feat(isogrid): Skip outer boundary in NX sketch import (subtract workflow)

Add DRAW_OUTER_BOUNDARY flag (default: False) to import_profile.py.

When False (default): only pocket profiles + holes are imported into the
sketch. This is the correct mode when subtracting rib pockets from an
existing solid body — the sandbox perimeter is not needed and would create
unwanted edges in the part.

When True: full profile including sandbox perimeter (original behavior,
for standalone plate creation only).

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

tools/adaptive-isogrid/src/nx/import_profile.py

@@ -39,6 +39,11 @@ SKETCH_NAME_PREFIX = "ISOGRID_RIB_"  # e.g., ISOGRID_RIB_sandbox_1
 EXTRUDE_NAME_PREFIX = "ISOGRID_EXTRUDE_"  # e.g., ISOGRID_EXTRUDE_sandbox_1
 DEFAULT_RIB_THICKNESS = 10.0  # mm, fallback if not in profile JSON
 
+# Set to False when importing into an existing solid body (subtract workflow).
+# The outer boundary is not needed — only the pocket profiles and holes.
+# Set to True only for standalone plate creation (no existing body).
+DRAW_OUTER_BOUNDARY = False
+
 
 # ---------------------------------------------------------------------------
 # Geometry helpers
@@ -841,9 +846,8 @@ def main():
         _clear_sketch_geometry(sketch, lister)
 
         # --- Draw geometry ---
-        # Strategy: draw outer boundary + pocket outlines (lines+arcs) + holes
+        # DRAW_OUTER_BOUNDARY = False: only pockets + holes (subtract from existing body)
-        # NX sketch regions: the rib web is the area BETWEEN outer boundary
+        # DRAW_OUTER_BOUNDARY = True:  full profile including sandbox perimeter
-        # and pocket/hole outlines. Extrude picks the rib material regions.
         pockets = profile.get("pockets", [])
         outer_2d = profile.get("outer_boundary", [])
 
@@ -852,15 +856,19 @@ def main():
                          and 'lines' in pockets[0])
 
         if is_structured:
-            lister.WriteLine(f"[import] Structured format: {len(pockets)} pockets + outer boundary")
+            lister.WriteLine(f"[import] Structured format: {len(pockets)} pockets"
+                             + (" + outer boundary" if DRAW_OUTER_BOUNDARY else " (no outer boundary)"))
 
-            # Outer boundary
+            # Outer boundary (only when creating standalone plate, not subtract workflow)
-            outer_lines, outer_arcs = _draw_outer_boundary(work_part, outer_2d, transform, lister)
+            total_lines = 0
-            lister.WriteLine(f"[import] Outer boundary: {outer_lines} lines + {outer_arcs} arcs")
+            total_arcs = 0
-
+            if DRAW_OUTER_BOUNDARY:
-            # Pocket outlines (the red lines: 3 lines + 3 arcs each)
+                outer_lines, outer_arcs = _draw_outer_boundary(work_part, outer_2d, transform, lister)
-            total_lines = outer_lines
+                total_lines = outer_lines
-            total_arcs = outer_arcs
+                total_arcs = outer_arcs
+                lister.WriteLine(f"[import] Outer boundary: {outer_lines} lines + {outer_arcs} arcs")
+            else:
+                lister.WriteLine(f"[import] Outer boundary skipped (DRAW_OUTER_BOUNDARY=False)")
             for idx, pocket in enumerate(pockets):
                 nl, na = _draw_structured_pocket(work_part, pocket, transform, lister)
                 total_lines += nl
@@ -899,8 +907,10 @@ def main():
         else:
             # Legacy format: pockets are point lists
             lister.WriteLine(f"[import] Legacy format: {len(pockets)} pocket polylines")
-            outer_lines, outer_arcs = _draw_outer_boundary(work_part, outer_2d, transform, lister)
+            total_lines = 0
-            total_lines = outer_lines
+            if DRAW_OUTER_BOUNDARY:
+                outer_lines, _ = _draw_outer_boundary(work_part, outer_2d, transform, lister)
+                total_lines = outer_lines
             for pocket_pts in pockets:
                 if len(pocket_pts) < 3:
                     continue