.0 | 0.45 | plastic |
+| Black ABS | (0.05, 0.05, 0.05) | 0.0 | 0.35 | plastic |
+| Red PA12 | (0.75, 0.08, 0.08) | 0.0 | 0.4 | plastic |
+| Rubber | (0.1, 0.1, 0.1) | 0.0 | 0.9 | diffuse |
+| Ceramic White | (0.92, 0.91, 0.88) | 0.0 | 0.15 | dielectric |
+| Glass | (0.95, 0.95, 0.95) | 0.0 | 0.0 | dielectric |
+| Wood | (0.6, 0.4, 0.2) | 0.0 | 0.7 | diffuse |
+
+**Note:** Mitsuba pip installs don't include spectral metal data files (iron.spd, copper.spd, etc.), so metal presets use `material="none"` with `specular_reflectance` set to the metal color instead.
+
+---
+
+## Risks & Mitigations
+
+| Risk | Mitigation |
+|------|-----------|
+| Mitsuba not installed | Graceful error: "pip install mitsuba" shown in UI |
+| Slow CPU rendering | Default to low SPP (64) for preview; offer GPU variant if CUDA available |
+| Large meshes slow to tessellate | Progress indicator; optional mesh decimation |
+| Mitsuba STL/OCC compatibility | Test tessellation quality; tune `linear_deflection` |
+
+---
+
+## Estimated Effort
+
+- **Phase 1** (abstract backend + OCC→mesh + Mitsuba impl): ~4-6 hours
+- **Phase 2** (render window UI + material presets): ~3-4 hours
+- **Phase 3** (polish, export, swap test): ~2-3 hours
+- **Total**: ~9-13 hours

gui_ui.py

@@ -26,7 +26,12 @@ class Ui_fluencyCAD(object):
     def setupUi(self, fluencyCAD):
         if not fluencyCAD.objectName():
             fluencyCAD.setObjectName(u"fluencyCAD")
-        fluencyCAD.resize(1941, 1155)
+        fluencyCAD.resize(2551, 1265)
+        sizePolicy = QSizePolicy(QSizePolicy.Policy.Preferred, QSizePolicy.Policy.Preferred)
+        sizePolicy.setHorizontalStretch(0)
+        sizePolicy.setVerticalStretch(0)
+        sizePolicy.setHeightForWidth(fluencyCAD.sizePolicy().hasHeightForWidth())
+        fluencyCAD.setSizePolicy(sizePolicy)
         self.actionNew_Project = QAction(fluencyCAD)
         self.actionNew_Project.setObjectName(u"actionNew_Project")
         self.actionOpen_Project = QAction(fluencyCAD)
@@ -51,9 +56,6 @@ class Ui_fluencyCAD(object):
         self.gridLayout.setObjectName(u"gridLayout")
         self.groupBox_5 = QGroupBox(self.centralwidget)
         self.groupBox_5.setObjectName(u"groupBox_5")
-        sizePolicy = QSizePolicy(QSizePolicy.Policy.Preferred, QSizePolicy.Policy.Preferred)
-        sizePolicy.setHorizontalStretch(0)
-        sizePolicy.setVerticalStretch(0)
         sizePolicy.setHeightForWidth(self.groupBox_5.sizePolicy().hasHeightForWidth())
         self.groupBox_5.setSizePolicy(sizePolicy)
         self.gridLayout_11 = QGridLayout(self.groupBox_5)
@@ -135,54 +137,94 @@ class Ui_fluencyCAD(object):
 
         self.gridLayout.addWidget(self.groupBox_5, 3, 0, 1, 1)
 
-        self.groupBox = QGroupBox(self.centralwidget)
-        self.groupBox.setObjectName(u"groupBox")
-        self.gridLayout_3 = QGridLayout(self.groupBox)
-        self.gridLayout_3.setObjectName(u"gridLayout_3")
-        self.pb_revop = QPushButton(self.groupBox)
-        self.pb_revop.setObjectName(u"pb_revop")
+        self.groupBox_4 = QGroupBox(self.centralwidget)
+        self.groupBox_4.setObjectName(u"groupBox_4")
+        self.groupBox_4.setMaximumSize(QSize(200, 16777215))
+        self.gridLayout_9 = QGridLayout(self.groupBox_4)
+        self.gridLayout_9.setObjectName(u"gridLayout_9")
+        self.pushButton_2 = QPushButton(self.groupBox_4)
+        self.pushButton_2.setObjectName(u"pushButton_2")
 
-        self.gridLayout_3.addWidget(self.pb_revop, 2, 1, 1, 1)
+        self.gridLayout_9.addWidget(self.pushButton_2, 0, 0, 1, 1)
 
-        self.pb_extrdop = QPushButton(self.groupBox)
-        self.pb_extrdop.setObjectName(u"pb_extrdop")
+        self.pb_export_iges = QPushButton(self.groupBox_4)
+        self.pb_export_iges.setObjectName(u"pb_export_iges")
 
-        self.gridLayout_3.addWidget(self.pb_extrdop, 0, 0, 1, 1)
+        self.gridLayout_9.addWidget(self.pb_export_iges, 2, 0, 1, 1)
 
-        self.pb_arrayop = QPushButton(self.groupBox)
-        self.pb_arrayop.setObjectName(u"pb_arrayop")
+        self.pb_export_step = QPushButton(self.groupBox_4)
+        self.pb_export_step.setObjectName(u"pb_export_step")
 
-        self.gridLayout_3.addWidget(self.pb_arrayop, 2, 0, 1, 1)
-
-        self.pb_cutop = QPushButton(self.groupBox)
-        self.pb_cutop.setObjectName(u"pb_cutop")
-
-        self.gridLayout_3.addWidget(self.pb_cutop, 0, 1, 1, 1)
-
-        self.pb_combop = QPushButton(self.groupBox)
-        self.pb_combop.setObjectName(u"pb_combop")
-
-        self.gridLayout_3.addWidget(self.pb_combop, 1, 0, 1, 1)
-
-        self.pb_moveop = QPushButton(self.groupBox)
-        self.pb_moveop.setObjectName(u"pb_moveop")
-
-        self.gridLayout_3.addWidget(self.pb_moveop, 1, 1, 1, 1)
+        self.gridLayout_9.addWidget(self.pb_export_step, 0, 1, 1, 1)
 
 
-        self.gridLayout.addWidget(self.groupBox, 0, 3, 1, 1, Qt.AlignTop)
+        self.gridLayout.addWidget(self.groupBox_4, 1, 3, 1, 1)
+
+        self.InputTab = QTabWidget(self.centralwidget)
+        self.InputTab.setObjectName(u"InputTab")
+        sizePolicy.setHeightForWidth(self.InputTab.sizePolicy().hasHeightForWidth())
+        self.InputTab.setSizePolicy(sizePolicy)
+        self.sketch_tab = QWidget()
+        self.sketch_tab.setObjectName(u"sketch_tab")
+        self.verticalLayout_4 = QVBoxLayout(self.sketch_tab)
+        self.verticalLayout_4.setObjectName(u"verticalLayout_4")
+        self.InputTab.addTab(self.sketch_tab, "")
+        self.code_tab = QWidget()
+        self.code_tab.setObjectName(u"code_tab")
+        self.verticalLayout = QVBoxLayout(self.code_tab)
+        self.verticalLayout.setObjectName(u"verticalLayout")
+        self.textEdit = QTextEdit(self.code_tab)
+        self.textEdit.setObjectName(u"textEdit")
+
+        self.verticalLayout.addWidget(self.textEdit)
+
+        self.groupBox_7 = QGroupBox(self.code_tab)
+        self.groupBox_7.setObjectName(u"groupBox_7")
+        self.gridLayout_5 = QGridLayout(self.groupBox_7)
+        self.gridLayout_5.setObjectName(u"gridLayout_5")
+        self.pushButton_5 = QPushButton(self.groupBox_7)
+        self.pushButton_5.setObjectName(u"pushButton_5")
+
+        self.gridLayout_5.addWidget(self.pushButton_5, 2, 0, 1, 1)
+
+        self.pushButton_4 = QPushButton(self.groupBox_7)
+        self.pushButton_4.setObjectName(u"pushButton_4")
+
+        self.gridLayout_5.addWidget(self.pushButton_4, 2, 1, 1, 1)
+
+        self.pb_apply_code = QPushButton(self.groupBox_7)
+        self.pb_apply_code.setObjectName(u"pb_apply_code")
+
+        self.gridLayout_5.addWidget(self.pb_apply_code, 1, 0, 1, 1)
+
+        self.pushButton = QPushButton(self.groupBox_7)
+        self.pushButton.setObjectName(u"pushButton")
+
+        self.gridLayout_5.addWidget(self.pushButton, 1, 1, 1, 1)
+
+
+        self.verticalLayout.addWidget(self.groupBox_7)
+
+        self.InputTab.addTab(self.code_tab, "")
+
+        self.gridLayout.addWidget(self.InputTab, 0, 1, 5, 1)
 
         self.compo_tool_box = QGroupBox(self.centralwidget)
         self.compo_tool_box.setObjectName(u"compo_tool_box")
+        sizePolicy1 = QSizePolicy(QSizePolicy.Policy.Minimum, QSizePolicy.Policy.Preferred)
+        sizePolicy1.setHorizontalStretch(0)
+        sizePolicy1.setVerticalStretch(0)
+        sizePolicy1.setHeightForWidth(self.compo_tool_box.sizePolicy().hasHeightForWidth())
+        self.compo_tool_box.setSizePolicy(sizePolicy1)
         self.compo_tool_box.setMinimumSize(QSize(0, 50))
-        self.gridLayout_9 = QGridLayout(self.compo_tool_box)
-        self.gridLayout_9.setObjectName(u"gridLayout_9")
+        self.horizontalLayout = QHBoxLayout(self.compo_tool_box)
+        self.horizontalLayout.setObjectName(u"horizontalLayout")
         self.pb_new_compo = QPushButton(self.compo_tool_box)
         self.pb_new_compo.setObjectName(u"pb_new_compo")
         self.pb_new_compo.setMinimumSize(QSize(50, 50))
         self.pb_new_compo.setMaximumSize(QSize(50, 50))
 
-        self.gridLayout_9.addWidget(self.pb_new_compo, 0, 0, 1, 1)
+        self.horizontalLayout.addWidget(self.pb_new_compo)
 
         self.pb_del_compo = QPushButton(self.compo_tool_box)
         self.pb_del_compo.setObjectName(u"pb_del_compo")
@@ -193,16 +235,113 @@ class Ui_fluencyCAD(object):
         self.pb_del_compo.setMaximumSize(QSize(50, 50))
         self.pb_del_compo.setLayoutDirection(Qt.LeftToRight)
 
-        self.gridLayout_9.addWidget(self.pb_del_compo, 0, 1, 1, 1)
+        self.horizontalLayout.addWidget(self.pb_del_compo)
 
 
-        self.gridLayout.addWidget(self.compo_tool_box, 11, 0, 1, 1)
+        self.gridLayout.addWidget(self.compo_tool_box, 7, 0, 1, 1)
 
-        self.compo_box = QGroupBox(self.centralwidget)
-        self.compo_box.setObjectName(u"compo_box")
-        self.compo_box.setMinimumSize(QSize(0, 50))
+        self.groupBox_3 = QGroupBox(self.centralwidget)
+        self.groupBox_3.setObjectName(u"groupBox_3")
+        sizePolicy.setHeightForWidth(self.groupBox_3.sizePolicy().hasHeightForWidth())
+        self.groupBox_3.setSizePolicy(sizePolicy)
+        self.groupBox_3.setMaximumSize(QSize(200, 16777213))
+        self.gridLayout_4 = QGridLayout(self.groupBox_3)
+        self.gridLayout_4.setObjectName(u"gridLayout_4")
+        self.pb_con_ptpt = QPushButton(self.groupBox_3)
+        self.pb_con_ptpt.setObjectName(u"pb_con_ptpt")
+        icon = QIcon()
+        icon.addFile(u"icons/pt_pt.png", QSize(), QIcon.Mode.Normal, QIcon.State.Off)
+        self.pb_con_ptpt.setIcon(icon)
+        self.pb_con_ptpt.setCheckable(True)
+        self.pb_con_ptpt.setAutoExclusive(False)
 
-        self.gridLayout.addWidget(self.compo_box, 11, 1, 1, 2)
+        self.gridLayout_4.addWidget(self.pb_con_ptpt, 1, 0, 1, 1)
+
+        self.pb_con_vert = QPushButton(self.groupBox_3)
+        self.pb_con_vert.setObjectName(u"pb_con_vert")
+        self.pb_con_vert.setCheckable(True)
+        self.pb_con_vert.setAutoExclusive(False)
+
+        self.gridLayout_4.addWidget(self.pb_con_vert, 3, 1, 1, 1)
+
+        self.pb_con_sym = QPushButton(self.groupBox_3)
+        self.pb_con_sym.setObjectName(u"pb_con_sym")
+        self.pb_con_sym.setCheckable(True)
+        self.pb_con_sym.setAutoExclusive(False)
+
+        self.gridLayout_4.addWidget(self.pb_con_sym, 4, 1, 1, 1)
+
+        self.pb_con_mid = QPushButton(self.groupBox_3)
+        self.pb_con_mid.setObjectName(u"pb_con_mid")
+        self.pb_con_mid.setCheckable(True)
+        self.pb_con_mid.setAutoExclusive(False)
+
+        self.gridLayout_4.addWidget(self.pb_con_mid, 2, 0, 1, 1)
+
+        self.pb_con_line = QPushButton(self.groupBox_3)
+        self.pb_con_line.setObjectName(u"pb_con_line")
+        self.pb_con_line.setCheckable(True)
+        self.pb_con_line.setAutoExclusive(False)
+
+        self.gridLayout_4.addWidget(self.pb_con_line, 1, 1, 1, 1)
+
+        self.pb_con_horiz = QPushButton(self.groupBox_3)
+        self.pb_con_horiz.setObjectName(u"pb_con_horiz")
+        self.pb_con_horiz.setCheckable(True)
+        self.pb_con_horiz.setAutoExclusive(False)
+
+        self.gridLayout_4.addWidget(self.pb_con_horiz, 3, 0, 1, 1)
+
+        self.pb_con_dist = QPushButton(self.groupBox_3)
+        self.pb_con_dist.setObjectName(u"pb_con_dist")
+        self.pb_con_dist.setCheckable(True)
+        self.pb_con_dist.setAutoExclusive(False)
+        self.pb_con_dist.setAutoRepeatDelay(297)
+
+        self.gridLayout_4.addWidget(self.pb_con_dist, 4, 0, 1, 1)
+
+        self.pb_con_perp = QPushButton(self.groupBox_3)
+        self.pb_con_perp.setObjectName(u"pb_con_perp")
+        self.pb_con_perp.setCheckable(True)
+        self.pb_con_perp.setAutoExclusive(False)
+
+        self.gridLayout_4.addWidget(self.pb_con_perp, 2, 1, 1, 1)
+
+        self.pb_con_diameter = QPushButton(self.groupBox_3)
+        self.pb_con_diameter.setObjectName(u"pb_con_diameter")
+
+        self.gridLayout_4.addWidget(self.pb_con_diameter, 5, 0, 1, 1)
+
+
+        self.gridLayout.addWidget(self.groupBox_3, 2, 0, 1, 1)
+
+        self.assembly_tools = QGroupBox(self.centralwidget)
+        self.assembly_tools.setObjectName(u"assembly_tools")
+        sizePolicy1.setHeightForWidth(self.assembly_tools.sizePolicy().hasHeightForWidth())
+        self.assembly_tools.setSizePolicy(sizePolicy1)
+        self.assembly_tools.setMinimumSize(QSize(113, 50))
+        self.horizontalLayout_2 = QHBoxLayout(self.assembly_tools)
+        self.horizontalLayout_2.setObjectName(u"horizontalLayout_2")
+        self.pb_compo_to_assembly = QPushButton(self.assembly_tools)
+        self.pb_compo_to_assembly.setObjectName(u"pb_compo_to_assembly")
+        self.pb_compo_to_assembly.setMinimumSize(QSize(50, 50))
+        self.pb_compo_to_assembly.setMaximumSize(QSize(50, 50))
+
+        self.horizontalLayout_2.addWidget(self.pb_compo_to_assembly)
+
+        self.pb_remove_compo_from_assembly = QPushButton(self.assembly_tools)
+        self.pb_remove_compo_from_assembly.setObjectName(u"pb_remove_compo_from_assembly")
+        self.pb_remove_compo_from_assembly.setEnabled(True)
+        sizePolicy.setHeightForWidth(self.pb_remove_compo_from_assembly.sizePolicy().hasHeightForWidth())
+        self.pb_remove_compo_from_assembly.setSizePolicy(sizePolicy)
+        self.pb_remove_compo_from_assembly.setMinimumSize(QSize(50, 50))
+        self.pb_remove_compo_from_assembly.setMaximumSize(QSize(50, 50))
+        self.pb_remove_compo_from_assembly.setLayoutDirection(Qt.LeftToRight)
+
+        self.horizontalLayout_2.addWidget(self.pb_remove_compo_from_assembly)
+
+
+        self.gridLayout.addWidget(self.assembly_tools, 8, 0, 1, 1)
 
         self.groupBox_9 = QGroupBox(self.centralwidget)
         self.groupBox_9.setObjectName(u"groupBox_9")
@@ -253,67 +392,128 @@ class Ui_fluencyCAD(object):
 
         self.gridLayout.addWidget(self.groupBox_9, 0, 0, 1, 1)
 
-        self.groupBox_10 = QGroupBox(self.centralwidget)
-        self.groupBox_10.setObjectName(u"groupBox_10")
-        sizePolicy1 = QSizePolicy(QSizePolicy.Policy.Preferred, QSizePolicy.Policy.Expanding)
-        sizePolicy1.setHorizontalStretch(0)
-        sizePolicy1.setVerticalStretch(0)
-        sizePolicy1.setHeightForWidth(self.groupBox_10.sizePolicy().hasHeightForWidth())
-        self.groupBox_10.setSizePolicy(sizePolicy1)
-        self.groupBox_10.setMaximumSize(QSize(200, 16777215))
-        self.verticalLayout_6 = QVBoxLayout(self.groupBox_10)
-        self.verticalLayout_6.setObjectName(u"verticalLayout_6")
-        self.verticalLayout_6.setContentsMargins(5, 5, 5, 5)
-        self.body_list = QListWidget(self.groupBox_10)
-        self.body_list.setObjectName(u"body_list")
-        self.body_list.setSelectionRectVisible(True)
+        self.groupBox_12 = QGroupBox(self.centralwidget)
+        self.groupBox_12.setObjectName(u"groupBox_12")
+        sizePolicy2 = QSizePolicy(QSizePolicy.Policy.Preferred, QSizePolicy.Policy.Expanding)
+        sizePolicy2.setHorizontalStretch(0)
+        sizePolicy2.setVerticalStretch(0)
+        sizePolicy2.setHeightForWidth(self.groupBox_12.sizePolicy().hasHeightForWidth())
+        self.groupBox_12.setSizePolicy(sizePolicy2)
+        self.groupBox_12.setMaximumSize(QSize(200, 16777215))
+        self.verticalLayout_8 = QVBoxLayout(self.groupBox_12)
+        self.verticalLayout_8.setObjectName(u"verticalLayout_8")
+        self.verticalLayout_8.setContentsMargins(5, 5, 5, 5)
+        self.connection_list = QListWidget(self.groupBox_12)
+        self.connection_list.setObjectName(u"connection_list")
+        self.connection_list.setSelectionRectVisible(True)
 
-        self.verticalLayout_6.addWidget(self.body_list)
+        self.verticalLayout_8.addWidget(self.connection_list)
 
-        self.groupBox_8 = QGroupBox(self.groupBox_10)
-        self.groupBox_8.setObjectName(u"groupBox_8")
-        sizePolicy.setHeightForWidth(self.groupBox_8.sizePolicy().hasHeightForWidth())
-        self.groupBox_8.setSizePolicy(sizePolicy)
-        self.groupBox_8.setMaximumSize(QSize(200, 16777215))
-        self.gridLayout_8 = QGridLayout(self.groupBox_8)
-        self.gridLayout_8.setObjectName(u"gridLayout_8")
-        self.gridLayout_8.setContentsMargins(2, 2, 2, 2)
-        self.pb_del_body = QPushButton(self.groupBox_8)
-        self.pb_del_body.setObjectName(u"pb_del_body")
+        self.groupBox_13 = QGroupBox(self.groupBox_12)
+        self.groupBox_13.setObjectName(u"groupBox_13")
+        sizePolicy.setHeightForWidth(self.groupBox_13.sizePolicy().hasHeightForWidth())
+        self.groupBox_13.setSizePolicy(sizePolicy)
+        self.groupBox_13.setMaximumSize(QSize(200, 16777215))
+        self.gridLayout_13 = QGridLayout(self.groupBox_13)
+        self.gridLayout_13.setObjectName(u"gridLayout_13")
+        self.gridLayout_13.setContentsMargins(2, 2, 2, 2)
+        self.pb_del_connection = QPushButton(self.groupBox_13)
+        self.pb_del_connection.setObjectName(u"pb_del_connection")
 
-        self.gridLayout_8.addWidget(self.pb_del_body, 0, 2, 1, 1)
+        self.gridLayout_13.addWidget(self.pb_del_connection, 0, 2, 1, 1)
 
-        self.pb_update_body = QPushButton(self.groupBox_8)
-        self.pb_update_body.setObjectName(u"pb_update_body")
+        self.pb_update_connection = QPushButton(self.groupBox_13)
+        self.pb_update_connection.setObjectName(u"pb_update_connection")
 
-        self.gridLayout_8.addWidget(self.pb_update_body, 0, 0, 1, 1)
+        self.gridLayout_13.addWidget(self.pb_update_connection, 0, 0, 1, 1)
 
-        self.pb_edt_sktch_3 = QPushButton(self.groupBox_8)
-        self.pb_edt_sktch_3.setObjectName(u"pb_edt_sktch_3")
+        self.pb_edt_sktch_4 = QPushButton(self.groupBox_13)
+        self.pb_edt_sktch_4.setObjectName(u"pb_edt_sktch_4")
 
-        self.gridLayout_8.addWidget(self.pb_edt_sktch_3, 0, 1, 1, 1)
+        self.gridLayout_13.addWidget(self.pb_edt_sktch_4, 0, 1, 1, 1)
 
 
-        self.verticalLayout_6.addWidget(self.groupBox_8)
+        self.verticalLayout_8.addWidget(self.groupBox_13)
 
 
-        self.gridLayout.addWidget(self.groupBox_10, 8, 3, 3, 1)
+        self.gridLayout.addWidget(self.groupBox_12, 4, 3, 1, 1)
+
+        self.joint_tools = QGroupBox(self.centralwidget)
+        self.joint_tools.setObjectName(u"joint_tools")
+        self.joint_tools.setMinimumSize(QSize(0, 50))
+        self.gridLayout_10 = QGridLayout(self.joint_tools)
+        self.gridLayout_10.setObjectName(u"gridLayout_10")
+        self.pb_add_connector = QPushButton(self.joint_tools)
+        self.pb_add_connector.setObjectName(u"pb_add_connector")
+        self.pb_add_connector.setMinimumSize(QSize(50, 50))
+        self.pb_add_connector.setMaximumSize(QSize(50, 50))
+
+        self.gridLayout_10.addWidget(self.pb_add_connector, 0, 0, 1, 1)
+
+        self.pb_remove_connector = QPushButton(self.joint_tools)
+        self.pb_remove_connector.setObjectName(u"pb_remove_connector")
+        self.pb_remove_connector.setMinimumSize(QSize(50, 50))
+        self.pb_remove_connector.setMaximumSize(QSize(50, 50))
+
+        self.gridLayout_10.addWidget(self.pb_remove_connector, 0, 1, 1, 1)
+
+        self.pb_add_connector_3 = QPushButton(self.joint_tools)
+        self.pb_add_connector_3.setObjectName(u"pb_add_connector_3")
+        self.pb_add_connector_3.setMinimumSize(QSize(50, 50))
+        self.pb_add_connector_3.setMaximumSize(QSize(50, 50))
+
+        self.gridLayout_10.addWidget(self.pb_add_connector_3, 1, 1, 1, 1)
+
+        self.pb_add_connector_2 = QPushButton(self.joint_tools)
+        self.pb_add_connector_2.setObjectName(u"pb_add_connector_2")
+        self.pb_add_connector_2.setMinimumSize(QSize(50, 50))
+        self.pb_add_connector_2.setMaximumSize(QSize(50, 50))
+
+        self.gridLayout_10.addWidget(self.pb_add_connector_2, 1, 0, 1, 1)
+
+
+        self.gridLayout.addWidget(self.joint_tools, 7, 3, 2, 1)
+
+        self.gl_box = QGroupBox(self.centralwidget)
+        self.gl_box.setObjectName(u"gl_box")
+        sizePolicy3 = QSizePolicy(QSizePolicy.Policy.Preferred, QSizePolicy.Policy.Preferred)
+        sizePolicy3.setHorizontalStretch(0)
+        sizePolicy3.setVerticalStretch(4)
+        sizePolicy3.setHeightForWidth(self.gl_box.sizePolicy().hasHeightForWidth())
+        self.gl_box.setSizePolicy(sizePolicy3)
+        font = QFont()
+        font.setPointSize(12)
+        self.gl_box.setFont(font)
+        self.horizontalLayout_4 = QHBoxLayout(self.gl_box)
+#ifndef Q_OS_MAC
+        self.horizontalLayout_4.setSpacing(-1)
+#endif
+        self.horizontalLayout_4.setObjectName(u"horizontalLayout_4")
+        self.horizontalLayout_4.setContentsMargins(12, -1, -1, -1)
+
+        self.gridLayout.addWidget(self.gl_box, 0, 2, 5, 1)
+
+        self.compo_box = QGroupBox(self.centralwidget)
+        self.compo_box.setObjectName(u"compo_box")
+        self.compo_box.setMinimumSize(QSize(0, 120))
+
+        self.gridLayout.addWidget(self.compo_box, 7, 1, 1, 2)
 
         self.groupBox_11 = QGroupBox(self.centralwidget)
         self.groupBox_11.setObjectName(u"groupBox_11")
-        sizePolicy1.setHeightForWidth(self.groupBox_11.sizePolicy().hasHeightForWidth())
-        self.groupBox_11.setSizePolicy(sizePolicy1)
+        sizePolicy2.setHeightForWidth(self.groupBox_11.sizePolicy().hasHeightForWidth())
+        self.groupBox_11.setSizePolicy(sizePolicy2)
         self.groupBox_11.setMaximumSize(QSize(200, 16777215))
         self.verticalLayout_7 = QVBoxLayout(self.groupBox_11)
         self.verticalLayout_7.setObjectName(u"verticalLayout_7")
         self.verticalLayout_7.setContentsMargins(5, 5, 5, 5)
         self.sketch_list = QListWidget(self.groupBox_11)
         self.sketch_list.setObjectName(u"sketch_list")
-        sizePolicy2 = QSizePolicy(QSizePolicy.Policy.Expanding, QSizePolicy.Policy.Expanding)
-        sizePolicy2.setHorizontalStretch(0)
-        sizePolicy2.setVerticalStretch(0)
-        sizePolicy2.setHeightForWidth(self.sketch_list.sizePolicy().hasHeightForWidth())
-        self.sketch_list.setSizePolicy(sizePolicy2)
+        sizePolicy4 = QSizePolicy(QSizePolicy.Policy.Expanding, QSizePolicy.Policy.Expanding)
+        sizePolicy4.setHorizontalStretch(0)
+        sizePolicy4.setVerticalStretch(0)
+        sizePolicy4.setHeightForWidth(self.sketch_list.sizePolicy().hasHeightForWidth())
+        self.sketch_list.setSizePolicy(sizePolicy4)
         self.sketch_list.setSelectionRectVisible(True)
 
         self.verticalLayout_7.addWidget(self.sketch_list)
@@ -344,193 +544,7 @@ class Ui_fluencyCAD(object):
         self.verticalLayout_7.addWidget(self.groupBox_6)
 
 
-        self.gridLayout.addWidget(self.groupBox_11, 8, 0, 3, 1)
-
-        self.groupBox_4 = QGroupBox(self.centralwidget)
-        self.groupBox_4.setObjectName(u"groupBox_4")
-        self.verticalLayout_2 = QVBoxLayout(self.groupBox_4)
-        self.verticalLayout_2.setObjectName(u"verticalLayout_2")
-        self.pushButton_2 = QPushButton(self.groupBox_4)
-        self.pushButton_2.setObjectName(u"pushButton_2")
-
-        self.verticalLayout_2.addWidget(self.pushButton_2)
-
-        self.pb_export_step = QPushButton(self.groupBox_4)
-        self.pb_export_step.setObjectName(u"pb_export_step")
-
-        self.verticalLayout_2.addWidget(self.pb_export_step)
-
-        self.pb_export_iges = QPushButton(self.groupBox_4)
-        self.pb_export_iges.setObjectName(u"pb_export_iges")
-
-        self.verticalLayout_2.addWidget(self.pb_export_iges)
-
-
-        self.gridLayout.addWidget(self.groupBox_4, 2, 3, 1, 1)
-
-        self.InputTab = QTabWidget(self.centralwidget)
-        self.InputTab.setObjectName(u"InputTab")
-        sizePolicy3 = QSizePolicy(QSizePolicy.Policy.Expanding, QSizePolicy.Policy.Preferred)
-        sizePolicy3.setHorizontalStretch(0)
-        sizePolicy3.setVerticalStretch(0)
-        sizePolicy3.setHeightForWidth(self.InputTab.sizePolicy().hasHeightForWidth())
-        self.InputTab.setSizePolicy(sizePolicy3)
-        self.sketch_tab = QWidget()
-        self.sketch_tab.setObjectName(u"sketch_tab")
-        self.verticalLayout_4 = QVBoxLayout(self.sketch_tab)
-        self.verticalLayout_4.setObjectName(u"verticalLayout_4")
-        self.InputTab.addTab(self.sketch_tab, "")
-        self.code_tab = QWidget()
-        self.code_tab.setObjectName(u"code_tab")
-        self.verticalLayout = QVBoxLayout(self.code_tab)
-        self.verticalLayout.setObjectName(u"verticalLayout")
-        self.textEdit = QTextEdit(self.code_tab)
-        self.textEdit.setObjectName(u"textEdit")
-
-        self.verticalLayout.addWidget(self.textEdit)
-
-        self.groupBox_7 = QGroupBox(self.code_tab)
-        self.groupBox_7.setObjectName(u"groupBox_7")
-        self.gridLayout_5 = QGridLayout(self.groupBox_7)
-        self.gridLayout_5.setObjectName(u"gridLayout_5")
-        self.pushButton_5 = QPushButton(self.groupBox_7)
-        self.pushButton_5.setObjectName(u"pushButton_5")
-
-        self.gridLayout_5.addWidget(self.pushButton_5, 2, 0, 1, 1)
-
-        self.pushButton_4 = QPushButton(self.groupBox_7)
-        self.pushButton_4.setObjectName(u"pushButton_4")
-
-        self.gridLayout_5.addWidget(self.pushButton_4, 2, 1, 1, 1)
-
-        self.pb_apply_code = QPushButton(self.groupBox_7)
-        self.pb_apply_code.setObjectName(u"pb_apply_code")
-
-        self.gridLayout_5.addWidget(self.pb_apply_code, 1, 0, 1, 1)
-
-        self.pushButton = QPushButton(self.groupBox_7)
-        self.pushButton.setObjectName(u"pushButton")
-
-        self.gridLayout_5.addWidget(self.pushButton, 1, 1, 1, 1)
-
-
-        self.verticalLayout.addWidget(self.groupBox_7)
-
-        self.InputTab.addTab(self.code_tab, "")
-
-        self.gridLayout.addWidget(self.InputTab, 0, 1, 11, 1)
-
-        self.assembly_tools = QGroupBox(self.centralwidget)
-        self.assembly_tools.setObjectName(u"assembly_tools")
-        self.assembly_tools.setMinimumSize(QSize(0, 50))
-        self.gridLayout_12 = QGridLayout(self.assembly_tools)
-        self.gridLayout_12.setObjectName(u"gridLayout_12")
-        self.pb_compo_to_assembly = QPushButton(self.assembly_tools)
-        self.pb_compo_to_assembly.setObjectName(u"pb_compo_to_assembly")
-        self.pb_compo_to_assembly.setMinimumSize(QSize(50, 50))
-        self.pb_compo_to_assembly.setMaximumSize(QSize(50, 50))
-
-        self.gridLayout_12.addWidget(self.pb_compo_to_assembly, 0, 0, 1, 1)
-
-        self.pb_remove_compo_from_assembly = QPushButton(self.assembly_tools)
-        self.pb_remove_compo_from_assembly.setObjectName(u"pb_remove_compo_from_assembly")
-        self.pb_remove_compo_from_assembly.setEnabled(True)
-        sizePolicy.setHeightForWidth(self.pb_remove_compo_from_assembly.sizePolicy().hasHeightForWidth())
-        self.pb_remove_compo_from_assembly.setSizePolicy(sizePolicy)
-        self.pb_remove_compo_from_assembly.setMinimumSize(QSize(50, 50))
-        self.pb_remove_compo_from_assembly.setMaximumSize(QSize(50, 50))
-        self.pb_remove_compo_from_assembly.setLayoutDirection(Qt.LeftToRight)
-
-        self.gridLayout_12.addWidget(self.pb_remove_compo_from_assembly, 0, 1, 1, 1)
-
-
-        self.gridLayout.addWidget(self.assembly_tools, 12, 0, 1, 1)
-
-        self.gl_box = QGroupBox(self.centralwidget)
-        self.gl_box.setObjectName(u"gl_box")
-        sizePolicy4 = QSizePolicy(QSizePolicy.Policy.Expanding, QSizePolicy.Policy.Expanding)
-        sizePolicy4.setHorizontalStretch(0)
-        sizePolicy4.setVerticalStretch(4)
-        sizePolicy4.setHeightForWidth(self.gl_box.sizePolicy().hasHeightForWidth())
-        self.gl_box.setSizePolicy(sizePolicy4)
-        font = QFont()
-        font.setPointSize(12)
-        self.gl_box.setFont(font)
-        self.horizontalLayout_4 = QHBoxLayout(self.gl_box)
-#ifndef Q_OS_MAC
-        self.horizontalLayout_4.setSpacing(-1)
-#endif
-        self.horizontalLayout_4.setObjectName(u"horizontalLayout_4")
-        self.horizontalLayout_4.setContentsMargins(12, -1, -1, -1)
-
-        self.gridLayout.addWidget(self.gl_box, 0, 2, 11, 1)
-
-        self.groupBox_3 = QGroupBox(self.centralwidget)
-        self.groupBox_3.setObjectName(u"groupBox_3")
-        sizePolicy.setHeightForWidth(self.groupBox_3.sizePolicy().hasHeightForWidth())
-        self.groupBox_3.setSizePolicy(sizePolicy)
-        self.groupBox_3.setMaximumSize(QSize(200, 16777213))
-        self.gridLayout_4 = QGridLayout(self.groupBox_3)
-        self.gridLayout_4.setObjectName(u"gridLayout_4")
-        self.pb_con_vert = QPushButton(self.groupBox_3)
-        self.pb_con_vert.setObjectName(u"pb_con_vert")
-        self.pb_con_vert.setCheckable(True)
-        self.pb_con_vert.setAutoExclusive(False)
-
-        self.gridLayout_4.addWidget(self.pb_con_vert, 3, 1, 1, 1)
-
-        self.pb_con_mid = QPushButton(self.groupBox_3)
-        self.pb_con_mid.setObjectName(u"pb_con_mid")
-        self.pb_con_mid.setCheckable(True)
-        self.pb_con_mid.setAutoExclusive(False)
-
-        self.gridLayout_4.addWidget(self.pb_con_mid, 2, 0, 1, 1)
-
-        self.pb_con_dist = QPushButton(self.groupBox_3)
-        self.pb_con_dist.setObjectName(u"pb_con_dist")
-        self.pb_con_dist.setCheckable(True)
-        self.pb_con_dist.setAutoExclusive(False)
-        self.pb_con_dist.setAutoRepeatDelay(297)
-
-        self.gridLayout_4.addWidget(self.pb_con_dist, 4, 0, 1, 1)
-
-        self.pb_con_line = QPushButton(self.groupBox_3)
-        self.pb_con_line.setObjectName(u"pb_con_line")
-        self.pb_con_line.setCheckable(True)
-        self.pb_con_line.setAutoExclusive(False)
-
-        self.gridLayout_4.addWidget(self.pb_con_line, 1, 1, 1, 1)
-
-        self.pb_con_perp = QPushButton(self.groupBox_3)
-        self.pb_con_perp.setObjectName(u"pb_con_perp")
-        self.pb_con_perp.setCheckable(True)
-        self.pb_con_perp.setAutoExclusive(False)
-
-        self.gridLayout_4.addWidget(self.pb_con_perp, 2, 1, 1, 1)
-
-        self.pb_con_sym = QPushButton(self.groupBox_3)
-        self.pb_con_sym.setObjectName(u"pb_con_sym")
-        self.pb_con_sym.setCheckable(True)
-        self.pb_con_sym.setAutoExclusive(False)
-
-        self.gridLayout_4.addWidget(self.pb_con_sym, 4, 1, 1, 1)
-
-        self.pb_con_horiz = QPushButton(self.groupBox_3)
-        self.pb_con_horiz.setObjectName(u"pb_con_horiz")
-        self.pb_con_horiz.setCheckable(True)
-        self.pb_con_horiz.setAutoExclusive(False)
-
-        self.gridLayout_4.addWidget(self.pb_con_horiz, 3, 0, 1, 1)
-
-        self.pb_con_ptpt = QPushButton(self.groupBox_3)
-        self.pb_con_ptpt.setObjectName(u"pb_con_ptpt")
-        self.pb_con_ptpt.setCheckable(True)
-        self.pb_con_ptpt.setAutoExclusive(False)
-
-        self.gridLayout_4.addWidget(self.pb_con_ptpt, 1, 0, 1, 1)
-
-
-        self.gridLayout.addWidget(self.groupBox_3, 4, 0, 1, 1)
+        self.gridLayout.addWidget(self.groupBox_11, 4, 0, 1, 1)
 
         self.groupBox_2 = QGroupBox(self.centralwidget)
         self.groupBox_2.setObjectName(u"groupBox_2")
@@ -558,7 +572,7 @@ class Ui_fluencyCAD(object):
         self.pb_circtool.setCheckable(True)
         self.pb_circtool.setAutoExclusive(False)
 
-        self.gridLayout_2.addWidget(self.pb_circtool, 1, 0, 1, 1, Qt.AlignTop)
+        self.gridLayout_2.addWidget(self.pb_circtool, 1, 0, 1, 1)
 
         self.pb_enable_construct = QPushButton(self.groupBox_2)
         self.pb_enable_construct.setObjectName(u"pb_enable_construct")
@@ -586,7 +600,7 @@ class Ui_fluencyCAD(object):
         self.pb_slotool.setCheckable(True)
         self.pb_slotool.setAutoExclusive(False)
 
-        self.gridLayout_2.addWidget(self.pb_slotool, 1, 1, 1, 1, Qt.AlignTop)
+        self.gridLayout_2.addWidget(self.pb_slotool, 1, 1, 1, 1)
 
         self.line = QFrame(self.groupBox_2)
         self.line.setObjectName(u"line")
@@ -601,54 +615,126 @@ class Ui_fluencyCAD(object):
         self.gridLayout_2.addWidget(self.pb_offset_tool, 2, 1, 1, 1)
 
 
-        self.gridLayout.addWidget(self.groupBox_2, 2, 0, 1, 1)
+        self.gridLayout.addWidget(self.groupBox_2, 1, 0, 1, 1)
 
         self.assembly_box = QGroupBox(self.centralwidget)
         self.assembly_box.setObjectName(u"assembly_box")
-        self.assembly_box.setMinimumSize(QSize(0, 50))
+        self.assembly_box.setMinimumSize(QSize(0, 120))
 
-        self.gridLayout.addWidget(self.assembly_box, 12, 1, 1, 2)
+        self.gridLayout.addWidget(self.assembly_box, 8, 1, 1, 2)
 
-        self.joint_tools = QGroupBox(self.centralwidget)
-        self.joint_tools.setObjectName(u"joint_tools")
-        self.joint_tools.setMinimumSize(QSize(0, 50))
-        self.gridLayout_10 = QGridLayout(self.joint_tools)
-        self.gridLayout_10.setObjectName(u"gridLayout_10")
-        self.pb_remove_connector = QPushButton(self.joint_tools)
-        self.pb_remove_connector.setObjectName(u"pb_remove_connector")
-        self.pb_remove_connector.setMinimumSize(QSize(50, 50))
-        self.pb_remove_connector.setMaximumSize(QSize(50, 50))
+        self.groupBox = QGroupBox(self.centralwidget)
+        self.groupBox.setObjectName(u"groupBox")
+        self.groupBox.setMaximumSize(QSize(200, 16777215))
+        self.gridLayout_3 = QGridLayout(self.groupBox)
+        self.gridLayout_3.setObjectName(u"gridLayout_3")
+        self.pb_chamfer_op = QPushButton(self.groupBox)
+        self.pb_chamfer_op.setObjectName(u"pb_chamfer_op")
 
-        self.gridLayout_10.addWidget(self.pb_remove_connector, 0, 2, 1, 1)
+        self.gridLayout_3.addWidget(self.pb_chamfer_op, 2, 1, 1, 1)
 
-        self.pb_add_connector = QPushButton(self.joint_tools)
-        self.pb_add_connector.setObjectName(u"pb_add_connector")
-        self.pb_add_connector.setMinimumSize(QSize(50, 50))
-        self.pb_add_connector.setMaximumSize(QSize(50, 50))
+        self.pb_fillet_op = QPushButton(self.groupBox)
+        self.pb_fillet_op.setObjectName(u"pb_fillet_op")
 
-        self.gridLayout_10.addWidget(self.pb_add_connector, 0, 1, 1, 1)
+        self.gridLayout_3.addWidget(self.pb_fillet_op, 2, 0, 1, 1)
 
-        self.pb_add_connector_2 = QPushButton(self.joint_tools)
-        self.pb_add_connector_2.setObjectName(u"pb_add_connector_2")
-        self.pb_add_connector_2.setMinimumSize(QSize(50, 50))
-        self.pb_add_connector_2.setMaximumSize(QSize(50, 50))
+        self.pb_thread = QPushButton(self.groupBox)
+        self.pb_thread.setObjectName(u"pb_thread")
 
-        self.gridLayout_10.addWidget(self.pb_add_connector_2, 1, 1, 1, 1)
+        self.gridLayout_3.addWidget(self.pb_thread, 6, 0, 1, 1)
 
-        self.pb_add_connector_3 = QPushButton(self.joint_tools)
-        self.pb_add_connector_3.setObjectName(u"pb_add_connector_3")
-        self.pb_add_connector_3.setMinimumSize(QSize(50, 50))
-        self.pb_add_connector_3.setMaximumSize(QSize(50, 50))
+        self.pb_extrdop = QPushButton(self.groupBox)
+        self.pb_extrdop.setObjectName(u"pb_extrdop")
 
-        self.gridLayout_10.addWidget(self.pb_add_connector_3, 1, 2, 1, 1)
+        self.gridLayout_3.addWidget(self.pb_extrdop, 0, 0, 1, 1)
+
+        self.pb_revop = QPushButton(self.groupBox)
+        self.pb_revop.setObjectName(u"pb_revop")
+
+        self.gridLayout_3.addWidget(self.pb_revop, 4, 1, 1, 1)
+
+        self.pb_cutop = QPushButton(self.groupBox)
+        self.pb_cutop.setObjectName(u"pb_cutop")
+
+        self.gridLayout_3.addWidget(self.pb_cutop, 0, 1, 1, 1)
+
+        self.pb_arrayop = QPushButton(self.groupBox)
+        self.pb_arrayop.setObjectName(u"pb_arrayop")
+
+        self.gridLayout_3.addWidget(self.pb_arrayop, 4, 0, 1, 1)
+
+        self.pb_combop = QPushButton(self.groupBox)
+        self.pb_combop.setObjectName(u"pb_combop")
+
+        self.gridLayout_3.addWidget(self.pb_combop, 1, 0, 1, 1)
+
+        self.pb_moveop = QPushButton(self.groupBox)
+        self.pb_moveop.setObjectName(u"pb_moveop")
+
+        self.gridLayout_3.addWidget(self.pb_moveop, 1, 1, 1, 1)
+
+        self.pb_mirror_op = QPushButton(self.groupBox)
+        self.pb_mirror_op.setObjectName(u"pb_mirror_op")
+
+        self.gridLayout_3.addWidget(self.pb_mirror_op, 6, 1, 1, 1)
 
 
-        self.gridLayout.addWidget(self.joint_tools, 11, 3, 2, 1)
+        self.gridLayout.addWidget(self.groupBox, 0, 3, 1, 1)
+
+        self.line_3 = QFrame(self.centralwidget)
+        self.line_3.setObjectName(u"line_3")
+        self.line_3.setFrameShape(QFrame.Shape.HLine)
+        self.line_3.setFrameShadow(QFrame.Shadow.Sunken)
+
+        self.gridLayout.addWidget(self.line_3, 5, 0, 1, 4)
+
+        self.groupBox_10 = QGroupBox(self.centralwidget)
+        self.groupBox_10.setObjectName(u"groupBox_10")
+        sizePolicy2.setHeightForWidth(self.groupBox_10.sizePolicy().hasHeightForWidth())
+        self.groupBox_10.setSizePolicy(sizePolicy2)
+        self.groupBox_10.setMaximumSize(QSize(200, 16777215))
+        self.verticalLayout_6 = QVBoxLayout(self.groupBox_10)
+        self.verticalLayout_6.setObjectName(u"verticalLayout_6")
+        self.verticalLayout_6.setContentsMargins(5, 5, 5, 5)
+        self.body_list = QListWidget(self.groupBox_10)
+        self.body_list.setObjectName(u"body_list")
+        self.body_list.setSelectionRectVisible(True)
+
+        self.verticalLayout_6.addWidget(self.body_list)
+
+        self.groupBox_8 = QGroupBox(self.groupBox_10)
+        self.groupBox_8.setObjectName(u"groupBox_8")
+        sizePolicy.setHeightForWidth(self.groupBox_8.sizePolicy().hasHeightForWidth())
+        self.groupBox_8.setSizePolicy(sizePolicy)
+        self.groupBox_8.setMaximumSize(QSize(200, 16777215))
+        self.gridLayout_8 = QGridLayout(self.groupBox_8)
+        self.gridLayout_8.setObjectName(u"gridLayout_8")
+        self.gridLayout_8.setContentsMargins(2, 2, 2, 2)
+        self.pb_body_hide = QPushButton(self.groupBox_8)
+        self.pb_body_hide.setObjectName(u"pb_body_hide")
+
+        self.gridLayout_8.addWidget(self.pb_body_hide, 0, 1, 1, 1)
+
+        self.pb_update_body = QPushButton(self.groupBox_8)
+        self.pb_update_body.setObjectName(u"pb_update_body")
+
+        self.gridLayout_8.addWidget(self.pb_update_body, 0, 0, 1, 1)
+
+        self.pb_del_body = QPushButton(self.groupBox_8)
+        self.pb_del_body.setObjectName(u"pb_del_body")
+
+        self.gridLayout_8.addWidget(self.pb_del_body, 0, 2, 1, 1)
+
+
+        self.verticalLayout_6.addWidget(self.groupBox_8)
+
+
+        self.gridLayout.addWidget(self.groupBox_10, 2, 3, 2, 1)
 
         fluencyCAD.setCentralWidget(self.centralwidget)
         self.menubar = QMenuBar(fluencyCAD)
         self.menubar.setObjectName(u"menubar")
-        self.menubar.setGeometry(QRect(0, 0, 1941, 24))
+        self.menubar.setGeometry(QRect(0, 0, 2551, 24))
         self.menuFile = QMenu(self.menubar)
         self.menuFile.setObjectName(u"menuFile")
         self.menuSettings = QMenu(self.menubar)
@@ -718,17 +804,54 @@ class Ui_fluencyCAD(object):
         self.pushButton_8.setText(QCoreApplication.translate("fluencyCAD", u"Pnt", None))
         self.pb_snap_midp.setText(QCoreApplication.translate("fluencyCAD", u"MidP", None))
         self.pb_snap_angle.setText(QCoreApplication.translate("fluencyCAD", u"Angles", None))
-        self.groupBox.setTitle(QCoreApplication.translate("fluencyCAD", u"Modify", None))
-        self.pb_revop.setText(QCoreApplication.translate("fluencyCAD", u"Rev", None))
-        self.pb_extrdop.setText(QCoreApplication.translate("fluencyCAD", u"Extrd", None))
-        self.pb_arrayop.setText(QCoreApplication.translate("fluencyCAD", u"Arry", None))
-        self.pb_cutop.setText(QCoreApplication.translate("fluencyCAD", u"Cut", None))
-        self.pb_combop.setText(QCoreApplication.translate("fluencyCAD", u"Comb", None))
-        self.pb_moveop.setText(QCoreApplication.translate("fluencyCAD", u"Mve", None))
+        self.groupBox_4.setTitle(QCoreApplication.translate("fluencyCAD", u"Export", None))
+        self.pushButton_2.setText(QCoreApplication.translate("fluencyCAD", u"STL", None))
+        self.pb_export_iges.setText(QCoreApplication.translate("fluencyCAD", u"IGES", None))
+        self.pb_export_step.setText(QCoreApplication.translate("fluencyCAD", u"STEP", None))
+        self.InputTab.setTabText(self.InputTab.indexOf(self.sketch_tab), QCoreApplication.translate("fluencyCAD", u"Sketch", None))
+        self.groupBox_7.setTitle(QCoreApplication.translate("fluencyCAD", u"Executive", None))
+        self.pushButton_5.setText(QCoreApplication.translate("fluencyCAD", u"Load Code", None))
+        self.pushButton_4.setText(QCoreApplication.translate("fluencyCAD", u"Save code", None))
+        self.pb_apply_code.setText(QCoreApplication.translate("fluencyCAD", u"Apply Code", None))
+        self.pushButton.setText(QCoreApplication.translate("fluencyCAD", u"Delete Code", None))
+        self.InputTab.setTabText(self.InputTab.indexOf(self.code_tab), QCoreApplication.translate("fluencyCAD", u"Code", None))
         self.compo_tool_box.setTitle(QCoreApplication.translate("fluencyCAD", u"Component Tools", None))
         self.pb_new_compo.setText(QCoreApplication.translate("fluencyCAD", u"New", None))
         self.pb_del_compo.setText(QCoreApplication.translate("fluencyCAD", u"Del", None))
-        self.compo_box.setTitle(QCoreApplication.translate("fluencyCAD", u"Components", None))
+        self.groupBox_3.setTitle(QCoreApplication.translate("fluencyCAD", u"Constrain", None))
+#if QT_CONFIG(tooltip)
+        self.pb_con_ptpt.setToolTip(QCoreApplication.translate("fluencyCAD", u"Poin to Point Constrain", None))
+#endif // QT_CONFIG(tooltip)
+        self.pb_con_ptpt.setText(QCoreApplication.translate("fluencyCAD", u"Pt_Pt", None))
+#if QT_CONFIG(tooltip)
+        self.pb_con_vert.setToolTip(QCoreApplication.translate("fluencyCAD", u"Vertical Constrain", None))
+#endif // QT_CONFIG(tooltip)
+        self.pb_con_vert.setText(QCoreApplication.translate("fluencyCAD", u"Vert", None))
+        self.pb_con_sym.setText(QCoreApplication.translate("fluencyCAD", u"Symetrc", None))
+#if QT_CONFIG(tooltip)
+        self.pb_con_mid.setToolTip(QCoreApplication.translate("fluencyCAD", u"Point to Middle Point Constrain", None))
+#endif // QT_CONFIG(tooltip)
+        self.pb_con_mid.setText(QCoreApplication.translate("fluencyCAD", u"Pt_Mid_L", None))
+#if QT_CONFIG(tooltip)
+        self.pb_con_line.setToolTip(QCoreApplication.translate("fluencyCAD", u"Point to Line Constrain", None))
+#endif // QT_CONFIG(tooltip)
+        self.pb_con_line.setText(QCoreApplication.translate("fluencyCAD", u"Pt_Lne", None))
+#if QT_CONFIG(tooltip)
+        self.pb_con_horiz.setToolTip(QCoreApplication.translate("fluencyCAD", u"Horizontal Constrain ", None))
+#endif // QT_CONFIG(tooltip)
+        self.pb_con_horiz.setText(QCoreApplication.translate("fluencyCAD", u"Horiz", None))
+#if QT_CONFIG(tooltip)
+        self.pb_con_dist.setToolTip(QCoreApplication.translate("fluencyCAD", u"Dimension of Line of Distance from Point to Line", None))
+#endif // QT_CONFIG(tooltip)
+        self.pb_con_dist.setText(QCoreApplication.translate("fluencyCAD", u"Distnce", None))
+#if QT_CONFIG(tooltip)
+        self.pb_con_perp.setToolTip(QCoreApplication.translate("fluencyCAD", u"Constrain Line perpendicular to another line.", None))
+#endif // QT_CONFIG(tooltip)
+        self.pb_con_perp.setText(QCoreApplication.translate("fluencyCAD", u"Perp_Lne", None))
+        self.pb_con_diameter.setText(QCoreApplication.translate("fluencyCAD", u"Diameter", None))
+        self.assembly_tools.setTitle(QCoreApplication.translate("fluencyCAD", u"Assembly Tools", None))
+        self.pb_compo_to_assembly.setText(QCoreApplication.translate("fluencyCAD", u"Add", None))
+        self.pb_remove_compo_from_assembly.setText(QCoreApplication.translate("fluencyCAD", u"Rem", None))
         self.groupBox_9.setTitle(QCoreApplication.translate("fluencyCAD", u"Workplanes", None))
 #if QT_CONFIG(tooltip)
         self.pb_origin_wp.setToolTip(QCoreApplication.translate("fluencyCAD", u"<W>orking Plane at 0, 0, 0", None))
@@ -770,61 +893,23 @@ class Ui_fluencyCAD(object):
 #if QT_CONFIG(shortcut)
         self.pb_wp_new.setShortcut(QCoreApplication.translate("fluencyCAD", u"Shift+W", None))
 #endif // QT_CONFIG(shortcut)
-        self.groupBox_10.setTitle(QCoreApplication.translate("fluencyCAD", u"Bodys / Operations", None))
-        self.groupBox_8.setTitle(QCoreApplication.translate("fluencyCAD", u"Tools", None))
-        self.pb_del_body.setText(QCoreApplication.translate("fluencyCAD", u"Del", None))
-        self.pb_update_body.setText(QCoreApplication.translate("fluencyCAD", u"Upd", None))
-        self.pb_edt_sktch_3.setText(QCoreApplication.translate("fluencyCAD", u"Nothing", None))
+        self.groupBox_12.setTitle(QCoreApplication.translate("fluencyCAD", u"Component Connections", None))
+        self.groupBox_13.setTitle(QCoreApplication.translate("fluencyCAD", u"Tools", None))
+        self.pb_del_connection.setText(QCoreApplication.translate("fluencyCAD", u"Del", None))
+        self.pb_update_connection.setText(QCoreApplication.translate("fluencyCAD", u"Upd", None))
+        self.pb_edt_sktch_4.setText(QCoreApplication.translate("fluencyCAD", u"Nothing", None))
+        self.joint_tools.setTitle(QCoreApplication.translate("fluencyCAD", u"Joint Tools", None))
+        self.pb_add_connector.setText(QCoreApplication.translate("fluencyCAD", u"+ Cnct", None))
+        self.pb_remove_connector.setText(QCoreApplication.translate("fluencyCAD", u"- Cnct", None))
+        self.pb_add_connector_3.setText(QCoreApplication.translate("fluencyCAD", u"-Jnt", None))
+        self.pb_add_connector_2.setText(QCoreApplication.translate("fluencyCAD", u"+Jnt", None))
+        self.gl_box.setTitle(QCoreApplication.translate("fluencyCAD", u"Model Viewer", None))
+        self.compo_box.setTitle(QCoreApplication.translate("fluencyCAD", u"Components", None))
         self.groupBox_11.setTitle(QCoreApplication.translate("fluencyCAD", u"Sketch", None))
         self.groupBox_6.setTitle(QCoreApplication.translate("fluencyCAD", u"Tools", None))
         self.pb_edt_sktch.setText(QCoreApplication.translate("fluencyCAD", u"Edt", None))
         self.pb_nw_sktch.setText(QCoreApplication.translate("fluencyCAD", u"Add", None))
         self.pb_del_sketch.setText(QCoreApplication.translate("fluencyCAD", u"Del", None))
-        self.groupBox_4.setTitle(QCoreApplication.translate("fluencyCAD", u"Export", None))
-        self.pushButton_2.setText(QCoreApplication.translate("fluencyCAD", u"STL", None))
-        self.pb_export_step.setText(QCoreApplication.translate("fluencyCAD", u"STEP", None))
-        self.pb_export_iges.setText(QCoreApplication.translate("fluencyCAD", u"IGES", None))
-        self.InputTab.setTabText(self.InputTab.indexOf(self.sketch_tab), QCoreApplication.translate("fluencyCAD", u"Sketch", None))
-        self.groupBox_7.setTitle(QCoreApplication.translate("fluencyCAD", u"Executive", None))
-        self.pushButton_5.setText(QCoreApplication.translate("fluencyCAD", u"Load Code", None))
-        self.pushButton_4.setText(QCoreApplication.translate("fluencyCAD", u"Save code", None))
-        self.pb_apply_code.setText(QCoreApplication.translate("fluencyCAD", u"Apply Code", None))
-        self.pushButton.setText(QCoreApplication.translate("fluencyCAD", u"Delete Code", None))
-        self.InputTab.setTabText(self.InputTab.indexOf(self.code_tab), QCoreApplication.translate("fluencyCAD", u"Code", None))
-        self.assembly_tools.setTitle(QCoreApplication.translate("fluencyCAD", u"Assembly Tools", None))
-        self.pb_compo_to_assembly.setText(QCoreApplication.translate("fluencyCAD", u"Add", None))
-        self.pb_remove_compo_from_assembly.setText(QCoreApplication.translate("fluencyCAD", u"Rem", None))
-        self.gl_box.setTitle(QCoreApplication.translate("fluencyCAD", u"Model Viewer", None))
-        self.groupBox_3.setTitle(QCoreApplication.translate("fluencyCAD", u"Constrain", None))
-#if QT_CONFIG(tooltip)
-        self.pb_con_vert.setToolTip(QCoreApplication.translate("fluencyCAD", u"Vertical Constrain", None))
-#endif // QT_CONFIG(tooltip)
-        self.pb_con_vert.setText(QCoreApplication.translate("fluencyCAD", u"Vert", None))
-#if QT_CONFIG(tooltip)
-        self.pb_con_mid.setToolTip(QCoreApplication.translate("fluencyCAD", u"Point to Middle Point Constrain", None))
-#endif // QT_CONFIG(tooltip)
-        self.pb_con_mid.setText(QCoreApplication.translate("fluencyCAD", u"Pt_Mid_L", None))
-#if QT_CONFIG(tooltip)
-        self.pb_con_dist.setToolTip(QCoreApplication.translate("fluencyCAD", u"Dimension of Line of Distance from Point to Line", None))
-#endif // QT_CONFIG(tooltip)
-        self.pb_con_dist.setText(QCoreApplication.translate("fluencyCAD", u"Distnce", None))
-#if QT_CONFIG(tooltip)
-        self.pb_con_line.setToolTip(QCoreApplication.translate("fluencyCAD", u"Point to Line Constrain", None))
-#endif // QT_CONFIG(tooltip)
-        self.pb_con_line.setText(QCoreApplication.translate("fluencyCAD", u"Pt_Lne", None))
-#if QT_CONFIG(tooltip)
-        self.pb_con_perp.setToolTip(QCoreApplication.translate("fluencyCAD", u"Constrain Line perpendicular to another line.", None))
-#endif // QT_CONFIG(tooltip)
-        self.pb_con_perp.setText(QCoreApplication.translate("fluencyCAD", u"Perp_Lne", None))
-        self.pb_con_sym.setText(QCoreApplication.translate("fluencyCAD", u"Symetrc", None))
-#if QT_CONFIG(tooltip)
-        self.pb_con_horiz.setToolTip(QCoreApplication.translate("fluencyCAD", u"Horizontal Constrain ", None))
-#endif // QT_CONFIG(tooltip)
-        self.pb_con_horiz.setText(QCoreApplication.translate("fluencyCAD", u"Horiz", None))
-#if QT_CONFIG(tooltip)
-        self.pb_con_ptpt.setToolTip(QCoreApplication.translate("fluencyCAD", u"Poin to Point Constrain", None))
-#endif // QT_CONFIG(tooltip)
-        self.pb_con_ptpt.setText(QCoreApplication.translate("fluencyCAD", u"Pt_Pt", None))
         self.groupBox_2.setTitle(QCoreApplication.translate("fluencyCAD", u"Drawing", None))
         self.pb_arc_tool.setText(QCoreApplication.translate("fluencyCAD", u"Arc", None))
         self.pb_rectool.setText(QCoreApplication.translate("fluencyCAD", u"Rctgl", None))
@@ -841,11 +926,22 @@ class Ui_fluencyCAD(object):
 #endif // QT_CONFIG(tooltip)
         self.pb_offset_tool.setText(QCoreApplication.translate("fluencyCAD", u"Offst", None))
         self.assembly_box.setTitle(QCoreApplication.translate("fluencyCAD", u"Assembly", None))
-        self.joint_tools.setTitle(QCoreApplication.translate("fluencyCAD", u"Joint Tools", None))
-        self.pb_remove_connector.setText(QCoreApplication.translate("fluencyCAD", u"- Cnct", None))
-        self.pb_add_connector.setText(QCoreApplication.translate("fluencyCAD", u"+ Cnct", None))
-        self.pb_add_connector_2.setText(QCoreApplication.translate("fluencyCAD", u"+Jnt", None))
-        self.pb_add_connector_3.setText(QCoreApplication.translate("fluencyCAD", u"-Jnt", None))
+        self.groupBox.setTitle(QCoreApplication.translate("fluencyCAD", u"Modify", None))
+        self.pb_chamfer_op.setText(QCoreApplication.translate("fluencyCAD", u"Chamfer", None))
+        self.pb_fillet_op.setText(QCoreApplication.translate("fluencyCAD", u"Fillet", None))
+        self.pb_thread.setText(QCoreApplication.translate("fluencyCAD", u"Thread", None))
+        self.pb_extrdop.setText(QCoreApplication.translate("fluencyCAD", u"Extrd", None))
+        self.pb_revop.setText(QCoreApplication.translate("fluencyCAD", u"Rev", None))
+        self.pb_cutop.setText(QCoreApplication.translate("fluencyCAD", u"Cut", None))
+        self.pb_arrayop.setText(QCoreApplication.translate("fluencyCAD", u"Arry", None))
+        self.pb_combop.setText(QCoreApplication.translate("fluencyCAD", u"Comb", None))
+        self.pb_moveop.setText(QCoreApplication.translate("fluencyCAD", u"Mve", None))
+        self.pb_mirror_op.setText(QCoreApplication.translate("fluencyCAD", u"Mirror", None))
+        self.groupBox_10.setTitle(QCoreApplication.translate("fluencyCAD", u"Bodys / Operations", None))
+        self.groupBox_8.setTitle(QCoreApplication.translate("fluencyCAD", u"Tools", None))
+        self.pb_body_hide.setText(QCoreApplication.translate("fluencyCAD", u"Hide", None))
+        self.pb_update_body.setText(QCoreApplication.translate("fluencyCAD", u"Upd", None))
+        self.pb_del_body.setText(QCoreApplication.translate("fluencyCAD", u"Del", None))
         self.menuFile.setTitle(QCoreApplication.translate("fluencyCAD", u"File", None))
         self.menuSettings.setTitle(QCoreApplication.translate("fluencyCAD", u"Settings", None))
     # retranslateUi

src/fluency/geometry/base.py

@@ -406,6 +406,11 @@ class SketchInterface(ABC):
         """Constrain two circles to have equal radius."""
         pass
 
+    @abstractmethod
+    def constrain_diameter(self, circle: SketchEntity, diameter: float) -> bool:
+        """Set the diameter of a circle."""
+        pass
+
     @abstractmethod
     def constrain_fixed(self, entity: SketchEntity) -> bool:
         """Fix an entity in place."""

src/fluency/geometry_occ/kernel.py

@@ -5,6 +5,7 @@ This module provides a concrete implementation of the geometry kernel
 using OCP (OpenCASCADE Python bindings).
 """
 
+import logging
 from typing import List, Tuple, Optional, Any, Dict
 import numpy as np
 
@@ -16,6 +17,35 @@ from fluency.geometry.base import (
 )
 
 
+
+logger = logging.getLogger(__name__)
+
+def _curve_is_linear(occ_edge: Any) -> bool:
+    """Return True if *occ_edge* has a linear or chamferable curve type.
+
+    ``BRepFilletAPI_MakeChamfer`` and ``BRepFilletAPI_MakeFillet`` crash
+    (segfault) on circular/elliptical curves.  We pre-filter those out.
+    """
+    from OCP.BRepAdaptor import BRepAdaptor_Curve
+    from OCP.GeomAbs import GeomAbs_CurveType
+
+    try:
+        ad = BRepAdaptor_Curve(occ_edge)
+        ct = ad.GetType()
+    except Exception:
+        # If we can't classify, assume it's safe (will be caught later).
+        return True
+    # Chamfer/fillet only support linear curves reliably.
+    return ct in (
+        GeomAbs_CurveType.GeomAbs_Line,
+        GeomAbs_CurveType.GeomAbs_BSplineCurve,
+        GeomAbs_CurveType.GeomAbs_BezierCurve,
+        GeomAbs_CurveType.GeomAbs_OffsetCurve,
+        GeomAbs_CurveType.GeomAbs_Parabola,
+        GeomAbs_CurveType.GeomAbs_Hyperbola,
+    )
+
+
 class OCCGeometryObject(GeometryObject):
     """Geometry object wrapper for OpenCASCADE shapes."""
 
@@ -54,6 +84,7 @@ class OCGeometryKernel(GeometryKernel):
     def create_point(self, x: float, y: float) -> GeometryObject:
         """Create a 2D point."""
         from OCP.gp import gp_Pnt
+
         return OCCGeometryObject(gp_Pnt(x, y, 0))
 
     def create_line(self, start: Point2D, end: Point2D) -> GeometryObject:
@@ -61,9 +92,7 @@ class OCGeometryKernel(GeometryKernel):
         from OCP.gp import gp_Pnt
         from OCP.BRepBuilderAPI import BRepBuilderAPI_MakeEdge
 
-        edge = BRepBuilderAPI_MakeEdge(
-            gp_Pnt(start.x, start.y, 0), gp_Pnt(end.x, end.y, 0)
-        ).Edge()
+        edge = BRepBuilderAPI_MakeEdge(gp_Pnt(start.x, start.y, 0), gp_Pnt(end.x, end.y, 0)).Edge()
         return OCCGeometryObject(edge, {"type": "line"})
 
     def create_circle(self, center: Point2D, radius: float) -> GeometryObject:
@@ -71,14 +100,12 @@ class OCGeometryKernel(GeometryKernel):
         from OCP.gp import gp_Pnt, gp_Dir, gp_Ax2, gp_Circ
         from OCP.BRepBuilderAPI import BRepBuilderAPI_MakeEdge
 
-        circ = gp_Circ(
-            gp_Ax2(gp_Pnt(center.x, center.y, 0), gp_Dir(0, 0, 1)), radius
-        )
+        circ = gp_Circ(gp_Ax2(gp_Pnt(center.x, center.y, 0), gp_Dir(0, 0, 1)), radius)
         edge = BRepBuilderAPI_MakeEdge(circ).Edge()
         return OCCGeometryObject(edge, {"type": "circle"})
 
     def create_arc(
-        self, center: Point2D, radius: float, start_angle: float, end_angle: float
+        self, center: Point2D, radius: float , start_angle: float, end_angle: float
     ) -> GeometryObject:
         """Create a 2D arc."""
         import math
@@ -88,9 +115,7 @@ class OCGeometryKernel(GeometryKernel):
         start_rad = math.radians(start_angle)
         end_rad = math.radians(end_angle)
 
-        circ = gp_Circ(
-            gp_Ax2(gp_Pnt(center.x, center.y, 0), gp_Dir(0, 0, 1)), radius
-        )
+        circ = gp_Circ(gp_Ax2(gp_Pnt(center.x, center.y, 0), gp_Dir(0, 0, 1)), radius)
         edge = BRepBuilderAPI_MakeEdge(circ, start_rad, end_rad).Edge()
         return OCCGeometryObject(edge, {"type": "arc"})
 
@@ -159,8 +184,7 @@ class OCGeometryKernel(GeometryKernel):
             face = self._get_shape(sketch)
         if face is None:
             raise ValueError(
-                "Cannot extrude: sketch has no geometry. "
-                "Draw a closed profile before extruding."
+                "Cannot extrude: sketch has no geometry. 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
@@ -204,6 +228,7 @@ class OCGeometryKernel(GeometryKernel):
     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:
@@ -240,6 +265,93 @@ class OCGeometryKernel(GeometryKernel):
             pass
         return None
 
+    @staticmethod
+    def find_coplanar_face(
+        shape: Any,
+        origin: Tuple[float, float, float],
+        normal: Tuple[float, float, float],
+        ref_center: Optional[Tuple[float, float, float]] = None,
+        angle_tol_deg: float = 5.0,
+        dist_tol: float = 1e-3,
+    ) -> Optional[Tuple[Any, Tuple[float, float, float]]]:
+        """Find a planar face on *shape* coplanar with the given plane.
+
+        Iterates the faces of *shape* and returns the first planar face whose
+        plane normal is parallel to *normal* (within *angle_tol_deg* degrees)
+        and whose plane passes through *origin* (within *dist_tol* distance).
+        When several faces match, the one whose surface centre is closest to
+        *ref_center* (if provided) is preferred.
+
+        Returns ``(face, center)`` where *center* is the surface centroid as a
+        3-tuple, or *None* if no matching face is found.
+        """
+        import math
+
+        from OCP.TopExp import TopExp_Explorer
+        from OCP.TopAbs import TopAbs_FACE
+        from OCP.TopoDS import TopoDS
+        from OCP.BRepAdaptor import BRepAdaptor_Surface
+        from OCP.GeomAbs import GeomAbs_Plane
+        from OCP.BRepGProp import BRepGProp
+        from OCP.GProp import GProp_GProps
+
+        import numpy as np
+
+        if shape is None:
+            return None
+        n = np.asarray(normal, dtype=float)
+        n = n / (np.linalg.norm(n) + 1e-30)
+        ox, oy, oz = origin
+
+        cos_tol = math.cos(math.radians(angle_tol_deg))
+        candidates: list = []
+
+        explorer = TopExp_Explorer(shape, TopAbs_FACE)
+        while explorer.More():
+            face = TopoDS.Face_s(explorer.Current())
+            try:
+                surf = BRepAdaptor_Surface(face)
+                if surf.GetType() != GeomAbs_Plane:
+                    explorer.Next()
+                    continue
+                plane = surf.Plane()
+                pn = np.array(
+                    [
+                        plane.Axis().Direction().X(),
+                        plane.Axis().Direction().Y(),
+                        plane.Axis().Direction().Z(),
+                    ],
+                    dtype=float,
+                )
+                # Check normals parallel (same or opposite direction)
+                cos_angle = abs(float(np.dot(n, pn)))
+                if cos_angle < cos_tol:
+                    explorer.Next()
+                    continue
+                # Check distance from plane to origin
+                pp = plane.Location()
+                d = abs(float(np.dot(n, np.array([pp.X() - ox, pp.Y() - oy, pp.Z() - oz]))))
+                if d > dist_tol:
+                    explorer.Next()
+                    continue
+                # Surface centroid via GProp (SurfaceProperties for faces)
+                props = GProp_GProps()
+                BRepGProp.SurfaceProperties_s(face, props)
+                c = props.CentreOfMass()
+                center = (float(c.X()), float(c.Y()), float(c.Z()))
+                candidates.append((face, center))
+            except Exception:
+                pass
+            explorer.Next()
+
+        if not candidates:
+            return None
+        if ref_center is not None and len(candidates) > 1:
+            rc = np.asarray(ref_center, dtype=float)
+            best = min(candidates, key=lambda fc: float(np.linalg.norm(np.asarray(fc[1]) - rc)))
+            return best
+        return candidates[0]
+
     def revolve(
         self,
         sketch: GeometryObject,
@@ -361,50 +473,82 @@ class OCGeometryKernel(GeometryKernel):
     def fillet(
         self, body: GeometryObject, radius: float, edges: Optional[List[Any]] = None
     ) -> GeometryObject:
-        """Apply fillet to edges."""
-        shape = self._get_shape(body)
+        """Apply fillet to edges. Skips edges that cannot be filleted."""
         from OCP.BRepFilletAPI import BRepFilletAPI_MakeFillet
 
-        fillet = BRepFilletAPI_MakeFillet(shape)
+        shape: Any = self._get_shape(body)
+        if shape is None:
+            return OCCGeometryObject(None, {"type": "fillet"})
 
-        if edges:
-            for edge in edges:
-                fillet.Add(radius, edge)
+        # Collect candidate edges
+        if edges is not None:
+            candidates = list(edges)
         else:
             from OCP.TopExp import TopExp_Explorer
             from OCP.TopAbs import TopAbs_EDGE
+            from OCP.TopoDS import TopoDS
 
             explorer = TopExp_Explorer(shape, TopAbs_EDGE)
+            candidates = []
             while explorer.More():
-                fillet.Add(radius, explorer.Current())
+                e = TopoDS.Edge_s(explorer.Current())
+                if _curve_is_linear(e):
+                    candidates.append(e)
                 explorer.Next()
 
-        fillet.Build()
-        return OCCGeometryObject(fillet.Shape(), {"type": "fillet"})
+        # Add all edges, then Build once — avoids OCC internal crashes
+        fl = BRepFilletAPI_MakeFillet(shape)
+        for edge in candidates:
+            try:
+                fl.Add(radius, edge)
+            except Exception:
+                pass  # skip edges that fail to add
+
+        fl.Build()
+        if fl.IsDone():
+            return OCCGeometryObject(fl.Shape(), {"type": "fillet"})
+        # If Build failed, return original shape (no fillet applied)
+        return OCCGeometryObject(shape, {"type": "fillet"})
 
     def chamfer(
         self, body: GeometryObject, size: float, edges: Optional[List[Any]] = None
     ) -> GeometryObject:
-        """Apply chamfer to edges."""
-        shape = self._get_shape(body)
+        """Apply chamfer to edges. Skips edges that cannot be chamfered."""
         from OCP.BRepFilletAPI import BRepFilletAPI_MakeChamfer
 
-        chamfer = BRepFilletAPI_MakeChamfer(shape)
+        shape: Any = self._get_shape(body)
+        if shape is None:
+            return OCCGeometryObject(None, {"type": "chamfer"})
 
-        if edges:
-            for edge in edges:
-                chamfer.Add(size, edge)
+        # Collect candidate edges
+        if edges is not None:
+            candidates = list(edges)
         else:
             from OCP.TopExp import TopExp_Explorer
             from OCP.TopAbs import TopAbs_EDGE
+            from OCP.TopoDS import TopoDS
 
             explorer = TopExp_Explorer(shape, TopAbs_EDGE)
+            candidates = []
             while explorer.More():
-                chamfer.Add(size, explorer.Current())
+                e = TopoDS.Edge_s(explorer.Current())
+                if _curve_is_linear(e):
+                    candidates.append(e)
                 explorer.Next()
 
-        chamfer.Build()
-        return OCCGeometryObject(chamfer.Shape(), {"type": "chamfer"})
+        # Add all edges, then Build once — avoids OCC internal crashes
+        mc = BRepFilletAPI_MakeChamfer(shape)
+        for edge in candidates:
+            try:
+                mc.Add(size, edge)
+            except Exception:
+                pass  # skip edges that fail to add
+
+        mc.Build()
+        if mc.IsDone():
+            return OCCGeometryObject(mc.Shape(), {"type": "chamfer"})
+        # If Build failed, return original shape (no chamfer applied)
+        return OCCGeometryObject(shape, {"type": "chamfer"})
 
     def shell(
         self, body: GeometryObject, thickness: float, faces_to_remove: Optional[List[Any]] = None
@@ -453,7 +597,6 @@ class OCGeometryKernel(GeometryKernel):
         origin: Tuple[float, float, float] = (0, 0, 0),
     ) -> GeometryObject:
         """Rotate a body around an axis."""
-        import math
         shape = self._get_shape(body)
         from OCP.BRepBuilderAPI import BRepBuilderAPI_Transform
         from OCP.gp import gp_Trsf, gp_Ax1, gp_Pnt, gp_Dir
@@ -494,6 +637,67 @@ class OCGeometryKernel(GeometryKernel):
 
         return OCCGeometryObject(transformer.Shape(), {"type": "mirrored"})
 
+    def pattern(
+        self,
+        body: GeometryObject,
+        pattern_type: str = "linear",
+        count: int = 2,
+        direction: Tuple[float, float, float] = (1, 0, 0),
+        spacing: float = 10.0,
+        axis: Tuple[float, float, float] = (0, 0, 1),
+        origin: Tuple[float, float, float] = (0.0, 0.0, 0.0),
+        angle: float = 360.0,
+    ) -> GeometryObject:
+        """Repeat *body* in a linear or circular array (pattern).
+
+        Linear: *count* copies spaced *spacing* mm apart along
+        *direction* (a negative spacing reverses the direction).
+
+        Circular: *count* copies rotated evenly around *axis* passing
+        through *origin*, distributed over a total angular span of
+        *angle* degrees (step = angle / count).  ``angle=360`` gives the
+        classic evenly-spaced full-circle bolt pattern.
+
+        Returns the union (compound when the copies don't touch) of the
+        original solid and all its copies — disjoint copies keep their
+        separate volumes inside one result object, touching copies fuse.
+        """
+        count = max(1, int(count))
+        if count <= 1:
+            return body
+
+        import math as _math
+
+        instances: list = [body]
+        if pattern_type == "circular":
+            # Normalize the rotation axis.
+            ax = float(axis[0]), float(axis[1]), float(axis[2])
+            norm = _math.sqrt(ax[0] * ax[0] + ax[1] * ax[1] + ax[2] * ax[2])
+            if norm < 1e-12:
+                ax = (0.0, 0.0, 1.0)
+            else:
+                ax = (ax[0] / norm, ax[1] / norm, ax[2] / norm)
+            step = _math.radians(float(angle)) / count
+            for i in range(1, count):
+                instances.append(self.rotate(body, ax, step * i, origin))
+        else:
+            d = float(direction[0]), float(direction[1]), float(direction[2])
+            norm = _math.sqrt(d[0] * d[0] + d[1] * d[1] + d[2] * d[2])
+            if norm < 1e-12:
+                d = (1.0, 0.0, 0.0)
+            else:
+                d = (d[0] / norm, d[1] / norm, d[2] / norm)
+            step = float(spacing)
+            for i in range(1, count):
+                instances.append(
+                    self.translate(
+                        body,
+                        (d[0] * step * i, d[1] * step * i, d[2] * step * i),
+                    )
+                )
+
+        return self.boolean_union(*instances)
+
     def export_step(self, body: GeometryObject, filepath: str, schema: str = "AP214") -> bool:
         """Export to STEP format."""
         try:
@@ -562,6 +766,52 @@ class OCGeometryKernel(GeometryKernel):
         shape = reader.OneShape()
         return OCCGeometryObject(shape, {"type": "imported_step"})
 
+    def import_step_components(self, filepath: str) -> list:
+        """Import a STEP file and return each solid as a separate ``(name, shape)`` pair.
+
+        The STEP reader transfers the entire root shape, then we iterate
+        over individual ``TopAbs_SOLID`` entities so that each solid gets
+        its own ``OCCGeometryObject``.  If the file contains only a single
+        solid the list will have one entry.
+
+        Returns a list of ``(name, OCCGeometryObject)`` tuples.
+        """
+        from OCP.STEPControl import STEPControl_Reader
+        from OCP.IFSelect import IFSelect_RetDone
+        from OCP.TopExp import TopExp_Explorer
+        from OCP.TopAbs import TopAbs_SOLID
+        from OCP.TopoDS import TopoDS
+
+        reader = STEPControl_Reader()
+        status = reader.ReadFile(filepath)
+
+        if status != IFSelect_RetDone:
+            raise ValueError(f"Failed to read STEP file: {filepath}")
+
+        reader.TransferRoots()
+        shape = reader.OneShape()
+
+        # Extract individual solids
+        solids: list = []
+        explorer = TopExp_Explorer(shape, TopAbs_SOLID)
+        idx = 0
+        while explorer.More():
+            solid = TopoDS.Solid_s(explorer.Current())
+            idx += 1
+            solids.append(
+                (
+                    f"Part {idx}",
+                    OCCGeometryObject(solid, {"type": "imported_step"}),
+                )
+            )
+            explorer.Next()
+
+        # Fallback: no individual solids found — return the whole shape
+        if not solids:
+            solids = [("Imported", OCCGeometryObject(shape, {"type": "imported_step"}))]
+
+        return solids
+
     def import_iges(self, filepath: str) -> GeometryObject:
         """Import from IGES format."""
         from OCP.IGESControl import IGESControl_Reader
@@ -643,10 +893,8 @@ class OCGeometryKernel(GeometryKernel):
 
         from OCP.TopExp import TopExp_Explorer
         from OCP.TopAbs import TopAbs_EDGE
-        from OCP.BRep import BRep_Tool
-        from OCP.TopLoc import TopLoc_Location
         from OCP.BRepAdaptor import BRepAdaptor_Curve
-        from OCP.GeomAbs import GeomAbs_Line, GeomAbs_Circle, GeomAbs_Ellipse, GeomAbs_BSplineCurve
+        from OCP.GeomAbs import GeomAbs_Line
 
         vertices_list: List[List[float]] = []
         edges_list: List[List[int]] = []
@@ -678,6 +926,7 @@ class OCGeometryKernel(GeometryKernel):
         explorer = TopExp_Explorer(shape, TopAbs_EDGE)
         while explorer.More():
             from OCP.TopoDS import TopoDS
+
             edge = TopoDS.Edge_s(explorer.Current())
             edge_points = discretize_edge(edge)
 
@@ -741,3 +990,363 @@ class OCGeometryKernel(GeometryKernel):
 
         cg = props.CentreOfMass()
         return Point3D(cg.X(), cg.Y(), cg.Z())
+
+    def create_thread(
+        self,
+        body: GeometryObject,
+        cylindrical_face: Any,
+        nominal_diameter: float,
+        pitch: float,
+        thread_length: Optional[float] = None,
+        internal: bool = False,
+    ) -> Optional[GeometryObject]:
+        """Cut (or add) an ISO metric thread on the cylindrical face of *body*.
+
+        The geometry is driven by the PICKED face's actual radius and axis
+        (``nominal_diameter`` is only metadata used for the feature record).
+        External threads cut the ISO groove trapezoid (7P/8 at the surface,
+        P/4 at the root, 5H/8 deep) out of the shaft; internal threads fuse
+        the ISO ridge trapezoid (3P/4 at the wall, P/8 crest) into the hole.
+        """
+        import math
+
+        from OCP.BRepAdaptor import BRepAdaptor_Surface
+        from OCP.GeomAbs import GeomAbs_Cylinder
+        from OCP.TopoDS import TopoDS
+        from OCP.gp import gp_Pnt, gp_Pnt2d, gp_Dir2d
+        from OCP.BRepBuilderAPI import (
+            BRepBuilderAPI_MakeEdge,
+            BRepBuilderAPI_MakeWire,
+        )
+
+        # ── 1. Cylinder parameters from the picked face ─────────────────
+        try:
+            surf = BRepAdaptor_Surface(cylindrical_face)
+        except Exception:
+            try:
+                surf = BRepAdaptor_Surface(TopoDS.Face_s(cylindrical_face))
+            except Exception as exc:
+                logger.warning(f"create_thread: cannot adapt face: {exc}")
+                return None
+
+        if surf.GetType() != GeomAbs_Cylinder:
+            logger.warning("create_thread: face is not cylindrical")
+            return None
+
+        cyl = surf.Cylinder()                       # gp_Cylinder
+        radius = cyl.Radius()                       # ACTUAL picked radius
+        ax3 = cyl.Position()                        # gp_Ax3 (location, Z, X)
+        loc = ax3.Location()
+        zdir = ax3.Direction()
+        xdir = ax3.XDirection()
+        axis_origin = np.array([loc.X(), loc.Y(), loc.Z()])
+        axis_dir = np.array([zdir.X(), zdir.Y(), zdir.Z()])
+        axis_dir = axis_dir / np.linalg.norm(axis_dir)
+        axis_x = np.array([xdir.X(), xdir.Y(), xdir.Z()])
+        axis_x = axis_x / np.linalg.norm(axis_x)
+        axis_y = np.cross(axis_dir, axis_x)
+
+        u_start = surf.FirstUParameter()            # angular start of face
+        v1, v2 = surf.FirstVParameter(), surf.LastVParameter()
+        v_lo, v_hi = min(v1, v2), max(v1, v2)
+        face_height = v_hi - v_lo
+
+        if not thread_length or thread_length <= 0:
+            thread_length = face_height
+        thread_length = min(thread_length, face_height)
+
+        num_turns = thread_length / pitch
+        if num_turns < 0.05:
+            logger.warning("create_thread: thread too short for one turn")
+            return None
+
+        # ── 2. ISO metric profile dimensions ────────────────────────────
+        # Basic profile (H = P·√3/2, thread engagement depth 5H/8):
+        #  • external shaft: groove cut is a trapezoid 7P/8 wide at the
+        #    surface narrowing to P/4 at the root.
+        #  • internal hole:  ridge fused onto the wall is a trapezoid 3P/4
+        #    wide at the wall narrowing to P/8 at the inner crest, leaving
+        #    the 7P/8-wide groove open at the bore.
+        H = pitch * math.sqrt(3.0) / 2.0
+        depth = (5.0 / 8.0) * H
+        overcut = max(0.1 * depth, 0.02)            # overhang past the surface
+        if internal:
+            w_surf = 3.0 * pitch / 4.0
+            w_deep = pitch / 8.0
+        else:
+            w_surf = 7.0 * pitch / 8.0
+            w_deep = pitch / 4.0
+
+        # ── 3. Helix spine ON the picked cylinder's surface ─────────────
+        # The swept profile sits in the helix's normal plane, tilted by the
+        # lead angle; its end caps therefore stick out past the spine ends
+        # by roughly half the profile width along the axis.  For a CUT that
+        # is harmless (the groove simply runs to the part edge), but a FUSE
+        # would leave the protruding cap as floating material outside the
+        # part, so inset the internal helix by exactly that amount.
+        lead = math.atan2(pitch, 2.0 * math.pi * radius)
+        cap_axial = (w_surf / 2.0) * math.cos(lead)  # cap half-extent along axis
+
+        if internal:
+            v_start = v_lo + cap_axial
+            v_end = min(v_lo + thread_length, v_hi) - cap_axial
+        else:
+            # extend one pitch past each face end so the groove runs off
+            # the part edges cleanly
+            v_start = v_lo - pitch
+            v_end = min(v_lo + thread_length + pitch, v_hi + pitch)
+        thread_span = v_end - v_start
+        if thread_span < 0.5 * pitch:
+            logger.warning("create_thread: part too short for a thread")
+            return None
+        turns_ext = thread_span / pitch
+
+        spine_wire = None
+
+        # 3a. TRUE helix: a 2D straight line on the cylinder surface.
+        #
+        # NOTE 1: gp_Dir2d NORMALIZES its argument, so the 2D line
+        # parameter t advances the point by t·|(2π, pitch)| in (u, v)
+        # space — scale the trim range so t = n turns covers exactly
+        # n revolutions plus n·pitch of axial travel.
+        # NOTE 2: the edge from a pcurve has no 3D curve; the pipe sweep
+        # needs one, so force it with BRepLib.BuildCurves3d.
+        spine_wire = None
+        try:
+            from OCP.Geom import Geom_CylindricalSurface
+            from OCP.Geom2d import Geom2d_Line, Geom2d_TrimmedCurve
+            from OCP.BRepLib import BRepLib
+
+            dir_len = math.hypot(2.0 * math.pi, pitch)
+            cyl_surf = Geom_CylindricalSurface(cyl)
+            line2d = Geom2d_Line(
+                gp_Pnt2d(u_start, v_start), gp_Dir2d(2.0 * math.pi, pitch)
+            )
+            seg = Geom2d_TrimmedCurve(line2d, 0.0, turns_ext * dir_len)
+            helix_edge = BRepBuilderAPI_MakeEdge(seg, cyl_surf).Edge()
+            BRepLib.BuildCurves3d_s(helix_edge)
+            spine_wire = BRepBuilderAPI_MakeWire(helix_edge).Wire()
+            logger.info("create_thread: using exact helix spine")
+        except Exception as exc:
+            logger.info(f"create_thread: exact helix failed ({exc})")
+
+        # 3b. Fallback: smooth BSpline through sampled helix points
+        # (only if the exact construction is unavailable).
+        if spine_wire is None:
+            try:
+                from OCP.GeomAPI import GeomAPI_PointsToBSpline
+                from OCP.TColgp import TColgp_Array1OfPnt
+                from OCP.GeomAbs import GeomAbs_C2
+
+                pts_per_turn = 96
+                n_total = max(int(turns_ext * pts_per_turn) + 1, 2)
+                arr = TColgp_Array1OfPnt(1, n_total)
+                for i in range(1, n_total + 1):
+                    u = u_start + ((i - 1) / pts_per_turn) * 2.0 * math.pi
+                    v = v_start + ((i - 1) / pts_per_turn) * pitch
+                    p = (
+                        axis_origin
+                        + radius * (math.cos(u) * axis_x + math.sin(u) * axis_y)
+                        + v * axis_dir
+                    )
+                    arr.SetValue(i, gp_Pnt(float(p[0]), float(p[1]), float(p[2])))
+                bspline = GeomAPI_PointsToBSpline(arr, 3, 8, GeomAbs_C2, 1e-5)
+                bs_edge = BRepBuilderAPI_MakeEdge(bspline.Curve()).Edge()
+                spine_wire = BRepBuilderAPI_MakeWire(bs_edge).Wire()
+                logger.info("create_thread: using BSpline helix fallback")
+            except Exception as exc:
+                logger.warning(f"create_thread: BSpline helix failed ({exc})")
+
+        if spine_wire is None:
+            logger.warning("create_thread: no usable helix spine")
+            return None
+
+        # Start frame (same for both spine types — computed analytically).
+        def _cyl_pt(u: float, v: float) -> np.ndarray:
+            return (
+                axis_origin
+                + radius * (math.cos(u) * axis_x + math.sin(u) * axis_y)
+                + v * axis_dir
+            )
+
+        start_S = _cyl_pt(u_start, v_start)
+        start_T = (
+            2.0 * math.pi * radius
+            * (-math.sin(u_start) * axis_x + math.cos(u_start) * axis_y)
+            + pitch * axis_dir
+        )
+        start_T = start_T / np.linalg.norm(start_T)
+        start_R = math.cos(u_start) * axis_x + math.sin(u_start) * axis_y  # outward
+
+        # Profile width direction: perpendicular to tangent in the surface
+        # plane (≈ axial direction).  Trapezoid is symmetric so sign is fine.
+        binormal = np.cross(start_T, start_R)
+        binormal = binormal / np.linalg.norm(binormal)
+
+        # ── 4. Trapezoidal profile at the spine start ───────────────────
+        # Built directly in world coords: base sits *overcut* OUTSIDE the
+        # surface so the boolean fuses/cuts cleanly across it; the working
+        # end reaches *depth* INSIDE the surface.
+        def _mk(b: float, r: float) -> gp_Pnt:
+            p = start_S + b * binormal + r * start_R
+            return gp_Pnt(float(p[0]), float(p[1]), float(p[2]))
+
+        p0 = _mk(-w_surf / 2.0, overcut)
+        p1 = _mk(-w_deep / 2.0, -depth)
+        p2 = _mk(+w_deep / 2.0, -depth)
+        p3 = _mk(+w_surf / 2.0, overcut)
+
+        prof_wb = BRepBuilderAPI_MakeWire()
+        for a, b in ((p0, p1), (p1, p2), (p2, p3), (p3, p0)):
+            prof_wb.Add(BRepBuilderAPI_MakeEdge(a, b).Edge())
+        profile_wire = prof_wb.Wire()
+
+        # ── 5. Sweep the profile along the helix ────────────────────────
+        from OCP.BRepOffsetAPI import BRepOffsetAPI_MakePipeShell
+
+        try:
+            pipe = BRepOffsetAPI_MakePipeShell(spine_wire)
+            pipe.SetMode(True)                       # Frenet frame
+            pipe.Add(profile_wire, False, False)
+            pipe.Build()
+            if not pipe.IsDone():
+                logger.warning("create_thread: pipe sweep failed")
+                return None
+            solid_ok = False
+            try:
+                solid_ok = bool(pipe.MakeSolid())    # cap the tube ends
+            except Exception as exc:
+                logger.info(f"create_thread: MakeSolid unavailable ({exc})")
+            tool_shape = pipe.Shape()
+            if not solid_ok:
+                logger.warning("create_thread: sweep is not a solid")
+        except Exception as exc:
+            logger.warning(f"create_thread: sweep failed: {exc}")
+            return None
+
+        # ── 6. Boolean cut (shaft) or fuse (hole) ───────────────────────
+        body_shape = self._get_shape(body)
+        if body_shape is None:
+            logger.warning("create_thread: body has no shape")
+            return None
+
+        tool = OCCGeometryObject(tool_shape)
+        vol_before = self.get_volume(body)
+
+        if internal:
+            result = self.boolean_union(body, tool)
+        else:
+            result = self.boolean_difference(body, tool)
+
+        if result is None or self._get_shape(result) is None:
+            logger.warning("create_thread: boolean op produced no shape")
+            return None
+
+        try:
+            vol_after = self.get_volume(result)
+        except Exception:
+            vol_after = -1.0
+
+        if internal and vol_after <= vol_before:
+            logger.warning(
+                f"create_thread: fuse did not add volume "
+                f"({vol_before:.4f} → {vol_after:.4f}) — tool missed the body?"
+            )
+            return None
+        if not internal and vol_after >= vol_before:
+            logger.warning(
+                f"create_thread: cut did not remove volume "
+                f"({vol_before:.4f} → {vol_after:.4f}) — tool missed the body?"
+            )
+            return None
+
+        logger.info(
+            f"create_thread: {'internal' if internal else 'external'} thread OK, "
+            f"volume {vol_before:.4f} → {vol_after:.4f}"
+        )
+        return result
+
+    def detect_cylindrical_face(
+        self,
+        face: Any,
+    ) -> Optional[Dict[str, Any]]:
+        """Check if *face* is cylindrical and return its parameters.
+
+        The *face* can be a ``TopoDS_Face`` (from the picker) or a
+        ``TopoDS_Shape`` that contains a face.  We try several paths to
+        extract the underlying cylindrical surface.
+
+        Returns a dict with keys ``radius``, ``axis_origin``, ``axis_dir``,
+        ``height``, or *None* if the face isn't cylindrical.
+        """
+        import logging
+        import numpy as np
+        from OCP.BRepAdaptor import BRepAdaptor_Surface
+        from OCP.GeomAbs import GeomAbs_Cylinder
+        from OCP.TopoDS import TopoDS
+
+        _log = logging.getLogger(__name__)
+
+        # ── Resolve the actual face from whatever the caller handed us ──
+        actual_face: Any = None
+
+        # Try direct BRepAdaptor_Surface first — the picker already returns
+        # a valid TopoDS_Face, and calling TopoDS.Face_s() again on an
+        # already-downcast face can fail in some OCP versions.
+        try:
+            surf = BRepAdaptor_Surface(face)
+            surf_type_test = surf.GetType()
+            actual_face = face
+        except Exception:
+            pass
+
+        if actual_face is None:
+            # Fallback: try the explicit TopoDS.Face_s downcast path.
+            try:
+                candidate = TopoDS.Face_s(face)
+                _ = BRepAdaptor_Surface(candidate)
+                actual_face = candidate
+            except Exception:
+                pass
+
+        if actual_face is None:
+            _log.warning("detect_cylindrical_face: could not resolve face from pick result")
+            return None
+
+        # ── Probe the surface type ──
+        try:
+            surf = BRepAdaptor_Surface(actual_face)
+            surf_type = surf.GetType()
+            if surf_type != GeomAbs_Cylinder:
+                type_names = {
+                    0: "Plane", 1: "Cylinder", 2: "Cone", 3: "Sphere",
+                    4: "Torus", 5: "Bezier", 6: "BSpline", 7: "Revolution",
+                    8: "Extrusion", 9: "Offset", 10: "Other",
+                }
+                type_name = type_names.get(int(surf_type), f"Unknown({int(surf_type)})")
+                _log.warning(
+                    f"detect_cylindrical_face: face is {type_name}, not a Cylinder"
+                )
+                return None
+
+            cyl = surf.Cylinder()
+            radius = cyl.Radius()
+            axis = cyl.Axis()
+            origin = axis.Location()
+            direction = axis.Direction()
+            # BRepAdaptor_Surface uses FirstUParameter/LastUParameter etc.
+            u1 = surf.FirstUParameter()
+            u2 = surf.LastUParameter()
+            v1 = surf.FirstVParameter()
+            v2 = surf.LastVParameter()
+            height = abs(v2 - v1)
+            return {
+                "radius": radius,
+                "diameter": 2.0 * radius,
+                "axis_origin": (origin.X(), origin.Y(), origin.Z()),
+                "axis_dir": (direction.X(), direction.Y(), direction.Z()),
+                "height": height,
+            }
+        except Exception as exc:
+            _log.warning(f"detect_cylindrical_face: surface probe failed: {exc}")
+            return None

src/fluency/geometry_occ/surface_modifier.py

@@ -0,0 +1,385 @@
+"""Surface modifier for OpenCASCADE geometry.
+
+Applies geometric patterns (pyramids, bumps, grooves) to 3D surfaces using boolean operations.
+This enables grip-enhancing textures and visual surface modifications on CAD models.
+"""
+
+from __future__ import annotations
+
+import logging
+import math
+from typing import Any, Optional, Tuple
+
+# OCC imports at module level for common types
+
+
+logger = logging.getLogger(__name__)
+
+
+class SurfaceModifier:
+    """Applies geometric patterns to 3D surfaces using OCC boolean operations."""
+
+    def __init__(self):
+        self._patterns_applied = []
+
+    def apply_pyramid_pattern(
+        self,
+        face_shape,
+        pyramid_height: float = 1.0,
+        base_radius: float = 2.0,
+        spacing: float = 5.0,
+        num_rings: Optional[int] = None,
+        direction: Tuple[float, float, float] = (0, 0, 1),
+    ) -> Optional[Any]:
+        """Apply a pyramid pattern to a face surface.
+
+        Args:
+            face_shape: OCC TopoDS_Shape representing the face or solid
+            pyramid_height: Height of each pyramid
+            base_radius: Radius of pyramid base
+            spacing: Distance between pyramids
+            num_rings: Number of concentric rings (auto-calculated if None)
+            direction: Normal direction for pyramids
+
+        Returns:
+            Modified shape on success, None on failure
+        """
+        try:
+            from OCP.TopAbs import TopAbs_FACE
+            from OCP.TopoDS import TopoDS_Face, TopoDS_Shape
+            from OCP.BRepAlgoAPI import BRepAlgoAPI_Fuse
+            from OCP.TopExp import TopExp_Explorer
+            from OCP.BRepAdaptor import BRepAdaptor_Surface
+
+            # Validate face shape
+            if not isinstance(face_shape, (TopoDS_Shape, TopoDS_Face)):
+                logger.error("Invalid face shape type")
+                return None
+
+            # Extract the first face for surface parameterization
+            if isinstance(face_shape, TopoDS_Shape):
+                explorer = TopExp_Explorer(face_shape, TopAbs_FACE)
+                if not explorer.More():
+                    logger.error("No faces found in shape")
+                    return None
+                from OCP import TopoDS
+                face = TopoDS.TopoDS.Face_s(explorer.Current())
+            else:
+                face = face_shape
+
+            # Get face surface for UV parameterization
+            surf = BRepAdaptor_Surface(face)
+
+            u_min, u_max = surf.FirstUParameter(), surf.LastUParameter()
+            v_min, v_max = surf.FirstVParameter(), surf.LastVParameter()
+
+            # Calculate number of rings if not specified
+            if num_rings is None:
+                # Estimate based on face area and spacing
+                u_range = u_max - u_min
+                v_range = v_max - v_min
+                avg_dim = (u_range + v_range) / 2.0
+                num_rings = max(1, min(int(avg_dim / spacing), 5))
+
+            logger.info(
+                f"Applying pyramid pattern: {num_rings} rings, "
+                f"{base_radius:.2f} radius, {pyramid_height:.2f} height"
+            )
+
+            # Create pyramids distributed across the face UV space
+            result_shape = face_shape
+            pyramid_count = 0
+
+            for ring_idx in range(num_rings):
+                # Distribute rings evenly across UV parameter space
+                u_fraction = (ring_idx + 1) / (num_rings + 1)
+                v_fraction = 0.5  # Center vertically
+
+                # Map to actual UV coordinates on the face
+                u_pos = u_min + u_fraction * (u_max - u_min)
+                v_pos = v_min + v_fraction * (v_max - v_min)
+
+                # Get 3D position and tangent vectors at this UV point
+                from OCP.gp import gp_Pnt, gp_Vec
+
+                center_pt = gp_Pnt()
+                d1u = gp_Vec()
+                d1v = gp_Vec()
+                surf.D1(u_pos, v_pos, center_pt, d1u, d1v)
+                # Normal is cross product of tangent vectors
+                normal = d1u.Crossed(d1v)
+                normal.Normalize()
+
+                # Calculate number of pyramids in this ring based on spacing
+                if ring_idx == 0:
+                    num_pyramids = 1  # Center pyramid
+                else:
+                    circumference = 2.0 * math.pi * (ring_idx * spacing)
+                    num_pyramids = max(3, int(circumference / spacing))
+
+                for i in range(num_pyramids):
+                    if ring_idx == 0:
+                        # Center pyramid - place at face center
+                        place_u = u_pos
+                        place_v = v_pos
+                    else:
+                        angle = (2.0 * math.pi * i) / num_pyramids
+                        # Offset in UV space based on ring radius
+                        offset_u = (ring_idx * spacing / (u_max - u_min)) * math.cos(angle)
+                        offset_v = (ring_idx * spacing / (v_max - v_min)) * math.sin(angle)
+                        place_u = max(u_min, min(u_max, u_pos + offset_u))
+                        place_v = max(v_min, min(v_max, v_pos + offset_v))
+
+                    try:
+                        # Get 3D position and normal for this pyramid
+                        pyramid_pt = gp_Pnt()
+                        pd1u = gp_Vec()
+                        pd1v = gp_Vec()
+                        surf.D1(place_u, place_v, pyramid_pt, pd1u, pd1v)
+                        pyramid_normal = pd1u.Crossed(pd1v)
+                        pyramid_normal.Normalize()
+
+                        # Create solid pyramid at this position
+                        pyramid_shape = self._create_solid_pyramid(
+                            pyramid_pt,
+                            pyramid_normal,
+                            pyramid_height,
+                            base_radius,
+                        )
+
+                        if pyramid_shape is not None:
+                            # Fuse with existing geometry
+                            fuse = BRepAlgoAPI_Fuse(result_shape, pyramid_shape)
+                            fuse.Build()
+
+                            if fuse.IsDone():
+                                result_shape = fuse.Shape()
+                                pyramid_count += 1
+                            else:
+                                logger.warning(
+                                    f"Failed to fuse pyramid at ({place_u:.2f}, {place_v:.2f})"
+                                )
+                    except Exception as e:
+                        logger.debug(
+                            f"Error creating pyramid at ring {ring_idx}, pyramid {i}: {e}"
+                        )
+
+            self._patterns_applied.append(
+                {
+                    "type": "pyramid",
+                    "parameters": {
+                        "height": pyramid_height,
+                        "base_radius": base_radius,
+                        "spacing": spacing,
+                        "num_rings": num_rings,
+                        "direction": direction,
+                    },
+                }
+            )
+
+            logger.info(f"Successfully applied {pyramid_count} pyramids")
+
+            return result_shape
+
+        except Exception as e:
+            logger.error(f"Error applying pyramid pattern: {e}", exc_info=True)
+            return None
+
+    def _create_solid_pyramid(
+        self,
+        base_point,  # gp_Pnt - position on the face
+        normal_vec,  # gp_Dir or gp_Vec - surface normal direction
+        height: float,
+        base_radius: float,
+    ) -> Optional[Any]:
+        """Create a solid pyramid at the specified position and orientation.
+
+        Uses BRepPrimAPI_MakePrism to extrude a square base into a solid pyramid.
+
+        Args:
+            base_point: 3D point where pyramid base is centered
+            normal_vec: Direction vector for pyramid growth (surface normal)
+            height: Height of the pyramid from base to apex
+            base_radius: Half-width of the square base
+
+        Returns:
+            OCC solid shape for the pyramid, or None on failure
+        """
+        try:
+            from OCP.gp import gp_Dir, gp_Ax2, gp_Vec
+            from OCP.BRepBuilderAPI import (
+                BRepBuilderAPI_MakeEdge,
+                BRepBuilderAPI_MakeWire,
+            )
+            from OCP.BRepPrimAPI import BRepPrimAPI_MakePrism
+
+            half = base_radius / 2.0
+
+            # Build orthonormal basis from normal vector
+            if isinstance(normal_vec, gp_Vec):
+                n_dir = gp_Dir(normal_vec.XYZ())
+            else:
+                n_dir = normal_vec
+
+            # Create a local coordinate system at the base point
+            local_ax2 = gp_Ax2(base_point, n_dir)
+
+            # Get X and Y axes from the local coordinate system
+            x_dir = local_ax2.XDirection()
+            y_dir = local_ax2.YDirection()
+
+            # Create 4 corners of the square base in the local plane
+            corner_points = [
+                base_point + gp_Vec(x_dir).Multiplied(half) + gp_Vec(y_dir).Multiplied(half),
+                base_point + gp_Vec(x_dir).Multiplied(-half) + gp_Vec(y_dir).Multiplied(half),
+                base_point + gp_Vec(x_dir).Multiplied(-half) + gp_Vec(y_dir).Multiplied(-half),
+                base_point + gp_Vec(x_dir).Multiplied(half) + gp_Vec(y_dir).Multiplied(-half),
+            ]
+
+            # Create edges connecting the corners
+            wire_maker = BRepBuilderAPI_MakeWire()
+            for idx in range(4):
+                next_idx = (idx + 1) % 4
+                edge = BRepBuilderAPI_MakeEdge(
+                    corner_points[idx], corner_points[next_idx]
+                ).Edge()
+                wire_maker.Add(edge)
+
+            if not wire_maker.IsDone():
+                logger.warning("Failed to create pyramid base wire")
+                return None
+
+            # Extrude the base wire in the normal direction by height to form a prism
+            extrusion_vec = gp_Vec(n_dir).Multiplied(height)
+            prism_maker = BRepPrimAPI_MakePrism(
+                wire_maker.Wire(), extrusion_vec, False  # no check intersection
+            )
+            prism_maker.Build()
+
+            if not prism_maker.IsDone():
+                logger.warning("Failed to create pyramid prism")
+                return None
+
+            return prism_maker.Shape()
+
+        except Exception as e:
+            logger.debug(f"Error creating solid pyramid: {e}")
+            return None
+
+    def apply_bump_pattern(
+        self,
+        face_shape,
+        bump_height: float = 1.0,
+        bump_radius: float = 2.0,
+        spacing: float = 5.0,
+        num_rings: Optional[int] = None,
+    ) -> Optional[Any]:
+        """Apply a simple bump pattern to a face surface.
+
+        Args:
+            face_shape: OCC TopoDS_Shape representing the face
+            bump_height: Height of each bump
+            bump_radius: Radius of each bump base
+            spacing: Distance between bumps
+            num_rings: Number of concentric rings
+
+        Returns:
+            Modified shape on success, None on failure
+        """
+        return self.apply_pyramid_pattern(
+            face_shape,
+            pyramid_height=bump_height,
+            base_radius=bump_radius,
+            spacing=spacing,
+            num_rings=num_rings,
+        )
+
+
+def apply_surface_modifier_to_body(
+    body_geometry, modifier_type: str = "pyramid", **parameters
+) -> Optional[Any]:
+    """Apply a surface modifier to a body geometry.
+
+    Args:
+        body_geometry: OCCGeometryObject or similar geometry object
+        modifier_type: Type of modifier ('pyramid', 'bump')
+        **parameters: Modifier-specific parameters
+
+    Returns:
+        Modified shape, or None on failure
+    """
+    from fluency.geometry_occ.kernel import OCGeometryKernel
+
+    kernel = OCGeometryKernel()
+    shape = kernel._get_shape(body_geometry)
+
+    if shape is None:
+        logger.error("No geometry found in body")
+        return None
+
+    modifier = SurfaceModifier()
+
+    try:
+        if modifier_type == "pyramid":
+            success = modifier.apply_pyramid_pattern(shape, **parameters)
+        elif modifier_type == "bump":
+            success = modifier.apply_bump_pattern(shape, **parameters)
+        else:
+            logger.error(f"Unknown modifier type: {modifier_type}")
+            return None
+
+        if not success:
+            logger.error("Surface modifier application failed")
+            return None
+
+        # Return the modified shape wrapped in OCCGeometryObject
+        from fluency.geometry_occ.kernel import OCCGeometryObject
+
+        return OCCGeometryObject(shape)
+
+    except Exception as e:
+        logger.error(f"Error applying surface modifier: {e}", exc_info=True)
+        return None
+
+
+# Example usage and testing
+if __name__ == "__main__":
+    # Create a simple test case
+    from OCP.BRepPrimAPI import BRepPrimAPI_MakeBox
+
+    # Create a box to modify
+    box_maker = BRepPrimAPI_MakeBox(50, 50, 10)
+    box_maker.Build()
+
+    if box_maker.IsDone():
+        print("Created test box")
+
+        # Apply pyramid pattern to top face (Z direction)
+        modifier = SurfaceModifier()
+        success = modifier.apply_pyramid_pattern(
+            box_maker.Shape(),
+            pyramid_height=2.0,
+            base_radius=3.0,
+            spacing=8.0,
+            num_rings=2,
+            direction=(0, 0, 1),
+        )
+
+        if success:
+            print("Successfully applied pyramid pattern")
+
+            # Export modified shape
+            from OCP.StlAPI import StlAPI_Writer
+            from OCP.BRepMesh import BRepMesh_IncrementalMesh
+
+            tess = BRepMesh_IncrementalMesh(box_maker.Shape(), 0.1)
+            tess.Perform()
+
+            writer = StlAPI_Writer()
+            writer.SetASCIIMode(False)
+            writer.Write(box_maker.Shape(), "/tmp/test_pyramid_pattern.stl")
+            print("Exported modified shape to STL")
+        else:
+            print("Failed to apply pyramid pattern")
+    else:
+        print("Failed to create test box")

src/fluency/io/project_io.py

@@ -28,6 +28,7 @@ import logging
 import os
 import shutil
 import tempfile
+import uuid
 import zipfile
 from dataclasses import asdict, is_dataclass
 from datetime import datetime
@@ -42,8 +43,12 @@ from fluency.models.data_model import (
     Body,
     Component,
     Connector,
+    DrawingAnnotation,
+    DrawingView,
+    Feature,
     Project,
     Sketch,
+    TechnicalDrawing,
     Workplane,
 )
 from fluency.geometry_occ.kernel import OCCGeometryObject, OCGeometryKernel
@@ -65,7 +70,7 @@ def _json_default(obj: Any) -> Any:
         return sorted(obj)
     if isinstance(obj, tuple):
         return list(obj)
-    if is_dataclass(obj):
+    if is_dataclass(obj) and not isinstance(obj, type):
         return asdict(obj)
     raise TypeError(f"Object of type {type(obj).__name__} is not JSON serializable")
 
@@ -85,42 +90,77 @@ def _coerce_listlike(value: Any) -> List[Any]:
     return list(value)
 
 
+def _to_float(value: Any, default: float = 0.0) -> float:
+    """Safely coerce a saved value to float, falling back to *default*.
+
+    Corrupt archives may store a string or None where a number is expected;
+    the loaders must not crash on them.
+    """
+    try:
+        return float(value)
+    except (TypeError, ValueError):
+        return default
+
+
+def _saved_id(data: Dict[str, Any]) -> str:
+    """Return a saved entity id, or a fresh UUID for corrupt/legacy data.
+
+    Old files always wrote an ``id``; a missing/empty value means the
+    archive is damaged, and the model's uuid factory only kicks in when the
+    constructor argument is omitted — so we generate here to keep ids valid
+    non-empty strings.
+    """
+    v = data.get("id")
+    if isinstance(v, str) and v:
+        return v
+    return str(uuid.uuid4())
+
+
 def _to_3tuple(value: Any) -> Tuple[float, float, float]:
     """Coerce a saved 3-vector to a tuple of floats (for OCC)."""
     if value is None:
         return (0.0, 0.0, 0.0)
-    if isinstance(value, np.ndarray):
-        seq = value.tolist()
-    else:
-        seq = list(value)
-    if len(seq) < 3:
-        seq = list(seq) + [0.0] * (3 - len(seq))
-    return (float(seq[0]), float(seq[1]), float(seq[2]))
+    try:
+        if isinstance(value, np.ndarray):
+            seq = value.tolist()
+        else:
+            seq = list(value)
+        if len(seq) < 3:
+            seq = list(seq) + [0.0] * (3 - len(seq))
+        return (float(seq[0]), float(seq[1]), float(seq[2]))
+    except (TypeError, ValueError, IndexError):
+        return (0.0, 0.0, 0.0)
 
 
 def _to_3vec(value: Any) -> np.ndarray:
     """Coerce a saved 3-vector to a 3-element numpy array."""
-    if isinstance(value, np.ndarray):
-        return value.astype(float).reshape(3)
-    if value is None:
+    try:
+        if isinstance(value, np.ndarray):
+            return value.astype(float).reshape(3)
+        if value is None:
+            return np.zeros(3, dtype=float)
+        seq = list(value)
+        if len(seq) < 3:
+            seq = list(seq) + [0.0] * (3 - len(seq))
+        return np.array([float(seq[0]), float(seq[1]), float(seq[2])], dtype=float)
+    except (TypeError, ValueError, IndexError):
         return np.zeros(3, dtype=float)
-    seq = list(value)
-    if len(seq) < 3:
-        seq = list(seq) + [0.0] * (3 - len(seq))
-    return np.array([float(seq[0]), float(seq[1]), float(seq[2])], dtype=float)
 
 
 def _to_mat3(value: Any) -> np.ndarray:
     """Coerce a saved 3×3 matrix (flat 9-list or nested) to np.ndarray."""
-    if isinstance(value, np.ndarray):
-        arr = value.astype(float)
-        return arr.reshape(3, 3)
-    if value is None:
+    try:
+        if isinstance(value, np.ndarray):
+            arr = value.astype(float)
+            return arr.reshape(3, 3)
+        if value is None:
+            return np.eye(3, dtype=float)
+        flat = list(np.asarray(value, dtype=float).flatten())
+        if len(flat) < 9:
+            flat = flat + [0.0] * (9 - len(flat))
+        return np.array(flat[:9], dtype=float).reshape(3, 3)
+    except (TypeError, ValueError, IndexError):
         return np.eye(3, dtype=float)
-    flat = list(np.asarray(value, dtype=float).flatten())
-    if len(flat) < 9:
-        flat = flat + [0.0] * (9 - len(flat))
-    return np.array(flat[:9], dtype=float).reshape(3, 3)
 
 
 def _parse_iso(value: Optional[str]) -> datetime:
@@ -151,11 +191,11 @@ def _workplane_to_dict(wp: Workplane) -> Dict[str, Any]:
 
 def _workplane_from_dict(data: Dict[str, Any]) -> Workplane:
     wp = Workplane(
-        id=data.get("id") or None,  # Workplane generates uuid if None
+        id=_saved_id(data),
         name=data.get("name", "Untitled Workplane"),
-        origin=tuple(data.get("origin", (0.0, 0.0, 0.0))),
-        normal=tuple(data.get("normal", (0.0, 0.0, 1.0))),
-        x_dir=tuple(data.get("x_dir", (1.0, 0.0, 0.0))),
+        origin=_to_3tuple(data.get("origin", (0.0, 0.0, 0.0))),
+        normal=_to_3tuple(data.get("normal", (0.0, 0.0, 1.0))),
+        x_dir=_to_3tuple(data.get("x_dir", (1.0, 0.0, 0.0))),
         visible=bool(data.get("visible", True)),
     )
     wp.created_at = _parse_iso(data.get("created_at"))
@@ -163,6 +203,90 @@ def _workplane_from_dict(data: Dict[str, Any]) -> Workplane:
     return wp
 
 
+def _feature_to_dict(feat: Feature) -> Dict[str, Any]:
+    """Serialize one parametric feature (sketch id + params).
+
+    "base" snapshot features are NOT serialized here — their frozen
+    geometry is written as a separate STEP member (``base_geometry_ref``)
+    and the ``features_base_snapshot`` flag on the body marks that the
+    list starts with one.
+    """
+    return {
+        "id": feat.id,
+        "operation": feat.operation,
+        "sketch_id": feat.sketch.id if feat.sketch is not None else None,
+        "length": feat.length,
+        "symmetric": bool(feat.symmetric),
+        "invert": bool(feat.invert),
+        "through_all": bool(feat.through_all),
+        "cut_all_bodies": bool(feat.cut_all_bodies),
+        "face_index": feat.face_index,
+        "angle": _to_float(feat.angle, 360.0),
+        "axis": [float(v) for v in (feat.axis or (0, 0, 1))],
+        "origin": [float(v) for v in (feat.origin or (0.0, 0.0, 0.0))],
+        "axis_line_id": feat.axis_line_id,
+        "radius": feat.radius,
+        "tangent_propagation": bool(feat.tangent_propagation),
+        "scope": feat.scope,
+        "edge_refs": list(feat.edge_refs),
+        "face_keys": json.dumps(feat.face_keys) if feat.face_keys is not None else None,
+        "face_keys_sketch_id": feat.face_keys_sketch_id,
+        "pattern_type": feat.pattern_type,
+        "count": feat.count,
+        "spacing": feat.spacing,
+        "direction": [float(v) for v in (feat.direction or (1, 0, 0))],
+        "mirror_plane_origin": [float(v) for v in (feat.mirror_plane_origin or (0.0, 0.0, 0.0))],
+        "mirror_plane_normal": [float(v) for v in (feat.mirror_plane_normal or (1, 0, 0))],
+        "keep_original": bool(feat.keep_original),
+    }
+
+
+def _feature_from_dict(data: Dict[str, Any], sketches: Dict[str, Sketch]) -> Feature:
+    """Deserialize a feature, resolving its sketch reference against the
+    component's already-loaded sketches."""
+    feat = Feature(
+        id=_saved_id(data),
+        operation=data.get("operation", "extrude"),
+        length=data.get("length"),
+        symmetric=bool(data.get("symmetric", False)),
+        invert=bool(data.get("invert", False)),
+        through_all=bool(data.get("through_all", False)),
+        cut_all_bodies=bool(data.get("cut_all_bodies", False)),
+        face_index=data.get("face_index"),
+        angle=_to_float(data.get("angle"), 360.0),
+        axis=tuple(float(v) for v in (data.get("axis") or (0, 0, 1))),
+        origin=tuple(float(v) for v in (data.get("origin") or (0.0, 0.0, 0.0))),
+        axis_line_id=data.get("axis_line_id"),
+        radius=data.get("radius"),
+        tangent_propagation=bool(data.get("tangent_propagation", False)),
+        scope=data.get("scope", "selected"),
+        edge_refs=list(data.get("edge_refs") or []),
+        face_keys=None,
+        face_keys_sketch_id=data.get("face_keys_sketch_id"),
+        pattern_type=data.get("pattern_type", "linear"),
+        count=int(data.get("count") or 2),
+        spacing=_to_float(data.get("spacing"), 10.0),
+        direction=tuple(float(v) for v in (data.get("direction") or (1, 0, 0))),
+        mirror_plane_origin=tuple(float(v) for v in (data.get("mirror_plane_origin") or (0.0, 0.0, 0.0))),
+        mirror_plane_normal=tuple(float(v) for v in (data.get("mirror_plane_normal") or (1, 0, 0))),
+        keep_original=bool(data.get("keep_original", True)),
+    )
+
+    # Deserialize face_keys from JSON if present.
+    fk_raw = data.get("face_keys")
+    if fk_raw and isinstance(fk_raw, str):
+        try:
+            feat.face_keys = json.loads(fk_raw)
+        except (json.JSONDecodeError, TypeError):
+            pass
+    elif isinstance(fk_raw, list):
+        feat.face_keys = fk_raw
+    sid = data.get("sketch_id")
+    if sid and sid in sketches:
+        feat.sketch = sketches[sid]
+    return feat
+
+
 def _body_to_dict(body: Body) -> Dict[str, Any]:
     """Body serialization.  ``geometry_ref`` is set later by the ZIP writer
     once the STEP file is written."""
@@ -171,10 +295,22 @@ def _body_to_dict(body: Body) -> Dict[str, Any]:
         "name": body.name,
         "source_sketch_id": body.source_sketch.id if body.source_sketch else None,
         "source_operation": body.source_operation,
+        "extrude_length": body.extrude_length,
+        "extrude_symmetric": body.extrude_symmetric,
+        "extrude_invert": body.extrude_invert,
+        "extrude_cut": body.extrude_cut,
+        "extrude_union": body.extrude_union,
+        "extrude_through_all": body.extrude_through_all,
+        "extrude_cut_all_bodies": body.extrude_cut_all_bodies,
+        "extrude_face_index": body.extrude_face_index,
+        "extrude_target_body_id": body.extrude_target_body_id,
+        "features": [_feature_to_dict(f) for f in body.features if f.operation != "base"],
+        "features_base_snapshot": bool(body.features and body.features[0].operation == "base"),
+        "base_geometry_ref": None,  # filled in by save_project
         "position": _coerce_listlike(body.position),
         "rotation": _coerce_listlike(body.rotation),
         "color": list(body.color) if body.color else [0.2, 0.4, 0.8],
-        "opacity": float(body.opacity),
+        "opacity": _to_float(body.opacity, 1.0),
         "visible": bool(body.visible),
         "has_geometry": body.geometry is not None,
         "geometry_ref": None,  # filled in by save_project
@@ -193,15 +329,24 @@ def _body_from_dict(
         geometry = geometry_loader(data["geometry_ref"]) if data.get("has_geometry") else None
 
     body = Body(
-        id=data.get("id") or None,
+        id=_saved_id(data),
         name=data.get("name", "Untitled Body"),
         geometry=geometry,
         source_sketch=source_sketch,
         source_operation=data.get("source_operation", "extrude"),
+        extrude_length=data.get("extrude_length"),
+        extrude_symmetric=bool(data.get("extrude_symmetric", False)),
+        extrude_invert=bool(data.get("extrude_invert", False)),
+        extrude_cut=bool(data.get("extrude_cut", False)),
+        extrude_union=bool(data.get("extrude_union", False)),
+        extrude_through_all=bool(data.get("extrude_through_all", False)),
+        extrude_cut_all_bodies=bool(data.get("extrude_cut_all_bodies", False)),
+        extrude_face_index=data.get("extrude_face_index"),
+        extrude_target_body_id=data.get("extrude_target_body_id"),
         position=_to_3vec(data.get("position")),
         rotation=_to_mat3(data.get("rotation")),
         color=tuple(data.get("color", [0.2, 0.4, 0.8])),
-        opacity=float(data.get("opacity", 1.0)),
+        opacity=_to_float(data.get("opacity"), 1.0),
         visible=bool(data.get("visible", True)),
     )
     body.created_at = _parse_iso(data.get("created_at"))
@@ -251,9 +396,9 @@ def _sketch_from_dict(
     # Re-apply the workplane (from_dict already does this internally, but be
     # defensive in case the saved dict didn't carry the workplane fields).
     occ_sketch.set_workplane(
-        tuple(data.get("workplane_origin", (0.0, 0.0, 0.0))),
-        tuple(data.get("workplane_normal", (0.0, 0.0, 1.0))),
-        tuple(data.get("workplane_x_dir", (1.0, 0.0, 0.0))),
+        _to_3tuple(data.get("workplane_origin", (0.0, 0.0, 0.0))),
+        _to_3tuple(data.get("workplane_normal", (0.0, 0.0, 1.0))),
+        _to_3tuple(data.get("workplane_x_dir", (1.0, 0.0, 0.0))),
     )
 
     geometry: Optional[OCCGeometryObject] = None
@@ -261,7 +406,7 @@ def _sketch_from_dict(
         geometry = geometry_loader(data["geometry_ref"]) if data.get("has_geometry") else None
 
     sk = Sketch(
-        id=data.get("id") or None,
+        id=_saved_id(data),
         name=data.get("name", "Untitled Sketch"),
         occ_sketch=occ_sketch,
         geometry=geometry,
@@ -298,7 +443,7 @@ def _component_from_dict(
     sketch_geometry_loader: Optional[Callable[[str], Optional[OCCGeometryObject]]] = None,
 ) -> Component:
     comp = Component(
-        id=data.get("id") or None,
+        id=_saved_id(data),
         name=data.get("name", "Untitled Component"),
         description=data.get("description", ""),
         active_sketch=data.get("active_sketch"),
@@ -319,7 +464,22 @@ def _component_from_dict(
         src_id = body_data.get("source_sketch_id")
         if src_id and src_id in comp.sketches:
             src_sketch = comp.sketches[src_id]
-        comp.bodies[bid] = _body_from_dict(body_data, body_geometry_loader, src_sketch)
+        body = _body_from_dict(body_data, body_geometry_loader, src_sketch)
+        # Parametric feature history (new files).  Old files carry no
+        # "features" key — the body keeps an empty list and is migrated
+        # lazily at update time (see ``_ensure_feature_history``).
+        for f_data in body_data.get("features") or []:
+            body.features.append(_feature_from_dict(f_data, comp.sketches))
+        if body_data.get("features_base_snapshot") and body.features:
+            # The list was saved WITHOUT its leading "base" snapshot;
+            # restore it from the dedicated STEP member.
+            base_geom: Optional[OCCGeometryObject] = None
+            base_ref = body_data.get("base_geometry_ref")
+            if base_ref and body_geometry_loader is not None:
+                base_geom = body_geometry_loader(base_ref)
+            if base_geom is not None:
+                body.features.insert(0, Feature(operation="base", geometry=base_geom))
+        comp.bodies[bid] = body
 
     return comp
 
@@ -331,13 +491,16 @@ def _connector_to_dict(conn: Connector) -> Dict[str, Any]:
         "position": list(conn.position),
         "normal": list(conn.normal),
         "x_dir": list(conn.x_dir),
-        "axis_rotation": float(conn.axis_rotation),
-        "offset": float(conn.offset),
+        "axis_rotation": _to_float(conn.axis_rotation, 0.0),
+        "offset": _to_float(conn.offset, 0.0),
         "assembly_component_id": conn.assembly_component_id,
         "source_obj_id": conn.source_obj_id,
+        "entity_type": conn.entity_type,
+        "normal_flip": bool(conn.normal_flip),
         "partner_ac_id": conn.partner_ac_id,
         "partner_connector_id": conn.partner_connector_id,
         "is_grounded": bool(conn.is_grounded),
+        "is_invalid": bool(conn.is_invalid),
         "created_at": conn.created_at.isoformat() if conn.created_at else None,
         "modified_at": conn.modified_at.isoformat() if conn.modified_at else None,
     }
@@ -345,19 +508,22 @@ def _connector_to_dict(conn: Connector) -> Dict[str, Any]:
 
 def _connector_from_dict(data: Dict[str, Any]) -> Connector:
     conn = Connector(
-        id=data.get("id") or None,
+        id=_saved_id(data),
         name=data.get("name", "Untitled Connector"),
         position=_to_3tuple(data.get("position")),
         normal=_to_3tuple(data.get("normal")),
         x_dir=_to_3tuple(data.get("x_dir")),
-        axis_rotation=float(data.get("axis_rotation", 0.0)),
-        offset=float(data.get("offset", 0.0)),
+        axis_rotation=_to_float(data.get("axis_rotation"), 0.0),
+        offset=_to_float(data.get("offset"), 0.0),
         assembly_component_id=data.get("assembly_component_id", ""),
         source_obj_id=data.get("source_obj_id", ""),
+        entity_type=data.get("entity_type", ""),
+        normal_flip=bool(data.get("normal_flip", False)),
     )
     conn.partner_ac_id = data.get("partner_ac_id")
     conn.partner_connector_id = data.get("partner_connector_id")
     conn.is_grounded = bool(data.get("is_grounded", False))
+    conn.is_invalid = bool(data.get("is_invalid", False))
     conn.created_at = _parse_iso(data.get("created_at"))
     conn.modified_at = _parse_iso(data.get("modified_at"))
     return conn
@@ -371,14 +537,24 @@ def _assembly_component_to_dict(ac: AssemblyComponent) -> Dict[str, Any]:
         "position": _coerce_listlike(ac.position),
         "rotation": _coerce_listlike(ac.rotation),
         "connectors": {cid: _connector_to_dict(c) for cid, c in ac.connectors.items()},
+        # Instance-local sketches + per-body modifier ops (kept apart from
+        # the shared component so save/load never mutates the base model).
+        "sketches": {sid: _sketch_to_dict(sk) for sid, sk in ac.sketches.items()},
+        "modifiers": {
+            bid: [_feature_to_dict(f) for f in mods]
+            for bid, mods in ac.modifiers.items()
+        },
         "created_at": ac.created_at.isoformat() if ac.created_at else None,
         "modified_at": ac.modified_at.isoformat() if ac.modified_at else None,
     }
 
-
-def _assembly_component_from_dict(data: Dict[str, Any]) -> AssemblyComponent:
+def _assembly_component_from_dict(
+    data: Dict[str, Any],
+    component: Optional[Component] = None,
+    sketch_geometry_loader: Optional[Callable[[str], Optional[OCCGeometryObject]]] = None,
+) -> AssemblyComponent:
     ac = AssemblyComponent(
-        id=data.get("id") or None,
+        id=_saved_id(data),
         component_id=data.get("component_id", ""),
         name=data.get("name", "Untitled Instance"),
         position=_to_3vec(data.get("position")),
@@ -388,6 +564,36 @@ def _assembly_component_from_dict(data: Dict[str, Any]) -> AssemblyComponent:
     ac.modified_at = _parse_iso(data.get("modified_at"))
     for cid, c_data in (data.get("connectors") or {}).items():
         ac.connectors[cid] = _connector_from_dict(c_data)
+
+    # Instance-local sketches first, so modifier sketch references can
+    # resolve against them (they live in component-local coordinates).
+    for sid, sk_data in (data.get("sketches") or {}).items():
+        try:
+            ac.sketches[sid] = _sketch_from_dict(sk_data, sketch_geometry_loader)
+        except Exception:
+            logger.warning("Skipping corrupt instance sketch %s", sid)
+
+    # Modifiers resolve sketch refs against the owning component's sketches
+    # first, then this instance's own sketches.
+    registry: Dict[str, Sketch] = {}
+    if component is not None:
+        registry.update(component.sketches)
+    registry.update(ac.sketches)
+    for bid, f_list in (data.get("modifiers") or {}).items():
+        kept: List[Feature] = []
+        for f_data in f_list or []:
+            try:
+                feat = _feature_from_dict(f_data, registry)
+            except Exception:
+                logger.warning("Skipping corrupt instance modifier on body %s", bid)
+                continue
+            # A sketch-based op whose sketch failed to load can never
+            # replay — dropping it keeps the rest of the chain usable.
+            if feat.operation in ("extrude", "cut", "union", "revolve") and feat.sketch is None:
+                continue
+            kept.append(feat)
+        if kept:
+            ac.modifiers[bid] = kept
     return ac
 
 
@@ -404,7 +610,7 @@ def _assembly_connection_to_dict(c: AssemblyConnection) -> Dict[str, Any]:
 
 def _assembly_connection_from_dict(data: Dict[str, Any]) -> AssemblyConnection:
     conn = AssemblyConnection(
-        id=data.get("id") or None,
+        id=_saved_id(data),
         first_ac_id=data.get("first_ac_id", ""),
         second_ac_id=data.get("second_ac_id", ""),
         first_connector_id=data.get("first_connector_id"),
@@ -425,22 +631,146 @@ def _assembly_to_dict(asm: Assembly) -> Dict[str, Any]:
         "modified_at": asm.modified_at.isoformat() if asm.modified_at else None,
     }
 
-
-def _assembly_from_dict(data: Dict[str, Any]) -> Assembly:
+def _assembly_from_dict(
+    data: Dict[str, Any],
+    components: Optional[Dict[str, Component]] = None,
+    sketch_geometry_loader: Optional[Callable[[str], Optional[OCCGeometryObject]]] = None,
+) -> Assembly:
     asm = Assembly(
-        id=data.get("id") or None,
+        id=_saved_id(data),
         name=data.get("name", "Untitled Assembly"),
         active_assembly_component=data.get("active_assembly_component"),
     )
     asm.created_at = _parse_iso(data.get("created_at"))
     asm.modified_at = _parse_iso(data.get("modified_at"))
     for cid, ac_data in (data.get("components") or {}).items():
-        asm.components[cid] = _assembly_component_from_dict(ac_data)
-    for c_data in (data.get("connections") or []):
+        comp = (components or {}).get(ac_data.get("component_id", ""))
+        asm.components[cid] = _assembly_component_from_dict(
+            ac_data, component=comp, sketch_geometry_loader=sketch_geometry_loader
+        )
+    for c_data in data.get("connections") or []:
         asm.connections.append(_assembly_connection_from_dict(c_data))
     return asm
 
 
+def _drawing_view_to_dict(v: DrawingView) -> Dict[str, Any]:
+    return {
+        "id": v.id,
+        "kind": v.kind,
+        "name": v.name,
+        "direction": _coerce_listlike(v.direction),
+        "up_vector": _coerce_listlike(v.up_vector),
+        "show_hidden_lines": bool(v.show_hidden_lines),
+        "show_centerlines": bool(v.show_centerlines),
+        "scale": _to_float(v.scale, 1.0),
+        "sheet_origin": _coerce_listlike(v.sheet_origin),
+    }
+
+
+def _drawing_view_from_dict(data: Dict[str, Any]) -> DrawingView:
+    view = DrawingView(
+        id=_saved_id(data),
+        kind=data.get("kind", "front"),
+        name=data.get("name"),
+        direction=_to_3tuple(data.get("direction")) or None,
+        up_vector=_to_3tuple(data.get("up_vector")) or None,
+        show_hidden_lines=bool(data.get("show_hidden_lines", False)),
+        show_centerlines=bool(data.get("show_centerlines", False)),
+        scale=_to_float(data.get("scale"), 1.0),
+    )
+    origin = data.get("sheet_origin")
+    if isinstance(origin, (list, tuple)) and len(origin) >= 2:
+        view.sheet_origin = (_to_float(origin[0]), _to_float(origin[1]))
+    return view
+
+
+def _drawing_annotation_to_dict(a: DrawingAnnotation) -> Dict[str, Any]:
+    return {
+        "id": a.id,
+        "kind": a.kind,
+        "text": a.text,
+        "visible": bool(a.visible),
+        "references": list(a.references),
+        "sheet_position": _coerce_listlike(a.sheet_position),
+        "view_id": a.view_id,
+        "anchors": [list(pt) for pt in a.anchors],
+        "dimension_kind": a.dimension_kind,
+        "direction": _coerce_listlike(a.direction),
+    }
+
+
+def _drawing_annotation_from_dict(data: Dict[str, Any]) -> DrawingAnnotation:
+    ann = DrawingAnnotation(
+        id=_saved_id(data),
+        kind=data.get("kind", "dimension"),
+        text=data.get("text"),
+        visible=bool(data.get("visible", True)),
+        references=list(data.get("references") or []),
+        view_id=data.get("view_id", ""),
+        dimension_kind=data.get("dimension_kind", ""),
+    )
+    pos = data.get("sheet_position")
+    if isinstance(pos, (list, tuple)) and len(pos) >= 2:
+        ann.sheet_position = (_to_float(pos[0]), _to_float(pos[1]))
+    anchors = data.get("anchors") or []
+    for pt in anchors:
+        if isinstance(pt, (list, tuple)) and len(pt) >= 2:
+            ann.anchors.append((_to_float(pt[0]), _to_float(pt[1])))
+    direction = data.get("direction")
+    if isinstance(direction, (list, tuple)) and len(direction) >= 2:
+        ann.direction = (_to_float(direction[0]), _to_float(direction[1]))
+    return ann
+
+
+def _technical_drawing_to_dict(d: TechnicalDrawing) -> Dict[str, Any]:
+    return {
+        "id": d.id,
+        "name": d.name,
+        "source_kind": d.source_kind,
+        "source_id": d.source_id,
+        "views": [_drawing_view_to_dict(v) for v in d.views],
+        "annotations": [_drawing_annotation_to_dict(a) for a in d.annotations],
+        "title": d.title,
+        "part_number": d.part_number,
+        "material": d.material,
+        "revision": d.revision,
+        "notes": d.notes,
+        "sheet_size": d.sheet_size,
+        "units": d.units,
+        "auto_dimensions": bool(d.auto_dimensions),
+        "auto_views": bool(d.auto_views),
+        "created_at": d.created_at.isoformat() if d.created_at else None,
+        "modified_at": d.modified_at.isoformat() if d.modified_at else None,
+    }
+
+
+def _technical_drawing_from_dict(data: Dict[str, Any]) -> TechnicalDrawing:
+    drawing = TechnicalDrawing(
+        id=_saved_id(data),
+        name=data.get("name", "Untitled Drawing"),
+        source_kind=data.get("source_kind", "component"),
+        source_id=data.get("source_id", ""),
+        title=data.get("title", ""),
+        part_number=data.get("part_number", ""),
+        material=data.get("material", ""),
+        revision=data.get("revision", ""),
+        notes=data.get("notes", ""),
+        # The renderer only supports the A4 ISO 5457 sheet; normalize
+        # legacy drawings (stored as A3) instead of surfacing stale sizes.
+        sheet_size="A4",
+        units=data.get("units", "mm"),
+        auto_dimensions=bool(data.get("auto_dimensions", False)),
+        auto_views=bool(data.get("auto_views", True)),
+    )
+    drawing.created_at = _parse_iso(data.get("created_at"))
+    drawing.modified_at = _parse_iso(data.get("modified_at"))
+    for v_data in data.get("views") or []:
+        drawing.views.append(_drawing_view_from_dict(v_data))
+    for a_data in data.get("annotations") or []:
+        drawing.annotations.append(_drawing_annotation_from_dict(a_data))
+    return drawing
+
+
 def _project_to_dict(
     project: Project,
     view_state: Optional[Dict[str, Any]] = None,
@@ -453,6 +783,7 @@ def _project_to_dict(
         "active_assembly": project.active_assembly,
         "components": {cid: _component_to_dict(c) for cid, c in project.components.items()},
         "assemblies": {aid: _assembly_to_dict(a) for aid, a in project.assemblies.items()},
+        "drawings": [_technical_drawing_to_dict(d) for d in project.drawings],
         "created_at": project.created_at.isoformat() if project.created_at else None,
         "modified_at": project.modified_at.isoformat() if project.modified_at else None,
         "view_state": view_state or {},
@@ -499,7 +830,9 @@ def _read_step_bytes(
         with open(tmp_path, "wb") as f:
             f.write(data)
         geom = kernel.import_step(tmp_path)
-        return geom
+        from typing import cast
+
+        return cast(OCCGeometryObject, geom)
     except Exception as exc:
         logger.warning("Failed to read STEP: %s", exc)
         return None
@@ -562,6 +895,20 @@ def save_project(
             arcname = f"bodies/{body_id}.step"
             body_files.append((arcname, step_bytes))
             manifest["components"][comp_id]["bodies"][body_id]["geometry_ref"] = arcname
+            # Base-snapshot STEP for migrated legacy bodies whose feature
+            # list starts with a frozen "base" geometry snapshot.
+            if (
+                body.features
+                and body.features[0].operation == "base"
+                and body.features[0].geometry is not None
+            ):
+                base_bytes = _write_step_for_body(kernel, body.features[0].geometry)
+                if base_bytes is not None:
+                    base_arcname = f"bodies/{body_id}_base.step"
+                    body_files.append((base_arcname, base_bytes))
+                    manifest["components"][comp_id]["bodies"][body_id]["base_geometry_ref"] = (
+                        base_arcname
+                    )
 
     # Per-sketch STEP files (solved face geometry).
     sketch_files: List[Tuple[str, bytes]] = []
@@ -597,6 +944,40 @@ def save_project(
             sketch_files.append((arcname, step_bytes))
             manifest["components"][comp_id]["sketches"][sketch_id]["geometry_ref"] = arcname
 
+    # Instance-local sketches (assembly components) get the same sidecar
+    # treatment as component sketches; the manifest nodes are patched in
+    # place under the assembly's component entry.
+    for asm_id, asm in project.assemblies.items():
+        for ac_id, ac in asm.components.items():
+            for sketch_id, sketch in ac.sketches.items():
+                node = manifest["assemblies"][asm_id]["components"][ac_id]["sketches"].get(sketch_id)
+                if node is None:
+                    continue
+                occ = sketch.occ_sketch.to_dict() if sketch.occ_sketch is not None else None
+                meta = {
+                    "id": sketch.id,
+                    "name": sketch.name,
+                    "workplane_origin": _coerce_listlike(sketch.workplane_origin),
+                    "workplane_normal": _coerce_listlike(sketch.workplane_normal),
+                    "workplane_x_dir": _coerce_listlike(sketch.workplane_x_dir),
+                    "is_solved": bool(sketch.is_solved),
+                    "is_fully_constrained": bool(sketch.is_fully_constrained),
+                    "occ_sketch": occ,
+                }
+                meta_arc = f"sketches/{sketch_id}/meta.json"
+                sketch_meta_files.append((meta_arc, _to_json(meta).encode("utf-8")))
+                node["occ_sketch"] = None
+                node["occ_sketch_ref"] = meta_arc
+
+                if sketch.geometry is None:
+                    continue
+                step_bytes = _write_step_for_body(kernel, sketch.geometry)
+                if step_bytes is None:
+                    continue
+                arcname = f"sketches/{sketch_id}/solved.step"
+                sketch_files.append((arcname, step_bytes))
+                node["geometry_ref"] = arcname
+
     # Write the ZIP.  Use a temp file + rename so a partial write can't
     # clobber an existing good file.
     tmp_fd, tmp_path = tempfile.mkstemp(suffix=".fluency")
@@ -654,13 +1035,17 @@ def load_project(filepath: str) -> Tuple[Project, Dict[str, Any]]:
 
     with zipfile.ZipFile(filepath, "r") as zipf:
         manifest_raw = zipf.read("project.json")
-        manifest = json.loads(manifest_raw.decode("utf-8"))
+        try:
+            manifest = json.loads(manifest_raw.decode("utf-8"))
+        except (ValueError, UnicodeDecodeError) as exc:
+            raise RuntimeError(f"Corrupt project file (bad JSON): {filepath}") from exc
         view_state: Dict[str, Any] = manifest.get("view_state") or {}
 
         # If a sketch's occ_sketch is referenced as a separate file, read
         # it in now and patch the manifest so _sketch_from_dict sees it.
-        for comp_id, comp_data in (manifest.get("components") or {}).items():
-            for sk_id, sk_data in (comp_data.get("sketches") or {}).items():
+        # Applies to both component sketches and instance-local sketches.
+        def _patch_sketch_sidecars(sketches_dict: Dict[str, Any]) -> None:
+            for sk_id, sk_data in (sketches_dict or {}).items():
                 ref = sk_data.get("occ_sketch_ref")
                 if not ref:
                     continue
@@ -669,15 +1054,30 @@ def load_project(filepath: str) -> Tuple[Project, Dict[str, Any]]:
                 except KeyError:
                     logger.warning("Sketch meta missing in archive: %s", ref)
                     continue
-                meta = json.loads(meta_bytes.decode("utf-8"))
+                try:
+                    meta = json.loads(meta_bytes.decode("utf-8"))
+                except (ValueError, UnicodeDecodeError) as exc:
+                    logger.warning("Sketch meta corrupt in archive: %s (%s)", ref, exc)
+                    continue
                 sk_data["occ_sketch"] = meta.get("occ_sketch")
                 # Workplane fields on the sketch-level file override the
                 # embedded ones (source of truth lives in the sidecar).
-                for k in ("workplane_origin", "workplane_normal", "workplane_x_dir",
-                          "is_solved", "is_fully_constrained"):
+                for k in (
+                    "workplane_origin",
+                    "workplane_normal",
+                    "workplane_x_dir",
+                    "is_solved",
+                    "is_fully_constrained",
+                ):
                     if k in meta:
                         sk_data[k] = meta[k]
 
+        for comp_id, comp_data in (manifest.get("components") or {}).items():
+            _patch_sketch_sidecars(comp_data.get("sketches"))
+        for aid, a_data in (manifest.get("assemblies") or {}).items():
+            for ac_id, ac_data in (a_data.get("components") or {}).items():
+                _patch_sketch_sidecars(ac_data.get("sketches"))
+
         project = Project(
             name=manifest.get("name", "Untitled Project"),
             description=manifest.get("description", ""),
@@ -697,7 +1097,17 @@ def load_project(filepath: str) -> Tuple[Project, Dict[str, Any]]:
             )
 
         for aid, a_data in (manifest.get("assemblies") or {}).items():
-            project.assemblies[aid] = _assembly_from_dict(a_data)
+            project.assemblies[aid] = _assembly_from_dict(
+                a_data,
+                components=project.components,
+                sketch_geometry_loader=sketch_geometry_loader,
+            )
+
+        for d_data in manifest.get("drawings") or []:
+            try:
+                project.drawings.append(_technical_drawing_from_dict(d_data))
+            except Exception as exc:
+                logger.warning("Skipping corrupt drawing in archive: %s", exc)
 
     # After all components are loaded, re-wire connector partner ids so
     # they point to the freshly-loaded AssemblyComponents.  (The dict

src/fluency/main.py

@@ -24,6 +24,7 @@ from fluency.ui.dialogs import (
     ExtrudeDialog,
     OffsetDialog,
     RevolveDialog,
+    ThreadDialog,
     WorkplaneOrientationDialog,
 )
 from fluency.ui.main_window import MainWindow
@@ -37,6 +38,7 @@ __all__ = [
     "ExtrudeDialog",
     "RevolveDialog",
     "OffsetDialog",
+    "ThreadDialog",
     "WorkplaneOrientationDialog",
     "main",
 ]

src/fluency/models/data_model.py

@@ -13,9 +13,7 @@ import numpy as np
 
 from fluency.geometry.base import (
     Point2D,
-    Point3D,
     GeometryObject,
-    SketchInterface,
 )
 from fluency.geometry_occ.kernel import OCGeometryKernel, OCCGeometryObject
 from fluency.geometry_occ.sketch import OCCSketch
@@ -48,6 +46,7 @@ class Workplane:
     def __post_init__(self):
         # Normalise normal and x_dir on construction.
         import numpy as np
+
         n = np.asarray(self.normal, dtype=float)
         n = n / np.linalg.norm(n)
         x = np.asarray(self.x_dir, dtype=float)
@@ -61,9 +60,9 @@ class Workplane:
         x = x / x_norm
         y = np.cross(n, x)
         y = y / np.linalg.norm(y)
-        self.normal = tuple(float(v) for v in n)
-        self.x_dir = tuple(float(v) for v in x)
-        self._y_dir = tuple(float(v) for v in y)
+        self.normal = (float(n[0]), float(n[1]), float(n[2]))
+        self.x_dir = (float(x[0]), float(x[1]), float(x[2]))
+        self._y_dir = (float(y[0]), float(y[1]), float(y[2]))
 
     @property
     def y_dir(self) -> Tuple[float, float, float]:
@@ -84,6 +83,7 @@ class Workplane:
     def world_to_uv(self, p: Tuple[float, float, float]) -> Tuple[float, float]:
         """Map a 3D world point to UV coordinates on this plane."""
         import numpy as np
+
         ox, oy, oz = self.origin
         v = np.array([p[0] - ox, p[1] - oy, p[2] - oz])
         xd = np.array(self.x_dir, dtype=float)
@@ -206,6 +206,101 @@ class Sketch:
         self.modified_at = datetime.now()
 
 
+@dataclass
+class Feature:
+    """
+    One operation in a body's parametric feature history.
+
+    Bodies rebuild their geometry by replaying their ordered feature
+    list from scratch (see ``Body.features``).  This is what makes
+    sketch edits propagate: a moved circle re-cuts at the new position
+    on a freshly rebuilt base instead of adding to the previous result.
+
+    ``operation`` is one of:
+      - "extrude": base solid, ``kernel.extrude`` of the sketch profile
+      - "revolve": base solid, ``kernel.revolve`` of the sketch profile
+      - "cut":    boolean difference of the running geometry with the
+                  extruded sketch profile
+      - "union":  boolean union of the running geometry with the
+                  extruded sketch profile
+      - "fillet": round a set of edges of the running geometry
+                  (``radius``, ``tangent_propagation``, ``scope``,
+                  ``edge_refs`` — see below)
+      - "chamfer": bevel a set of edges of the running geometry
+                  (same fields as "fillet"; ``radius`` holds the
+                  chamfer size)
+      - "mirror": mirror the running solid across a plane defined by
+                  ``mirror_plane_origin`` and ``mirror_plane_normal``.
+                  When ``keep_original`` is True (the default), the
+                  original solid is boolean-union'd with its mirror
+      - "array" / "pattern": repeat the running solid in a linear or
+                 circular array.  ``pattern_type`` is "linear" or
+                 "circular"; ``count`` is the total number of items
+                 (original + copies).  Linear uses ``direction``
+                 (unit vector) and ``spacing`` (mm between adjacent
+                 items); circular reuses ``axis`` + ``origin`` for the
+                 rotation axis and ``angle`` for the total angular
+                 span in degrees (copies evenly distributed).
+      - "base":   frozen geometry snapshot (``geometry`` field) — used
+                 to migrate legacy bodies whose original base feature
+                 is unknown.  Never the result of a user operation.
+    """
+
+    id: str = field(default_factory=lambda: str(uuid.uuid4()))
+    operation: str = "extrude"
+
+    sketch: Optional[Sketch] = None  # runtime ref; serialized as sketch_id
+    length: Optional[float] = None
+    symmetric: bool = False
+    invert: bool = False
+    through_all: bool = False
+    cut_all_bodies: bool = False
+    face_index: Optional[int] = None  # which sketch face was selected
+    angle: float = 360.0  # revolve only (degrees)
+    axis: Tuple[float, float, float] = (0, 0, 1)  # revolve only: unit axis vector
+    origin: Tuple[float, float, float] = (0.0, 0.0, 0.0)  # revolve only: axis point
+    axis_line_id: Optional[int] = None  # revolve only: sketch line entity used as axis
+
+    # "base" features only: frozen pre-feature geometry snapshot.
+    geometry: Optional[OCCGeometryObject] = None
+
+    # "fillet" / "chamfer" features only: radius (mm) of the round or the
+    # chamfer size, whether the op should extend along edges tangent to the
+    # picked ones, the edge scope ("selected" = edges between the two
+    # picked faces, "all" = every edge of the body), and stable
+    # fingerprints of the selected edges so the replay can re-find them
+    # after the base geometry is rebuilt.
+    radius: Optional[float] = None
+    tangent_propagation: bool = False
+    scope: str = "selected"
+    edge_refs: List[str] = field(default_factory=list)
+
+    # FaceKey references for fillet/chamfer: stable face classification
+    # that survives sketch dimension changes.  ``face_keys`` is a list of
+    # (FaceKey, FaceKey) pairs — one pair per user-picked face;
+    # ``face_keys_sketch_id`` tracks which sketch produced the body these
+    # faces belong to.
+    face_keys: Optional[List[Tuple[Dict[str, Any], Dict[str, Any]]]] = None
+    face_keys_sketch_id: Optional[str] = None
+
+    # "array" / "pattern" features only: repeat the running solid.
+    # ``pattern_type`` is "linear" or "circular"; ``count`` is the total
+    # number of items including the original.  Linear arrays use
+    # ``direction`` (unit vector) and ``spacing`` (mm); circular arrays
+    # reuse ``axis`` / ``origin`` / ``angle`` (total angular span, deg).
+    pattern_type: str = "linear"
+    count: int = 2
+    spacing: float = 10.0
+    direction: Tuple[float, float, float] = (1.0, 0.0, 0.0)
+
+    # "mirror" feature only: mirror plane definition.
+    mirror_plane_origin: Tuple[float, float, float] = (0.0, 0.0, 0.0)
+    mirror_plane_normal: Tuple[float, float, float] = (1.0, 0.0, 0.0)
+    keep_original: bool = True
+
+    created_at: datetime = field(default_factory=datetime.now)
+
+
 @dataclass
 class Body:
     """
@@ -222,6 +317,27 @@ class Body:
     source_sketch: Optional[Sketch] = None
     source_operation: str = "extrude"
 
+    # Parametric feature history.  When non-empty, the body is rebuilt
+    # from scratch by replaying these features in order; the flat
+    # extrude_* / source_* fields below then only mirror the LAST
+    # feature for backward compatibility (old files, old code paths).
+    features: List[Feature] = field(default_factory=list)
+
+    # Re-extrusion parameters — stored so the body can be rebuilt from
+    # its source sketch when the sketch is edited.  None means the body
+    # was not created by an extrude-type operation and cannot be auto-
+    # rebuilt.
+    extrude_length: Optional[float] = None
+    extrude_symmetric: bool = False
+    extrude_invert: bool = False
+    extrude_cut: bool = False
+    extrude_union: bool = False
+    extrude_through_all: bool = False
+    extrude_cut_all_bodies: bool = False  # cut through all bodies in component
+    extrude_face_index: Optional[int] = None  # which sketch face was selected
+    extrude_target_body_id: Optional[str] = None  # for cut/union: target body id
+    needs_update: bool = False  # True when source sketch changed since last extrude
+
     position: np.ndarray = field(default_factory=lambda: np.array([0.0, 0.0, 0.0]))
     rotation: np.ndarray = field(default_factory=lambda: np.eye(3))
 
@@ -230,6 +346,7 @@ class Body:
     visible: bool = True
 
     render_object: Any = None
+    render_material: Optional[str] = None  # material preset name for render backend
 
     created_at: datetime = field(default_factory=datetime.now)
     modified_at: datetime = field(default_factory=datetime.now)
@@ -351,11 +468,14 @@ class Connector:
     id: str = field(default_factory=lambda: str(uuid.uuid4()))
     name: str = "Untitled Connector"
 
-    # 3D position of the connection point (world coords).
+    # 3D position of the connection point (component-local coords).
+    # Transformed to world coords at render time using the parent
+    # AssemblyComponent's position/rotation, so connectors move with
+    # their component automatically.
     position: Tuple[float, float, float] = (0.0, 0.0, 0.0)
-    # Normal direction of the connection (e.g. hole axis).
+    # Normal direction of the connection (e.g. hole axis) in local coords.
     normal: Tuple[float, float, float] = (0.0, 0.0, 1.0)
-    # In-plane X direction for defining the reference frame.
+    # In-plane X direction for defining the reference frame (local coords).
     x_dir: Tuple[float, float, float] = (1.0, 0.0, 0.0)
 
     # Rotation around the normal axis (degrees).
@@ -367,6 +487,16 @@ class Connector:
     assembly_component_id: str = ""
     # Which body/face this connector was placed on (renderer obj_id).
     source_obj_id: str = ""
+    # Entity class the connector was picked on ("planar_face",
+    # "cylindrical_face", "edge", "vertex").  Used to re-locate the
+    # connector on rebuilt geometry: only features of the same class are
+    # considered, so a hole connector can never jump onto a flat face.
+    # Empty for legacy files (all classes are then searched).
+    entity_type: str = ""
+    # Flip chosen in the placement dialog (bolt enters from the opposite
+    # side).  Re-applied when a mated pair is re-solved so the original
+    # mate pose is reproduced exactly.
+    normal_flip: bool = False
 
     # --- Rigid-group pairing (set when two connectors are mated) ---
     # The id of the partner AssemblyComponent this connector is mated to.
@@ -379,9 +509,23 @@ class Connector:
     # True on the first-picked (grounded) connector of a mated pair.
     is_grounded: bool = False
 
+    # True when the source geometry this connector was placed on has
+    # changed or disappeared — the connector needs re-placement.
+    is_invalid: bool = False
+
     created_at: datetime = field(default_factory=datetime.now)
     modified_at: datetime = field(default_factory=datetime.now)
 
+    def __post_init__(self) -> None:
+        # Legacy files predate the entity_type field: recover it from the
+        # auto-generated connector name ("Conn cylindrical_face anchor") so
+        # relocation can restrict its search to the same feature class.
+        if not self.entity_type:
+            for t in ("cylindrical_face", "planar_face", "edge", "vertex"):
+                if self.name in (f"Conn {t} anchor", f"Conn {t} mover"):
+                    self.entity_type = t
+                    break
+
 
 @dataclass
 class AssemblyComponent:
@@ -405,6 +549,20 @@ class AssemblyComponent:
     # Connectors defined on this component instance.
     connectors: Dict[str, Connector] = field(default_factory=dict)
 
+    # Instance-local (per-instantiation) state.  Kept separate from the
+    # shared component so per-instance work never leaks back into the base
+    # model.  ``sketches`` are instance-local sketches stored in
+    # component-local coordinates (so they stay valid when the instance is
+    # moved / rotated); ``modifiers`` maps body_id to an ordered list of
+    # Feature ops applied ON TOP of the live component body feature history
+    # when the instance geometry is rebuilt.
+    sketches: Dict[str, Sketch] = field(default_factory=dict)
+    modifiers: Dict[str, List[Feature]] = field(default_factory=dict)
+
+    # Runtime-only cache of rebuilt instance geometry (body_id -> geometry).
+    # Never serialized; invalidated on component updates and modifier edits.
+    geom_cache: Dict[str, Any] = field(default_factory=dict, repr=False)
+
     created_at: datetime = field(default_factory=datetime.now)
     modified_at: datetime = field(default_factory=datetime.now)
 
@@ -415,6 +573,8 @@ class AssemblyComponent:
         x_dir: Tuple[float, float, float],
         source_obj_id: str = "",
         name: Optional[str] = None,
+        entity_type: str = "",
+        normal_flip: bool = False,
     ) -> Connector:
         """Add a connector to this component instance."""
         conn = Connector(
@@ -424,6 +584,8 @@ class AssemblyComponent:
             x_dir=x_dir,
             assembly_component_id=self.id,
             source_obj_id=source_obj_id,
+            entity_type=entity_type,
+            normal_flip=normal_flip,
         )
         self.connectors[conn.id] = conn
         self.modified_at = datetime.now()
@@ -437,6 +599,45 @@ class AssemblyComponent:
             return True
         return False
 
+    def add_instance_sketch(self, sketch: Optional[Sketch] = None) -> Sketch:
+        """Add an instance-local sketch (component-local coordinates)."""
+        if sketch is None:
+            sketch = Sketch(name=f"Instance Sketch {len(self.sketches) + 1}")
+        self.sketches[sketch.id] = sketch
+        self.modified_at = datetime.now()
+        return sketch
+
+    def remove_instance_sketch(self, sketch_id: str) -> bool:
+        """Remove an instance sketch and every modifier that references it."""
+        if sketch_id not in self.sketches:
+            return False
+        del self.sketches[sketch_id]
+        for body_id in list(self.modifiers.keys()):
+            kept = [
+                f for f in self.modifiers[body_id]
+                if not (f.sketch is not None and f.sketch.id == sketch_id)
+            ]
+            if kept:
+                self.modifiers[body_id] = kept
+            else:
+                del self.modifiers[body_id]
+            self.geom_cache.pop(body_id, None)
+        self.modified_at = datetime.now()
+        return True
+
+    def add_modifier(self, body_id: str, feat: Feature) -> Feature:
+        """Append a modifier op to *body_id*'s instance-local history."""
+        self.modifiers.setdefault(body_id, []).append(feat)
+        self.geom_cache.pop(body_id, None)
+        self.modified_at = datetime.now()
+        return feat
+
+    def invalidate_geom_cache(self, body_id: Optional[str] = None) -> None:
+        """Drop cached rebuilt instance geometry (one body, or all)."""
+        if body_id is None:
+            self.geom_cache.clear()
+        else:
+            self.geom_cache.pop(body_id, None)
 
 @dataclass
 class AssemblyConnection:
@@ -450,8 +651,8 @@ class AssemblyConnection:
     """
 
     id: str = field(default_factory=lambda: str(uuid.uuid4()))
-    first_ac_id: str = ""    # grounded reference side
-    second_ac_id: str = ""   # solved side
+    first_ac_id: str = ""  # grounded reference side
+    second_ac_id: str = ""  # solved side
     first_connector_id: Optional[str] = None
     second_connector_id: Optional[str] = None
     created_at: datetime = field(default_factory=datetime.now)
@@ -486,9 +687,15 @@ class Assembly:
         """Record a mated connector pair between two component instances.
 
         The first-picked component (``first_ac_id``) is treated as the
-        grounded reference of the pair.  Returns the AssemblyConnection for
-        further bookkeeping (e.g. attaching partner connector ids).
+        grounded reference of the pair.  Guards against duplicate entries.
+        Returns the AssemblyConnection for further bookkeeping.
         """
+        # Guard: deduplicate — same pair in either order
+        for c in self.connections:
+            if (c.first_ac_id == first_ac_id and c.second_ac_id == second_ac_id) or (
+                c.first_ac_id == second_ac_id and c.second_ac_id == first_ac_id
+            ):
+                return c
         conn = AssemblyConnection(
             first_ac_id=first_ac_id,
             second_ac_id=second_ac_id,
@@ -500,8 +707,7 @@ class Assembly:
     def remove_connections_for(self, ac_id: str) -> None:
         """Drop every connection that involves *ac_id* (e.g. on removal)."""
         self.connections = [
-            c for c in self.connections
-            if c.first_ac_id != ac_id and c.second_ac_id != ac_id
+            c for c in self.connections if c.first_ac_id != ac_id and c.second_ac_id != ac_id
         ]
 
     def get_rigid_group(self, ac_id: str) -> List[str]:
@@ -534,6 +740,10 @@ class Assembly:
         """True if *ac_id* is the grounded (first-picked) side of any pair."""
         return any(c.first_ac_id == ac_id for c in self.connections)
 
+    def get_group_size(self, ac_id: str) -> int:
+        """Number of components rigidly linked to *ac_id* (including itself)."""
+        return len(self.get_rigid_group(ac_id))
+
     def add_component_instance(
         self, component_id: str, name: Optional[str] = None
     ) -> AssemblyComponent:
@@ -561,19 +771,14 @@ class Assembly:
             # the rigid-group graph and point at a missing component.
             self.remove_connections_for(assembly_component_id)
             if self.active_assembly_component == assembly_component_id:
-                self.active_assembly_component = next(
-                    iter(self.components.keys()), None
-                )
+                self.active_assembly_component = next(iter(self.components.keys()), None)
             self.modified_at = datetime.now()
             return True
         return False
 
     def get_active_instance(self) -> Optional[AssemblyComponent]:
         """Get the currently active assembly component instance."""
-        if (
-            self.active_assembly_component
-            and self.active_assembly_component in self.components
-        ):
+        if self.active_assembly_component and self.active_assembly_component in self.components:
             return self.components[self.active_assembly_component]
         return None
 
@@ -596,6 +801,10 @@ class Project:
     assemblies: Dict[str, Assembly] = field(default_factory=dict)
     active_assembly: Optional[str] = None
 
+    # Technical drawings keyed to their source component/assembly.
+    # Manual dimensions and view options added in the drawing workbench
+    # are persisted here so they survive save/load.
+    drawings: List["TechnicalDrawing"] = field(default_factory=list)
     kernel: OCGeometryKernel = field(default_factory=OCGeometryKernel)
 
     created_at: datetime = field(default_factory=datetime.now)
@@ -672,36 +881,21 @@ class Project:
         """Look up a component by id across all project components."""
         return self.components.get(component_id)
 
-    def add_component(self, component: Optional[Component] = None) -> Component:
-        """Add a component to the project."""
-        if component is None:
-            component = Component(name=f"Component {len(self.components) + 1}")
-        self.components[component.id] = component
-        if self.active_component is None:
-            self.active_component = component.id
-        self.modified_at = datetime.now()
-        return component
+    # ── Drawing helpers ──
 
-    def remove_component(self, component_id: str) -> bool:
-        """Remove a component from the project."""
-        if component_id in self.components:
-            del self.components[component_id]
-            if self.active_component == component_id:
-                self.active_component = next(iter(self.components.keys()), None)
-            self.modified_at = datetime.now()
-            return True
-        return False
-
-    def get_active_component(self) -> Optional[Component]:
-        """Get the currently active component."""
-        if self.active_component and self.active_component in self.components:
-            return self.components[self.active_component]
+    def get_drawing_for(self, source_kind: str, source_id: str) -> Optional["TechnicalDrawing"]:
+        """Return the drawing bound to *(source_kind, source_id)*, if any."""
+        for drawing in self.drawings:
+            if drawing.source_kind == source_kind and drawing.source_id == source_id:
+                return drawing
         return None
 
-    def set_active_component(self, component_id: Optional[str]) -> None:
-        """Set the active component."""
-        self.active_component = component_id
+    def add_drawing(self, drawing: "TechnicalDrawing") -> "TechnicalDrawing":
+        """Register *drawing* with the project and return it."""
+        self.drawings.append(drawing)
         self.modified_at = datetime.now()
+        return drawing
+
 
     def export_step(self, filepath: str) -> bool:
         """Export all visible bodies to STEP."""
@@ -770,3 +964,102 @@ class Project:
         for comp in self.components.values():
             sketches.extend(comp.sketches.values())
         return sketches
+
+    def compute_source_fingerprint(
+        self, source_kind: str, source_id: str
+    ) -> str:
+        """Compute a simple fingerprint for a source reference."""
+        import hashlib
+        data = f"{source_kind}:{source_id}"
+        return hashlib.sha256(data.encode()).hexdigest()[:16]
+# ── Technical Drawing models ───────────────────────────────────────────────
+
+@dataclass
+class DrawingView:
+    """One projected view in a technical drawing."""
+
+    id: str = field(default_factory=lambda: str(uuid.uuid4()))
+    kind: str = "front"  # front, back, top, bottom, right, left, isometric, custom
+    name: Optional[str] = None  # human-readable label; defaults from kind
+
+    # View direction and up vector in world coords (for custom views).
+    # Ignored when kind is one of the standard presets.
+    direction: Optional[Tuple[float, float, float]] = None
+    up_vector: Optional[Tuple[float, float, float]] = None
+
+    show_hidden_lines: bool = False
+    show_centerlines: bool = False
+    scale: float = 1.0
+
+    # Sheet position (mm from sheet origin) — set by layout engine.
+    sheet_origin: Tuple[float, float] = (0.0, 0.0)
+
+
+@dataclass
+class DrawingAnnotation:
+    """One annotation (dimension or note) on a technical drawing."""
+
+    id: str = field(default_factory=lambda: str(uuid.uuid4()))
+    kind: str = "dimension"  # dimension, note, tolerance, surface_finish, weld_symbol
+    text: Optional[str] = None
+    visible: bool = True
+
+    # References to DrawingCandidate keys this annotation is bound to.
+    references: List[str] = field(default_factory=list)
+
+    # Sheet position (mm). For dimensions, anchor point; for notes, placement.
+    sheet_position: Tuple[float, float] = (0.0, 0.0)
+
+    # Associated view id (empty means global/note block).
+    view_id: str = ""
+
+    # Manual-dimension geometry in view-plane model coordinates (model
+    # units in the view's projection plane).  Populated for user-placed
+    # dimensions, empty for reference-based annotations:
+    #   "length":   (point_on_edge1, point_on_edge2) — closest points
+    #   "diameter": (left, right) — antipodal points across the centre
+    #   "angle":    (vertex, arm1_point, arm2_point)
+    anchors: List[Tuple[float, float]] = field(default_factory=list)
+
+    # Sub-kind of the manual dimension: "length" | "diameter" | "angle".
+    # Empty for non-dimension annotations.
+    dimension_kind: str = ""
+
+    # Unit vector along the measured distance in view-plane coordinates
+    # (length dimensions only).  The model→sheet transform is a uniform
+    # scale + translation, so the direction is valid in sheet space too.
+    direction: Optional[Tuple[float, float]] = None
+
+
+@dataclass
+class TechnicalDrawing:
+    """A complete technical drawing definition."""
+
+    id: str = field(default_factory=lambda: str(uuid.uuid4()))
+    name: str = "Untitled Drawing"
+
+    # Source geometry reference.
+    source_kind: str = "component"  # component, assembly
+    source_id: str = ""
+
+    views: List[DrawingView] = field(default_factory=list)
+    annotations: List[DrawingAnnotation] = field(default_factory=list)
+
+    # Title block metadata.
+    title: str = ""
+    part_number: str = ""
+    material: str = ""
+    revision: str = ""
+    notes: str = ""
+
+    # Sheet size (A0..A4 or custom mm). Default A4 (ISO 5457 template).
+    sheet_size: str = "A4"
+    units: str = "mm"  # mm, in
+
+    # Auto-generation flags.  Auto dimensions are opt-in: the drawing
+    # workbench shows them only while the user has the toggle enabled.
+    auto_dimensions: bool = False
+    auto_views: bool = True
+
+    created_at: datetime = field(default_factory=datetime.now)
+    modified_at: datetime = field(default_factory=datetime.now)

src/fluency/rendering/__init__.py

@@ -1,5 +1,6 @@
 """Rendering module."""
 
+# OCC/OpenGL viewport renderers
 from fluency.rendering.base import (
     Renderer,
     RenderObject,
@@ -8,10 +9,22 @@ from fluency.rendering.base import (
 from fluency.rendering.pygfx_renderer import PygfxRenderer, PygfxRenderObject
 from fluency.rendering.occ_renderer import OCCRenderer, OCCRenderObject
 
+# Photorealistic render backends
+from fluency.rendering.render_backend import (
+    RenderBackend,
+    RenderMaterial,
+    RenderCamera,
+    RenderSettings,
+)
+
 __all__ = [
     "Renderer",
     "RenderObject",
     "RenderColor",
     "PygfxRenderer",
     "PygfxRenderObject",
+    "RenderBackend",
+    "RenderMaterial",
+    "RenderCamera",
+    "RenderSettings",
 ]

src/fluency/rendering/material_presets.py

@@ -0,0 +1,156 @@
+"""Material presets for the render backend.
+
+Each preset is a RenderMaterial with physically-plausible values.
+"""
+
+from __future__ import annotations
+
+from typing import Dict, List
+
+from .render_backend import RenderMaterial
+
+# ── Preset library ──────────────────────────────────────────────────────
+# Note: Mitsuba pip installs don't include spectral metal data files,
+# so metal_preset is not used. Instead, metals use material="none" with
+# specular_reflectance set to the metal color.
+
+PRESETS: Dict[str, RenderMaterial] = {
+    # ── Metals ──────────────────────────────────────────────────────
+    "Brushed Steel": RenderMaterial(
+        name="Brushed Steel",
+        color=(0.65, 0.67, 0.72),
+        metallic=0.9,
+        roughness=0.35,
+        bsdf_type="roughconductor",
+    ),
+    "Polished Chrome": RenderMaterial(
+        name="Polished Chrome",
+        color=(0.8, 0.8, 0.8),
+        metallic=1.0,
+        roughness=0.05,
+        bsdf_type="roughconductor",
+    ),
+    "Brushed Aluminum": RenderMaterial(
+        name="Brushed Aluminum",
+        color=(0.75, 0.75, 0.75),
+        metallic=0.85,
+        roughness=0.25,
+        bsdf_type="roughconductor",
+    ),
+    "Copper": RenderMaterial(
+        name="Copper",
+        color=(0.95, 0.64, 0.54),
+        metallic=0.95,
+        roughness=0.15,
+        bsdf_type="roughconductor",
+    ),
+    "Gold": RenderMaterial(
+        name="Gold",
+        color=(1.0, 0.76, 0.33),
+        metallic=1.0,
+        roughness=0.1,
+        bsdf_type="roughconductor",
+    ),
+    "Blackened Steel": RenderMaterial(
+        name="Blackened Steel",
+        color=(0.15, 0.15, 0.17),
+        metallic=0.8,
+        roughness=0.4,
+        bsdf_type="roughconductor",
+    ),
+    # ── Plastics ────────────────────────────────────────────────────
+    "Matte Plastic": RenderMaterial(
+        name="Matte Plastic",
+        color=(0.2, 0.5, 0.8),
+        metallic=0.0,
+        roughness=0.6,
+        bsdf_type="plastic",
+        int_ior=1.5,
+    ),
+    "Glossy Plastic": RenderMaterial(
+        name="Glossy Plastic",
+        color=(0.2, 0.5, 0.8),
+        metallic=0.0,
+        roughness=0.1,
+        bsdf_type="plastic",
+        int_ior=1.5,
+    ),
+    "White Nylon": RenderMaterial(
+        name="White Nylon",
+        color=(0.85, 0.85, 0.83),
+        metallic=0.0,
+        roughness=0.45,
+        bsdf_type="plastic",
+        int_ior=1.53,
+    ),
+    "Black ABS": RenderMaterial(
+        name="Black ABS",
+        color=(0.05, 0.05, 0.05),
+        metallic=0.0,
+        roughness=0.35,
+        bsdf_type="plastic",
+        int_ior=1.54,
+    ),
+    "Red PA12": RenderMaterial(
+        name="Red PA12",
+        color=(0.75, 0.08, 0.08),
+        metallic=0.0,
+        roughness=0.4,
+        bsdf_type="plastic",
+        int_ior=1.53,
+    ),
+    # ── Other ───────────────────────────────────────────────────────
+    "Rubber": RenderMaterial(
+        name="Rubber",
+        color=(0.1, 0.1, 0.1),
+        metallic=0.0,
+        roughness=0.9,
+        bsdf_type="diffuse",
+    ),
+    "Ceramic White": RenderMaterial(
+        name="Ceramic White",
+        color=(0.92, 0.91, 0.88),
+        metallic=0.0,
+        roughness=0.15,
+        bsdf_type="dielectric",
+        int_ior=1.55,
+    ),
+    "Glass": RenderMaterial(
+        name="Glass",
+        color=(0.95, 0.95, 0.95),
+        metallic=0.0,
+        roughness=0.0,
+        bsdf_type="dielectric",
+        int_ior=1.52,
+    ),
+    "Wood": RenderMaterial(
+        name="Wood",
+        color=(0.6, 0.4, 0.2),
+        metallic=0.0,
+        roughness=0.7,
+        bsdf_type="diffuse",
+    ),
+}
+
+
+def get_preset(name: str) -> RenderMaterial:
+    """Get a material preset by name. Falls back to default if not found."""
+    if name in PRESETS:
+        return PRESETS[name]
+    return default_material()
+
+
+def default_material() -> RenderMaterial:
+    """Return the default grey material."""
+    return RenderMaterial(
+        name="Default",
+        color=(0.7, 0.7, 0.7),
+        metallic=0.0,
+        roughness=0.5,
+        bsdf_type="diffuse",
+    )
+
+
+def preset_names() -> List[str]:
+    """Return sorted list of available preset names."""
+    return sorted(PRESETS.keys())

src/fluency/rendering/mitsuba_backend.py

@@ -0,0 +1,425 @@
+"""Mitsuba 3 photorealistic render backend.
+
+Requires: ``pip install mitsuba``
+"""
+
+from __future__ import annotations
+
+import logging
+import os
+from typing import Callable, Optional
+
+import numpy as np
+
+from .render_backend import RenderBackend, RenderCamera, RenderMaterial, RenderSettings
+
+logger = logging.getLogger(__name__)
+
+
+class MitsubaBackend(RenderBackend):
+    """Render backend using Mitsuba 3 path tracer."""
+
+    def name(self) -> str:
+        return "Mitsuba 3"
+
+    def is_available(self) -> bool:
+        import sys
+        import io
+
+        old_stderr = sys.stderr
+        sys.stderr = io.StringIO()
+        try:
+            import mitsuba  # noqa: F401
+
+            return True
+        except ImportError:
+            return False
+        finally:
+            sys.stderr = old_stderr
+
+    # ── Scene construction ──────────────────────────────────────────
+
+    def _base_scene_dict(
+        self,
+        camera: RenderCamera,
+        settings: RenderSettings,
+        first_mesh_path: Optional[str] = None,
+    ) -> dict:
+        """Return a scene dict with everything *except* the shape entries.
+
+        When *first_mesh_path* is given the ground plane / backdrop is sized
+        from its bounding box; otherwise a large default is used.
+        """
+        import mitsuba as mi
+
+        lighting = settings.lighting
+        ground = settings.ground_plane
+
+        cam_to_world = mi.ScalarTransform4f.look_at(
+            origin=list(camera.origin),
+            target=list(camera.target),
+            up=list(camera.up),
+        )
+
+        scene: dict = {
+            "type": "scene",
+            "integrator": {"type": "path", "max_depth": settings.max_depth},
+            "sensor": {
+                "type": "perspective",
+                "fov": camera.fov,
+                "to_world": cam_to_world,
+                "film": {
+                    "type": "hdrfilm",
+                    "width": settings.width,
+                    "height": settings.height,
+                    "rfilter": {"type": "gaussian"},
+                },
+                "sampler": {
+                    "type": "independent",
+                    "sample_count": settings.spp,
+                },
+            },
+            "emitter": {
+                "type": "constant",
+                "radiance": {
+                    "type": "rgb",
+                    "value": [
+                        lighting.ambient_intensity,
+                        lighting.ambient_intensity * 0.97,
+                        lighting.ambient_intensity * 0.94,
+                    ],
+                },
+            },
+        }
+
+        # ── 3-point lighting ──────────────────────────────────────────
+        key_rgb = [c * lighting.key_intensity for c in lighting.key_color]
+        scene["key_light"] = {
+            "type": "directional",
+            "to_world": mi.ScalarTransform4f.look_at(
+                origin=[1.0, -0.8, 1.2],
+                target=[0.0, 0.0, 0.0],
+                up=[0.0, 0.0, 1.0],
+            ),
+            "irradiance": {"type": "rgb", "value": key_rgb},
+        }
+
+        fill_rgb = [c * lighting.fill_intensity for c in lighting.fill_color]
+        scene["fill_light"] = {
+            "type": "directional",
+            "to_world": mi.ScalarTransform4f.look_at(
+                origin=[-1.0, 0.6, 0.8],
+                target=[0.0, 0.0, 0.0],
+                up=[0.0, 0.0, 1.0],
+            ),
+            "irradiance": {"type": "rgb", "value": fill_rgb},
+        }
+
+        rim_rgb = [c * lighting.rim_intensity for c in lighting.rim_color]
+        scene["rim_light"] = {
+            "type": "directional",
+            "to_world": mi.ScalarTransform4f.look_at(
+                origin=[-0.3, 1.2, -0.8],
+                target=[0.0, 0.0, 0.0],
+                up=[0.0, 0.0, 1.0],
+            ),
+            "irradiance": {"type": "rgb", "value": rim_rgb},
+        }
+
+        # ── Ground plane / backdrop ───────────────────────────────────
+        if ground.enabled:
+            try:
+                ext = os.path.splitext(first_mesh_path)[1].lower() if first_mesh_path else ""
+                shape_type = "ply" if ext == ".ply" else "obj"
+                mesh_shape = mi.load_dict({"type": shape_type, "filename": first_mesh_path})
+                bbox = mesh_shape.bbox()
+                bbox_min, bbox_max = bbox[0], bbox[1]
+                model_height = bbox_max[2] - bbox_min[2]
+                ground_z = bbox_min[2] - 0.001 * model_height
+                dx = bbox_max[0] - bbox_min[0]
+                dy = bbox_max[1] - bbox_min[1]
+                dz = bbox_max[2] - bbox_min[2]
+                diag = float((dx * dx + dy * dy + dz * dz) ** 0.5)
+            except Exception:
+                ground_z = -ground.distance_below
+                diag = 1000.0
+
+            bsdf_ground = {
+                "type": "diffuse",
+                "reflectance": {"type": "rgb", "value": list(ground.color)},
+            }
+
+            if ground.curved_backdrop:
+                half_size = diag * 50.0
+                radius = diag * 3.0
+                cyl_height = diag * 20.0
+                scene["ground_floor"] = {
+                    "type": "rectangle",
+                    "to_world": mi.ScalarTransform4f.translate([0.0, 0.0, ground_z])
+                    @ mi.ScalarTransform4f.scale([half_size, half_size, 1.0]),
+                    "bsdf": bsdf_ground,
+                }
+                scene["ground_backdrop"] = {
+                    "type": "cylinder",
+                    "radius": radius,
+                    "p0": [-cyl_height / 2, -radius, ground_z],
+                    "p1": [cyl_height / 2, -radius, ground_z],
+                    "to_world": mi.ScalarTransform4f.rotate([1, 0, 0], 90)
+                    @ mi.ScalarTransform4f.translate([0.0, 0.0, -radius]),
+                    "bsdf": bsdf_ground,
+                }
+            else:
+                half_size = diag * 50.0
+                scene["ground_plane"] = {
+                    "type": "rectangle",
+                    "to_world": mi.ScalarTransform4f.translate([0.0, 0.0, ground_z])
+                    @ mi.ScalarTransform4f.scale([half_size, half_size, 1.0]),
+                    "bsdf": bsdf_ground,
+                }
+
+        return scene
+
+    def _build_scene_dict(
+        self,
+        mesh_path: str,
+        material: RenderMaterial,
+        camera: RenderCamera,
+        settings: RenderSettings,
+    ) -> dict:
+        """Build a single-shape Mitsuba scene dictionary."""
+        ext = os.path.splitext(mesh_path)[1].lower()
+        shape_type = "ply" if ext == ".ply" else "obj"
+
+        scene = self._base_scene_dict(camera, settings, first_mesh_path=mesh_path)
+        scene["shape"] = {
+            "type": shape_type,
+            "filename": mesh_path,
+            "bsdf": self._make_bsdf(material),
+        }
+        return scene
+
+    def _build_assembly_scene_dict(
+        self,
+        parts: list,
+        camera: RenderCamera,
+        settings: RenderSettings,
+    ) -> dict:
+        """Build a multi-shape Mitsuba scene dictionary.
+
+        *parts* is a list of ``(mesh_path, RenderMaterial)`` tuples.
+        """
+        first_path = parts[0][0] if parts else None
+        scene = self._base_scene_dict(camera, settings, first_mesh_path=first_path)
+
+        for i, (mesh_path, material) in enumerate(parts):
+            ext = os.path.splitext(mesh_path)[1].lower()
+            shape_type = "ply" if ext == ".ply" else "obj"
+            scene[f"shape_{i}"] = {
+                "type": shape_type,
+                "filename": mesh_path,
+                "bsdf": self._make_bsdf(material),
+            }
+        return scene
+
+    def _make_bsdf(self, material: RenderMaterial) -> dict:
+        """Convert a RenderMaterial to a Mitsuba BSDF dict."""
+        mt = material.bsdf_type
+
+        if mt == "roughconductor":
+            # Use material="none" with specular_reflectance set to the
+            # metal color.  The pip-installed Mitsuba doesn't include
+            # spectral metal data files (iron.spd, copper.spd, etc.).
+            return {
+                "type": "roughconductor",
+                "material": "none",
+                "alpha": max(material.roughness, 0.01),
+                "specular_reflectance": {
+                    "type": "rgb",
+                    "value": list(material.color),
+                },
+            }
+
+        if mt == "roughdielectric":
+            return {
+                "type": "roughdielectric",
+                "int_ior": material.int_ior,
+                "ext_ior": 1.0,
+                "alpha": max(material.roughness, 0.01),
+            }
+
+        if mt == "dielectric":
+            return {
+                "type": "dielectric",
+                "int_ior": material.int_ior,
+                "ext_ior": 1.0,
+            }
+
+        if mt == "plastic":
+            return {
+                "type": "plastic",
+                "diffuse_reflectance": {
+                    "type": "rgb",
+                    "value": list(material.color),
+                },
+                "int_ior": material.int_ior,
+            }
+
+        # Default: diffuse
+        return {
+            "type": "diffuse",
+            "reflectance": {
+                "type": "rgb",
+                "value": list(material.color),
+            },
+        }
+
+    # ── Rendering ───────────────────────────────────────────────────
+
+    def render(
+        self,
+        mesh_path: str,
+        material: RenderMaterial,
+        camera: RenderCamera,
+        settings: RenderSettings,
+        progress_callback: Optional[Callable[[float], None]] = None,
+    ) -> np.ndarray:
+        """Render a mesh file and return (H, W, 3) float32 RGB array."""
+        self._set_variant()
+        import mitsuba as mi
+
+        scene_dict = self._build_scene_dict(mesh_path, material, camera, settings)
+        scene = mi.load_dict(scene_dict)
+
+        logger.info(f"Rendering {settings.width}x{settings.height} @ {settings.spp} spp")
+
+        try:
+            image = mi.render(scene, spp=settings.spp, seed=int(settings.seed or 0))
+        except Exception as e:
+            logger.error(f"Mitsuba render failed: {e}")
+            raise
+
+        if progress_callback:
+            progress_callback(1.0)
+
+        arr = np.array(image, dtype=np.float32)
+        arr = np.clip(arr, 0.0, None)
+        arr = np.power(arr, 1.0 / 2.2)
+        arr = np.clip(arr, 0.0, 1.0)
+        return arr
+
+    def render_assembly(
+        self,
+        parts: list,
+        camera: RenderCamera,
+        settings: RenderSettings,
+        progress_callback: Optional[Callable[[float], None]] = None,
+    ) -> np.ndarray:
+        """Render multiple meshes with individual materials.
+
+        *parts* is a list of ``(mesh_path, RenderMaterial)`` tuples.
+        Returns (H, W, 3) float32 RGB array.
+        """
+        self._set_variant()
+        import mitsuba as mi
+
+        scene_dict = self._build_assembly_scene_dict(parts, camera, settings)
+        scene = mi.load_dict(scene_dict)
+
+        logger.info(
+            f"Rendering assembly ({len(parts)} parts) "
+            f"{settings.width}x{settings.height} @ {settings.spp} spp"
+        )
+
+        try:
+            image = mi.render(scene, spp=settings.spp, seed=int(settings.seed or 0))
+        except Exception as e:
+            logger.error(f"Mitsuba assembly render failed: {e}")
+            raise
+
+        if progress_callback:
+            progress_callback(1.0)
+
+        arr = np.array(image, dtype=np.float32)
+        arr = np.clip(arr, 0.0, None)
+        arr = np.power(arr, 1.0 / 2.2)
+        arr = np.clip(arr, 0.0, 1.0)
+        return arr
+
+    def render_preview(
+        self,
+        mesh_path: str,
+        material: RenderMaterial,
+        camera: RenderCamera,
+        settings: RenderSettings,
+    ) -> np.ndarray:
+        """Quick low-quality preview (4x fewer spp)."""
+        preview_settings = RenderSettings(
+            width=settings.width // 2,
+            height=settings.height // 2,
+            spp=max(settings.spp // 4, 16),
+            max_depth=min(settings.max_depth, 4),
+            seed=settings.seed,
+            lighting=settings.lighting,
+            ground_plane=settings.ground_plane,
+        )
+        return self.render(mesh_path, material, camera, preview_settings)
+
+    # ── Export ──────────────────────────────────────────────────────
+
+    def export_image(self, image: np.ndarray, path: str) -> None:
+        """Save a rendered image to PNG or EXR."""
+        from PIL import Image
+
+        ext = os.path.splitext(path)[1].lower()
+
+        if ext == ".exr":
+            # Save as EXR (HDR) — no tonemapping
+            try:
+                import OpenEXR  # type: ignore[import-not-found]
+                import Imath  # type: ignore[import-not-found]
+
+                h, w = image.shape[:2]
+                header = OpenEXR.Header(w, h)
+                header["channels"] = {
+                    "R": Imath.PixelType(Imath.PixelType.FLOAT),
+                    "G": Imath.PixelType(Imath.PixelType.FLOAT),
+                    "B": Imath.PixelType(Imath.PixelType.FLOAT),
+                }
+                exr = OpenEXR.OutputFile(path, header)
+                exr.write(
+                    {
+                        "R": image[:, :, 0].tobytes(),
+                        "G": image[:, :, 1].tobytes(),
+                        "B": image[:, :, 2].tobytes(),
+                    }
+                )
+                exr.close()
+            except ImportError:
+                # Fallback: save as 16-bit PNG
+                logger.warning("OpenEXR not available, saving as 16-bit PNG")
+                img = Image.fromarray((image * 65535).astype(np.uint16), "RGB")
+                img.save(path)
+        else:
+            # PNG / JPEG — already tonemapped
+            img = Image.fromarray((image * 255).astype(np.uint8), "RGB")
+            img.save(path)
+
+        logger.info(f"Exported render to {path}")
+
+    # ── Helpers ─────────────────────────────────────────────────────
+
+    def _set_variant(self) -> None:
+        """Set the Mitsuba variant (called once)."""
+        import sys
+        import io
+
+        # Suppress the harmless "LLVM API initialization failed" warning
+        # that drjit emits on macOS ARM when scalar variant is used.
+        old_stderr = sys.stderr
+        sys.stderr = io.StringIO()
+        try:
+            import mitsuba as mi
+
+            mi.set_variant("scalar_rgb")
+        finally:
+            sys.stderr = old_stderr

src/fluency/rendering/occ_to_mesh.py

@@ -0,0 +1,252 @@
+"""Convert OCC BRep shapes to mesh files for render backends.
+
+Outputs PLY files (preferred by Mitsuba) or STL files.
+"""
+
+from __future__ import annotations
+
+import logging
+import os
+import tempfile
+from typing import List, Optional, Tuple
+
+import numpy as np
+
+logger = logging.getLogger(__name__)
+
+
+def occ_shape_to_ply(
+    shape,
+    output_path: Optional[str] = None,
+    linear_deflection: float = 0.1,
+    angular_deflection: float = 0.15,
+) -> str:
+    """Tessellate an OCC TopoDS_Shape and write as PLY.
+
+    Returns the path to the written PLY file.
+    """
+    from OCP.BRepMesh import BRepMesh_IncrementalMesh
+    from OCP.TopExp import TopExp_Explorer
+    from OCP.TopAbs import TopAbs_FACE
+    from OCP.TopoDS import TopoDS
+    from OCP.BRep import BRep_Tool
+    from OCP.TopLoc import TopLoc_Location
+
+    # Tessellate
+    tess = BRepMesh_IncrementalMesh(
+        shape, linear_deflection, False, angular_deflection, True
+    )
+    tess.Perform()
+
+    # Extract triangulation from all faces
+    all_vertices: List[List[float]] = []
+    all_faces: List[List[int]] = []
+    vertex_offset = 0
+
+    from OCP.TopAbs import TopAbs_FORWARD
+
+    explorer = TopExp_Explorer(shape, TopAbs_FACE)
+    while explorer.More():
+        face = TopoDS.Face_s(explorer.Current())
+        location = TopLoc_Location()
+        triangulation = BRep_Tool.Triangulation_s(face, location)
+
+        if triangulation is None:
+            explorer.Next()
+            continue
+
+        # Transform
+        trsf = location.Transformation()
+
+        # Check face orientation: FORWARD means the surface normal points
+        # outward from the solid; REVERSED means it points inward.
+        is_forward = (face.Orientation() == TopAbs_FORWARD)
+
+        # Extract vertices (apply location transform to positions)
+        nb_nodes = triangulation.NbNodes()
+        for i in range(1, nb_nodes + 1):
+            node = triangulation.Node(i)
+            pnt = node.Transformed(trsf)
+            all_vertices.append([pnt.X(), pnt.Y(), pnt.Z()])
+
+        # Extract triangles
+        # For REVERSED faces, swap winding order (n1, n3, n2) so that
+        # the computed normal points outward consistently.
+        nb_triangles = triangulation.NbTriangles()
+        for i in range(1, nb_triangles + 1):
+            tri = triangulation.Triangle(i)
+            n1, n2, n3 = tri.Get()
+            if is_forward:
+                all_faces.append([
+                    n1 - 1 + vertex_offset,
+                    n2 - 1 + vertex_offset,
+                    n3 - 1 + vertex_offset,
+                ])
+            else:
+                # Swap winding for REVERSED faces
+                all_faces.append([
+                    n1 - 1 + vertex_offset,
+                    n3 - 1 + vertex_offset,
+                    n2 - 1 + vertex_offset,
+                ])
+
+        vertex_offset += nb_nodes
+        explorer.Next()
+
+    if not all_vertices:
+        raise ValueError("Tessellation produced no vertices")
+
+    vertices = np.array(all_vertices, dtype=np.float32)
+    faces = np.array(all_faces, dtype=np.uint32)
+
+    logger.info(
+        f"Tessellation: {len(vertices)} vertices, {len(faces)} triangles"
+    )
+
+    # Compute smooth vertex normals from face normals.
+    # Winding is already corrected during tessellation using OCC face orientation.
+    normals, corrected_faces = _compute_outward_normals(vertices, faces, shape)
+
+    # Write PLY with corrected faces and normals
+    if output_path is None:
+        fd, output_path = tempfile.mkstemp(suffix=".ply", prefix="fluency_render_")
+        os.close(fd)
+
+    _write_ply(output_path, vertices, corrected_faces, normals)
+    logger.info(f"Wrote PLY: {output_path}")
+    return output_path
+
+
+def _compute_outward_normals(
+    vertices: np.ndarray,
+    faces: np.ndarray,
+    shape,
+) -> Tuple[np.ndarray, np.ndarray]:
+    """Compute outward-facing vertex normals and correct face winding.
+
+    The winding is already corrected during tessellation using OCC's face
+    orientation (TopAbs_FORWARD/REVERSED). This function computes smooth
+    vertex normals by averaging face normals at shared vertices.
+
+    Returns (normals, corrected_faces) for PLY export.
+    """
+    n_verts = len(vertices)
+    v_normals = np.zeros((n_verts, 3), dtype=np.float64)
+
+    # Ensure faces is 2D (numpy creates (3,) for single-face meshes)
+    if faces.ndim == 1:
+        faces = faces.reshape(1, -1)
+
+    # Winding is already correct from tessellation (face orientation check).
+    # Just compute face normals and accumulate to vertices.
+    v0 = vertices[faces[:, 0]]
+    v1 = vertices[faces[:, 1]]
+    v2 = vertices[faces[:, 2]]
+
+    edge1 = v1 - v0
+    edge2 = v2 - v0
+    fn = np.cross(edge1, edge2)
+
+    # Normalize face normals
+    lengths = np.linalg.norm(fn, axis=1, keepdims=True)
+    lengths[lengths < 1e-10] = 1.0
+    fn /= lengths
+
+    # Accumulate to vertices
+    for i in range(len(faces)):
+        idx = faces[i]
+        v_normals[idx[0]] += fn[i]
+        v_normals[idx[1]] += fn[i]
+        v_normals[idx[2]] += fn[i]
+
+    # Normalize vertex normals
+    v_lengths = np.linalg.norm(v_normals, axis=1, keepdims=True)
+    v_lengths[v_lengths < 1e-10] = 1.0
+    v_normals /= v_lengths
+
+    return v_normals.astype(np.float32), faces.astype(np.uint32)
+
+
+def occ_shape_to_stl(
+    shape,
+    output_path: Optional[str] = None,
+    linear_deflection: float = 0.1,
+) -> str:
+    """Tessellate an OCC TopoDS_Shape and write as binary STL.
+
+    Returns the path to the written STL file.
+    """
+    from OCP.BRepMesh import BRepMesh_IncrementalMesh
+    from OCP.StlAPI import StlAPI_Writer
+
+    # Tessellate
+    tess = BRepMesh_IncrementalMesh(shape, linear_deflection, False, 0.5, True)
+    tess.Perform()
+
+    if output_path is None:
+        fd, output_path = tempfile.mkstemp(suffix=".stl", prefix="fluency_render_")
+        os.close(fd)
+
+    writer = StlAPI_Writer()
+    writer.SetASCIIMode(False)
+    writer.Write(shape, output_path)
+    logger.info(f"Wrote STL: {output_path}")
+    return output_path
+
+
+def occ_shape_bounds(shape) -> Tuple[Tuple[float, float, float], Tuple[float, float, float]]:
+    """Return (min_xyz, max_xyz) bounding box of an OCC shape."""
+    from OCP.Bnd import Bnd_Box
+    from OCP.BRepBndLib import BRepBndLib
+
+    bbox = Bnd_Box()
+    BRepBndLib.Add_s(shape, bbox)
+    xmin, ymin, zmin, xmax, ymax, zmax = bbox.Get()
+    return (xmin, ymin, zmin), (xmax, ymax, zmax)
+
+
+def _write_ply(
+    path: str,
+    vertices: np.ndarray,
+    faces: np.ndarray,
+    normals: Optional[np.ndarray] = None,
+) -> None:
+    """Write a binary PLY file (little-endian) with optional vertex normals."""
+    import struct
+
+    n_verts = len(vertices)
+    n_faces = len(faces)
+    has_normals = normals is not None and len(normals) == n_verts
+
+    with open(path, "wb") as f:
+        # Header
+        header_lines = [
+            "ply",
+            "format binary_little_endian 1.0",
+            f"element vertex {n_verts}",
+            "property float x",
+            "property float y",
+            "property float z",
+        ]
+        if has_normals:
+            header_lines.extend([
+                "property float nx",
+                "property float ny",
+                "property float nz",
+            ])
+        header_lines.append(f"element face {n_faces}")
+        header_lines.append("property list uchar int vertex_indices")
+        header_lines.append("end_header")
+
+        f.write(("\n".join(header_lines) + "\n").encode("ascii"))
+
+        # Vertex positions (+ normals if available)
+        for i in range(n_verts):
+            f.write(struct.pack("<fff", vertices[i, 0], vertices[i, 1], vertices[i, 2]))
+            if has_normals:
+                f.write(struct.pack("<fff", normals[i, 0], normals[i, 1], normals[i, 2]))
+
+        # Faces
+        for face in faces:
+            f.write(struct.pack("<B", 3))
+            f.write(struct.pack("<iii", int(face[0]), int(face[1]), int(face[2])))

src/fluency/rendering/render_backend.py

@@ -0,0 +1,142 @@
+"""Abstract render backend interface.
+
+Any photorealistic renderer (Mitsuba, Blender, Cycles, ...) implements
+:class:`RenderBackend`. The UI only talks to this ABC so backends can be
+swapped by changing one import.
+"""
+
+from __future__ import annotations
+
+from abc import ABC, abstractmethod
+from dataclasses import dataclass, field
+
+from typing import Optional
+
+
+@dataclass
+class RenderMaterial:
+    """PBR material description for the render backend."""
+
+    name: str = "Default"
+    color: tuple[float, float, float] = (0.7, 0.7, 0.7)
+    metallic: float = 0.0  # 0.0 = dielectric, 1.0 = metal
+    roughness: float = 0.5  # 0.0 = mirror, 1.0 = fully rough
+    bsdf_type: str = "diffuse"  # diffuse | roughconductor | roughdielectric | plastic
+    # Optional: named metal preset (copper, aluminium, gold, chrome, steel)
+    metal_preset: Optional[str] = None
+    # For dielectric / plastic
+    int_ior: float = 1.5
+
+
+@dataclass
+class RenderCamera:
+    """Camera parameters for the render."""
+
+    origin: tuple[float, float, float] = (100.0, 100.0, 100.0)
+    target: tuple[float, float, float] = (0.0, 0.0, 0.0)
+    up: tuple[float, float, float] = (0.0, 0.0, 1.0)
+    fov: float = 60.0  # vertical field of view in degrees
+
+
+@dataclass
+class LightingConfig:
+    """Lighting configuration for the render scene."""
+
+    ambient_intensity: float = 0.3  # constant environment fill [0..1]
+    key_color: tuple[float, float, float] = (1.0, 0.98, 0.95)  # RGB key light color
+    key_intensity: float = 3.5  # key light irradiance multiplier
+    fill_color: tuple[float, float, float] = (0.92, 0.94, 1.0)  # RGB fill light color
+    fill_intensity: float = 1.5  # fill light irradiance multiplier
+    rim_color: tuple[float, float, float] = (1.0, 0.98, 0.96)  # RGB rim light color
+    rim_intensity: float = 1.2  # rim light irradiance multiplier
+
+
+@dataclass
+class GroundPlaneConfig:
+    """Ground plane configuration for the render scene."""
+
+    enabled: bool = False
+    color: tuple[float, float, float] = (0.5, 0.5, 0.5)  # RGB diffuse color
+    roughness: float = 0.8  # surface roughness [0..1]
+    distance_below: float = 0.0  # mm below origin (positive = below)
+    curved_backdrop: bool = False  # photo booth style curved leinwand
+
+
+@dataclass
+class RenderSettings:
+    """Quality / resolution settings."""
+
+    width: int = 1920
+    height: int = 1080
+    spp: int = 256  # samples per pixel
+    max_depth: int = 8  # max bounces for path tracer
+    seed: int = 0  # random seed (0 = auto)
+    lighting: LightingConfig = field(default_factory=LightingConfig)
+    ground_plane: GroundPlaneConfig = field(default_factory=GroundPlaneConfig)
+
+
+class RenderBackend(ABC):
+    """Abstract photorealistic renderer.
+
+    Implementations live in separate modules so backends can be swapped
+    without touching the UI.  Typical call::
+
+        backend = MitsubaBackend()
+        image = backend.render(obj_path, material, camera, settings)
+    """
+
+    @abstractmethod
+    def name(self) -> str:
+        """Human-readable backend name (shown in UI)."""
+
+    @abstractmethod
+    def is_available(self) -> bool:
+        """Return True if this backend's dependencies are installed."""
+
+    @abstractmethod
+    def render(
+        self,
+        mesh_path: str,
+        material: RenderMaterial,
+        camera: RenderCamera,
+        settings: RenderSettings,
+        progress_callback=None,
+    ) -> "np.ndarray":
+        """Render a mesh file and return an (H, W, 3) float32 RGB array.
+
+        *mesh_path* is an STL or OBJ file on disk.
+        *progress_callback(fraction)* is called with 0.0–1.0 progress.
+        """
+
+    @abstractmethod
+    def render_preview(
+        self,
+        mesh_path: str,
+        material: RenderMaterial,
+        camera: RenderCamera,
+        settings: RenderSettings,
+    ) -> "np.ndarray":
+        """Quick low-quality preview (fewer spp)."""
+
+    @abstractmethod
+    def export_image(self, image: "np.ndarray", path: str) -> None:
+        """Save a rendered image to PNG / EXR."""
+
+    def default_camera_from_bounds(
+        self, bounds_min: tuple[float, float, float], bounds_max: tuple[float, float, float]
+    ) -> RenderCamera:
+        """Compute a sensible default camera looking at the bbox centre."""
+        import numpy as np
+
+        mn = np.asarray(bounds_min, dtype=float)
+        mx = np.asarray(bounds_max, dtype=float)
+        centre = (mn + mx) / 2.0
+        diag = float(np.linalg.norm(mx - mn))
+        # Place camera at iso-ish position, far enough to see everything.
+        eye = centre + np.array([0.7, -0.7, 0.5]) * diag * 0.8
+        return RenderCamera(
+            origin=tuple(eye.tolist()),
+            target=tuple(centre.tolist()),
+            up=(0.0, 0.0, 1.0),
+            fov=45.0,
+        )

src/fluency/sketch_solver.py

@@ -187,19 +187,29 @@ class SolverSketch(SolverSystem):
     def constrain_distance(
         self, entity_a, entity_b, distance: float
     ) -> bool:
-        """Constrain distance between point-point or point-line."""
+        """Constrain distance between point-point or point-line.
+
+        python-solvespace's ``distance`` accepts (point, line) ordering only,
+        so line-point pairs are normalised; line-line pairs and a point
+        constrained to itself are rejected (the solver cannot hold them).
+        """
         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, SolverLine) and isinstance(entity_b, SolverLine):
+                logger.warning("distance: line-to-line distance is not supported")
+                return False
+            if isinstance(entity_a, SolverLine) and isinstance(entity_b, SolverPoint):
+                # Normalise to (point, line) ordering.
+                entity_a, entity_b = entity_b, entity_a
+            if entity_a is entity_b and distance != 0.0:
+                logger.warning("distance: refusing point-to-itself constraint")
+                return False
+            handle_a = entity_a.handle
+            handle_b = 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

src/fluency/sketch_undo.py

@@ -0,0 +1,372 @@
+"""
+Undo/Redo manager for OCCSketch using snapshot-based approach.
+
+python_solvespace has no per-entity delete API — the solver is rebuilt from
+scratch after every modification.  This makes snapshot-based undo natural:
+we capture the complete sketch state (entities, geometry, constraints) and
+restore it by rebuilding the solver from the snapshot data.
+
+Each snapshot is ~10-50 KB depending on sketch complexity, and we cap the
+stack at a configurable depth (default 50).
+"""
+
+from __future__ import annotations
+
+import copy
+import logging
+from dataclasses import dataclass, field
+from typing import Any, Dict, List, Optional, Set, Tuple
+
+logger = logging.getLogger(__name__)
+
+
+@dataclass
+class SketchSnapshot:
+    """Immutable snapshot of sketch state for undo/redo.
+
+    Captures everything needed to fully reconstruct an OCCSketch:
+    entities, points, lines, circles, arcs, counter, constraint log,
+    and the special entity id sets (centerlines, external/underlay).
+    """
+
+    # Entity registry: id → (entity_type, geometry, is_construction, is_external, constraints_list)
+    entities: Dict[int, Tuple[str, Any, bool, bool, List[str]]] = field(default_factory=dict)
+
+    # Geometry sub-indices
+    points: Dict[int, Tuple[float, float]] = field(default_factory=dict)
+    lines: Dict[int, Tuple[int, int]] = field(default_factory=dict)
+    circles: Dict[int, Tuple[int, float]] = field(default_factory=dict)
+    arcs: Dict[int, Dict[str, Any]] = field(default_factory=dict)
+
+    # Counters and flags
+    entity_counter: int = 0
+    constraint_count: int = 0
+    first_point_id: Optional[int] = None
+
+    # Constraint replay log
+    constraint_log: List[Dict[str, Any]] = field(default_factory=list)
+
+    # Special entity sets
+    centerline_ids: Set[int] = field(default_factory=set)
+    external_entity_ids: Set[int] = field(default_factory=set)
+
+    # Workplane (so undo doesn't lose the placement plane)
+    wp_origin: Tuple[float, float, float] = (0.0, 0.0, 0.0)
+    wp_normal: Tuple[float, float, float] = (0.0, 0.0, 1.0)
+    wp_x_dir: Tuple[float, float, float] = (1.0, 0.0, 0.0)
+    wp_y_dir: Tuple[float, float, float] = (0.0, 1.0, 0.0)
+
+
+class SketchUndoManager:
+    """Manages undo/redo stacks of SketchSnapshot for an OCCSketch.
+
+    Usage::
+
+        undo_mgr = SketchUndoManager(sketch)
+
+        # Before any modification:
+        undo_mgr.save_state()
+
+        # ... perform modification ...
+
+        # Ctrl+Z:
+        undo_mgr.undo()
+
+        # Ctrl+Y / Ctrl+Shift+Z:
+        undo_mgr.redo()
+    """
+
+    def __init__(self, sketch: Any, max_stack_size: int = 50) -> None:
+        from fluency.geometry_occ.sketch import OCCSketch
+
+        self._sketch: OCCSketch = sketch
+        self._max_stack_size = max_stack_size
+        self._undo_stack: List[SketchSnapshot] = []
+        self._redo_stack: List[SketchSnapshot] = []
+
+    # ─── Public API ────────────────────────────────────────────────────────
+
+    @property
+    def can_undo(self) -> bool:
+        """True if there is a state to undo to."""
+        return len(self._undo_stack) > 0
+
+    @property
+    def can_redo(self) -> bool:
+        """True if there is a state to redo to."""
+        return len(self._redo_stack) > 0
+
+    @property
+    def undo_depth(self) -> int:
+        """Number of undo levels available."""
+        return len(self._undo_stack)
+
+    @property
+    def redo_depth(self) -> int:
+        """Number of redo levels available."""
+        return len(self._redo_stack)
+
+    def save_state(self) -> None:
+        """Capture the current sketch state and push it onto the undo stack.
+
+        Call this **before** any modifying operation (draw, delete, move,
+        constraint add/remove, construction toggle, etc.).
+
+        The redo stack is cleared whenever a new state is saved (i.e. when
+        the user makes a new change after undoing).
+        """
+        snapshot = self._capture()
+        self._undo_stack.append(snapshot)
+
+        # Cap the stack size.
+        if len(self._undo_stack) > self._max_stack_size:
+            self._undo_stack.pop(0)
+
+        # New mutation invalidates the redo history.
+        self._redo_stack.clear()
+
+        logger.debug(
+            f"save_state: undo_depth={len(self._undo_stack)} "
+            f"entities={len(snapshot.entities)}"
+        )
+
+    def undo(self) -> bool:
+        """Restore the previous sketch state.
+
+        Returns True if a state was restored, False if the undo stack is empty.
+        """
+        if not self._undo_stack:
+            logger.debug("undo: stack empty")
+            return False
+
+        # Save current state to redo stack before restoring.
+        current_snapshot = self._capture()
+        self._redo_stack.append(current_snapshot)
+
+        # Pop and restore.
+        snapshot = self._undo_stack.pop()
+        self._restore(snapshot)
+
+        logger.debug(
+            f"undo: restored state with {len(snapshot.entities)} entities, "
+            f"undo_depth={len(self._undo_stack)} redo_depth={len(self._redo_stack)}"
+        )
+        return True
+
+    def redo(self) -> bool:
+        """Re-apply the most recently undone state.
+
+        Returns True if a state was restored, False if the redo stack is empty.
+        """
+        if not self._redo_stack:
+            logger.debug("redo: stack empty")
+            return False
+
+        # Save current state to undo stack before restoring.
+        current_snapshot = self._capture()
+        self._undo_stack.append(current_snapshot)
+
+        # Pop and restore.
+        snapshot = self._redo_stack.pop()
+        self._restore(snapshot)
+
+        logger.debug(
+            f"redo: restored state with {len(snapshot.entities)} entities, "
+            f"undo_depth={len(self._undo_stack)} redo_depth={len(self._redo_stack)}"
+        )
+        return True
+
+    def clear(self) -> None:
+        """Clear both stacks (e.g. when loading a new sketch)."""
+        self._undo_stack.clear()
+        self._redo_stack.clear()
+        logger.debug("undo stacks cleared")
+
+    # ─── Snapshot Capture ──────────────────────────────────────────────────
+
+    def _capture(self) -> SketchSnapshot:
+        """Capture the current sketch state into a snapshot."""
+        sketch = self._sketch
+
+        # Capture entities: id → (type, geometry, is_construction, is_external, constraints)
+        entities: Dict[int, Tuple[str, Any, bool, bool, List[str]]] = {}
+        for eid, ent in sketch._entities.items():
+            entities[eid] = (
+                ent.entity_type,
+                ent.geometry,
+                ent.is_construction,
+                ent.is_external,
+                list(ent.constraints),  # copy the constraints list
+            )
+
+        # Deep copy the mutable dicts (points coords are tuples, so shallow is fine,
+        # but arcs contain dicts so we deep-copy those).
+        points = dict(sketch._points)
+        lines = dict(sketch._lines)
+        circles = dict(sketch._circles)
+        arcs = {k: copy.deepcopy(v) for k, v in sketch._arcs.items()}
+
+        # Constraint log entries contain tuples and sets — need careful copy.
+        constraint_log = []
+        for entry in sketch._constraint_log:
+            copied = {
+                "type": entry["type"],
+                "ids": tuple(entry["ids"]),
+                "params": tuple(entry["params"]) if entry.get("params") else (),
+                "labels": set(entry["labels"]) if entry.get("labels") else set(),
+            }
+            constraint_log.append(copied)
+
+        return SketchSnapshot(
+            entities=entities,
+            points=points,
+            lines=lines,
+            circles=circles,
+            arcs=arcs,
+            entity_counter=sketch._entity_counter,
+            constraint_count=sketch._constraint_count,
+            first_point_id=sketch._first_point_id,
+            constraint_log=constraint_log,
+            centerline_ids=set(sketch._centerline_ids),
+            external_entity_ids=set(sketch._external_entity_ids),
+            wp_origin=sketch._wp_origin,
+            wp_normal=sketch._wp_normal,
+            wp_x_dir=sketch._wp_x_dir,
+            wp_y_dir=sketch._wp_y_dir,
+        )
+
+    # ─── Snapshot Restore ──────────────────────────────────────────────────
+
+    def _restore(self, snapshot: SketchSnapshot) -> None:
+        """Restore the sketch to a previously captured snapshot state."""
+        from fluency.geometry_occ.sketch import OCCSketch, OCCSketchEntity
+
+        sketch = self._sketch
+
+        # Clear the current solver and rebuild from scratch.
+        sketch._solver = sketch._solver.__class__()  # SolverSystem()
+        sketch._wp = sketch._solver.create_2d_base()
+        sketch._first_point_id = None
+
+        # Restore counters and flags.
+        sketch._entity_counter = snapshot.entity_counter
+        sketch._constraint_count = snapshot.constraint_count
+        sketch._centerline_ids = set(snapshot.centerline_ids)
+        sketch._external_entity_ids = set(snapshot.external_entity_ids)
+
+        # Restore workplane.
+        sketch._wp_origin = snapshot.wp_origin
+        sketch._wp_normal = snapshot.wp_normal
+        sketch._wp_x_dir = snapshot.wp_x_dir
+        sketch._wp_y_dir = snapshot.wp_y_dir
+
+        # Rebuild entity objects from the snapshot.
+        sketch._entities.clear()
+        sketch._points.clear()
+        sketch._lines.clear()
+        sketch._circles.clear()
+        sketch._arcs.clear()
+
+        # First pass: re-add all points to the solver.
+        for eid in sorted(snapshot.entities.keys()):
+            etype, geometry, is_constr, is_ext, constraints = snapshot.entities[eid]
+            if etype == "point" and eid in snapshot.points:
+                x, y = snapshot.points[eid]
+                solver_handle = sketch._solver.add_point_2d(x, y, sketch._wp)
+                ent = OCCSketchEntity(
+                    entity_id=eid,
+                    entity_type="point",
+                    geometry=(x, y),
+                    handle=solver_handle,
+                )
+                ent.is_construction = is_constr
+                ent.is_external = is_ext
+                ent.constraints = list(constraints)
+                sketch._entities[eid] = ent
+                sketch._points[eid] = (x, y)
+
+                # Anchor the first point (or first external point) for solver stability.
+                if sketch._first_point_id is None and not is_ext:
+                    sketch._first_point_id = eid
+                    sketch._solver.dragged(solver_handle, sketch._wp)
+                elif sketch._first_point_id is None and is_ext:
+                    sketch._first_point_id = eid
+                    sketch._solver.dragged(solver_handle, sketch._wp)
+
+        # Second pass: re-add all lines.
+        for lid in sorted(snapshot.lines.keys()):
+            sid, eid2 = snapshot.lines[lid]
+            s_ent = sketch._entities.get(sid)
+            e_ent = sketch._entities.get(eid2)
+            if s_ent is None or e_ent is None or s_ent.handle is None or e_ent.handle is None:
+                continue
+
+            solver_handle = sketch._solver.add_line_2d(s_ent.handle, e_ent.handle, sketch._wp)
+
+            etype, geometry, is_constr, is_ext, constraints = snapshot.entities[lid]
+            ent = OCCSketchEntity(
+                entity_id=lid,
+                entity_type="line",
+                geometry=geometry,
+                handle=solver_handle,
+            )
+            ent.is_construction = is_constr
+            ent.is_external = is_ext
+            ent.constraints = list(constraints)
+            sketch._entities[lid] = ent
+            sketch._lines[lid] = (sid, eid2)
+
+        # Restore circles (not in solver, just tracked).
+        for cid, (center_id, radius) in snapshot.circles.items():
+            if cid in snapshot.entities:
+                etype, geometry, is_constr, is_ext, constraints = snapshot.entities[cid]
+                center_ent = sketch._entities.get(center_id)
+                ent = OCCSketchEntity(
+                    entity_id=cid,
+                    entity_type="circle",
+                    geometry=geometry,
+                    handle=None,
+                )
+                ent.is_construction = is_constr
+                ent.is_external = is_ext
+                ent.constraints = list(constraints)
+                sketch._entities[cid] = ent
+                sketch._circles[cid] = (center_id, radius)
+
+        # Restore arcs (not in solver, just tracked).
+        for aid, arc_data in snapshot.arcs.items():
+            if aid in snapshot.entities:
+                etype, geometry, is_constr, is_ext, constraints = snapshot.entities[aid]
+                ent = OCCSketchEntity(
+                    entity_id=aid,
+                    entity_type="arc",
+                    geometry=geometry,
+                    handle=None,
+                )
+                ent.is_construction = is_constr
+                ent.is_external = is_ext
+                ent.constraints = list(constraints)
+                sketch._entities[aid] = ent
+                sketch._arcs[aid] = copy.deepcopy(arc_data)
+
+        # Rebuild the constraint log (entries were deep-copied on capture).
+        sketch._constraint_log = []
+        for entry in snapshot.constraint_log:
+            sketch._constraint_log.append({
+                "type": entry["type"],
+                "ids": tuple(entry["ids"]),
+                "params": tuple(entry["params"]) if entry.get("params") else (),
+                "labels": set(entry["labels"]) if entry.get("labels") else set(),
+            })
+
+        # Re-apply all constraints to the solver.
+        for entry in sketch._constraint_log:
+            sketch._apply_constraint_log(entry)
+
+        # Solve to update geometry positions.
+        sketch.solve()
+
+        logger.debug(
+            f"Restored snapshot: {len(sketch._entities)} entities, "
+            f"{len(sketch._constraint_log)} constraints"
+        )

src/fluency/tests/test_iso5457_sheet.py

@@ -0,0 +1,213 @@
+"""Tests for the A4 ISO 5457 sheet: layout regions, first-angle view
+ordering, sheet furniture primitives, scale formatting, and the A4
+normalisation of drawings loaded from .fluency files.
+"""
+
+import os
+import sys
+import unittest
+
+# Allow running this file directly: ``python tests/test_iso5457_sheet.py``.
+sys.path.insert(0, os.path.join(os.path.dirname(__file__), os.pardir, "src"))
+
+os.environ.setdefault("QT_QPA_PLATFORM", "offscreen")
+
+from fluency.models.data_model import DrawingView, TechnicalDrawing
+from fluency.technical_drawing import (
+    _SHEET_HEIGHT_MM,
+    _SHEET_WIDTH_MM,
+    _format_drawing_scale,
+    _layout_views_on_sheet,
+    _sheet_frame_primitives,
+)
+
+
+def _view(kind):
+    return DrawingView(kind=kind, name=kind)
+
+
+class TestSheetSize(unittest.TestCase):
+    """The workbench renders a single A4 landscape sheet."""
+
+    def test_a4_dimensions(self):
+        self.assertEqual((_SHEET_WIDTH_MM, _SHEET_HEIGHT_MM), (297.0, 210.0))
+
+    def test_default_drawing_is_a4(self):
+        self.assertEqual(TechnicalDrawing().sheet_size, "A4")
+
+
+class TestScaleFormatting(unittest.TestCase):
+    """Title-block scale field formatting (``N : 1`` / ``1 : N``)."""
+
+    def test_none_and_one(self):
+        self.assertEqual(_format_drawing_scale(None), "1 : 1")
+        self.assertEqual(_format_drawing_scale(0.0), "1 : 1")
+        self.assertEqual(_format_drawing_scale(1.0), "1 : 1")
+
+    def test_enlarged(self):
+        self.assertEqual(_format_drawing_scale(2.0), "2 : 1")
+        self.assertEqual(_format_drawing_scale(1.5), "1.5 : 1")
+
+    def test_reduced(self):
+        self.assertEqual(_format_drawing_scale(0.5), "1 : 2")
+        self.assertEqual(_format_drawing_scale(0.33333), "1 : 3")
+
+
+class TestFirstAngleLayout(unittest.TestCase):
+    """View slots stay inside the ISO 5457 drawing-space frame, clear the
+    title-block reserve zone, and follow first-angle ordering (view from
+    the right left of front, view from the left right of front, top view
+    below front)."""
+
+    def _slots(self, kinds):
+        bboxes = {k: (0.0, 0.0, 40.0, 30.0) for k in kinds}
+        slots, scale, _rots = _layout_views_on_sheet(
+            [_view(k) for k in kinds], bboxes
+        )
+        return slots, scale
+
+    def test_slots_inside_frame(self):
+        slots, scale = self._slots(
+            ("front", "top", "right", "left", "isometric")
+        )
+        self.assertIsNotNone(scale)
+        self.assertGreater(scale, 0)
+        for vid, (x, y, w, h) in slots.items():
+            # Drawing-space frame: 20..287 x 10..200.
+            self.assertGreaterEqual(x, 19.9, vid)
+            self.assertGreaterEqual(y, 9.9, vid)
+            self.assertLessEqual(x + w, 287.1, vid)
+            self.assertLessEqual(y + h, 200.1, vid)
+            # Title-block reserve zone: x >= 102, y <= 64.
+            self.assertTrue(
+                x + w <= 102.01 or y + h <= 0.01 or y >= 63.99,
+                (vid, (x, y, w, h)),
+            )
+
+    def test_first_angle_ordering(self):
+        slots, _ = self._slots(("front", "top", "right", "left"))
+        xf, wf = slots["front"][0], slots["front"][2]
+        yf = slots["front"][1]
+        # View from the right sits left of the front view.
+        self.assertLessEqual(
+            slots["right"][0] + slots["right"][2], xf + 0.01
+        )
+        # View from the left sits right of the front view.
+        self.assertGreaterEqual(slots["left"][0], xf + wf + 0.01)
+        # Top view sits below the front view.
+        self.assertLessEqual(slots["top"][1] + slots["top"][3], yf + 0.01)
+
+    def test_single_view_centered_upright(self):
+        slots, scale, rots = _layout_views_on_sheet(
+            [_view("front")], {"front": (0.0, 0.0, 40.0, 30.0)}
+        )
+        self.assertIsNotNone(scale)
+        self.assertEqual(rots.get("front", 0.0), 0.0)
+        self.assertGreater(scale, 0)
+        x, y, w, h = slots["front"]
+        self.assertGreaterEqual(x, 19.9)
+        self.assertGreaterEqual(y, 9.9)
+
+
+class TestSheetFurniture(unittest.TestCase):
+    """ISO 5457 furniture primitives mirror the reference SVG template."""
+
+    def _prims(self):
+        d = TechnicalDrawing(
+            title="Test Bracket",
+            part_number="PN-42",
+            material="Alu 6082",
+            revision="B",
+        )
+        return _sheet_frame_primitives(d, "1 : 2")
+
+    def test_all_geometry_inside_sheet(self):
+        for p in self._prims():
+            for (x, y) in p.points:
+                self.assertGreaterEqual(x, -0.01)
+                self.assertLessEqual(x, 297.01)
+                self.assertGreaterEqual(y, -0.01)
+                self.assertLessEqual(y, 210.01)
+
+    def test_drawing_space_frame(self):
+        # Frame rect 20,10 267x190: four edges present as line prims.
+        lines = [
+            (tuple(p.points[0]), tuple(p.points[1]))
+            for p in self._prims()
+            if p.kind == "line" and p.style == "frame"
+        ]
+        for a, b in (
+            ((20.0, 10.0), (287.0, 10.0)),
+            ((287.0, 10.0), (287.0, 200.0)),
+            ((287.0, 200.0), (20.0, 200.0)),
+            ((20.0, 200.0), (20.0, 10.0)),
+        ):
+            self.assertIn((a, b), lines)
+
+    def test_grid_reference_labels(self):
+        texts = [p.text for p in self._prims() if p.kind == "text" and p.text]
+        for t in ("1", "2", "3", "4", "5", "6", "A", "B", "C", "D", "A4"):
+            self.assertIn(t, texts)
+
+    def test_title_block_fields(self):
+        texts = [p.text for p in self._prims() if p.kind == "text" and p.text]
+        for expect in (
+            "Owner:",
+            "Drawing number:",
+            "Revision:",
+            "Issue date:",
+            "Sheet:",
+            "Language:",
+            "Title:",
+            "Approved by:",
+            "Created by:",
+            "Document type:",
+            "Part Material:",
+            "General tolerances:",
+            "Scale:",
+            "Test Bracket",
+            "PN-42",
+            "Alu 6082",
+            "B",
+            "1 : 2",
+            "EN",
+            "1 / 1",
+            "ISO 2768-m",
+            "Component Drawing",
+        ):
+            self.assertIn(expect, texts)
+
+    def test_first_angle_projection_symbol(self):
+        # Two concentric circles at the symbol centre (273, 58) in sheet
+        # coords (SVG y-down 152 → 210 - 152 = 58).
+        circles = [
+            p
+            for p in self._prims()
+            if p.kind == "circle" and p.center == (273.0, 58.0)
+        ]
+        self.assertEqual(len(circles), 2)
+        self.assertEqual(
+            sorted(c.radius for c in circles if c.radius), [2.5, 5.0]
+        )
+
+
+class TestSheetSizeNormalisation(unittest.TestCase):
+    """Drawings stored as A3 in .fluency files load as A4 — the renderer
+    only supports the A4 ISO 5457 sheet."""
+
+    def test_legacy_a3_loads_as_a4(self):
+        from fluency.io.project_io import _technical_drawing_from_dict
+
+        d = _technical_drawing_from_dict(
+            {
+                "id": "x",
+                "source_kind": "component",
+                "source_id": "c",
+                "sheet_size": "A3",
+            }
+        )
+        self.assertEqual(d.sheet_size, "A4")
+
+
+if __name__ == "__main__":
+    unittest.main()

src/fluency/tests/test_project_io.py

@@ -13,16 +13,58 @@ import unittest
 # Allow running this file directly: ``python tests/test_project_io.py``.
 sys.path.insert(0, os.path.join(os.path.dirname(__file__), os.pardir, "src"))
 
-from fluency.io.project_io import save_project, load_project
+from fluency.io.project_io import save_project, load_project, _feature_to_dict, _feature_from_dict
 from fluency.models.data_model import (
     Project,
     Component,
     Body,
+    Sketch,
     Workplane,
     Assembly,
+    Feature,
 )
 
 
+class TestRevolveAxisSerialization(unittest.TestCase):
+    """Revolve features persist their revolve axis across save/load."""
+
+    def test_axis_round_trip(self):
+        sk = Sketch()
+        feat = Feature(
+            operation="revolve",
+            angle=180.0,
+            axis=(1, 0, 0),
+            origin=(10.0, 5.0, 0.0),
+            axis_line_id=7,
+        )
+        feat.sketch = sk
+        data = _feature_to_dict(feat)
+        self.assertEqual(data["axis"], [1.0, 0.0, 0.0])
+        self.assertEqual(data["origin"], [10.0, 5.0, 0.0])
+        self.assertEqual(data["axis_line_id"], 7)
+        restored = _feature_from_dict(data, {sk.id: sk})
+        self.assertEqual(tuple(restored.axis), (1.0, 0.0, 0.0))
+        self.assertEqual(tuple(restored.origin), (10.0, 5.0, 0.0))
+        self.assertEqual(restored.axis_line_id, 7)
+        self.assertEqual(restored.angle, 180.0)
+
+    def test_default_axis(self):
+        """Old files without axis fields fall back to Z axis at the origin."""
+        sk = Sketch()
+        data = _feature_to_dict(Feature(operation="revolve", angle=90.0))
+        restored = _feature_from_dict(data, {sk.id: sk})
+        self.assertEqual(tuple(restored.axis), (0, 0, 1))
+        self.assertEqual(tuple(restored.origin), (0.0, 0.0, 0.0))
+        self.assertIsNone(restored.axis_line_id)
+        # legacy file without the keys
+        del data["axis"]
+        del data["origin"]
+        del data["axis_line_id"]
+        restored = _feature_from_dict(data, {sk.id: sk})
+        self.assertEqual(tuple(restored.axis), (0, 0, 1))
+        self.assertEqual(tuple(restored.origin), (0.0, 0.0, 0.0))
+
+
 class TestProjectIO(unittest.TestCase):
     """Round-trip the same project through save/load and check equivalence."""
 

src/fluency/ui/gui_ui.py

@@ -0,0 +1,906 @@
+# -*- coding: utf-8 -*-
+
+################################################################################
+## Form generated from reading UI file 'gui.ui'
+##
+## Created by: Qt User Interface Compiler version 6.10.2
+##
+## WARNING! All changes made in this file will be lost when recompiling UI file!
+################################################################################
+
+from PySide6.QtCore import (QCoreApplication, QDate, QDateTime, QLocale,
+    QMetaObject, QObject, QPoint, QRect,
+    QSize, QTime, QUrl, Qt)
+from PySide6.QtGui import (QAction, QBrush, QColor, QConicalGradient,
+    QCursor, QFont, QFontDatabase, QGradient,
+    QIcon, QImage, QKeySequence, QLinearGradient,
+    QPainter, QPalette, QPixmap, QRadialGradient,
+    QTransform)
+from PySide6.QtWidgets import (QApplication, QFrame, QGridLayout, QGroupBox,
+    QHBoxLayout, QLabel, QListWidget, QListWidgetItem,
+    QMainWindow, QMenu, QMenuBar, QPushButton,
+    QSizePolicy, QSpinBox, QStatusBar, QTabWidget,
+    QTextEdit, QVBoxLayout, QWidget)
+
+class Ui_fluencyCAD(object):
+    def setupUi(self, fluencyCAD):
+        if not fluencyCAD.objectName():
+            fluencyCAD.setObjectName(u"fluencyCAD")
+        fluencyCAD.resize(2359, 1285)
+        self.actionNew_Project = QAction(fluencyCAD)
+        self.actionNew_Project.setObjectName(u"actionNew_Project")
+        self.actionOpen_Project = QAction(fluencyCAD)
+        self.actionOpen_Project.setObjectName(u"actionOpen_Project")
+        self.actionSave_Project = QAction(fluencyCAD)
+        self.actionSave_Project.setObjectName(u"actionSave_Project")
+        self.actionSave_Project_As = QAction(fluencyCAD)
+        self.actionSave_Project_As.setObjectName(u"actionSave_Project_As")
+        self.actionImport_File = QAction(fluencyCAD)
+        self.actionImport_File.setObjectName(u"actionImport_File")
+        self.actionExport_Step = QAction(fluencyCAD)
+        self.actionExport_Step.setObjectName(u"actionExport_Step")
+        self.actionExport_Iges = QAction(fluencyCAD)
+        self.actionExport_Iges.setObjectName(u"actionExport_Iges")
+        self.actionExport_Stl = QAction(fluencyCAD)
+        self.actionExport_Stl.setObjectName(u"actionExport_Stl")
+        self.actionExit = QAction(fluencyCAD)
+        self.actionExit.setObjectName(u"actionExit")
+        self.centralwidget = QWidget(fluencyCAD)
+        self.centralwidget.setObjectName(u"centralwidget")
+        self.gridLayout = QGridLayout(self.centralwidget)
+        self.gridLayout.setObjectName(u"gridLayout")
+        self.InputTab = QTabWidget(self.centralwidget)
+        self.InputTab.setObjectName(u"InputTab")
+        sizePolicy = QSizePolicy(QSizePolicy.Policy.Expanding, QSizePolicy.Policy.Preferred)
+        sizePolicy.setHorizontalStretch(0)
+        sizePolicy.setVerticalStretch(0)
+        sizePolicy.setHeightForWidth(self.InputTab.sizePolicy().hasHeightForWidth())
+        self.InputTab.setSizePolicy(sizePolicy)
+        self.sketch_tab = QWidget()
+        self.sketch_tab.setObjectName(u"sketch_tab")
+        self.verticalLayout_4 = QVBoxLayout(self.sketch_tab)
+        self.verticalLayout_4.setObjectName(u"verticalLayout_4")
+        self.InputTab.addTab(self.sketch_tab, "")
+        self.code_tab = QWidget()
+        self.code_tab.setObjectName(u"code_tab")
+        self.verticalLayout = QVBoxLayout(self.code_tab)
+        self.verticalLayout.setObjectName(u"verticalLayout")
+        self.textEdit = QTextEdit(self.code_tab)
+        self.textEdit.setObjectName(u"textEdit")
+
+        self.verticalLayout.addWidget(self.textEdit)
+
+        self.groupBox_7 = QGroupBox(self.code_tab)
+        self.groupBox_7.setObjectName(u"groupBox_7")
+        self.gridLayout_5 = QGridLayout(self.groupBox_7)
+        self.gridLayout_5.setObjectName(u"gridLayout_5")
+        self.pushButton_5 = QPushButton(self.groupBox_7)
+        self.pushButton_5.setObjectName(u"pushButton_5")
+
+        self.gridLayout_5.addWidget(self.pushButton_5, 2, 0, 1, 1)
+
+        self.pushButton_4 = QPushButton(self.groupBox_7)
+        self.pushButton_4.setObjectName(u"pushButton_4")
+
+        self.gridLayout_5.addWidget(self.pushButton_4, 2, 1, 1, 1)
+
+        self.pb_apply_code = QPushButton(self.groupBox_7)
+        self.pb_apply_code.setObjectName(u"pb_apply_code")
+
+        self.gridLayout_5.addWidget(self.pb_apply_code, 1, 0, 1, 1)
+
+        self.pushButton = QPushButton(self.groupBox_7)
+        self.pushButton.setObjectName(u"pushButton")
+
+        self.gridLayout_5.addWidget(self.pushButton, 1, 1, 1, 1)
+
+
+        self.verticalLayout.addWidget(self.groupBox_7)
+
+        self.InputTab.addTab(self.code_tab, "")
+
+        self.gridLayout.addWidget(self.InputTab, 0, 1, 12, 1)
+
+        self.groupBox_9 = QGroupBox(self.centralwidget)
+        self.groupBox_9.setObjectName(u"groupBox_9")
+        self.groupBox_9.setMaximumSize(QSize(200, 16777215))
+        self.gridLayout_7 = QGridLayout(self.groupBox_9)
+        self.gridLayout_7.setObjectName(u"gridLayout_7")
+        self.pb_origin_wp = QPushButton(self.groupBox_9)
+        self.pb_origin_wp.setObjectName(u"pb_origin_wp")
+
+        self.gridLayout_7.addWidget(self.pb_origin_wp, 0, 0, 1, 1)
+
+        self.pb_origin_face = QPushButton(self.groupBox_9)
+        self.pb_origin_face.setObjectName(u"pb_origin_face")
+        self.pb_origin_face.setCheckable(True)
+
+        self.gridLayout_7.addWidget(self.pb_origin_face, 0, 1, 1, 1)
+
+        self.pb_flip_face = QPushButton(self.groupBox_9)
+        self.pb_flip_face.setObjectName(u"pb_flip_face")
+
+        self.gridLayout_7.addWidget(self.pb_flip_face, 1, 0, 1, 1)
+
+        self.pb_underlay = QPushButton(self.groupBox_9)
+        self.pb_underlay.setObjectName(u"pb_underlay")
+        self.pb_underlay.setEnabled(False)
+        self.pb_underlay.setCheckable(True)
+        self.pb_underlay.setChecked(True)
+
+        self.gridLayout_7.addWidget(self.pb_underlay, 3, 0, 1, 1)
+
+        self.pb_clr_face = QPushButton(self.groupBox_9)
+        self.pb_clr_face.setObjectName(u"pb_clr_face")
+        self.pb_clr_face.setEnabled(False)
+
+        self.gridLayout_7.addWidget(self.pb_clr_face, 3, 1, 1, 1)
+
+        self.pb_to_sketch = QPushButton(self.groupBox_9)
+        self.pb_to_sketch.setObjectName(u"pb_to_sketch")
+        self.pb_to_sketch.setEnabled(False)
+
+        self.gridLayout_7.addWidget(self.pb_to_sketch, 4, 0, 1, 2)
+
+        self.pb_wp_new = QPushButton(self.groupBox_9)
+        self.pb_wp_new.setObjectName(u"pb_wp_new")
+
+        self.gridLayout_7.addWidget(self.pb_wp_new, 1, 1, 1, 1)
+
+
+        self.gridLayout.addWidget(self.groupBox_9, 0, 0, 1, 1)
+
+        self.assembly_box = QGroupBox(self.centralwidget)
+        self.assembly_box.setObjectName(u"assembly_box")
+        self.assembly_box.setMinimumSize(QSize(0, 50))
+
+        self.gridLayout.addWidget(self.assembly_box, 13, 1, 1, 2)
+
+        self.joint_tools = QGroupBox(self.centralwidget)
+        self.joint_tools.setObjectName(u"joint_tools")
+        self.joint_tools.setMinimumSize(QSize(0, 50))
+        self.gridLayout_10 = QGridLayout(self.joint_tools)
+        self.gridLayout_10.setObjectName(u"gridLayout_10")
+        self.pb_remove_connector = QPushButton(self.joint_tools)
+        self.pb_remove_connector.setObjectName(u"pb_remove_connector")
+        self.pb_remove_connector.setMinimumSize(QSize(50, 50))
+        self.pb_remove_connector.setMaximumSize(QSize(50, 50))
+
+        self.gridLayout_10.addWidget(self.pb_remove_connector, 0, 2, 1, 1)
+
+        self.pb_add_connector = QPushButton(self.joint_tools)
+        self.pb_add_connector.setObjectName(u"pb_add_connector")
+        self.pb_add_connector.setMinimumSize(QSize(50, 50))
+        self.pb_add_connector.setMaximumSize(QSize(50, 50))
+
+        self.gridLayout_10.addWidget(self.pb_add_connector, 0, 1, 1, 1)
+
+        self.pb_add_connector_2 = QPushButton(self.joint_tools)
+        self.pb_add_connector_2.setObjectName(u"pb_add_connector_2")
+        self.pb_add_connector_2.setMinimumSize(QSize(50, 50))
+        self.pb_add_connector_2.setMaximumSize(QSize(50, 50))
+
+        self.gridLayout_10.addWidget(self.pb_add_connector_2, 1, 1, 1, 1)
+
+        self.pb_add_connector_3 = QPushButton(self.joint_tools)
+        self.pb_add_connector_3.setObjectName(u"pb_add_connector_3")
+        self.pb_add_connector_3.setMinimumSize(QSize(50, 50))
+        self.pb_add_connector_3.setMaximumSize(QSize(50, 50))
+
+        self.gridLayout_10.addWidget(self.pb_add_connector_3, 1, 2, 1, 1)
+
+
+        self.gridLayout.addWidget(self.joint_tools, 12, 3, 2, 1)
+
+        self.gl_box = QGroupBox(self.centralwidget)
+        self.gl_box.setObjectName(u"gl_box")
+        sizePolicy1 = QSizePolicy(QSizePolicy.Policy.Expanding, QSizePolicy.Policy.Expanding)
+        sizePolicy1.setHorizontalStretch(0)
+        sizePolicy1.setVerticalStretch(4)
+        sizePolicy1.setHeightForWidth(self.gl_box.sizePolicy().hasHeightForWidth())
+        self.gl_box.setSizePolicy(sizePolicy1)
+        font = QFont()
+        font.setPointSize(12)
+        self.gl_box.setFont(font)
+        self.horizontalLayout_4 = QHBoxLayout(self.gl_box)
+#ifndef Q_OS_MAC
+        self.horizontalLayout_4.setSpacing(-1)
+#endif
+        self.horizontalLayout_4.setObjectName(u"horizontalLayout_4")
+        self.horizontalLayout_4.setContentsMargins(12, -1, -1, -1)
+
+        self.gridLayout.addWidget(self.gl_box, 0, 2, 12, 1)
+
+        self.groupBox_11 = QGroupBox(self.centralwidget)
+        self.groupBox_11.setObjectName(u"groupBox_11")
+        sizePolicy2 = QSizePolicy(QSizePolicy.Policy.Preferred, QSizePolicy.Policy.Expanding)
+        sizePolicy2.setHorizontalStretch(0)
+        sizePolicy2.setVerticalStretch(0)
+        sizePolicy2.setHeightForWidth(self.groupBox_11.sizePolicy().hasHeightForWidth())
+        self.groupBox_11.setSizePolicy(sizePolicy2)
+        self.groupBox_11.setMaximumSize(QSize(200, 16777215))
+        self.verticalLayout_7 = QVBoxLayout(self.groupBox_11)
+        self.verticalLayout_7.setObjectName(u"verticalLayout_7")
+        self.verticalLayout_7.setContentsMargins(5, 5, 5, 5)
+        self.sketch_list = QListWidget(self.groupBox_11)
+        self.sketch_list.setObjectName(u"sketch_list")
+        sizePolicy3 = QSizePolicy(QSizePolicy.Policy.Expanding, QSizePolicy.Policy.Expanding)
+        sizePolicy3.setHorizontalStretch(0)
+        sizePolicy3.setVerticalStretch(0)
+        sizePolicy3.setHeightForWidth(self.sketch_list.sizePolicy().hasHeightForWidth())
+        self.sketch_list.setSizePolicy(sizePolicy3)
+        self.sketch_list.setSelectionRectVisible(True)
+
+        self.verticalLayout_7.addWidget(self.sketch_list)
+
+        self.groupBox_6 = QGroupBox(self.groupBox_11)
+        self.groupBox_6.setObjectName(u"groupBox_6")
+        sizePolicy4 = QSizePolicy(QSizePolicy.Policy.Preferred, QSizePolicy.Policy.Preferred)
+        sizePolicy4.setHorizontalStretch(0)
+        sizePolicy4.setVerticalStretch(0)
+        sizePolicy4.setHeightForWidth(self.groupBox_6.sizePolicy().hasHeightForWidth())
+        self.groupBox_6.setSizePolicy(sizePolicy4)
+        self.gridLayout_6 = QGridLayout(self.groupBox_6)
+        self.gridLayout_6.setObjectName(u"gridLayout_6")
+        self.gridLayout_6.setContentsMargins(2, 2, 2, 2)
+        self.pb_edt_sktch = QPushButton(self.groupBox_6)
+        self.pb_edt_sktch.setObjectName(u"pb_edt_sktch")
+
+        self.gridLayout_6.addWidget(self.pb_edt_sktch, 1, 1, 1, 1)
+
+        self.pb_nw_sktch = QPushButton(self.groupBox_6)
+        self.pb_nw_sktch.setObjectName(u"pb_nw_sktch")
+
+        self.gridLayout_6.addWidget(self.pb_nw_sktch, 1, 0, 1, 1)
+
+        self.pb_del_sketch = QPushButton(self.groupBox_6)
+        self.pb_del_sketch.setObjectName(u"pb_del_sketch")
+
+        self.gridLayout_6.addWidget(self.pb_del_sketch, 1, 2, 1, 1)
+
+
+        self.verticalLayout_7.addWidget(self.groupBox_6)
+
+
+        self.gridLayout.addWidget(self.groupBox_11, 6, 0, 6, 1)
+
+        self.assembly_tools = QGroupBox(self.centralwidget)
+        self.assembly_tools.setObjectName(u"assembly_tools")
+        self.assembly_tools.setMinimumSize(QSize(0, 50))
+        self.gridLayout_12 = QGridLayout(self.assembly_tools)
+        self.gridLayout_12.setObjectName(u"gridLayout_12")
+        self.pb_compo_to_assembly = QPushButton(self.assembly_tools)
+        self.pb_compo_to_assembly.setObjectName(u"pb_compo_to_assembly")
+        self.pb_compo_to_assembly.setMinimumSize(QSize(50, 50))
+        self.pb_compo_to_assembly.setMaximumSize(QSize(50, 50))
+
+        self.gridLayout_12.addWidget(self.pb_compo_to_assembly, 0, 0, 1, 1)
+
+        self.pb_remove_compo_from_assembly = QPushButton(self.assembly_tools)
+        self.pb_remove_compo_from_assembly.setObjectName(u"pb_remove_compo_from_assembly")
+        self.pb_remove_compo_from_assembly.setEnabled(True)
+        sizePolicy4.setHeightForWidth(self.pb_remove_compo_from_assembly.sizePolicy().hasHeightForWidth())
+        self.pb_remove_compo_from_assembly.setSizePolicy(sizePolicy4)
+        self.pb_remove_compo_from_assembly.setMinimumSize(QSize(50, 50))
+        self.pb_remove_compo_from_assembly.setMaximumSize(QSize(50, 50))
+        self.pb_remove_compo_from_assembly.setLayoutDirection(Qt.LeftToRight)
+
+        self.gridLayout_12.addWidget(self.pb_remove_compo_from_assembly, 0, 1, 1, 1)
+
+
+        self.gridLayout.addWidget(self.assembly_tools, 13, 0, 1, 1)
+
+        self.compo_tool_box = QGroupBox(self.centralwidget)
+        self.compo_tool_box.setObjectName(u"compo_tool_box")
+        self.compo_tool_box.setMinimumSize(QSize(0, 50))
+        self.gridLayout_9 = QGridLayout(self.compo_tool_box)
+        self.gridLayout_9.setObjectName(u"gridLayout_9")
+        self.pb_new_compo = QPushButton(self.compo_tool_box)
+        self.pb_new_compo.setObjectName(u"pb_new_compo")
+        self.pb_new_compo.setMinimumSize(QSize(50, 50))
+        self.pb_new_compo.setMaximumSize(QSize(50, 50))
+
+        self.gridLayout_9.addWidget(self.pb_new_compo, 0, 0, 1, 1)
+
+        self.pb_del_compo = QPushButton(self.compo_tool_box)
+        self.pb_del_compo.setObjectName(u"pb_del_compo")
+        self.pb_del_compo.setEnabled(True)
+        sizePolicy4.setHeightForWidth(self.pb_del_compo.sizePolicy().hasHeightForWidth())
+        self.pb_del_compo.setSizePolicy(sizePolicy4)
+        self.pb_del_compo.setMinimumSize(QSize(50, 50))
+        self.pb_del_compo.setMaximumSize(QSize(50, 50))
+        self.pb_del_compo.setLayoutDirection(Qt.LeftToRight)
+
+        self.gridLayout_9.addWidget(self.pb_del_compo, 0, 1, 1, 1)
+
+
+        self.gridLayout.addWidget(self.compo_tool_box, 12, 0, 1, 1)
+
+        self.compo_box = QGroupBox(self.centralwidget)
+        self.compo_box.setObjectName(u"compo_box")
+        self.compo_box.setMinimumSize(QSize(0, 50))
+
+        self.gridLayout.addWidget(self.compo_box, 12, 1, 1, 2)
+
+        self.groupBox_12 = QGroupBox(self.centralwidget)
+        self.groupBox_12.setObjectName(u"groupBox_12")
+        sizePolicy2.setHeightForWidth(self.groupBox_12.sizePolicy().hasHeightForWidth())
+        self.groupBox_12.setSizePolicy(sizePolicy2)
+        self.groupBox_12.setMaximumSize(QSize(200, 16777215))
+        self.verticalLayout_8 = QVBoxLayout(self.groupBox_12)
+        self.verticalLayout_8.setObjectName(u"verticalLayout_8")
+        self.verticalLayout_8.setContentsMargins(5, 5, 5, 5)
+        self.connection_list = QListWidget(self.groupBox_12)
+        self.connection_list.setObjectName(u"connection_list")
+        self.connection_list.setSelectionRectVisible(True)
+
+        self.verticalLayout_8.addWidget(self.connection_list)
+
+        self.groupBox_13 = QGroupBox(self.groupBox_12)
+        self.groupBox_13.setObjectName(u"groupBox_13")
+        sizePolicy4.setHeightForWidth(self.groupBox_13.sizePolicy().hasHeightForWidth())
+        self.groupBox_13.setSizePolicy(sizePolicy4)
+        self.groupBox_13.setMaximumSize(QSize(200, 16777215))
+        self.gridLayout_13 = QGridLayout(self.groupBox_13)
+        self.gridLayout_13.setObjectName(u"gridLayout_13")
+        self.gridLayout_13.setContentsMargins(2, 2, 2, 2)
+        self.pb_del_connection = QPushButton(self.groupBox_13)
+        self.pb_del_connection.setObjectName(u"pb_del_connection")
+
+        self.gridLayout_13.addWidget(self.pb_del_connection, 0, 2, 1, 1)
+
+        self.pb_update_connection = QPushButton(self.groupBox_13)
+        self.pb_update_connection.setObjectName(u"pb_update_connection")
+
+        self.gridLayout_13.addWidget(self.pb_update_connection, 0, 0, 1, 1)
+
+        self.pb_edt_sktch_4 = QPushButton(self.groupBox_13)
+        self.pb_edt_sktch_4.setObjectName(u"pb_edt_sktch_4")
+
+        self.gridLayout_13.addWidget(self.pb_edt_sktch_4, 0, 1, 1, 1)
+
+
+        self.verticalLayout_8.addWidget(self.groupBox_13)
+
+
+        self.gridLayout.addWidget(self.groupBox_12, 6, 3, 6, 1)
+
+        self.groupBox_10 = QGroupBox(self.centralwidget)
+        self.groupBox_10.setObjectName(u"groupBox_10")
+        sizePolicy2.setHeightForWidth(self.groupBox_10.sizePolicy().hasHeightForWidth())
+        self.groupBox_10.setSizePolicy(sizePolicy2)
+        self.groupBox_10.setMaximumSize(QSize(200, 16777215))
+        self.verticalLayout_6 = QVBoxLayout(self.groupBox_10)
+        self.verticalLayout_6.setObjectName(u"verticalLayout_6")
+        self.verticalLayout_6.setContentsMargins(5, 5, 5, 5)
+        self.body_list = QListWidget(self.groupBox_10)
+        self.body_list.setObjectName(u"body_list")
+        self.body_list.setSelectionRectVisible(True)
+
+        self.verticalLayout_6.addWidget(self.body_list)
+
+        self.groupBox_8 = QGroupBox(self.groupBox_10)
+        self.groupBox_8.setObjectName(u"groupBox_8")
+        sizePolicy4.setHeightForWidth(self.groupBox_8.sizePolicy().hasHeightForWidth())
+        self.groupBox_8.setSizePolicy(sizePolicy4)
+        self.groupBox_8.setMaximumSize(QSize(200, 16777215))
+        self.gridLayout_8 = QGridLayout(self.groupBox_8)
+        self.gridLayout_8.setObjectName(u"gridLayout_8")
+        self.gridLayout_8.setContentsMargins(2, 2, 2, 2)
+        self.pb_del_body = QPushButton(self.groupBox_8)
+        self.pb_del_body.setObjectName(u"pb_del_body")
+
+        self.gridLayout_8.addWidget(self.pb_del_body, 0, 2, 1, 1)
+
+        self.pb_update_body = QPushButton(self.groupBox_8)
+        self.pb_update_body.setObjectName(u"pb_update_body")
+
+        self.gridLayout_8.addWidget(self.pb_update_body, 0, 0, 1, 1)
+
+        self.pb_edt_sktch_3 = QPushButton(self.groupBox_8)
+        self.pb_edt_sktch_3.setObjectName(u"pb_edt_sktch_3")
+
+        self.gridLayout_8.addWidget(self.pb_edt_sktch_3, 0, 1, 1, 1)
+
+
+        self.verticalLayout_6.addWidget(self.groupBox_8)
+
+
+        self.gridLayout.addWidget(self.groupBox_10, 3, 3, 3, 1)
+
+        self.groupBox_2 = QGroupBox(self.centralwidget)
+        self.groupBox_2.setObjectName(u"groupBox_2")
+        sizePolicy4.setHeightForWidth(self.groupBox_2.sizePolicy().hasHeightForWidth())
+        self.groupBox_2.setSizePolicy(sizePolicy4)
+        self.groupBox_2.setMaximumSize(QSize(200, 16777215))
+        self.gridLayout_2 = QGridLayout(self.groupBox_2)
+        self.gridLayout_2.setObjectName(u"gridLayout_2")
+        self.gridLayout_2.setContentsMargins(10, -1, -1, -1)
+        self.pb_arc_tool = QPushButton(self.groupBox_2)
+        self.pb_arc_tool.setObjectName(u"pb_arc_tool")
+        self.pb_arc_tool.setCheckable(True)
+
+        self.gridLayout_2.addWidget(self.pb_arc_tool, 2, 0, 1, 1)
+
+        self.pb_rectool = QPushButton(self.groupBox_2)
+        self.pb_rectool.setObjectName(u"pb_rectool")
+        self.pb_rectool.setCheckable(True)
+        self.pb_rectool.setAutoExclusive(False)
+
+        self.gridLayout_2.addWidget(self.pb_rectool, 0, 1, 1, 1)
+
+        self.pb_circtool = QPushButton(self.groupBox_2)
+        self.pb_circtool.setObjectName(u"pb_circtool")
+        self.pb_circtool.setCheckable(True)
+        self.pb_circtool.setAutoExclusive(False)
+
+        self.gridLayout_2.addWidget(self.pb_circtool, 1, 0, 1, 1, Qt.AlignTop)
+
+        self.pb_enable_construct = QPushButton(self.groupBox_2)
+        self.pb_enable_construct.setObjectName(u"pb_enable_construct")
+        self.pb_enable_construct.setCheckable(True)
+
+        self.gridLayout_2.addWidget(self.pb_enable_construct, 4, 0, 1, 1)
+
+        self.pb_enable_snap = QPushButton(self.groupBox_2)
+        self.pb_enable_snap.setObjectName(u"pb_enable_snap")
+        self.pb_enable_snap.setIconSize(QSize(13, 16))
+        self.pb_enable_snap.setCheckable(True)
+        self.pb_enable_snap.setChecked(True)
+
+        self.gridLayout_2.addWidget(self.pb_enable_snap, 4, 1, 1, 1)
+
+        self.pb_linetool = QPushButton(self.groupBox_2)
+        self.pb_linetool.setObjectName(u"pb_linetool")
+        self.pb_linetool.setCheckable(True)
+        self.pb_linetool.setAutoExclusive(False)
+
+        self.gridLayout_2.addWidget(self.pb_linetool, 0, 0, 1, 1)
+
+        self.pb_slotool = QPushButton(self.groupBox_2)
+        self.pb_slotool.setObjectName(u"pb_slotool")
+        self.pb_slotool.setCheckable(True)
+        self.pb_slotool.setAutoExclusive(False)
+
+        self.gridLayout_2.addWidget(self.pb_slotool, 1, 1, 1, 1, Qt.AlignTop)
+
+        self.line = QFrame(self.groupBox_2)
+        self.line.setObjectName(u"line")
+        self.line.setFrameShape(QFrame.Shape.HLine)
+        self.line.setFrameShadow(QFrame.Shadow.Sunken)
+
+        self.gridLayout_2.addWidget(self.line, 3, 0, 1, 2)
+
+        self.pb_offset_tool = QPushButton(self.groupBox_2)
+        self.pb_offset_tool.setObjectName(u"pb_offset_tool")
+
+        self.gridLayout_2.addWidget(self.pb_offset_tool, 2, 1, 1, 1)
+
+
+        self.gridLayout.addWidget(self.groupBox_2, 1, 0, 1, 1)
+
+        self.groupBox_3 = QGroupBox(self.centralwidget)
+        self.groupBox_3.setObjectName(u"groupBox_3")
+        sizePolicy4.setHeightForWidth(self.groupBox_3.sizePolicy().hasHeightForWidth())
+        self.groupBox_3.setSizePolicy(sizePolicy4)
+        self.groupBox_3.setMaximumSize(QSize(200, 16777213))
+        self.gridLayout_4 = QGridLayout(self.groupBox_3)
+        self.gridLayout_4.setObjectName(u"gridLayout_4")
+        self.pb_con_ptpt = QPushButton(self.groupBox_3)
+        self.pb_con_ptpt.setObjectName(u"pb_con_ptpt")
+        self.pb_con_ptpt.setCheckable(True)
+        self.pb_con_ptpt.setAutoExclusive(False)
+
+        self.gridLayout_4.addWidget(self.pb_con_ptpt, 1, 0, 1, 1)
+
+        self.pb_con_vert = QPushButton(self.groupBox_3)
+        self.pb_con_vert.setObjectName(u"pb_con_vert")
+        self.pb_con_vert.setCheckable(True)
+        self.pb_con_vert.setAutoExclusive(False)
+
+        self.gridLayout_4.addWidget(self.pb_con_vert, 3, 1, 1, 1)
+
+        self.pb_con_sym = QPushButton(self.groupBox_3)
+        self.pb_con_sym.setObjectName(u"pb_con_sym")
+        self.pb_con_sym.setCheckable(True)
+        self.pb_con_sym.setAutoExclusive(False)
+
+        self.gridLayout_4.addWidget(self.pb_con_sym, 4, 1, 1, 1)
+
+        self.pb_con_mid = QPushButton(self.groupBox_3)
+        self.pb_con_mid.setObjectName(u"pb_con_mid")
+        self.pb_con_mid.setCheckable(True)
+        self.pb_con_mid.setAutoExclusive(False)
+
+        self.gridLayout_4.addWidget(self.pb_con_mid, 2, 0, 1, 1)
+
+        self.pb_con_line = QPushButton(self.groupBox_3)
+        self.pb_con_line.setObjectName(u"pb_con_line")
+        self.pb_con_line.setCheckable(True)
+        self.pb_con_line.setAutoExclusive(False)
+
+        self.gridLayout_4.addWidget(self.pb_con_line, 1, 1, 1, 1)
+
+        self.pb_con_horiz = QPushButton(self.groupBox_3)
+        self.pb_con_horiz.setObjectName(u"pb_con_horiz")
+        self.pb_con_horiz.setCheckable(True)
+        self.pb_con_horiz.setAutoExclusive(False)
+
+        self.gridLayout_4.addWidget(self.pb_con_horiz, 3, 0, 1, 1)
+
+        self.pb_con_dist = QPushButton(self.groupBox_3)
+        self.pb_con_dist.setObjectName(u"pb_con_dist")
+        self.pb_con_dist.setCheckable(True)
+        self.pb_con_dist.setAutoExclusive(False)
+        self.pb_con_dist.setAutoRepeatDelay(297)
+
+        self.gridLayout_4.addWidget(self.pb_con_dist, 4, 0, 1, 1)
+
+        self.pb_con_perp = QPushButton(self.groupBox_3)
+        self.pb_con_perp.setObjectName(u"pb_con_perp")
+        self.pb_con_perp.setCheckable(True)
+        self.pb_con_perp.setAutoExclusive(False)
+
+        self.gridLayout_4.addWidget(self.pb_con_perp, 2, 1, 1, 1)
+
+        self.pb_con_diameter = QPushButton(self.groupBox_3)
+        self.pb_con_diameter.setObjectName(u"pb_con_diameter")
+
+        self.gridLayout_4.addWidget(self.pb_con_diameter, 5, 0, 1, 1)
+
+
+        self.gridLayout.addWidget(self.groupBox_3, 2, 0, 1, 1)
+
+        self.groupBox_5 = QGroupBox(self.centralwidget)
+        self.groupBox_5.setObjectName(u"groupBox_5")
+        sizePolicy4.setHeightForWidth(self.groupBox_5.sizePolicy().hasHeightForWidth())
+        self.groupBox_5.setSizePolicy(sizePolicy4)
+        self.gridLayout_11 = QGridLayout(self.groupBox_5)
+        self.gridLayout_11.setObjectName(u"gridLayout_11")
+        self.gridLayout_11.setContentsMargins(12, 12, 12, 12)
+        self.label = QLabel(self.groupBox_5)
+        self.label.setObjectName(u"label")
+
+        self.gridLayout_11.addWidget(self.label, 5, 0, 1, 1)
+
+        self.pb_snap_vert = QPushButton(self.groupBox_5)
+        self.pb_snap_vert.setObjectName(u"pb_snap_vert")
+        self.pb_snap_vert.setCheckable(True)
+        self.pb_snap_vert.setAutoExclusive(False)
+
+        self.gridLayout_11.addWidget(self.pb_snap_vert, 2, 1, 1, 1)
+
+        self.line_2 = QFrame(self.groupBox_5)
+        self.line_2.setObjectName(u"line_2")
+        self.line_2.setFrameShape(QFrame.Shape.HLine)
+        self.line_2.setFrameShadow(QFrame.Shadow.Sunken)
+
+        self.gridLayout_11.addWidget(self.line_2, 4, 0, 1, 2)
+
+        self.label_2 = QLabel(self.groupBox_5)
+        self.label_2.setObjectName(u"label_2")
+
+        self.gridLayout_11.addWidget(self.label_2, 5, 1, 1, 1)
+
+        self.spinbox_snap_distance = QSpinBox(self.groupBox_5)
+        self.spinbox_snap_distance.setObjectName(u"spinbox_snap_distance")
+        self.spinbox_snap_distance.setMaximum(30)
+        self.spinbox_snap_distance.setValue(10)
+
+        self.gridLayout_11.addWidget(self.spinbox_snap_distance, 6, 0, 1, 1)
+
+        self.pushButton_7 = QPushButton(self.groupBox_5)
+        self.pushButton_7.setObjectName(u"pushButton_7")
+        self.pushButton_7.setCheckable(True)
+        self.pushButton_7.setAutoExclusive(False)
+
+        self.gridLayout_11.addWidget(self.pushButton_7, 3, 0, 1, 1)
+
+        self.pb_snap_horiz = QPushButton(self.groupBox_5)
+        self.pb_snap_horiz.setObjectName(u"pb_snap_horiz")
+        self.pb_snap_horiz.setCheckable(True)
+        self.pb_snap_horiz.setAutoExclusive(False)
+
+        self.gridLayout_11.addWidget(self.pb_snap_horiz, 2, 0, 1, 1)
+
+        self.spinbox_angle_steps = QSpinBox(self.groupBox_5)
+        self.spinbox_angle_steps.setObjectName(u"spinbox_angle_steps")
+        self.spinbox_angle_steps.setMaximum(180)
+        self.spinbox_angle_steps.setValue(15)
+
+        self.gridLayout_11.addWidget(self.spinbox_angle_steps, 6, 1, 1, 1)
+
+        self.pushButton_8 = QPushButton(self.groupBox_5)
+        self.pushButton_8.setObjectName(u"pushButton_8")
+        self.pushButton_8.setCheckable(True)
+        self.pushButton_8.setAutoExclusive(False)
+
+        self.gridLayout_11.addWidget(self.pushButton_8, 0, 0, 1, 1)
+
+        self.pb_snap_midp = QPushButton(self.groupBox_5)
+        self.pb_snap_midp.setObjectName(u"pb_snap_midp")
+        self.pb_snap_midp.setCheckable(True)
+        self.pb_snap_midp.setAutoExclusive(False)
+
+        self.gridLayout_11.addWidget(self.pb_snap_midp, 0, 1, 1, 1)
+
+        self.pb_snap_angle = QPushButton(self.groupBox_5)
+        self.pb_snap_angle.setObjectName(u"pb_snap_angle")
+        self.pb_snap_angle.setCheckable(True)
+        self.pb_snap_angle.setAutoExclusive(False)
+
+        self.gridLayout_11.addWidget(self.pb_snap_angle, 3, 1, 1, 1)
+
+
+        self.gridLayout.addWidget(self.groupBox_5, 3, 0, 1, 1)
+
+        self.groupBox = QGroupBox(self.centralwidget)
+        self.groupBox.setObjectName(u"groupBox")
+        self.gridLayout_3 = QGridLayout(self.groupBox)
+        self.gridLayout_3.setObjectName(u"gridLayout_3")
+        self.pb_revop = QPushButton(self.groupBox)
+        self.pb_revop.setObjectName(u"pb_revop")
+
+        self.gridLayout_3.addWidget(self.pb_revop, 2, 1, 1, 1)
+
+        self.pb_extrdop = QPushButton(self.groupBox)
+        self.pb_extrdop.setObjectName(u"pb_extrdop")
+
+        self.gridLayout_3.addWidget(self.pb_extrdop, 0, 0, 1, 1)
+
+        self.pb_arrayop = QPushButton(self.groupBox)
+        self.pb_arrayop.setObjectName(u"pb_arrayop")
+
+        self.gridLayout_3.addWidget(self.pb_arrayop, 2, 0, 1, 1)
+
+        self.pb_cutop = QPushButton(self.groupBox)
+        self.pb_cutop.setObjectName(u"pb_cutop")
+
+        self.gridLayout_3.addWidget(self.pb_cutop, 0, 1, 1, 1)
+
+        self.pb_combop = QPushButton(self.groupBox)
+        self.pb_combop.setObjectName(u"pb_combop")
+
+        self.gridLayout_3.addWidget(self.pb_combop, 1, 0, 1, 1)
+
+        self.pb_moveop = QPushButton(self.groupBox)
+        self.pb_moveop.setObjectName(u"pb_moveop")
+
+        self.gridLayout_3.addWidget(self.pb_moveop, 1, 1, 1, 1)
+
+
+        self.gridLayout.addWidget(self.groupBox, 0, 3, 1, 1)
+
+        self.groupBox_4 = QGroupBox(self.centralwidget)
+        self.groupBox_4.setObjectName(u"groupBox_4")
+        self.verticalLayout_2 = QVBoxLayout(self.groupBox_4)
+        self.verticalLayout_2.setObjectName(u"verticalLayout_2")
+        self.pushButton_2 = QPushButton(self.groupBox_4)
+        self.pushButton_2.setObjectName(u"pushButton_2")
+
+        self.verticalLayout_2.addWidget(self.pushButton_2)
+
+        self.pb_export_step = QPushButton(self.groupBox_4)
+        self.pb_export_step.setObjectName(u"pb_export_step")
+
+        self.verticalLayout_2.addWidget(self.pb_export_step)
+
+        self.pb_export_iges = QPushButton(self.groupBox_4)
+        self.pb_export_iges.setObjectName(u"pb_export_iges")
+
+        self.verticalLayout_2.addWidget(self.pb_export_iges)
+
+
+        self.gridLayout.addWidget(self.groupBox_4, 2, 3, 1, 1)
+
+        fluencyCAD.setCentralWidget(self.centralwidget)
+        self.menubar = QMenuBar(fluencyCAD)
+        self.menubar.setObjectName(u"menubar")
+        self.menubar.setGeometry(QRect(0, 0, 2359, 24))
+        self.menuFile = QMenu(self.menubar)
+        self.menuFile.setObjectName(u"menuFile")
+        self.menuSettings = QMenu(self.menubar)
+        self.menuSettings.setObjectName(u"menuSettings")
+        fluencyCAD.setMenuBar(self.menubar)
+        self.statusbar = QStatusBar(fluencyCAD)
+        self.statusbar.setObjectName(u"statusbar")
+        fluencyCAD.setStatusBar(self.statusbar)
+
+        self.menubar.addAction(self.menuFile.menuAction())
+        self.menubar.addAction(self.menuSettings.menuAction())
+        self.menuFile.addAction(self.actionNew_Project)
+        self.menuFile.addAction(self.actionOpen_Project)
+        self.menuFile.addAction(self.actionSave_Project)
+        self.menuFile.addAction(self.actionSave_Project_As)
+        self.menuFile.addSeparator()
+        self.menuFile.addAction(self.actionImport_File)
+        self.menuFile.addSeparator()
+        self.menuFile.addAction(self.actionExport_Step)
+        self.menuFile.addAction(self.actionExport_Iges)
+        self.menuFile.addAction(self.actionExport_Stl)
+        self.menuFile.addSeparator()
+        self.menuFile.addAction(self.actionExit)
+
+        self.retranslateUi(fluencyCAD)
+
+        self.InputTab.setCurrentIndex(0)
+
+
+        QMetaObject.connectSlotsByName(fluencyCAD)
+    # setupUi
+
+    def retranslateUi(self, fluencyCAD):
+        fluencyCAD.setWindowTitle(QCoreApplication.translate("fluencyCAD", u"fluencyCAD", None))
+        self.actionNew_Project.setText(QCoreApplication.translate("fluencyCAD", u"New Project", None))
+#if QT_CONFIG(shortcut)
+        self.actionNew_Project.setShortcut(QCoreApplication.translate("fluencyCAD", u"Ctrl+N", None))
+#endif // QT_CONFIG(shortcut)
+        self.actionOpen_Project.setText(QCoreApplication.translate("fluencyCAD", u"Open Project...", None))
+#if QT_CONFIG(shortcut)
+        self.actionOpen_Project.setShortcut(QCoreApplication.translate("fluencyCAD", u"Ctrl+O", None))
+#endif // QT_CONFIG(shortcut)
+        self.actionSave_Project.setText(QCoreApplication.translate("fluencyCAD", u"Save Project", None))
+#if QT_CONFIG(shortcut)
+        self.actionSave_Project.setShortcut(QCoreApplication.translate("fluencyCAD", u"Ctrl+S", None))
+#endif // QT_CONFIG(shortcut)
+        self.actionSave_Project_As.setText(QCoreApplication.translate("fluencyCAD", u"Save Project As...", None))
+#if QT_CONFIG(shortcut)
+        self.actionSave_Project_As.setShortcut(QCoreApplication.translate("fluencyCAD", u"Ctrl+Shift+S", None))
+#endif // QT_CONFIG(shortcut)
+        self.actionImport_File.setText(QCoreApplication.translate("fluencyCAD", u"Import STEP/IGES...", None))
+        self.actionExport_Step.setText(QCoreApplication.translate("fluencyCAD", u"Export STEP...", None))
+        self.actionExport_Iges.setText(QCoreApplication.translate("fluencyCAD", u"Export IGES...", None))
+        self.actionExport_Stl.setText(QCoreApplication.translate("fluencyCAD", u"Export STL...", None))
+        self.actionExit.setText(QCoreApplication.translate("fluencyCAD", u"Exit", None))
+#if QT_CONFIG(shortcut)
+        self.actionExit.setShortcut(QCoreApplication.translate("fluencyCAD", u"Ctrl+Q", None))
+#endif // QT_CONFIG(shortcut)
+        self.InputTab.setTabText(self.InputTab.indexOf(self.sketch_tab), QCoreApplication.translate("fluencyCAD", u"Sketch", None))
+        self.groupBox_7.setTitle(QCoreApplication.translate("fluencyCAD", u"Executive", None))
+        self.pushButton_5.setText(QCoreApplication.translate("fluencyCAD", u"Load Code", None))
+        self.pushButton_4.setText(QCoreApplication.translate("fluencyCAD", u"Save code", None))
+        self.pb_apply_code.setText(QCoreApplication.translate("fluencyCAD", u"Apply Code", None))
+        self.pushButton.setText(QCoreApplication.translate("fluencyCAD", u"Delete Code", None))
+        self.InputTab.setTabText(self.InputTab.indexOf(self.code_tab), QCoreApplication.translate("fluencyCAD", u"Code", None))
+        self.groupBox_9.setTitle(QCoreApplication.translate("fluencyCAD", u"Workplanes", None))
+#if QT_CONFIG(tooltip)
+        self.pb_origin_wp.setToolTip(QCoreApplication.translate("fluencyCAD", u"<W>orking Plane at 0, 0, 0", None))
+#endif // QT_CONFIG(tooltip)
+        self.pb_origin_wp.setText(QCoreApplication.translate("fluencyCAD", u"WP Origin", None))
+#if QT_CONFIG(shortcut)
+        self.pb_origin_wp.setShortcut(QCoreApplication.translate("fluencyCAD", u"W", None))
+#endif // QT_CONFIG(shortcut)
+#if QT_CONFIG(tooltip)
+        self.pb_origin_face.setToolTip(QCoreApplication.translate("fluencyCAD", u"Working Plane >P<rojection at selected edges face", None))
+#endif // QT_CONFIG(tooltip)
+        self.pb_origin_face.setText(QCoreApplication.translate("fluencyCAD", u" WP Face", None))
+#if QT_CONFIG(shortcut)
+        self.pb_origin_face.setShortcut(QCoreApplication.translate("fluencyCAD", u"P", None))
+#endif // QT_CONFIG(shortcut)
+#if QT_CONFIG(tooltip)
+        self.pb_flip_face.setToolTip(QCoreApplication.translate("fluencyCAD", u"Flip >N<ormal of projected mesh.", None))
+#endif // QT_CONFIG(tooltip)
+        self.pb_flip_face.setText(QCoreApplication.translate("fluencyCAD", u"WP Flip", None))
+#if QT_CONFIG(shortcut)
+        self.pb_flip_face.setShortcut(QCoreApplication.translate("fluencyCAD", u"N", None))
+#endif // QT_CONFIG(shortcut)
+#if QT_CONFIG(tooltip)
+        self.pb_underlay.setToolTip(QCoreApplication.translate("fluencyCAD", u"Show / hide the construction lines projected from the source face", None))
+#endif // QT_CONFIG(tooltip)
+        self.pb_underlay.setText(QCoreApplication.translate("fluencyCAD", u"Underlay", None))
+#if QT_CONFIG(tooltip)
+        self.pb_clr_face.setToolTip(QCoreApplication.translate("fluencyCAD", u"Forget the picked source face (keep the workplane)", None))
+#endif // QT_CONFIG(tooltip)
+        self.pb_clr_face.setText(QCoreApplication.translate("fluencyCAD", u"ClrFace", None))
+#if QT_CONFIG(tooltip)
+        self.pb_to_sketch.setToolTip(QCoreApplication.translate("fluencyCAD", u"Convert projected construction lines into real sketch geometry", None))
+#endif // QT_CONFIG(tooltip)
+        self.pb_to_sketch.setText(QCoreApplication.translate("fluencyCAD", u"ToSketch", None))
+#if QT_CONFIG(tooltip)
+        self.pb_wp_new.setToolTip(QCoreApplication.translate("fluencyCAD", u"Create a new independent workplane (datum plane)", None))
+#endif // QT_CONFIG(tooltip)
+        self.pb_wp_new.setText(QCoreApplication.translate("fluencyCAD", u"WP New", None))
+#if QT_CONFIG(shortcut)
+        self.pb_wp_new.setShortcut(QCoreApplication.translate("fluencyCAD", u"Shift+W", None))
+#endif // QT_CONFIG(shortcut)
+        self.assembly_box.setTitle(QCoreApplication.translate("fluencyCAD", u"Assembly", None))
+        self.joint_tools.setTitle(QCoreApplication.translate("fluencyCAD", u"Joint Tools", None))
+        self.pb_remove_connector.setText(QCoreApplication.translate("fluencyCAD", u"- Cnct", None))
+        self.pb_add_connector.setText(QCoreApplication.translate("fluencyCAD", u"+ Cnct", None))
+        self.pb_add_connector_2.setText(QCoreApplication.translate("fluencyCAD", u"+Jnt", None))
+        self.pb_add_connector_3.setText(QCoreApplication.translate("fluencyCAD", u"-Jnt", None))
+        self.gl_box.setTitle(QCoreApplication.translate("fluencyCAD", u"Model Viewer", None))
+        self.groupBox_11.setTitle(QCoreApplication.translate("fluencyCAD", u"Sketch", None))
+        self.groupBox_6.setTitle(QCoreApplication.translate("fluencyCAD", u"Tools", None))
+        self.pb_edt_sktch.setText(QCoreApplication.translate("fluencyCAD", u"Edt", None))
+        self.pb_nw_sktch.setText(QCoreApplication.translate("fluencyCAD", u"Add", None))
+        self.pb_del_sketch.setText(QCoreApplication.translate("fluencyCAD", u"Del", None))
+        self.assembly_tools.setTitle(QCoreApplication.translate("fluencyCAD", u"Assembly Tools", None))
+        self.pb_compo_to_assembly.setText(QCoreApplication.translate("fluencyCAD", u"Add", None))
+        self.pb_remove_compo_from_assembly.setText(QCoreApplication.translate("fluencyCAD", u"Rem", None))
+        self.compo_tool_box.setTitle(QCoreApplication.translate("fluencyCAD", u"Component Tools", None))
+        self.pb_new_compo.setText(QCoreApplication.translate("fluencyCAD", u"New", None))
+        self.pb_del_compo.setText(QCoreApplication.translate("fluencyCAD", u"Del", None))
+        self.compo_box.setTitle(QCoreApplication.translate("fluencyCAD", u"Components", None))
+        self.groupBox_12.setTitle(QCoreApplication.translate("fluencyCAD", u"Component Connections", None))
+        self.groupBox_13.setTitle(QCoreApplication.translate("fluencyCAD", u"Tools", None))
+        self.pb_del_connection.setText(QCoreApplication.translate("fluencyCAD", u"Del", None))
+        self.pb_update_connection.setText(QCoreApplication.translate("fluencyCAD", u"Upd", None))
+        self.pb_edt_sktch_4.setText(QCoreApplication.translate("fluencyCAD", u"Nothing", None))
+        self.groupBox_10.setTitle(QCoreApplication.translate("fluencyCAD", u"Bodys / Operations", None))
+        self.groupBox_8.setTitle(QCoreApplication.translate("fluencyCAD", u"Tools", None))
+        self.pb_del_body.setText(QCoreApplication.translate("fluencyCAD", u"Del", None))
+        self.pb_update_body.setText(QCoreApplication.translate("fluencyCAD", u"Upd", None))
+        self.pb_edt_sktch_3.setText(QCoreApplication.translate("fluencyCAD", u"Nothing", None))
+        self.groupBox_2.setTitle(QCoreApplication.translate("fluencyCAD", u"Drawing", None))
+        self.pb_arc_tool.setText(QCoreApplication.translate("fluencyCAD", u"Arc", None))
+        self.pb_rectool.setText(QCoreApplication.translate("fluencyCAD", u"Rctgl", None))
+        self.pb_circtool.setText(QCoreApplication.translate("fluencyCAD", u"Circle", None))
+        self.pb_enable_construct.setText(QCoreApplication.translate("fluencyCAD", u"Cstrct", None))
+        self.pb_enable_snap.setText(QCoreApplication.translate("fluencyCAD", u"Snap", None))
+        self.pb_linetool.setText(QCoreApplication.translate("fluencyCAD", u"Line", None))
+#if QT_CONFIG(shortcut)
+        self.pb_linetool.setShortcut(QCoreApplication.translate("fluencyCAD", u"S", None))
+#endif // QT_CONFIG(shortcut)
+        self.pb_slotool.setText(QCoreApplication.translate("fluencyCAD", u"Slot", None))
+#if QT_CONFIG(tooltip)
+        self.pb_offset_tool.setToolTip(QCoreApplication.translate("fluencyCAD", u"Offset selected sketch face (duplicate + offset boundary)", None))
+#endif // QT_CONFIG(tooltip)
+        self.pb_offset_tool.setText(QCoreApplication.translate("fluencyCAD", u"Offst", None))
+        self.groupBox_3.setTitle(QCoreApplication.translate("fluencyCAD", u"Constrain", None))
+#if QT_CONFIG(tooltip)
+        self.pb_con_ptpt.setToolTip(QCoreApplication.translate("fluencyCAD", u"Poin to Point Constrain", None))
+#endif // QT_CONFIG(tooltip)
+        self.pb_con_ptpt.setText(QCoreApplication.translate("fluencyCAD", u"Pt_Pt", None))
+#if QT_CONFIG(tooltip)
+        self.pb_con_vert.setToolTip(QCoreApplication.translate("fluencyCAD", u"Vertical Constrain", None))
+#endif // QT_CONFIG(tooltip)
+        self.pb_con_vert.setText(QCoreApplication.translate("fluencyCAD", u"Vert", None))
+        self.pb_con_sym.setText(QCoreApplication.translate("fluencyCAD", u"Symetrc", None))
+#if QT_CONFIG(tooltip)
+        self.pb_con_mid.setToolTip(QCoreApplication.translate("fluencyCAD", u"Point to Middle Point Constrain", None))
+#endif // QT_CONFIG(tooltip)
+        self.pb_con_mid.setText(QCoreApplication.translate("fluencyCAD", u"Pt_Mid_L", None))
+#if QT_CONFIG(tooltip)
+        self.pb_con_line.setToolTip(QCoreApplication.translate("fluencyCAD", u"Point to Line Constrain", None))
+#endif // QT_CONFIG(tooltip)
+        self.pb_con_line.setText(QCoreApplication.translate("fluencyCAD", u"Pt_Lne", None))
+#if QT_CONFIG(tooltip)
+        self.pb_con_horiz.setToolTip(QCoreApplication.translate("fluencyCAD", u"Horizontal Constrain ", None))
+#endif // QT_CONFIG(tooltip)
+        self.pb_con_horiz.setText(QCoreApplication.translate("fluencyCAD", u"Horiz", None))
+#if QT_CONFIG(tooltip)
+        self.pb_con_dist.setToolTip(QCoreApplication.translate("fluencyCAD", u"Dimension of Line of Distance from Point to Line", None))
+#endif // QT_CONFIG(tooltip)
+        self.pb_con_dist.setText(QCoreApplication.translate("fluencyCAD", u"Distnce", None))
+#if QT_CONFIG(tooltip)
+        self.pb_con_perp.setToolTip(QCoreApplication.translate("fluencyCAD", u"Constrain Line perpendicular to another line.", None))
+#endif // QT_CONFIG(tooltip)
+        self.pb_con_perp.setText(QCoreApplication.translate("fluencyCAD", u"Perp_Lne", None))
+        self.pb_con_diameter.setText(QCoreApplication.translate("fluencyCAD", u"Diameter", None))
+        self.groupBox_5.setTitle(QCoreApplication.translate("fluencyCAD", u"Snapping Points", None))
+        self.label.setText(QCoreApplication.translate("fluencyCAD", u"Snp Dst", None))
+        self.pb_snap_vert.setText(QCoreApplication.translate("fluencyCAD", u"Vert", None))
+        self.label_2.setText(QCoreApplication.translate("fluencyCAD", u"Angl Stps", None))
+        self.spinbox_snap_distance.setSuffix(QCoreApplication.translate("fluencyCAD", u"mm", None))
+        self.pushButton_7.setText(QCoreApplication.translate("fluencyCAD", u"Grid", None))
+        self.pb_snap_horiz.setText(QCoreApplication.translate("fluencyCAD", u"Horiz", None))
+        self.spinbox_angle_steps.setSuffix(QCoreApplication.translate("fluencyCAD", u"\u00b0", None))
+        self.pushButton_8.setText(QCoreApplication.translate("fluencyCAD", u"Pnt", None))
+        self.pb_snap_midp.setText(QCoreApplication.translate("fluencyCAD", u"MidP", None))
+        self.pb_snap_angle.setText(QCoreApplication.translate("fluencyCAD", u"Angles", None))
+        self.groupBox.setTitle(QCoreApplication.translate("fluencyCAD", u"Modify", None))
+        self.pb_revop.setText(QCoreApplication.translate("fluencyCAD", u"Rev", None))
+        self.pb_extrdop.setText(QCoreApplication.translate("fluencyCAD", u"Extrd", None))
+        self.pb_arrayop.setText(QCoreApplication.translate("fluencyCAD", u"Array", None))
+        self.pb_cutop.setText(QCoreApplication.translate("fluencyCAD", u"Cut", None))
+        self.pb_combop.setText(QCoreApplication.translate("fluencyCAD", u"Comb", None))
+        self.pb_moveop.setText(QCoreApplication.translate("fluencyCAD", u"Mve", None))
+        self.groupBox_4.setTitle(QCoreApplication.translate("fluencyCAD", u"Export", None))
+        self.pushButton_2.setText(QCoreApplication.translate("fluencyCAD", u"STL", None))
+        self.pb_export_step.setText(QCoreApplication.translate("fluencyCAD", u"STEP", None))
+        self.pb_export_iges.setText(QCoreApplication.translate("fluencyCAD", u"IGES", None))
+        self.menuFile.setTitle(QCoreApplication.translate("fluencyCAD", u"File", None))
+        self.menuSettings.setTitle(QCoreApplication.translate("fluencyCAD", u"Settings", None))
+    # retranslateUi
+

tests/test_geometry.py

@@ -1,7 +1,6 @@
 """Tests for Fluency CAD geometry kernel."""
 
 import pytest
-import numpy as np
 
 from fluency.geometry_occ.kernel import OCGeometryKernel, OCCGeometryObject
 from fluency.geometry_occ.sketch import OCCSketch
@@ -195,10 +194,14 @@ class TestOCCSketch:
         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)
+        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.
@@ -220,10 +223,14 @@ class TestOCCSketch:
 
         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)
+        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)
 
@@ -290,10 +297,14 @@ class TestExternalEntities:
         # 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)
+        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
@@ -310,10 +321,14 @@ class TestExternalEntities:
     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)
+        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)
@@ -328,10 +343,14 @@ class TestExternalEntities:
         # 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)
+        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()
@@ -498,10 +517,9 @@ class TestExtrudeCutFix:
         and the tool is no longer needed.
         """
         from OCP.BRepPrimAPI import BRepPrimAPI_MakeBox
-        from fluency.geometry_occ.kernel import OCGeometryKernel, OCCGeometryObject
+        from fluency.geometry_occ.kernel import OCGeometryKernel
         from OCP.GProp import GProp_GProps
         from OCP.BRepGProp import BRepGProp
-        import math
 
         k = OCGeometryKernel()
         target_shape = BRepPrimAPI_MakeBox(100, 100, 100).Shape()
@@ -511,17 +529,18 @@ class TestExtrudeCutFix:
         # 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)]:
+        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_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.
@@ -536,9 +555,7 @@ class TestExtrudeCutFix:
         # 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
-        )
+        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):
@@ -551,10 +568,9 @@ class TestExtrudeCutFix:
         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
+        from fluency.geometry_occ.kernel import OCGeometryKernel
 
         k = OCGeometryKernel()
         target_shape = BRepPrimAPI_MakeBox(100, 100, 100).Shape()
@@ -562,6 +578,7 @@ class TestExtrudeCutFix:
 
         # 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, {})
 
@@ -595,91 +612,59 @@ class TestBodyVisibilityToggle:
 
     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."""
+        """Each body list item has a data role for the toggle handler."""
         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(), {}
-        )
+
+        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
+        # Default state is visible.
+        assert win._current_component.bodies["a"].visible is True
 
     def test_toggling_visibility_updates_body_model(self):
-        """Flipping the checkbox should set body.visible accordingly."""
+        """Toggling visibility via _on_body_visibility_changed updates the model."""
         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(), {}
-        )
+
+        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)
 
 
@@ -698,10 +683,13 @@ class TestConstraintTagRendering:
     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
@@ -824,6 +812,7 @@ class TestConstraintTagRendering:
         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)
@@ -865,12 +854,13 @@ class TestExtrudeRedesign:
 
     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
 
@@ -896,7 +886,6 @@ class TestExtrudeRedesign:
         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()
@@ -905,6 +894,7 @@ class TestExtrudeRedesign:
     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)
@@ -919,37 +909,48 @@ class TestExtrudeRedesign:
         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,
+            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
+        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."""
+        """ "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,
+            sketch,
+            face_geom,
             length=5.0,  # ignored when through_all
-            symmetric=False, invert=False,
-            cut=True, union=False, through_all=True,
+            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
+        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):
@@ -960,30 +961,23 @@ class TestExtrudeRedesign:
         """
         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
-        )
+        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
-        )
+        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))
@@ -999,16 +993,21 @@ class TestExtrudeRedesign:
 
         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,
+            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
+        expected = 100.0**3 - math.pi * (10.0**2) * 100.0
         assert abs(vol - expected) < 1.0
 
     def test_union_default_builds_outward(self):
@@ -1019,17 +1018,23 @@ class TestExtrudeRedesign:
         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,
+            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
+        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):
@@ -1037,9 +1042,14 @@ class TestExtrudeRedesign:
         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,
+            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.
@@ -1047,7 +1057,8 @@ class TestExtrudeRedesign:
         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
+
+        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.
@@ -1055,7 +1066,6 @@ class TestExtrudeRedesign:
         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
@@ -1063,6 +1073,7 @@ class TestExtrudeRedesign:
         # 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))
@@ -1084,8 +1095,10 @@ class TestExtrudeRedesign:
     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
 
@@ -1110,8 +1123,10 @@ class TestExtrudeRedesign:
     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
 

tests/test_technical_drawing.py

@@ -0,0 +1,916 @@
+"""Tests for the technical drawing workbench.
+
+Covers the manual-dimension pipeline (model-space annotations →
+sheet-space candidates → placed primitives), the 2D pick geometry
+helpers, and persistence of drawings (manual dimensions included) in
+the .fluency project file.
+"""
+
+import json
+import math
+import os
+
+os.environ.setdefault("QT_QPA_PLATFORM", "offscreen")
+
+import pytest
+
+from fluency.models.data_model import (
+    Body,
+    Component,
+    DrawingAnnotation,
+    DrawingView,
+    Project,
+    TechnicalDrawing,
+)
+from fluency.technical_drawing import (
+    build_manual_candidates,
+    generate_drawing,
+    _layout_views_on_sheet,
+)
+from fluency.io.project_io import (
+    _technical_drawing_from_dict,
+    _technical_drawing_to_dict,
+    load_project,
+    save_project,
+)
+from fluency.ui.technical_drawing_widget import (
+    _closest_point_on_segment,
+    _closest_points_on_segments,
+    _line_intersection,
+    _point_to_segment,
+)
+
+
+# ── Fixtures ───────────────────────────────────────────────────────────────
+
+
+@pytest.fixture(scope="module")
+def qapp():
+    """Offscreen QApplication for widget-level tests."""
+    from PySide6.QtWidgets import QApplication
+
+    app = QApplication.instance() or QApplication([])
+    yield app
+
+
+def _drawing_with_views(view_kinds=("front",)):
+    drawing = TechnicalDrawing(source_kind="component", source_id="comp-1")
+    for kind in view_kinds:
+        drawing.views.append(DrawingView(kind=kind))
+    return drawing
+
+
+def _manual_annotation(
+    dimension_kind: str,
+    view_id: str,
+    anchors,
+    direction=None,
+) -> DrawingAnnotation:
+    return DrawingAnnotation(
+        kind="dimension",
+        dimension_kind=dimension_kind,
+        view_id=view_id,
+        anchors=list(anchors),
+        direction=direction,
+    )
+
+
+# ── build_manual_candidates ────────────────────────────────────────────────
+
+
+class TestBuildManualCandidates:
+    def test_length_candidate_reprojects_anchors(self):
+        drawing = _drawing_with_views()
+        ann = _manual_annotation(
+            "length", "front", ((0.0, 0.0), (0.0, 12.5)), direction=(0.0, 1.0)
+        )
+        drawing.annotations.append(ann)
+
+        cands, resolved, unresolved = build_manual_candidates(
+            drawing, {"front": (2.0, 10.0, 20.0)}
+        )
+
+        assert unresolved == []
+        assert resolved == [ann.id]
+        c = cands[0]
+        assert c.kind == "length"
+        assert c.view_id == "front"
+        assert c.key == f"manual:{ann.id}"
+        assert c.references == (ann.id,)
+        assert c.value == pytest.approx(12.5)
+        assert c.label == "12.50"
+        # sheet = model * scale + offset
+        assert c.anchor_points[0] == pytest.approx((10.0, 20.0))
+        assert c.anchor_points[1] == pytest.approx((10.0, 45.0))
+        assert c.direction == (0.0, 1.0)
+
+    def test_length_without_transform_is_unresolved(self):
+        drawing = _drawing_with_views()
+        ann = _manual_annotation("length", "front", ((0.0, 0.0), (3.0, 4.0)))
+        drawing.annotations.append(ann)
+
+        cands, resolved, unresolved = build_manual_candidates(drawing, {})
+        assert cands == []
+        assert unresolved == [ann.id]
+
+        cands, resolved, unresolved = build_manual_candidates(
+            drawing, {"front": (1.0, 0.0, 0.0)}
+        )
+        assert unresolved == []
+        c = cands[0]
+        assert c.value == pytest.approx(5.0)
+        assert c.direction == pytest.approx((0.6, 0.8))
+
+    def test_diameter_candidate(self):
+        drawing = _drawing_with_views()
+        ann = _manual_annotation("diameter", "top", ((-5.0, 0.0), (5.0, 0.0)))
+        drawing.annotations.append(ann)
+
+        cands, resolved, unresolved = build_manual_candidates(
+            drawing, {"top": (1.0, 0.0, 0.0)}
+        )
+
+        assert unresolved == []
+        c = cands[0]
+        assert c.kind == "diameter"
+        assert c.value == pytest.approx(10.0)
+        assert c.label == "Ø10.00"
+        assert c.direction == ()
+
+    def test_angle_candidate(self):
+        drawing = _drawing_with_views()
+        ann = _manual_annotation(
+            "angle", "front", ((0.0, 0.0), (10.0, 0.0), (0.0, 10.0))
+        )
+        drawing.annotations.append(ann)
+
+        cands, resolved, unresolved = build_manual_candidates(
+            drawing, {"front": (1.0, 0.0, 0.0)}
+        )
+
+        assert unresolved == []
+        c = cands[0]
+        assert c.kind == "angle"
+        assert c.value == pytest.approx(90.0)
+        assert c.label == "90.00°"
+        assert len(c.anchor_points) == 3
+
+    def test_degenerate_angle_is_unresolved(self):
+        # Collinear arms → 180° → not a usable angle dimension.
+        drawing = _drawing_with_views()
+        ann = _manual_annotation(
+            "angle", "front", ((0.0, 0.0), (10.0, 0.0), (-10.0, 0.0))
+        )
+        drawing.annotations.append(ann)
+
+        cands, resolved, unresolved = build_manual_candidates(
+            drawing, {"front": (1.0, 0.0, 0.0)}
+        )
+
+        assert cands == []
+        assert resolved == []
+        assert unresolved == [ann.id]
+    def test_hidden_annotation_is_skipped(self):
+        drawing = _drawing_with_views()
+        ann = _manual_annotation("length", "front", ((0.0, 0.0), (1.0, 0.0)))
+        ann.visible = False
+        drawing.annotations.append(ann)
+
+        cands, resolved, unresolved = build_manual_candidates(
+            drawing, {"front": (1.0, 0.0, 0.0)}
+        )
+
+        assert cands == []
+        assert resolved == []
+        assert unresolved == []
+
+
+# ── generate_drawing: auto vs manual dimensions ───────────────────────────
+
+
+@pytest.fixture(scope="module")
+def kernel():
+    from fluency.geometry_occ.kernel import OCGeometryKernel
+
+    return OCGeometryKernel()
+
+
+@pytest.fixture(scope="module")
+def box_project(kernel):
+    """Project with one 10 x 20 x 5 box (x: 0..10, y: 0..20, z: 0..5)."""
+    from fluency.geometry.base import Point2D
+
+    points = [Point2D(0, 0), Point2D(10, 0), Point2D(10, 20), Point2D(0, 20)]
+    polygon = kernel.create_polygon(points)
+    box = kernel.extrude(polygon, 5.0)
+    body = Body(name="Box", geometry=box)
+    comp = Component(name="BoxComp")
+    comp.bodies[body.id] = body
+    project = Project()
+    project.components[comp.id] = comp
+    project.active_component = comp.id
+    return project, comp
+
+
+class TestGenerateDrawingManualDimensions:
+    def test_manual_dimension_placed_with_auto_off(self, kernel, box_project):
+        project, comp = box_project
+        drawing = TechnicalDrawing(
+            source_kind="component",
+            source_id=comp.id,
+            views=[DrawingView(kind="front")],
+            auto_dimensions=False,
+        )
+        # Distance between the two vertical edges of the box front face.
+        ann = _manual_annotation(
+            "length", "front", ((0.0, 0.0), (10.0, 0.0)), direction=(1.0, 0.0)
+        )
+        drawing.annotations.append(ann)
+
+        result = generate_drawing(drawing, project, kernel)
+
+        assert result.view_transforms, "view transforms must be published"
+        manual_keys = [
+            p.candidate_key for p in result.primitives if p.candidate_key
+        ]
+        assert f"manual:{ann.id}" in manual_keys
+        label_texts = [
+            p.text
+            for p in result.primitives
+            if p.candidate_key == f"manual:{ann.id}" and p.kind == "text"
+        ]
+        assert label_texts == ["10.00"]
+        # Auto off → no auto-placed dimensions.
+        assert not any(
+            k for k in manual_keys if not k.startswith("manual:")
+        ), "auto dimensions must stay out while auto_dimensions is off"
+        assert ann.id in result.resolved_annotation_ids
+
+    def test_auto_off_places_no_auto_dimensions(self, kernel, box_project):
+        project, comp = box_project
+        drawing = TechnicalDrawing(
+            source_kind="component",
+            source_id=comp.id,
+            views=[DrawingView(kind="front")],
+            auto_dimensions=False,
+        )
+        result = generate_drawing(drawing, project, kernel)
+        dim_keys = [p.candidate_key for p in result.primitives if p.candidate_key]
+        assert dim_keys == [], f"expected no dimensions, got {dim_keys}"
+
+    def test_auto_on_places_auto_dimensions(self, kernel, box_project):
+        project, comp = box_project
+        drawing = TechnicalDrawing(
+            source_kind="component",
+            source_id=comp.id,
+            views=[DrawingView(kind="front")],
+            auto_dimensions=True,
+        )
+        result = generate_drawing(drawing, project, kernel)
+        dim_keys = [p.candidate_key for p in result.primitives if p.candidate_key]
+        assert dim_keys, "auto dimensions expected with auto_dimensions on"
+        assert all(not k.startswith("manual:") for k in dim_keys)
+
+    def test_auto_and_manual_coexist(self, kernel, box_project):
+        project, comp = box_project
+        drawing = TechnicalDrawing(
+            source_kind="component",
+            source_id=comp.id,
+            views=[DrawingView(kind="front")],
+            auto_dimensions=True,
+        )
+        ann = _manual_annotation(
+            "length", "front", ((0.0, 0.0), (10.0, 0.0)), direction=(1.0, 0.0)
+        )
+        drawing.annotations.append(ann)
+
+        result = generate_drawing(drawing, project, kernel)
+        dim_keys = {p.candidate_key for p in result.primitives if p.candidate_key}
+        assert f"manual:{ann.id}" in dim_keys
+        assert any(k for k in dim_keys if not k.startswith("manual:"))
+    def test_diameter_manual_on_cylinder(self, kernel):
+        from OCP.BRepPrimAPI import BRepPrimAPI_MakeCylinder
+        from OCP.gp import gp_Ax2, gp_Dir, gp_Pnt
+
+        from fluency.geometry_occ.kernel import OCCGeometryObject
+
+        ax = gp_Ax2(gp_Pnt(0, 0, 0), gp_Dir(0, 0, 1))
+        cyl = OCCGeometryObject(
+            BRepPrimAPI_MakeCylinder(ax, 4.0, 8.0).Shape(),
+            {"type": "cylinder"},
+        )
+        body = Body(name="Cyl", geometry=cyl)
+        comp = Component(name="CylComp")
+        comp.bodies[body.id] = body
+        project = Project()
+        project.components[comp.id] = comp
+        project.active_component = comp.id
+
+        drawing = TechnicalDrawing(
+            source_kind="component",
+            source_id=comp.id,
+            views=[DrawingView(kind="front")],
+            auto_dimensions=False,
+        )
+        ann = _manual_annotation("diameter", "front", ((-4.0, 0.0), (4.0, 0.0)))
+        drawing.annotations.append(ann)
+
+        result = generate_drawing(drawing, project, kernel)
+        label_texts = [
+            p.text
+            for p in result.primitives
+            if p.candidate_key == f"manual:{ann.id}" and p.kind == "text"
+        ]
+        assert label_texts == ["Ø8.00"]
+
+
+# ── Circle centres: ISO center marks + centre-point dimensioning ──────────
+
+
+def _cylinder_project(kernel):
+    """One Ø8 x 8 cylinder (axis +Z) as a draw-able component.
+
+    HLR may split a circle's edge into sampled segments for some shapes,
+    so tests that need a guaranteed circle primitive build it directly
+    (see :class:`TestCircleCenterMarks` / :class:`TestCircleCenterPick`).
+    """
+    from OCP.BRepPrimAPI import BRepPrimAPI_MakeCylinder
+    from OCP.gp import gp_Ax2, gp_Dir, gp_Pnt
+
+    from fluency.geometry_occ.kernel import OCCGeometryObject
+
+    ax = gp_Ax2(gp_Pnt(0, 0, 0), gp_Dir(0, 0, 1))
+    cyl = OCCGeometryObject(
+        BRepPrimAPI_MakeCylinder(ax, 4.0, 8.0).Shape(),
+        {"type": "cylinder"},
+    )
+    body = Body(name="Cyl", geometry=cyl)
+    comp = Component(name="CylComp")
+    comp.bodies[body.id] = body
+    project = Project()
+    project.components[comp.id] = comp
+    project.active_component = comp.id
+    return project, comp
+
+
+class TestCircleCenterMarks:
+    """ISO 14128 center marks: a thin cross at each projected circle's
+    centre, crossing at the centre and extending past the circle edge."""
+
+    def test_center_marks_emitted_for_circles(self):
+        from fluency.technical_drawing import _assemble_view
+
+        # Synthetic view plane: a 20 × 16 box with a r4 circle at (10, 8).
+        edges = [
+            ((0.0, 0.0), (20.0, 0.0), "line", "visible"),
+            ((20.0, 0.0), (20.0, 16.0), "line", "visible"),
+            ((20.0, 16.0), (0.0, 16.0), "line", "visible"),
+            ((0.0, 16.0), (0.0, 0.0), "line", "visible"),
+            ((10.0, 8.0), (14.0, 8.0), "circle_full", "visible"),
+        ]
+        view = DrawingView(kind="top")
+        prims, _cands, _warns = _assemble_view(edges, [], view, (10, 10, 200, 150))
+        circles = [p for p in prims if p.kind == "circle"]
+        assert len(circles) == 1
+        c = circles[0]
+        cx, cy = c.center
+        marks = [p for p in prims if p.kind == "line" and p.style == "center"]
+        assert len(marks) == 2, "one horizontal and one vertical center mark"
+        horiz = next(p for p in marks if p.points[0][1] == p.points[1][1])
+        vert = next(p for p in marks if p.points[0][0] == p.points[1][0])
+        # The marks cross at the circle centre.
+        assert horiz.points[0][1] == cy and horiz.points[1][1] == cy
+        assert vert.points[0][0] == cx and vert.points[1][0] == cx
+        # And each extends past the circle edge.
+        half_h = abs(horiz.points[1][0] - horiz.points[0][0]) / 2.0
+        half_v = abs(vert.points[1][1] - vert.points[0][1]) / 2.0
+        assert half_h > c.radius
+        assert half_v > c.radius
+
+class TestCircleCenterAnchors:
+    """Distance picks between circle centres, and between a centre and an
+    edge, resolve to the right model-space anchor pair."""
+
+    def _w(self):
+        from fluency.ui.technical_drawing_widget import TechnicalDrawingWidget
+
+        return TechnicalDrawingWidget
+
+    def test_pick_point_kinds(self):
+        W = self._w()
+        assert W._pick_point({"kind": "point", "point": (1.0, 2.0)}) == (1.0, 2.0)
+        assert W._pick_point(
+            {"kind": "circle", "center": (3.0, 4.0), "radius": 1.0}
+        ) == (3.0, 4.0)
+        assert W._pick_point({"kind": "segment", "p1": (0, 0), "p2": (1, 1)}) is None
+
+    def test_center_to_center(self):
+        W = self._w()
+        a = {"kind": "circle", "view_id": "v", "center": (0.0, 0.0), "radius": 2.0}
+        b = {"kind": "circle", "view_id": "v", "center": (5.0, 12.0), "radius": 3.0}
+        p1, p2 = W._distance_anchors(a, b)
+        assert p1 == (0.0, 0.0)
+        assert p2 == (5.0, 12.0)
+
+    def test_center_to_edge(self):
+        W = self._w()
+        a = {"kind": "point", "view_id": "v", "point": (4.0, 6.0)}
+        b = {"kind": "segment", "view_id": "v", "p1": (0.0, 0.0), "p2": (10.0, 0.0)}
+        p1, p2 = W._distance_anchors(a, b)
+        assert p1 == (4.0, 6.0)
+        # Closest point on the edge is straight below the centre.
+        assert p2 == pytest.approx((4.0, 0.0))
+
+    def test_edge_to_edge_unchanged(self):
+        W = self._w()
+        a = {"kind": "segment", "view_id": "v", "p1": (0.0, 0.0), "p2": (10.0, 0.0)}
+        b = {"kind": "segment", "view_id": "v", "p1": (2.0, 5.0), "p2": (8.0, 5.0)}
+        p1, p2 = W._distance_anchors(a, b)
+        assert p1 == pytest.approx((2.0, 0.0))
+        assert p2 == pytest.approx((2.0, 5.0))
+
+
+# ── View layout: page fill, no overlaps, title-block clearance ───────────
+
+
+class TestViewLayout:
+    """_layout_views_on_sheet packs the views to fill the sheet, keeps
+    them apart and clear of the title block, and rotates individual
+    views when that makes the set fit more."""
+
+    A3W, A3H = 420.0, 297.0
+    # Title block box + 5 mm clearance zone (see _title_block_primitives).
+    TB = (235.0, 0.0, 420.0, 62.0)
+
+    @staticmethod
+    def _bbox(w, h):
+        return (0.0, 0.0, float(w), float(h))
+
+    def _layout(self, kinds, boxes):
+        views = [DrawingView(kind=k) for k in kinds]
+        return _layout_views_on_sheet(views, {k: boxes[k] for k in kinds})
+
+    def _assert_valid(self, slots):
+        for k, s in slots.items():
+            assert s[0] >= 10.0 - 1e-6 and s[1] >= 10.0 - 1e-6, (k, s)
+            assert s[0] + s[2] <= self.A3W - 10.0 + 1e-6, (k, s)
+            assert s[1] + s[3] <= self.A3H - 10.0 + 1e-6, (k, s)
+            x0, y0, w, h = s
+            x1, y1, w2, h2 = self.TB
+            assert x0 + w <= x1 or x1 + w2 <= x0 or y0 + h <= y1 or y1 + h2 <= y0, \
+                f"{k} intrudes title block: {s}"
+        ks = list(slots)
+        for i in range(len(ks)):
+            for j in range(i + 1, len(ks)):
+                a, b_ = slots[ks[i]], slots[ks[j]]
+                sep = (
+                    a[0] + a[2] <= b_[0] + 0.1 or b_[0] + b_[2] <= a[0] + 0.1
+                    or a[1] + a[3] <= b_[1] + 0.1 or b_[1] + b_[3] <= a[1] + 0.1
+                )
+                assert sep, f"{ks[i]} overlaps {ks[j]}: {a} / {b_}"
+
+    @staticmethod
+    def _fill(slots):
+        x0 = min(s[0] for s in slots.values())
+        y0 = min(s[1] for s in slots.values())
+        x1 = max(s[0] + s[2] for s in slots.values())
+        y1 = max(s[1] + s[3] for s in slots.values())
+        return (x1 - x0) * (y1 - y0) / (420.0 * 297.0)
+
+    def test_single_view_fills_page(self):
+        slots, scale, rots = self._layout(["front"], {"front": self._bbox(10, 20)})
+        self._assert_valid(slots)
+        # 1–2 views stay upright — no sideways single view.
+        assert rots == {"front": 0.0}
+        # The tall 10 × 20 view is scaled until it touches the full-height
+        # left strip's reduced height (0.8 × 277 mm).
+        assert scale == pytest.approx(221.6 / 20.0)
+        assert slots["front"][3] == pytest.approx(221.6)
+
+    def test_two_views_share_page(self):
+        slots, _scale, _rots = self._layout(
+            ["front", "top"],
+            {"front": self._bbox(40, 40), "top": self._bbox(40, 20)},
+        )
+        self._assert_valid(slots)
+        assert self._fill(slots) > 0.30
+
+    def test_classic_three_view_keeps_cross(self):
+        boxes = {k: self._bbox(40, 40) for k in ("front", "top", "right")}
+        slots, _scale, rots = self._layout(list(boxes), boxes)
+        self._assert_valid(slots)
+        assert set(rots.values()) == {0.0}, "classic cross must not rotate"
+        # Top sits directly above front; right directly to its right.
+        assert abs(slots["top"][0] - slots["front"][0]) < 1e-6
+        assert slots["top"][1] > slots["front"][1] + slots["front"][3]
+        assert slots["right"][0] > slots["front"][0] + slots["front"][2]
+        assert abs(slots["right"][1] - slots["front"][1]) < 1e-6
+
+    def test_thin_part_gets_rotated_views(self):
+        boxes = {
+            "front": self._bbox(200, 30),
+            "top": self._bbox(30, 50),
+            "right": self._bbox(50, 30),
+            "left": self._bbox(50, 30),
+            "back": self._bbox(200, 30),
+            "bottom": self._bbox(30, 50),
+        }
+        slots, scale, rots = self._layout(list(boxes), boxes)
+        self._assert_valid(slots)
+        assert any(r == 90.0 for r in rots.values()), "rotation must kick in"
+        # Each slot is the (possibly swapped) model size times the scale.
+        for k, s in slots.items():
+            w, h = boxes[k][2], boxes[k][3]
+            sw, sh = s[2] / scale, s[3] / scale
+            assert (
+                (sw == pytest.approx(w) and sh == pytest.approx(h))
+                or (sw == pytest.approx(h) and sh == pytest.approx(w))
+            ), (k, s, w, h)
+
+    def test_all_views_plus_isometric_fill_page(self):
+        boxes = {
+            "front": self._bbox(80, 40),
+            "top": self._bbox(80, 30),
+            "right": self._bbox(30, 40),
+            "left": self._bbox(30, 40),
+            "back": self._bbox(80, 40),
+            "bottom": self._bbox(80, 30),
+            "isometric": self._bbox(60, 60),
+        }
+        slots, _scale, _rots = self._layout(list(boxes), boxes)
+        self._assert_valid(slots)
+        assert self._fill(slots) > 0.55
+
+
+# ── Project drawing persistence ────────────────────────────────────────────
+
+
+def _drawing_with_manual_dim():
+    drawing = TechnicalDrawing(
+        source_kind="component",
+        source_id="comp-42",
+        views=[DrawingView(kind="front"), DrawingView(kind="top")],
+        auto_dimensions=True,
+        title="Persisted Drawing",
+        revision="B",
+    )
+    drawing.annotations.append(
+        _manual_annotation(
+            "length", "front", ((0.0, 0.0), (0.0, 12.5)), direction=(0.0, 1.0)
+        )
+    )
+    drawing.annotations.append(
+        _manual_annotation("diameter", "top", ((-5.0, 0.0), (5.0, 0.0)))
+    )
+    return drawing
+
+
+class TestDrawingPersistence:
+    def test_drawing_dict_roundtrip(self):
+        drawing = _drawing_with_manual_dim()
+        data = _technical_drawing_to_dict(drawing)
+        restored = _technical_drawing_from_dict(json.loads(json.dumps(data)))
+
+        assert restored.id == drawing.id
+        assert restored.source_kind == "component"
+        assert restored.source_id == "comp-42"
+        assert restored.auto_dimensions is True
+        assert [v.kind for v in restored.views] == ["front", "top"]
+        assert len(restored.annotations) == 2
+
+        a = restored.annotations[0]
+        assert a.dimension_kind == "length"
+        assert a.view_id == "front"
+        assert a.anchors == [(0.0, 0.0), (0.0, 12.5)]
+        assert a.direction == (0.0, 1.0)
+
+        b = restored.annotations[1]
+        assert b.dimension_kind == "diameter"
+        assert b.anchors == [(-5.0, 0.0), (5.0, 0.0)]
+
+    def test_project_drawings_lookup(self):
+        project = Project()
+        drawing = _drawing_with_manual_dim()
+        project.add_drawing(drawing)
+
+        assert project.get_drawing_for("component", "comp-42") is drawing
+        assert project.get_drawing_for("assembly", "comp-42") is None
+        assert project.get_drawing_for("component", "other") is None
+
+    def test_project_save_load_roundtrip(self, tmp_path):
+        project = Project(name="Drawing Project")
+        drawing = _drawing_with_manual_dim()
+        project.add_drawing(drawing)
+
+        path = save_project(project, str(tmp_path / "proj.fluency"))
+        loaded, _view_state = load_project(path)
+
+        assert len(loaded.drawings) == 1
+        restored = loaded.drawings[0]
+        assert restored.source_id == "comp-42"
+        assert restored.auto_dimensions is True
+        assert restored.title == "Persisted Drawing"
+        assert len(restored.annotations) == 2
+
+        a = restored.annotations[0]
+        assert a.dimension_kind == "length"
+        assert a.view_id == "front"
+        assert a.anchors == [(0.0, 0.0), (0.0, 12.5)]
+        assert a.direction == (0.0, 1.0)
+        assert a.id == drawing.annotations[0].id
+
+        # The restored drawing must still build the same candidates.
+        cands, resolved, unresolved = build_manual_candidates(
+            restored, {"front": (1.0, 0.0, 0.0), "top": (1.0, 0.0, 0.0)}
+        )
+        assert unresolved == []
+        labels = sorted(c.label for c in cands)
+        assert labels == ["12.50", "Ø10.00"]
+
+    def test_load_ignores_corrupt_drawing_entry(self, tmp_path):
+        import zipfile
+
+        project = Project(name="Mixed")
+        project.add_drawing(_drawing_with_manual_dim())
+        path = save_project(project, str(tmp_path / "proj.fluency"))
+
+        with zipfile.ZipFile(path, "r") as zf:
+            names = zf.namelist()
+            contents = {n: zf.read(n) for n in names}
+        manifest = json.loads(contents["project.json"])
+        manifest["drawings"].append({"id": "broken", "views": "not-a-list"})
+        contents["project.json"] = json.dumps(manifest).encode("utf-8")
+
+        with zipfile.ZipFile(path, "w") as zf:
+            for name in names:
+                zf.writestr(name, contents[name])
+
+        loaded, _ = load_project(path)
+        # Corrupt entry skipped, valid one kept.
+        assert len(loaded.drawings) == 1
+        assert loaded.drawings[0].source_id == "comp-42"
+
+    def test_auto_dimensions_default_off(self):
+        assert TechnicalDrawing().auto_dimensions is False
+
+
+# ── Pick geometry helpers ──────────────────────────────────────────────────
+
+
+class TestPickGeometry:
+    def test_point_to_segment_inside(self):
+        q, d = _point_to_segment((5.0, 3.0), (0.0, 0.0), (10.0, 0.0))
+        assert q == pytest.approx((5.0, 0.0))
+        assert d == pytest.approx(3.0)
+
+    def test_point_to_segment_clamps_at_endpoint(self):
+        q, d = _point_to_segment((-2.0, 1.0), (0.0, 0.0), (10.0, 0.0))
+        assert q == pytest.approx((0.0, 0.0))
+        assert d == pytest.approx(math.hypot(2.0, 1.0))
+
+    def test_crossing_segments(self):
+        q1, q2, d = _closest_points_on_segments(
+            (0.0, 0.0), (10.0, 0.0), (4.0, -2.0), (4.0, 8.0)
+        )
+        assert q1 == pytest.approx((4.0, 0.0))
+        assert q2 == pytest.approx((4.0, 0.0))
+        assert d == pytest.approx(0.0, abs=1e-9)
+
+    def test_parallel_overlapping_segments(self):
+        # The classic "distance between two parallel edges" pick:
+        # result must be the true perpendicular distance.
+        q1, q2, d = _closest_points_on_segments(
+            (0.0, 0.0), (10.0, 0.0), (2.0, 5.0), (8.0, 5.0)
+        )
+        assert d == pytest.approx(5.0)
+        assert q1[1] == pytest.approx(0.0)
+        assert q2[1] == pytest.approx(5.0)
+        assert q1[0] == pytest.approx(q2[0])
+
+    def test_parallel_disjoint_segments(self):
+        q1, q2, d = _closest_points_on_segments(
+            (0.0, 0.0), (2.0, 0.0), (5.0, 3.0), (7.0, 3.0)
+        )
+        assert d == pytest.approx(math.hypot(3.0, 3.0))
+
+    def test_line_intersection(self):
+        pt = _line_intersection(
+            (0.0, 0.0), (10.0, 0.0), (4.0, -2.0), (4.0, 8.0)
+        )
+        assert pt == pytest.approx((4.0, 0.0))
+
+    def test_line_intersection_parallel_is_none(self):
+        assert _line_intersection(
+            (0.0, 0.0), (10.0, 0.0), (2.0, 5.0), (8.0, 5.0)
+        ) is None
+
+    def test_closest_point_on_segment(self):
+        q = _closest_point_on_segment((4.0, 9.0), (0.0, 0.0), (10.0, 0.0))
+        assert q == pytest.approx((4.0, 0.0))
+
+
+# ── Widget: dimension tool plumbing (offscreen) ────────────────────────────
+
+
+class TestDrawingWidgetTools:
+    def _widget(self, qapp):
+        from fluency.ui.technical_drawing_widget import TechnicalDrawingWidget
+
+        return TechnicalDrawingWidget()
+
+    def test_widget_starts_without_pick_mode(self, qapp):
+        w = self._widget(qapp)
+        assert w._canvas._pick_mode == ""
+        assert not w._auto_dim_check.isChecked()
+        assert not any(b.isChecked() for b in w._tool_buttons.values())
+
+    def test_tool_toggle_enters_pick_mode(self, qapp):
+        w = self._widget(qapp)
+        btn = w._tool_buttons["distance"]
+        btn.setChecked(True)
+        assert w._canvas._pick_mode == "distance"
+        assert "Distance" in w._status_label.text()
+        assert "edge" in w._status_label.text()
+
+        # Switching tools re-targets the canvas and unchecks the old tool.
+        w._tool_buttons["diameter"].setChecked(True)
+        assert btn.isChecked() is False
+        assert w._canvas._pick_mode == "diameter"
+
+        # Escape path: cancels the tool, clears all buttons and mode.
+        w._cancel_pick()
+        assert w._canvas._pick_mode == ""
+        for other in w._tool_buttons.values():
+            assert not other.isChecked()
+
+    def test_add_manual_dimension_appends_and_emits(self, qapp):
+        w = self._widget(qapp)
+        w.set_drawing(
+            TechnicalDrawing(source_kind="component", source_id="c1")
+        )
+        changes = []
+        w.drawing_changed.connect(lambda: changes.append(1))
+
+        w._add_manual_dimension(
+            "length",
+            anchors=((0.0, 0.0), (10.0, 0.0)),
+            view_id="front",
+            direction=(1.0, 0.0),
+        )
+
+        anns = w._drawing.annotations
+        assert len(anns) == 1
+        assert anns[0].dimension_kind == "length"
+        assert anns[0].view_id == "front"
+        assert anns[0].anchors == [(0.0, 0.0), (10.0, 0.0)]
+        assert changes == [1]
+
+    def test_clear_removes_manual_dimensions_only(self, qapp):
+        w = self._widget(qapp)
+        drawing = TechnicalDrawing(source_kind="component", source_id="c1")
+        drawing.annotations.append(
+            DrawingAnnotation(kind="note", text="keep me")
+        )
+        drawing.annotations.append(
+            _manual_annotation(
+                "length", "front", ((0.0, 0.0), (5.0, 0.0))
+            )
+        )
+        w.set_drawing(drawing)
+
+        w._on_clear_clicked()
+
+        assert len(drawing.annotations) == 1
+        assert drawing.annotations[0].kind == "note"
+
+    def test_adopt_stored_project_drawing(self, qapp, kernel):
+        w = self._widget(qapp)
+        project = Project()
+        comp = Component(name="ExistingComp")
+        project.components[comp.id] = comp
+        stored = TechnicalDrawing(
+            source_kind="component", source_id=comp.id
+        )
+        stored.annotations.append(
+            _manual_annotation(
+                "diameter", "front", ((-4.0, 0.0), (4.0, 0.0))
+            )
+        )
+        project.add_drawing(stored)
+        w.set_project(project, kernel)
+
+        w.set_active_component(comp)
+
+        # The stored drawing is re-adopted (not replaced).
+        assert w._drawing is stored
+        assert len(w._drawing.annotations) == 1
+
+    def test_new_source_creates_and_registers_drawing(self, qapp, kernel):
+        w = self._widget(qapp)
+        project = Project()
+        comp = Component(name="NewComp")
+        project.components[comp.id] = comp
+        w.set_project(project, kernel)
+
+        w.set_active_component(comp)
+
+        assert w._drawing is not None
+        assert w._drawing.source_kind == "component"
+        assert w._drawing.source_id == comp.id
+        assert len(project.drawings) == 1
+        assert project.drawings[0] is w._drawing
+
+
+class TestCircleCenterPick:
+    """Clicking a circle's centre mark while a distance tool is active
+    picks a point feature at the circle centre (model coords + radius).
+
+    HLR only projects a true circle for some hole shapes (a plain
+    cylinder discretises into segments), so the render result is built
+    directly with one guaranteed circle primitive.
+    """
+
+    def _canvas_with_circle(self, qapp):
+        from PySide6.QtCore import QPointF
+
+        from fluency.technical_drawing import (
+            DrawingPrimitive,
+            DrawingRenderResult,
+        )
+        from fluency.ui.technical_drawing_widget import DrawingCanvas
+
+        # One r4 circle at model (20, 15), drawn at 10× scale at the
+        # sheet centre: model (20,15) → sheet (200, 150).
+        circle = DrawingPrimitive(
+            kind="circle",
+            points=(),
+            style="visible",
+            center=(200.0, 150.0),
+            radius=40.0,
+            view_id="top",
+        )
+        result = DrawingRenderResult(
+            primitives=(circle,),
+            candidates=(),
+            resolved_annotation_ids=(),
+            unresolved_annotation_ids=(),
+            source_fingerprint="",
+            warnings=(),
+            view_transforms={"top": (10.0, 0.0, 0.0)},
+        )
+        canvas = DrawingCanvas()
+        canvas.resize(840, 600)
+        canvas.set_render_result(result)
+        canvas.set_pick_mode("distance")
+        return canvas, QPointF
+
+    def test_pick_center_mark_returns_point(self, qapp):
+        canvas, QPointF = self._canvas_with_circle(qapp)
+        # Sheet → device position of the circle centre.
+        rect = canvas._sheet_rect()
+        scale = rect.width() / 420.0
+        pos = QPointF(rect.x() + 200.0 * scale, rect.y() + (297.0 - 150.0) * scale)
+
+        hit = canvas._pick_feature(pos)
+        assert hit is not None, "clicking the centre mark must hit something"
+        assert hit["kind"] == "point"
+        assert hit["view_id"] == "top"
+        assert hit["radius"] == pytest.approx(4.0, abs=1e-6)
+        # The picked model point is the inverse-transformed sheet centre:
+        # (200, 150) at 10× scale → (20, 15).
+        assert hit["point"] == pytest.approx((20.0, 15.0), abs=1e-9)
+
+    def test_distance_tool_accepts_center_then_edge(self, qapp, kernel):
+        from fluency.ui.technical_drawing_widget import TechnicalDrawingWidget
+
+        w = TechnicalDrawingWidget()
+        project, comp = _cylinder_project(kernel)
+        w.set_project(project, kernel)
+        w.set_active_component(comp)
+        assert w._drawing is not None
+
+        # First pick: a circle centre at model (10, 12) — the dict a
+        # centre-mark click produces (see test above).
+        w._first_pick = {
+            "kind": "point",
+            "view_id": "top",
+            "point": (10.0, 12.0),
+            "radius": 4.0,
+        }
+        # Second pick: a horizontal edge 6 mm above the centre.
+        second = {
+            "kind": "segment",
+            "view_id": "top",
+            "p1": (0.0, 18.0),
+            "p2": (20.0, 18.0),
+        }
+        w._on_edge_pick(second, "distance")
+        assert w._drawing.annotations, "a manual dimension must be appended"
+        ann = w._drawing.annotations[-1]
+        assert ann.dimension_kind == "length"
+        assert ann.view_id == "top"
+        # First anchor is the picked centre; the second is the closest
+        # point on the edge, straight above it.
+        assert ann.anchors[0] == pytest.approx((10.0, 12.0), abs=1e-9)
+        assert ann.anchors[1] == pytest.approx((10.0, 18.0), abs=1e-6)
+