diff --git a/freecad/silo_commands.py b/freecad/silo_commands.py
index 8b8bc90..b5a0fb3 100644
--- a/freecad/silo_commands.py
+++ b/freecad/silo_commands.py
@@ -234,41 +234,45 @@ def get_projects_dir() -> Path:
 def get_cad_file_path(part_number: str, description: str = "") -> Path:
     """Generate canonical file path for a CAD file.
 
-    Path format: ~/projects/cad/{category_code}_{category_name}/{part_number}_{description}.FCStd
+    Path format: ~/projects/cad/{category_code}_{category_name}/{part_number}_{description}.kc
     """
     category, _ = parse_part_number(part_number)
     folder_name = get_category_folder_name(category)
 
     if description:
-        filename = f"{part_number}_{sanitize_filename(description)}.FCStd"
+        filename = f"{part_number}_{sanitize_filename(description)}.kc"
     else:
-        filename = f"{part_number}.FCStd"
+        filename = f"{part_number}.kc"
 
     return get_projects_dir() / "cad" / folder_name / filename
 
 
 def find_file_by_part_number(part_number: str) -> Optional[Path]:
-    """Find existing CAD file for a part number."""
+    """Find existing CAD file for a part number. Prefers .kc over .FCStd."""
     category, _ = parse_part_number(part_number)
     folder_name = get_category_folder_name(category)
     cad_dir = get_projects_dir() / "cad" / folder_name
 
-    if cad_dir.exists():
-        matches = list(cad_dir.glob(f"{part_number}*.FCStd"))
-        if matches:
-            return matches[0]
-
-    base_cad_dir = get_projects_dir() / "cad"
-    if base_cad_dir.exists():
-        for subdir in base_cad_dir.iterdir():
-            if subdir.is_dir():
-                matches = list(subdir.glob(f"{part_number}*.FCStd"))
-                if matches:
-                    return matches[0]
+    for search_dir in _search_dirs(cad_dir):
+        for ext in ("*.kc", "*.FCStd"):
+            matches = list(search_dir.glob(f"{part_number}{ext[1:]}"))
+            if matches:
+                return matches[0]
 
     return None
 
 
+def _search_dirs(category_dir: Path):
+    """Yield the category dir, then all sibling dirs under cad/."""
+    if category_dir.exists():
+        yield category_dir
+    base_cad_dir = category_dir.parent
+    if base_cad_dir.exists():
+        for subdir in base_cad_dir.iterdir():
+            if subdir.is_dir() and subdir != category_dir:
+                yield subdir
+
+
 def search_local_files(search_term: str = "", category_filter: str = "") -> list:
     """Search for CAD files in local cad directory."""
     results = []
@@ -288,7 +292,9 @@ def search_local_files(search_term: str = "", category_filter: str = "") -> list
         if category_filter and category_code.upper() != category_filter.upper():
             continue
 
-        for fcstd_file in category_dir.glob("*.FCStd"):
+        for fcstd_file in sorted(
+            list(category_dir.glob("*.kc")) + list(category_dir.glob("*.FCStd"))
+        ):
             filename = fcstd_file.stem
             parts = filename.split("_", 1)
             part_number = parts[0]