get_transforms

__init__.py

@@ -36,6 +36,7 @@ def register():
     print('Nodeslicer Loaded')
 
 def unregister():
+
     try:
         tree.cancel_timer()
     except Exception as e:

core/nodeslicer/nodes/mesh.py

@@ -72,6 +72,8 @@ class SLICENODE_JoinMesh(SliceNodeJoiner):
 class SLICENODE_JoinMeshGroups(SliceNodeJoiner):
     bl_label = "Join Mesh Groups"
     socket_type = "SLICESOCK_Mesh"
+    is_list_output = True
+    always_list_outputs = ["Mesh"]
 
     def init(self, context):
         self.add_output(self.output_socket_type or self.socket_type, display_shape='LIST')
@@ -221,6 +223,10 @@ class SLICENODE_SeparateMeshByRange(SliceNode):
         if inp is not None:
             set_socket_shape(inp, "LIST" if is_list else "CIRCLE")
 
+        attr_inp = self.inputs.get("Attribute") if hasattr(self, "inputs") else None
+        if attr_inp is not None:
+            set_socket_shape(attr_inp, "LIST" if is_socket_linked_to_list(attr_inp) else "CIRCLE")
+
         # Remove outputs that are no longer in the range
         to_remove = [o for o in self.outputs if o.identifier not in expected_ids]
         for o in to_remove:
@@ -229,7 +235,7 @@ class SLICENODE_SeparateMeshByRange(SliceNode):
         # Add new outputs
         for id_str in expected_ids:
             if id_str not in self.outputs:
-                self.add_output("SLICESOCK_Mesh", id_str, identifier=id_str, display_shape="LIST" if is_list else "")
+                self.add_output("SLICESOCK_Mesh", id_str, identifier=id_str, display_shape="LIST" if is_list else "CIRCLE")
             else:
                 set_socket_shape(self.outputs[id_str], "LIST" if is_list else "CIRCLE")
         
@@ -539,6 +545,10 @@ def _transform_geometry_item(geom: Any, t_arr: np.ndarray, r_arr: np.ndarray, s_
 
         copied_data.transforms = update_transform(getattr(geom, "transforms", []), t_arr, r_arr, s_arr)
         return copied_data
+    elif hasattr(geom, "location") and hasattr(geom, "rotation_euler") and hasattr(geom, "scale") and not hasattr(geom, "mesh"):
+        from ....infra.blender.blender_slice_nodes_generic import object_to_mesh
+        mesh_geom = object_to_mesh(geom, include_children=True)
+        return _transform_geometry_item(mesh_geom, t_arr, r_arr, s_arr)
     return geom
 
 
@@ -582,14 +592,40 @@ class SLICENODE_GetTransforms(SliceNode):
 
     def evaluate_output(self, socket_name: str, **_kwargs) -> Any:
         from ....core.slice import extract_geometry_transforms
-        default = (1.0, 1.0, 1.0) if socket_name == "Scale" else (0.0, 0.0, 0.0)
-        return self.eval_multivalue(
-            extract_geometry_transforms,
-            main_socket="Geometry",
-            secondary_sockets=[],
-            socket_name=socket_name,
-            default=default,
-        )
+        from ....infra.blender.list_utils import is_input_a_list
+
+        sock_lower = socket_name.lower()
+        default = (1.0, 1.0, 1.0) if sock_lower == "scale" else (0.0, 0.0, 0.0)
+        idx = 0 if sock_lower == "translation" else (1 if sock_lower == "rotation" else 2)
+
+        geom = self.resolve("Geometry")
+        if geom is None:
+            return default
+
+        is_list = is_input_a_list(geom, is_vector=False)
+        if not is_list and isinstance(geom, (list, tuple)):
+            if type(geom).__name__ != "SlicePaths" and not getattr(geom, "is_slice_paths", False):
+                is_list = True
+        elif not is_list and hasattr(geom, "__iter__") and not hasattr(geom, "shape") and not isinstance(geom, (str, bytes, dict, set)) and type(geom).__name__ != "SlicePaths" and not getattr(geom, "is_slice_paths", False) and not hasattr(geom, "mesh") and not hasattr(geom, "objects") and not hasattr(geom, "collections") and not hasattr(geom, "location"):
+            is_list = True
+
+        if is_list:
+            items = list(geom)
+            if len(items) == 0:
+                return []
+            results = []
+            for item in items:
+                trans = extract_geometry_transforms(item)
+                if isinstance(trans, tuple) and len(trans) > idx:
+                    results.append(trans[idx])
+                else:
+                    results.append(default)
+            return results
+        else:
+            trans = extract_geometry_transforms(geom)
+            if isinstance(trans, tuple) and len(trans) > idx:
+                return trans[idx]
+            return default
 
 
 @register_class

core/nodeslicer/nodes/path.py

@@ -104,6 +104,18 @@ def _slice_single_mesh_item(coll: Any, layer_height: float, fl_height: float | N
     else:
         z_values = np.array([], dtype=np.float64)
 
+    return _finish_slice_paths(merged_object, coll, objects, z_values, rotation, ignore_holes, fl_height, layer_height)
+
+def _finish_slice_paths(
+    merged_object: Any,
+    coll: Any,
+    objects: list[Any],
+    z_values: np.ndarray,
+    rotation: Any,
+    ignore_holes: bool,
+    fl_height: float | None,
+    layer_height: float,
+) -> SlicePaths:
     slices_group: list[list[np.ndarray]] | None = slice_at_range(
         [merged_object.mesh],
         z_values,
@@ -155,6 +167,7 @@ def _slice_single_mesh_item(coll: Any, layer_height: float, fl_height: float | N
             else:
                 break
 
+    has_rot = bool(rotation and any(rotation))
     if has_rot:
         from mathutils import Euler
         mat_inv = np.array(Euler(rotation).to_matrix())
@@ -163,6 +176,99 @@ def _slice_single_mesh_item(coll: Any, layer_height: float, fl_height: float | N
 
     return slices
 
+def _slice_single_mesh_item_with_layers(coll: Any, layers: Any, rotation: Any, ignore_holes: bool) -> SlicePaths:
+    if not coll or layers is None:
+        return SlicePaths()
+
+    # Handle SlicingGroup, SlicingCollection, SlicingObject
+    if isinstance(coll, SlicingGroup):
+        objects = []
+        for c in coll.collections.values():
+            objects.extend(c.objects)
+    elif isinstance(coll, SlicingCollection):
+        objects = list(coll.objects)
+    elif isinstance(coll, SlicingObject):
+        objects = [coll]
+    else:
+        objects = getattr(coll, "objects", [coll] if hasattr(coll, "mesh") else [])
+
+    merged_object = SlicingObject.merge(objects)
+    if merged_object.mesh is None or merged_object.mesh.size == 0:
+        return SlicePaths()
+
+    has_rot = bool(rotation and any(rotation))
+    if has_rot:
+        from mathutils import Euler
+        mat = np.array(Euler(rotation).to_matrix().inverted())
+        merged_object.mesh[:, :3, :] = merged_object.mesh[:, :3, :] @ mat.T
+        merged_object.mesh[:, 3:4, :] = merged_object.mesh[:, 3:4, :] @ mat.T
+
+    min_z = float(merged_object.mesh[:, :3, 2].min())
+    if abs(min_z) < 1e-6:
+        min_z = 0.0
+    max_z = float(merged_object.mesh[:, :3, 2].max())
+
+    min_z_um = int(round(min_z * 1000))
+    max_z_um = int(round(max_z * 1000))
+
+    raw_layers = layers if isinstance(layers, (list, tuple, np.ndarray)) else [layers]
+    valid_z: list[float] = []
+    for z in raw_layers:
+        try:
+            zf = float(z)
+            z_um = int(round(zf * 1000))
+            if min_z_um <= z_um <= max_z_um:
+                valid_z.append(zf)
+        except (ValueError, TypeError):
+            continue
+
+    if not valid_z:
+        return SlicePaths()
+
+    z_values = np.array(valid_z, dtype=np.float64)
+    fl_height = float(z_values[0]) if len(z_values) > 0 else None
+    layer_height = float(z_values[1] - z_values[0]) if len(z_values) > 1 else (fl_height or 0.2)
+
+    return _finish_slice_paths(merged_object, coll, objects, z_values, rotation, ignore_holes, fl_height, layer_height)
+
+@register_class
+class SLICENODE_Layers(SliceNode):
+    bl_label = "Layers"
+    is_list_output = True
+    always_list_outputs = ["Layers"]
+    list_socket_mapping = [("Layer Height", "Layers")]
+
+    def init(self, context):
+        self.add_input("NodeSocketFloat", "First Layer Height").value = 0.2
+        self.add_input("NodeSocketFloat", "Layer Height").value = 0.2
+        self.add_input("NodeSocketFloat", "Total Height").value = 250.0
+        self.add_output("NodeSocketFloat", "Layers", display_shape='LIST')
+
+    def evaluate_output(self, socket_name: str, **_kwargs) -> Any:
+        def _calc_layers(lh_val: Any, flh_val: Any, tot_val: Any) -> list[float]:
+            flh = float(flh_val) if flh_val is not None and float(flh_val) > 0 else 0.2
+            lh = float(lh_val) if lh_val is not None and float(lh_val) > 0 else 0.2
+            tot = float(tot_val) if tot_val is not None and float(tot_val) > 0 else 250.0
+
+            flh_um = max(1, int(round(flh * 1000)))
+            lh_um = max(1, int(round(lh * 1000)))
+            tot_um = int(round(tot * 1000))
+
+            layers: list[float] = []
+            z_um = flh_um
+            while z_um <= tot_um:
+                layers.append(z_um / 1000.0)
+                z_um += lh_um
+            return layers
+
+        return self.eval_multivalue(
+            _calc_layers,
+            main_socket="Layer Height",
+            secondary_sockets=["First Layer Height", "Total Height"],
+            socket_name=socket_name,
+            default=[],
+        )
+
 @register_class
 class SLICENODE_SliceShells(SliceNode):
     bl_label = "Slice Shells"
@@ -209,6 +315,52 @@ class SLICENODE_SliceShells(SliceNode):
             default=SlicePaths(),
         )
 
+@register_class
+class SLICENODE_SliceShellsLayers(SliceNode):
+    bl_label = "Slice Shells (Layers)"
+    always_list_inputs = ["Layers"]
+    list_socket_mapping = [("Mesh", "Paths")]
+
+    ignore_holes: bool = NfBoolProperty(
+        name="Ignore Holes",
+        description="Ignore interior hole boundaries and generate only outer shells",
+        default=False
+    )
+
+    def init(self, context):
+        self.add_input("SLICESOCK_Mesh")
+        self.add_input("NodeSocketFloat", "Layers", display_shape='LIST')
+        self.add_input("NodeSocketRotation", "Rotation")
+        self.add_output("SLICESOCK_Paths")
+
+    def draw_buttons(self, context, layout):
+        assert layout
+        if hasattr(self, "ignore_holes"):
+            layout.prop(self, "ignore_holes")
+
+    def evaluate_output(self, socket_name: str, **_kwargs) -> Any:
+        ignore_holes: bool = bool(getattr(self, "ignore_holes", False))
+        if hasattr(self, "inputs") and "Ignore Holes" in self.inputs:
+            try:
+                val = self.resolve("Ignore Holes")
+                if val is not None:
+                    ignore_holes = bool(val)
+            except Exception:
+                pass
+
+        def _slice_one(item: Any, layers_val: Any, rot_val: Any) -> SlicePaths:
+            return _slice_single_mesh_item_with_layers(item, layers_val, rot_val, ignore_holes)
+
+        return self.eval_multivalue(
+            _slice_one,
+            main_socket="Mesh",
+            secondary_sockets=["Layers", "Rotation"],
+            is_vector=[False, True],
+            is_atomic=[True, False],
+            socket_name=socket_name,
+            default=SlicePaths(),
+        )
+
 @register_class
 class SLICENODE_BufferShells(SliceNode):
     bl_label = "Buffer Shells"

core/nodeslicer/tree.py

@@ -369,8 +369,8 @@ def depsgraph_update_handler(scene, depsgraph):
     for tree in bpy.data.node_groups:
         if tree.bl_idname == "SLICETREE_NodeTree":
             try:
-                from ...infra.blender.list_utils import sync_group_tree_internal_sockets
-                sync_group_tree_internal_sockets(tree)
+                from ...infra.blender.list_utils import sync_tree_socket_shapes
+                sync_tree_socket_shapes(tree)
             except Exception:
                 pass
             for node in tree.nodes:
@@ -406,50 +406,19 @@ class SLICETREE_NodeTree(NodeTree):
     bl_use_group_interface = True
 
     def update(self):
-        super_update = getattr(super(), "update", None)
-        if callable(super_update):
-            try:
-                super_update()
-            except Exception:
-                pass
-        if _is_updating:
+        global _is_updating
+        if _is_updating or getattr(self, "_is_syncing_shapes", False):
             return
+        try:
+            self._is_syncing_shapes = True
+            from ...infra.blender.list_utils import sync_tree_socket_shapes
+            sync_tree_socket_shapes(self)
+        except Exception:
+            pass
+        finally:
+            self._is_syncing_shapes = False
         request_auto_refresh(self)
 
-    def valid_link(self, from_socket: Any, to_socket: Any) -> bool:
-        geom_sockets = {"SLICESOCK_Mesh", "SLICESOCK_Paths", "SLICESOCK_Geometry"}
-        out_s, in_s = from_socket, to_socket
-        if getattr(from_socket, "is_output", None) is False or getattr(to_socket, "is_output", None) is True:
-            out_s, in_s = to_socket, from_socket
-
-        is_obj_to_mesh = (
-            getattr(out_s, "bl_idname", "") in ("NodeSocketObject", "SLICESOCK_Object")
-            and getattr(in_s, "bl_idname", "") == "SLICESOCK_Mesh"
-        )
-
-        compatible = (
-            (out_s.bl_idname in geom_sockets and in_s.bl_idname in geom_sockets)
-            or out_s.bl_idname == in_s.bl_idname
-            or is_obj_to_mesh
-        )
-        if not compatible:
-            return False
-
-        from ...infra.blender.list_utils import is_output_socket_a_list, group_input_can_accept_list
-        if is_output_socket_a_list(out_s):
-            to_node = getattr(in_s, "node", None)
-            if to_node is not None:
-                # Start Print and Printer List reject lists
-                if to_node.bl_idname in ("SLICENODE_StartPrint", "SLICENODE_PrinterList"):
-                    return False
-                # Group node: check if input can accept list
-                if to_node.bl_idname == "SLICENODE_Group":
-                    tree = getattr(to_node, "slicer_tree", None) or getattr(to_node, "node_tree", None)
-                    if tree and not group_input_can_accept_list(tree, in_s):
-                        return False
-
-        return True
-
 
 @register_class
 class SLICENODE_OT_GroupToggle(Operator):
@@ -813,6 +782,7 @@ class SLICENODE_MT_DataInput(Menu):
         layout.operator("node.add_node", text="Integer").type = "SLICENODE_InputInt"
         layout.operator("node.add_node", text="Rotation").type = "SLICENODE_InputVectorRotation"
         layout.operator("node.add_node", text="Vector").type = "SLICENODE_InputVector"
+        layout.operator("node.add_node", text="Layers").type = "SLICENODE_Layers"
         layout.separator()
         layout.operator("node.add_node", text="Object").type = "SLICENODE_InputObject"
         layout.operator("node.add_node", text="Collection Objects").type = "SLICENODE_CollectionObjects"
@@ -840,7 +810,9 @@ class SLICENODE_MT_Geometry(Menu):
         layout.operator("node.add_node", text="Arrange Slicing Group").type = "SLICENODE_ArrangeMesh"
         layout.operator("node.add_node", text="Get Paths").type = "SLICENODE_GetPaths"
         layout.separator()
+        layout.operator("node.add_node", text="Layers").type = "SLICENODE_Layers"
         layout.operator("node.add_node", text="Slice Shells").type = "SLICENODE_SliceShells"
+        layout.operator("node.add_node", text="Slice Shells (Layers)").type = "SLICENODE_SliceShellsLayers"
         layout.operator("node.add_node", text="Seam Placement").type = "SLICENODE_SeamPlacement"
         layout.operator("node.add_node", text="Buffer Shells").type = "SLICENODE_BufferShells"
         layout.operator("node.add_node", text="Buffer Shells Multiple").type = "SLICENODE_BufferShellsMultiple"

core/slice.py

@@ -415,6 +415,13 @@ def extract_mesh_transforms(mesh_input: Any) -> list[dict[str, Any]]:
         for o in mesh_input.objects:
             if hasattr(o, "transforms") and o.transforms:
                 return [dict(t) for t in o.transforms if isinstance(t, dict)]
+    if hasattr(mesh_input, "location") and hasattr(mesh_input, "rotation_euler") and hasattr(mesh_input, "scale"):
+        return [{
+            "type": "INIT",
+            "translation": tuple(float(v) for v in mesh_input.location),
+            "rotation": tuple(float(v) for v in mesh_input.rotation_euler),
+            "scale": tuple(float(v) for v in mesh_input.scale),
+        }]
     if isinstance(mesh_input, list):
         for item in mesh_input:
             trans = extract_mesh_transforms(item)
@@ -425,15 +432,23 @@ def extract_mesh_transforms(mesh_input: Any) -> list[dict[str, Any]]:
 
 def extract_geometry_transforms(
     geom: Any
-) -> tuple[tuple[float, float, float], tuple[float, float, float], tuple[float, float, float]]:
+) -> tuple[tuple[float, float, float], tuple[float, float, float], tuple[float, float, float]] | list[Any]:
     """
     Extracts consolidated (translation, rotation, scale) from a geometry item
     (SlicePaths, SlicingObject, SlicingCollection, SlicingGroup, or Blender Object).
     Rotation is returned as Euler angles in radians (rx, ry, rz).
+    If geom is a list/tuple of geometry items (not a single SlicePaths),
+    returns a list of consolidated (translation, rotation, scale) tuples.
     """
     if geom is None:
         return (0.0, 0.0, 0.0), (0.0, 0.0, 0.0), (1.0, 1.0, 1.0)
 
+    # Check if geom is a list or tuple of geometry items (excluding SlicePaths)
+    if isinstance(geom, (list, tuple)) and type(geom).__name__ != "SlicePaths" and not getattr(geom, "is_slice_paths", False):
+        return [extract_geometry_transforms(item) for item in geom]
+    elif hasattr(geom, "__iter__") and not hasattr(geom, "shape") and not isinstance(geom, (str, bytes, dict, set)) and type(geom).__name__ != "SlicePaths" and not getattr(geom, "is_slice_paths", False) and not hasattr(geom, "mesh") and not hasattr(geom, "objects") and not hasattr(geom, "collections") and not hasattr(geom, "location"):
+        return [extract_geometry_transforms(item) for item in geom]
+
     transforms = extract_mesh_transforms(geom)
     if not transforms and hasattr(geom, "transforms") and isinstance(geom.transforms, list):
         transforms = [dict(t) for t in geom.transforms if isinstance(t, dict)]

doc/MODULES.md

@@ -46,6 +46,15 @@ This file provides a mapping of modules to their primary responsibilities and ke
 - `geometry.py`:
     - Geometry utility functions.
 
+## `/core/nodeslicer` (Node Definitions & Tree Infrastructure)
+
+- `tree.py`:
+    - `SLICETREE_NodeTree`: Custom node tree type for NodeSlicer nodes.
+
+- `nodes/path.py`:
+    - `SLICENODE_Layers`: Generates bounded list of layer slicing heights.
+    - `SLICENODE_SliceShellsLayers`: Slices meshes using an explicit list of layer heights for multi-object layer alignment.
+
 ## `/core/pdf_exporter` (PDF Export & Technical Marking Engine)
 
 - `sa2_measures.py`:
@@ -83,4 +92,4 @@ This file provides a mapping of modules to their primary responsibilities and ke
     - `eval_element_wise()`: Vectorized applicator executing operations element-wise on lists or directly on single items.
     - `prepare_indexed_inputs()`: Normalizes and matches secondary inputs index-per-index against the primary input, broadcasting single values or validating that list lengths match exactly (raising `ValueError` on mismatch).
     - `eval_element_wise_multivalue()`: General element-wise operator executing multi-argument operations with index matching and broadcasting.
-    - `set_socket_shape()` / `is_socket_linked_to_list()` / `is_output_socket_a_list()` / `sync_node_list_sockets()`: Dynamic socket visual appearance management (`LIST` vs `CIRCLE`).
+    - `set_socket_shape()` / `is_socket_linked_to_list()` / `is_output_socket_a_list()` / `sync_node_list_sockets()` / `sync_tree_socket_shapes()`: Dynamic socket visual appearance management (`LIST` vs `CIRCLE`) and tree-wide propagation.

doc/NODES.md

@@ -45,6 +45,7 @@ NodeSlicer supports generalized list processing across geometry, path, G-code, a
 - **Index-per-index Matching**: Secondary input sockets (such as translation vectors, rotations, scale vectors, drop Z coordinates, cutting meshes, rename templates, and parameters) also accept lists. When supplied with a list, secondary inputs are matched index-per-index with the main input list.
 - **Broadcasting**: If a secondary input receives a single value (or a list of length 1), that value is automatically broadcast across all elements of the main input list.
 - **Length Constraint**: It is mandatory that secondary input lists have either the exact same length as the main input list, or length 1. If lengths mismatch ($M \ne N$ and $M \ne 1$), or if a single main input receives a multi-item secondary list, a `ValueError` is raised with a descriptive error message.
+- **Consistent Socket Appearance**: Sockets representing lists display Blender's `LIST` shape, while single-value sockets display `CIRCLE`. Sockets adapt dynamically based on upstream connections (e.g. connecting a list output to `Mesh` dynamically converts `Mesh` input and downstream outputs to `LIST`), and dedicated list sockets (such as `Layers` output on the **Layers** node, `Layers` input on **Slice Shells (Layers)**, and list joiner outputs) consistently maintain `LIST` shape across link creations, deletions, and tree updates.
 
 ## Nodes
 
@@ -60,6 +61,11 @@ All nodes are found in the **Add (Shift+A)** menu under the **SliceNodes** categ
 - **Printer**: Printer name picker.
 - **Printer List**: List of configured printers.
 - **Printer Intrinsics**: Configures bed size, extrusion/travel rates, retraction distance & feedrate, and Z-lift.
+- **Layers**: Generates an ordered list of slicing heights (floats) bounded by the maximum build height.
+    - **First Layer Height**: Float value specifying the initial slicing height (defaults to `0.2` mm).
+    - **Layer Height**: Float value specifying the interval between successive layers (defaults to `0.2` mm).
+    - **Total Height**: Float value specifying the maximum build height to bound layer generation (defaults to `250.0` mm).
+    - **Layers**: Output socket delivering the list of layer Z heights `[first_layer, first_layer + layer_height, ...]`.
 
 ### Geometry Processing
 - **Get Mesh**: Converts a Blender Object into internal `SlicingObject` format.
@@ -94,6 +100,11 @@ All nodes are found in the **Add (Shift+A)** menu under the **SliceNodes** categ
     - **Extra Attributes**: Dictionary mapping mesh attribute names to custom G-code prefixes (e.g., `opening_size` -> `S`).
 - **Slice Shells**: Slices a `SlicingObject` into 2D `SlicePaths` at a given layer height. Automatically aligns path seams to the back (+Y) of each layer. Supports rotation for slicing at an angle.
     - **Ignore Holes**: Boolean option to omit interior hole perimeters and generate only the outer shell boundaries.
+- **Slice Shells (Layers)**: Slices a `SlicingObject` into 2D `SlicePaths` using an explicit list of layer heights rather than fixed layer intervals. This ensures multiple objects sliced separately align precisely at identical layer elevations. Automatically filters layers within the mesh's Z-bounds, aligns seams to the back (+Y), and supports rotation for slicing at an angle.
+    - **Mesh**: Input mesh data (`SlicingObject`, `SlicingCollection`, `SlicingGroup`, or lists).
+    - **Layers**: List of float numbers representing the slicing Z heights (e.g. from the **Layers** node).
+    - **Rotation**: 3D vector/Euler rotation values.
+    - **Ignore Holes**: Boolean option to omit interior hole perimeters and generate only outer shell boundaries.
 - **Seam Placement**: Repositions the starting vertex (seam) of closed slice paths (including outer contours and interior holes) to the intersection points between the slice paths and a guide/seam mesh. If there is no intersection for a given path, its seam remains unchanged. Agnostic to mesh input type (`SlicingObject`, `SlicingCollection`, `SlicingGroup`, or lists).
     - **Mesh**: Input cutting mesh socket.
     - **Seam Staggering**: Float input socket specifying a distance in millimeters to shift seams along the perimeter alternating layer-by-layer (+stagger on even layers, -stagger on odd layers) to avoid vertical seam alignment weak spots. Can also be used standalone without a cutting mesh.

infra/blender/blender_mesh_capture.py

@@ -117,7 +117,15 @@ class SlicingObject():
         self.name = str(obj.name) if obj else ""
         self.parent = parent
         self.attributes = {}
-        self.transforms = []
+        if obj and hasattr(obj, "location") and hasattr(obj, "rotation_euler") and hasattr(obj, "scale"):
+            self.transforms = [{
+                "type": "INIT",
+                "translation": tuple(float(v) for v in obj.location),
+                "rotation": tuple(float(v) for v in obj.rotation_euler),
+                "scale": tuple(float(v) for v in obj.scale),
+            }]
+        else:
+            self.transforms = []
         self.pdf_properties = PdfProperties()
         self.pdf_object_properties = []
 
@@ -250,7 +258,15 @@ class SlicingCollection():
         self.objects = [SlicingObject(obj, parent) for obj in objs]
         self.objects = [o for o in self.objects if o.mesh.size]
         self.name = parent
-        self.transforms = []
+        if objs and objs[0] and hasattr(objs[0], "location") and hasattr(objs[0], "rotation_euler") and hasattr(objs[0], "scale"):
+            self.transforms = [{
+                "type": "INIT",
+                "translation": tuple(float(v) for v in objs[0].location),
+                "rotation": tuple(float(v) for v in objs[0].rotation_euler),
+                "scale": tuple(float(v) for v in objs[0].scale),
+            }]
+        else:
+            self.transforms = []
 
     def _clear_cache(self):
         for prop in ["all_verts", "unique_verts"]:
@@ -373,7 +389,15 @@ class SlicingGroup():
     transforms: list[dict[str, Any]]
 
     def __init__(self, selected_objs: list[Object]) -> None:
-        self.transforms = []
+        if selected_objs and selected_objs[0] and hasattr(selected_objs[0], "location") and hasattr(selected_objs[0], "rotation_euler") and hasattr(selected_objs[0], "scale"):
+            self.transforms = [{
+                "type": "INIT",
+                "translation": tuple(float(v) for v in selected_objs[0].location),
+                "rotation": tuple(float(v) for v in selected_objs[0].rotation_euler),
+                "scale": tuple(float(v) for v in selected_objs[0].scale),
+            }]
+        else:
+            self.transforms = []
 
         family = []
         for obj in selected_objs:

infra/blender/blender_slice_nodes_generic.py

@@ -119,16 +119,17 @@ class SliceNode(Node, AutoBlIdName):
         return False
 
     list_socket_mapping: list[tuple[str, list[str] | str]] = []
+    always_list_inputs: list[str] = []
+    always_list_outputs: list[str] = []
+    is_list_output: bool = False
 
     def update(self) -> None: 
         self._update_multi_groups()
         self._sync_list_socket_shapes()
 
     def _sync_list_socket_shapes(self) -> None:
-        mapping = getattr(self, "list_socket_mapping", None)
-        if mapping:
-            from .list_utils import sync_node_list_sockets
-            sync_node_list_sockets(self, mapping)
+        from .list_utils import sync_node_list_sockets
+        sync_node_list_sockets(self, getattr(self, "list_socket_mapping", None))
 
     def evaluate_output(self, socket_name: str, **_kwargs) -> Any: ...
 
@@ -154,6 +155,7 @@ class SliceNode(Node, AutoBlIdName):
         socket_name: str | None = None,
         default: Any = None,
         is_vector: list[bool] | None = None,
+        is_atomic: list[bool] | None = None,
     ) -> Any:
         from .list_utils import eval_multivalue
         return eval_multivalue(
@@ -164,6 +166,7 @@ class SliceNode(Node, AutoBlIdName):
             socket_name=socket_name,
             default=default,
             is_vector=is_vector,
+            is_atomic=is_atomic,
         )
 
     def add_output(self, bl_idname: str, name: str = "", identifier: str = "", hide: bool = False, display_shape: str = "", description: str = ""):
@@ -171,6 +174,9 @@ class SliceNode(Node, AutoBlIdName):
         eval_name = name or NATIVE_SOCKET_LABELS.get(bl_idname) or get_label_by_name(bl_idname) or bl_idname
         sock = self.outputs.new(bl_idname, eval_name, identifier=identifier or eval_name)
         sock.hide = hide
+        if not display_shape:
+            if getattr(self, "is_list_output", False) or (getattr(self, "always_list_outputs", None) and eval_name in self.always_list_outputs):
+                display_shape = 'LIST'
         if display_shape:
             sock.display_shape = display_shape
         if description and hasattr(sock, "description"):
@@ -185,6 +191,9 @@ class SliceNode(Node, AutoBlIdName):
         eval_name = name or NATIVE_SOCKET_LABELS.get(bl_idname) or get_label_by_name(bl_idname) or bl_idname
         sock = self.inputs.new(bl_idname, eval_name, identifier=identifier or eval_name)
         sock.hide = hide
+        if not display_shape:
+            if getattr(self, "always_list_inputs", None) and eval_name in self.always_list_inputs:
+                display_shape = 'LIST'
         if display_shape:
             sock.display_shape = display_shape
         if description and hasattr(sock, "description"):

infra/blender/list_utils.py

@@ -36,6 +36,18 @@ def is_vector_value(val: Any) -> bool:
             return True
     return False
 
+def _is_sequence_collection(val: Any) -> bool:
+    if isinstance(val, (list, tuple)):
+        return True
+    if hasattr(val, "__iter__") and not hasattr(val, "shape") and not isinstance(val, (str, bytes, dict, set)):
+        cls_name = type(val).__name__
+        if "bpy_prop" in cls_name or "Collection" in cls_name or hasattr(val, "foreach_get"):
+            return True
+        import collections.abc
+        if isinstance(val, collections.abc.Sequence):
+            return True
+    return False
+
 def is_input_a_list(val: Any, is_vector: bool = False) -> bool:
     """Determines whether an input value represents a list of items.
     If is_vector is True, a single vector/rotation/color is treated as an atomic single value."""
@@ -46,8 +58,8 @@ def is_input_a_list(val: Any, is_vector: bool = False) -> bool:
     if is_vector:
         if is_vector_value(val):
             return False
-        return isinstance(val, (list, tuple))
-    return isinstance(val, (list, tuple))
+        return _is_sequence_collection(val)
+    return _is_sequence_collection(val)
 
 def is_list_data(val: Any) -> bool:
     """Checks if val represents a list of items (Object, Mesh, Path, Gcode).
@@ -74,12 +86,15 @@ def prepare_indexed_inputs(
     *secondary_inputs: Any,
     is_vector: list[bool] | None = None,
     input_names: list[str] | None = None,
+    is_atomic: list[bool] | None = None,
 ) -> tuple[bool, list[Any], list[list[Any]]]:
     """Prepares and validates main and secondary inputs according to the generalized list architecture:
     - Main input can be a list or a single item.
     - Secondary inputs that are lists must have either the same length as the main input, or be a single value (length 1 or non-list).
     - If a secondary input is a single value, it is broadcast across all elements of the main input.
     - If list lengths mismatch and length != 1, raises ValueError.
+    - If is_atomic is True for a secondary input, it is treated as a single atomic data value (e.g. layer height list)
+      unless it is explicitly a nested list matching the main input length.
     
     Returns:
         (is_main_list, main_items, broadcasted_secondary_lists)
@@ -89,13 +104,37 @@ def prepare_indexed_inputs(
     n = len(main_items)
 
     vec_flags = is_vector or [False] * len(secondary_inputs)
+    atom_flags = is_atomic or [False] * len(secondary_inputs)
     names = input_names or [f"input_{i+1}" for i in range(len(secondary_inputs))]
     broadcasted_secondaries: list[list[Any]] = []
 
     for i, sec_val in enumerate(secondary_inputs):
         is_vec = vec_flags[i] if i < len(vec_flags) else False
+        is_atom = atom_flags[i] if i < len(atom_flags) else False
         name = names[i] if i < len(names) else f"input_{i+1}"
 
+        if is_atom:
+            is_nested_list = (
+                isinstance(sec_val, (list, tuple))
+                and len(sec_val) > 0
+                and isinstance(sec_val[0], (list, tuple))
+            )
+            if not is_nested_list:
+                broadcasted_secondaries.append([sec_val] * n)
+            elif len(sec_val) == n:
+                broadcasted_secondaries.append(list(sec_val))
+            elif len(sec_val) == 1:
+                broadcasted_secondaries.append([sec_val[0]] * n)
+            else:
+                m = len(sec_val)
+                expected = "1 or a single value" if not main_is_list else f"{n} or 1"
+                main_desc = f"{n} items" if main_is_list else "a single item"
+                raise ValueError(
+                    f"Input list length mismatch: main input has {main_desc}, "
+                    f"but secondary input '{name}' has {m} items (must be {expected})."
+                )
+            continue
+
         if not is_input_a_list(sec_val, is_vector=is_vec):
             broadcasted_secondaries.append([sec_val] * n)
         elif len(sec_val) == n:
@@ -120,6 +159,7 @@ def eval_element_wise_multivalue(
     is_vector: list[bool] | None = None,
     input_names: list[str] | None = None,
     output_index: int | None = None,
+    is_atomic: list[bool] | None = None,
 ) -> Any:
     """Evaluates op_func element-wise with support for main and secondary list inputs:
     - If main_data is a list, returns a list of results.
@@ -134,6 +174,7 @@ def eval_element_wise_multivalue(
         *secondary_inputs,
         is_vector=is_vector,
         input_names=input_names,
+        is_atomic=is_atomic,
     )
 
     def _call(item: Any, i: int) -> Any:
@@ -179,6 +220,7 @@ def eval_multivalue(
     socket_name: str | None = None,
     default: Any = None,
     is_vector: list[bool] | None = None,
+    is_atomic: list[bool] | None = None,
 ) -> Any:
     """Generalized element-wise multi-value evaluator for SliceNode instances."""
     mapping = getattr(node, "list_socket_mapping", None)
@@ -197,14 +239,15 @@ def eval_multivalue(
     # Determine output index / socket validation
     output_index: int | None = None
     if socket_name is not None and mapping:
-        out_spec = next((outs for m_in, outs in mapping if m_in == main_socket), None)
+        out_spec = next((outs for m_in, outs in mapping if m_in.lower() == (main_socket or "").lower()), None)
         if out_spec is not None:
             if isinstance(out_spec, (list, tuple)):
-                if socket_name not in out_spec:
+                matched_idx = next((idx for idx, s in enumerate(out_spec) if s.lower() == socket_name.lower()), None)
+                if matched_idx is None:
                     return default
-                output_index = out_spec.index(socket_name)
+                output_index = matched_idx
             elif isinstance(out_spec, str) and out_spec:
-                if socket_name != out_spec:
+                if socket_name.lower() != out_spec.lower():
                     return default
 
     # Resolve main input
@@ -240,6 +283,7 @@ def eval_multivalue(
             is_vector=vec_flags,
             input_names=secondary_sockets,
             output_index=output_index,
+            is_atomic=is_atomic,
         )
     except Exception as e:
         from .blender_slice_nodes_generic import attach_node_failure_info
@@ -258,7 +302,8 @@ def set_socket_shape(sock: Any, shape: str) -> None:
     """Safely updates socket display_shape property ('LIST', 'CIRCLE', etc.)."""
     if sock is not None:
         try:
-            sock.display_shape = shape
+            if getattr(sock, "display_shape", "") != shape:
+                sock.display_shape = shape
         except (AttributeError, TypeError):
             pass
 
@@ -463,6 +508,29 @@ def is_internal_socket_a_list(group_node: Any, tree: Any, in_sock: Any, visited:
     if getattr(from_node, "is_list_output", False):
         return True
 
+    always_outs = getattr(from_node, "always_list_outputs", None)
+    if always_outs and getattr(from_sock, "name", "") in always_outs:
+        return True
+
+    if getattr(from_node, "bl_idname", "") in ("SLICENODE_FloatMath", "SLICENODE_IntMath"):
+        for inp in getattr(from_node, "inputs", []):
+            if is_internal_socket_a_list(group_node, tree, inp, visited):
+                return True
+        return False
+
+    if getattr(from_node, "bl_idname", "") == "SLICENODE_PathOperations":
+        inputs = getattr(from_node, "inputs", [])
+        if inputs:
+            return is_internal_socket_a_list(group_node, tree, inputs[0], visited)
+        return False
+
+    if getattr(from_node, "bl_idname", "") == "SLICENODE_SeparateMeshByRange":
+        inputs = getattr(from_node, "inputs", None)
+        mesh_inp = inputs.get("Mesh") if inputs else None
+        if mesh_inp:
+            return is_internal_socket_a_list(group_node, tree, mesh_inp, visited)
+        return False
+
     if getattr(from_node, "bl_idname", "") == "NodeGroupInput":
         in_item = _get_input_interface_item(tree, from_sock)
         if not in_item:
@@ -543,6 +611,29 @@ def is_group_output_a_list(
     if getattr(src_node, "is_list_output", False):
         return True
 
+    always_outs = getattr(src_node, "always_list_outputs", None)
+    if always_outs and getattr(src_sock, "name", "") in always_outs:
+        return True
+
+    if src_bl_id in ("SLICENODE_FloatMath", "SLICENODE_IntMath"):
+        for inp in getattr(src_node, "inputs", []):
+            if is_internal_socket_a_list(group_node, tree, inp, visited):
+                return True
+        return False
+
+    if src_bl_id == "SLICENODE_PathOperations":
+        inputs = getattr(src_node, "inputs", [])
+        if inputs:
+            return is_internal_socket_a_list(group_node, tree, inputs[0], visited)
+        return False
+
+    if src_bl_id == "SLICENODE_SeparateMeshByRange":
+        inputs = getattr(src_node, "inputs", None)
+        mesh_inp = inputs.get("Mesh") if inputs else None
+        if mesh_inp:
+            return is_internal_socket_a_list(group_node, tree, mesh_inp, visited)
+        return False
+
     if src_bl_id == "SLICENODE_JoinGcode":
         for inp in getattr(src_node, "inputs", []):
             if getattr(inp, "name", "") == "Gcode" or getattr(inp, "identifier", "").startswith("Gcode_ms_in_"):
@@ -634,6 +725,10 @@ def is_output_socket_a_list(sock: Any, visited: set | None = None) -> bool:
     if getattr(node, "is_list_output", False):
         return True
 
+    always_outs = getattr(node, "always_list_outputs", None)
+    if always_outs and getattr(sock, "name", "") in always_outs:
+        return True
+
     if bl_idname in ("SLICENODE_FloatMath", "SLICENODE_IntMath"):
         return any(is_socket_linked_to_list(inp) for inp in getattr(node, "inputs", []))
 
@@ -651,6 +746,15 @@ def is_output_socket_a_list(sock: Any, visited: set | None = None) -> bool:
             if getattr(inp, "name", "") == "Gcode" or getattr(inp, "identifier", "").startswith("Gcode_ms_in_")
         )
 
+    if bl_idname == "SLICENODE_PathOperations":
+        inputs = getattr(node, "inputs", None)
+        return is_socket_linked_to_list(inputs[0]) if inputs else False
+
+    if bl_idname == "SLICENODE_SeparateMeshByRange":
+        inputs = getattr(node, "inputs", None)
+        mesh_inp = inputs.get("Mesh") if inputs else None
+        return is_socket_linked_to_list(mesh_inp) if mesh_inp else False
+
     if bl_idname == "SLICENODE_Group":
         tree = getattr(node, "slicer_tree", None) or getattr(node, "node_tree", None)
         if tree:
@@ -683,31 +787,111 @@ def is_socket_linked_to_list(sock: Any) -> bool:
     from_socket = _follow_reroute_upstream(from_socket)
     return is_output_socket_a_list(from_socket)
 
-def sync_node_list_sockets(node: Any, mapping: list[tuple[str, list[str] | str]]) -> None:
-    """Updates display_shape on input and output sockets based on mapping.
-    Also updates display_shape for any secondary input sockets linked to a list.
-    mapping is a list of tuples: (input_socket_name, output_socket_names)
-    e.g. [('Paths', ['Paths']), ('Mesh', ['Selection', 'Inverted'])]
+def sync_node_list_sockets(node: Any, mapping: list[tuple[str, list[str] | str]] | None = None) -> None:
+    """Updates display_shape on input and output sockets based on mapping and node rules.
+    Ensures list inputs/outputs consistently display as 'LIST', and single values as 'CIRCLE'.
     """
+    if node is None:
+        return
+
+    bl_id = getattr(node, "bl_idname", "")
+    if bl_id == "NodeReroute":
+        return
+    if bl_id == "SLICENODE_Group":
+        sync_group_node_socket_shapes(node)
+        return
+
+    if mapping is None:
+        mapping = getattr(node, "list_socket_mapping", None) or []
+
+    always_in = set(getattr(node, "always_list_inputs", []) or [])
+    always_out = set(getattr(node, "always_list_outputs", []) or [])
+    is_list_out = bool(getattr(node, "is_list_output", False))
+
+    if bl_id in ("SLICENODE_FloatMath", "SLICENODE_IntMath"):
+        inputs = getattr(node, "inputs", [])
+        any_list = any(is_socket_linked_to_list(inp) for inp in inputs)
+        for inp in inputs:
+            set_socket_shape(inp, "LIST" if is_socket_linked_to_list(inp) else "CIRCLE")
+        for outp in getattr(node, "outputs", []):
+            set_socket_shape(outp, "LIST" if any_list else "CIRCLE")
+        return
+
+    if bl_id == "SLICENODE_JoinGcode":
+        inputs = getattr(node, "inputs", [])
+        has_list = any(
+            is_socket_linked_to_list(inp)
+            for inp in inputs
+            if getattr(inp, "name", "") == "Gcode" or getattr(inp, "identifier", "").startswith("Gcode_ms_in_")
+        )
+        for inp in inputs:
+            set_socket_shape(inp, "LIST" if is_socket_linked_to_list(inp) else "CIRCLE")
+        out_sock = getattr(node, "outputs", None) and node.outputs.get("Gcode")
+        if out_sock:
+            set_socket_shape(out_sock, "LIST" if has_list else "CIRCLE")
+        return
+
+    if bl_id == "SLICENODE_PathOperations":
+        inputs = getattr(node, "inputs", [])
+        first_is_list = is_socket_linked_to_list(inputs[0]) if inputs else False
+        for inp in inputs:
+            set_socket_shape(inp, "LIST" if is_socket_linked_to_list(inp) else "CIRCLE")
+        out_sock = getattr(node, "outputs", None) and (node.outputs.get("Paths") or (node.outputs[0] if node.outputs else None))
+        if out_sock:
+            set_socket_shape(out_sock, "LIST" if first_is_list else "CIRCLE")
+        return
+
+    if bl_id == "SLICENODE_SeparateMeshByRange":
+        if hasattr(node, "_update_outputs"):
+            node._update_outputs()
+        return
+
     mapped_inputs = set()
+    mapped_outputs = set()
+
     for in_name, out_names in mapping:
         mapped_inputs.add(in_name)
         inp = getattr(node, "inputs", None) and node.inputs.get(in_name)
         if inp is None:
             continue
-        is_list = is_socket_linked_to_list(inp)
-        set_socket_shape(inp, "LIST" if is_list else "CIRCLE")
+        in_is_list = (in_name in always_in) or is_socket_linked_to_list(inp)
+        set_socket_shape(inp, "LIST" if in_is_list else "CIRCLE")
 
         if isinstance(out_names, str):
             targets = [out_names]
         else:
             targets = list(out_names)
         for out_name in targets:
+            mapped_outputs.add(out_name)
             out_sock = getattr(node, "outputs", None) and node.outputs.get(out_name)
             if out_sock is not None:
-                set_socket_shape(out_sock, "LIST" if is_list else "CIRCLE")
+                out_is_list = is_list_out or (out_name in always_out) or in_is_list
+                set_socket_shape(out_sock, "LIST" if out_is_list else "CIRCLE")
 
     for inp in getattr(node, "inputs", []):
-        if getattr(inp, "name", "") not in mapped_inputs:
-            is_list = is_socket_linked_to_list(inp)
-            set_socket_shape(inp, "LIST" if is_list else "CIRCLE")
+        inp_name = getattr(inp, "name", "")
+        if inp_name not in mapped_inputs:
+            in_is_list = (inp_name in always_in) or is_socket_linked_to_list(inp)
+            set_socket_shape(inp, "LIST" if in_is_list else "CIRCLE")
+
+    for outp in getattr(node, "outputs", []):
+        outp_name = getattr(outp, "name", "")
+        if outp_name not in mapped_outputs:
+            out_is_list = is_list_out or (outp_name in always_out)
+            set_socket_shape(outp, "LIST" if out_is_list else "CIRCLE")
+
+
+def sync_tree_socket_shapes(tree: Any) -> None:
+    """Updates display_shape ('LIST' vs 'CIRCLE') consistently across all nodes in the tree."""
+    if not tree or not hasattr(tree, "nodes"):
+        return
+
+    sync_group_tree_internal_sockets(tree)
+
+    for _ in range(2):
+        for node in tree.nodes:
+            bl_id = getattr(node, "bl_idname", "")
+            if bl_id in ("NodeReroute", "NodeGroupInput", "NodeGroupOutput"):
+                continue
+            sync_node_list_sockets(node)
+

tests/test_layers.py

@@ -0,0 +1,379 @@
+import sys
+from pathlib import Path
+import unittest
+from unittest.mock import MagicMock
+import numpy as np
+
+# Add workspace directory to sys.path to resolve root package name (NodeSlicer)
+PROJECT_ROOT = Path(__file__).resolve().parent.parent
+if str(PROJECT_ROOT.parent) not in sys.path:
+    sys.path.append(str(PROJECT_ROOT.parent))
+
+class DummyNodeSocket: pass
+class DummyNode: pass
+class DummyObject: pass
+class DummyMesh: pass
+class DummyNodeSocketShader: pass
+class DummyNodeCustomGroup: pass
+class DummyNodeTree: pass
+class DummyOperator: pass
+class DummyMenu: pass
+class DummyPanel: pass
+class DummyPropertyGroup: pass
+
+mock_types = MagicMock()
+mock_types.NodeSocket = DummyNodeSocket
+mock_types.Node = DummyNode
+mock_types.Object = DummyObject
+mock_types.Mesh = DummyMesh
+mock_types.NodeSocketShader = DummyNodeSocketShader
+mock_types.NodeCustomGroup = DummyNodeCustomGroup
+mock_types.NodeTree = DummyNodeTree
+mock_types.Operator = DummyOperator
+mock_types.Menu = DummyMenu
+mock_types.Panel = DummyPanel
+mock_types.PropertyGroup = DummyPropertyGroup
+
+mock_bpy = MagicMock()
+mock_bpy.context.scene = MagicMock()
+mock_bpy.context.scene.unit_settings.scale_length = 0.001
+mock_bpy.types = mock_types
+
+sys.modules['bpy'] = mock_bpy
+sys.modules['bpy.types'] = mock_types
+sys.modules['bpy.props'] = MagicMock()
+sys.modules['bpy.utils'] = MagicMock()
+sys.modules['bpy.utils.previews'] = MagicMock()
+sys.modules['bpy.app'] = MagicMock()
+sys.modules['bpy.app.handlers'] = MagicMock()
+
+from NodeSlicer.core.slice import SlicePaths
+from NodeSlicer.infra.blender.blender_mesh_capture import SlicingObject
+from NodeSlicer.core.nodeslicer.nodes.path import SLICENODE_Layers, SLICENODE_SliceShellsLayers
+
+
+def _make_box_mesh(z_min: float = 0.0, z_max: float = 1.0) -> SlicingObject:
+    """Helper to create a box mesh between z_min and z_max."""
+    vertices = np.array([
+        [0.0, 0.0, z_min],
+        [10.0, 0.0, z_min],
+        [10.0, 10.0, z_min],
+        [0.0, 10.0, z_min],
+        [0.0, 0.0, z_max],
+        [10.0, 0.0, z_max],
+        [10.0, 10.0, z_max],
+        [0.0, 10.0, z_max],
+    ], dtype=np.float64)
+
+    faces = [
+        [0, 1, 2], [0, 2, 3],  # Bottom
+        [4, 6, 5], [4, 7, 6],  # Top
+        [0, 4, 5], [0, 5, 1],  # Front
+        [2, 6, 7], [2, 7, 3],  # Back
+        [0, 3, 7], [0, 7, 4],  # Left
+        [1, 5, 6], [1, 6, 2],  # Right
+    ]
+
+    triangles = np.zeros((len(faces), 3, 3), dtype=np.float64)
+    for i, face in enumerate(faces):
+        triangles[i, 0] = vertices[face[0]]
+        triangles[i, 1] = vertices[face[1]]
+        triangles[i, 2] = vertices[face[2]]
+
+    sobj = SlicingObject()
+    sobj.name = "TestBox"
+    sobj.mesh = triangles
+    return sobj
+
+
+class TestLayersNode(unittest.TestCase):
+    def test_layers_generation_single(self):
+        node = SLICENODE_Layers()
+        node.resolve = lambda name: 0.2 if name == "First Layer Height" else (0.2 if name == "Layer Height" else (1.0 if name == "Total Height" else None))
+        res = node.evaluate_output("Layers")
+        self.assertEqual(res, [0.2, 0.4, 0.6, 0.8, 1.0])
+
+    def test_layers_different_flh(self):
+        node = SLICENODE_Layers()
+        node.resolve = lambda name: 0.3 if name == "First Layer Height" else (0.2 if name == "Layer Height" else (0.8 if name == "Total Height" else None))
+        res = node.evaluate_output("Layers")
+        self.assertEqual(res, [0.3, 0.5, 0.7])
+
+    def test_layers_list_layer_height(self):
+        node = SLICENODE_Layers()
+        # Layer Height is a list of two values
+        node.resolve = lambda name: 0.2 if name == "First Layer Height" else ([0.2, 0.5] if name == "Layer Height" else (1.0 if name == "Total Height" else None))
+        res = node.evaluate_output("Layers")
+        self.assertIsInstance(res, list)
+        self.assertEqual(len(res), 2)
+        self.assertEqual(res[0], [0.2, 0.4, 0.6, 0.8, 1.0])
+        self.assertEqual(res[1], [0.2, 0.7])
+
+
+class TestSliceShellsLayersNode(unittest.TestCase):
+    def test_slice_shells_layers_single_mesh(self):
+        box = _make_box_mesh(z_min=0.0, z_max=1.0)
+        node = SLICENODE_SliceShellsLayers()
+        layers = [0.2, 0.4, 0.6, 0.8, 1.0, 1.2, 1.4]  # Has layers above box
+        node.resolve = lambda name: box if name == "Mesh" else (layers if name == "Layers" else None)
+
+        slices = node.evaluate_output("Paths")
+        self.assertIsInstance(slices, SlicePaths)
+        # Should only slice in box range 0.0 .. 1.0
+        self.assertEqual(len(slices), 5)
+        np.testing.assert_allclose([s[0, 2] for s in slices], [0.2, 0.4, 0.6, 0.8, 1.0])
+
+    def test_slice_shells_layers_multi_mesh(self):
+        box1 = _make_box_mesh(z_min=0.0, z_max=0.5)
+        box2 = _make_box_mesh(z_min=0.0, z_max=1.0)
+        node = SLICENODE_SliceShellsLayers()
+        layers = [0.2, 0.4, 0.6, 0.8, 1.0]
+
+        # Multi-mesh with single layer plan
+        node.resolve = lambda name: [box1, box2] if name == "Mesh" else (layers if name == "Layers" else None)
+
+        slices_list = node.evaluate_output("Paths")
+        self.assertIsInstance(slices_list, list)
+        self.assertEqual(len(slices_list), 2)
+        # Box1 has layers up to 0.5 -> 0.2, 0.4 (2 layers)
+        self.assertEqual(len(slices_list[0]), 2)
+        np.testing.assert_allclose([s[0, 2] for s in slices_list[0]], [0.2, 0.4])
+        # Box2 has layers up to 1.0 -> 0.2, 0.4, 0.6, 0.8, 1.0 (5 layers)
+        self.assertEqual(len(slices_list[1]), 5)
+        np.testing.assert_allclose([s[0, 2] for s in slices_list[1]], [0.2, 0.4, 0.6, 0.8, 1.0])
+
+
+class DummySock:
+    def __init__(self, name="Socket", bl_idname="NodeSocketFloat", display_shape="CIRCLE"):
+        self.name = name
+        self.identifier = name
+        self.bl_idname = bl_idname
+        self.display_shape = display_shape
+        self.is_linked = False
+        self.links = []
+        self.node = None
+        self.is_output = False
+
+
+class DummyLink:
+    def __init__(self, from_sock, to_sock):
+        self.from_socket = from_sock
+        self.to_socket = to_sock
+        self.from_node = getattr(from_sock, "node", None)
+        self.to_node = getattr(to_sock, "node", None)
+
+
+class DummySocketCollection(list):
+    def get(self, name, default=None):
+        for s in self:
+            if getattr(s, "name", None) == name or getattr(s, "identifier", None) == name:
+                return s
+        return default
+
+
+class DummyNodeContainer:
+    def __init__(self, bl_idname="SliceNode"):
+        self.bl_idname = bl_idname
+        self.name = bl_idname
+        self.inputs = DummySocketCollection()
+        self.outputs = DummySocketCollection()
+        self.list_socket_mapping = []
+        self.always_list_inputs = []
+        self.always_list_outputs = []
+        self.is_list_output = False
+
+    def add_in(self, sock):
+        sock.node = self
+        sock.is_output = False
+        self.inputs.append(sock)
+
+    def add_out(self, sock):
+        sock.node = self
+        sock.is_output = True
+        self.outputs.append(sock)
+
+
+class TestConsistentSocketAppearance(unittest.TestCase):
+    def test_layers_node_output_always_list(self):
+        from NodeSlicer.infra.blender.list_utils import sync_node_list_sockets, is_output_socket_a_list
+
+        node = DummyNodeContainer("SLICENODE_Layers")
+        node.is_list_output = True
+        node.always_list_outputs = ["Layers"]
+        node.list_socket_mapping = [("Layer Height", "Layers")]
+
+        in_flh = DummySock("First Layer Height", "NodeSocketFloat", "CIRCLE")
+        in_lh = DummySock("Layer Height", "NodeSocketFloat", "CIRCLE")
+        in_tot = DummySock("Total Height", "NodeSocketFloat", "CIRCLE")
+        out_layers = DummySock("Layers", "NodeSocketFloat", "LIST")
+
+        node.add_in(in_flh)
+        node.add_in(in_lh)
+        node.add_in(in_tot)
+        node.add_out(out_layers)
+
+        # Sync with unlinked inputs
+        sync_node_list_sockets(node)
+        self.assertEqual(out_layers.display_shape, "LIST")
+        self.assertTrue(is_output_socket_a_list(out_layers))
+        self.assertEqual(in_lh.display_shape, "CIRCLE")
+
+        # When Layer Height is linked to a list
+        upstream_list = DummySock("ListOut", "NodeSocketFloat", "LIST")
+        link = DummyLink(upstream_list, in_lh)
+        in_lh.is_linked = True
+        in_lh.links = [link]
+
+        sync_node_list_sockets(node)
+        self.assertEqual(in_lh.display_shape, "LIST")
+        self.assertEqual(out_layers.display_shape, "LIST")
+
+    def test_slice_shells_layers_socket_shapes(self):
+        from NodeSlicer.infra.blender.list_utils import sync_node_list_sockets
+
+        node = DummyNodeContainer("SLICENODE_SliceShellsLayers")
+        node.always_list_inputs = ["Layers"]
+        node.list_socket_mapping = [("Mesh", "Paths")]
+
+        in_mesh = DummySock("Mesh", "SLICESOCK_Mesh", "CIRCLE")
+        in_layers = DummySock("Layers", "NodeSocketFloat", "LIST")
+        in_rot = DummySock("Rotation", "NodeSocketRotation", "CIRCLE")
+        out_paths = DummySock("Paths", "SLICESOCK_Paths", "CIRCLE")
+
+        node.add_in(in_mesh)
+        node.add_in(in_layers)
+        node.add_in(in_rot)
+        node.add_out(out_paths)
+
+        # Before linking: Layers is LIST, Mesh/Paths/Rotation are CIRCLE
+        sync_node_list_sockets(node)
+        self.assertEqual(in_layers.display_shape, "LIST")
+        self.assertEqual(in_mesh.display_shape, "CIRCLE")
+        self.assertEqual(out_paths.display_shape, "CIRCLE")
+        self.assertEqual(in_rot.display_shape, "CIRCLE")
+
+        # Link Mesh to a list output
+        mesh_list_out = DummySock("Meshes", "SLICESOCK_Mesh", "LIST")
+        link_mesh = DummyLink(mesh_list_out, in_mesh)
+        in_mesh.is_linked = True
+        in_mesh.links = [link_mesh]
+
+        sync_node_list_sockets(node)
+        self.assertEqual(in_layers.display_shape, "LIST")
+        self.assertEqual(in_mesh.display_shape, "LIST")
+        self.assertEqual(out_paths.display_shape, "LIST")
+        self.assertEqual(in_rot.display_shape, "CIRCLE")
+
+        # Link Rotation to a list output
+        rot_list_out = DummySock("Rotations", "NodeSocketRotation", "LIST")
+        link_rot = DummyLink(rot_list_out, in_rot)
+        in_rot.is_linked = True
+        in_rot.links = [link_rot]
+
+        sync_node_list_sockets(node)
+        self.assertEqual(in_rot.display_shape, "LIST")
+
+        # Disconnect Mesh list: should revert Mesh and Paths back to CIRCLE, Layers stays LIST
+        in_mesh.is_linked = False
+        in_mesh.links = []
+
+        sync_node_list_sockets(node)
+        self.assertEqual(in_layers.display_shape, "LIST")
+        self.assertEqual(in_mesh.display_shape, "CIRCLE")
+        self.assertEqual(out_paths.display_shape, "CIRCLE")
+
+    def test_get_transforms_socket_shapes(self):
+        from NodeSlicer.infra.blender.list_utils import sync_node_list_sockets
+
+        node = DummyNodeContainer("SLICENODE_GetTransforms")
+        node.list_socket_mapping = [("Geometry", ["Translation", "Rotation", "Scale"])]
+
+        in_geom = DummySock("Geometry", "SLICESOCK_Geometry", "CIRCLE")
+        out_t = DummySock("Translation", "NodeSocketVector", "CIRCLE")
+        out_r = DummySock("Rotation", "NodeSocketRotation", "CIRCLE")
+        out_s = DummySock("Scale", "NodeSocketVector", "CIRCLE")
+
+        node.add_in(in_geom)
+        node.add_out(out_t)
+        node.add_out(out_r)
+        node.add_out(out_s)
+
+        # Unlinked -> all CIRCLE
+        sync_node_list_sockets(node)
+        self.assertEqual(in_geom.display_shape, "CIRCLE")
+        self.assertEqual(out_t.display_shape, "CIRCLE")
+        self.assertEqual(out_r.display_shape, "CIRCLE")
+        self.assertEqual(out_s.display_shape, "CIRCLE")
+
+        # Linked to list -> all 3 outputs become LIST
+        geom_list_out = DummySock("Geometry", "SLICESOCK_Geometry", "LIST")
+        link = DummyLink(geom_list_out, in_geom)
+        in_geom.is_linked = True
+        in_geom.links = [link]
+
+        sync_node_list_sockets(node)
+        self.assertEqual(in_geom.display_shape, "LIST")
+        self.assertEqual(out_t.display_shape, "LIST")
+        self.assertEqual(out_r.display_shape, "LIST")
+        self.assertEqual(out_s.display_shape, "LIST")
+
+    def test_sync_tree_socket_shapes_propagation(self):
+        from NodeSlicer.infra.blender.list_utils import sync_tree_socket_shapes
+
+        # Chain: NodeA (List Output) -> NodeB (GetMesh) -> NodeC (SliceShells)
+        node_a = DummyNodeContainer("SLICENODE_ObjectsToList")
+        node_a.is_list_output = True
+        node_a.always_list_outputs = ["Objects"]
+        out_a = DummySock("Objects", "NodeSocketObject", "LIST")
+        node_a.add_out(out_a)
+
+        node_b = DummyNodeContainer("SLICENODE_GetMesh")
+        node_b.list_socket_mapping = [("Object", "Mesh")]
+        in_b = DummySock("Object", "NodeSocketObject", "CIRCLE")
+        out_b = DummySock("Mesh", "SLICESOCK_Mesh", "CIRCLE")
+        node_b.add_in(in_b)
+        node_b.add_out(out_b)
+
+        node_c = DummyNodeContainer("SLICENODE_SliceShells")
+        node_c.list_socket_mapping = [("Mesh", "Paths")]
+        in_c = DummySock("Mesh", "SLICESOCK_Mesh", "CIRCLE")
+        out_c = DummySock("Paths", "SLICESOCK_Paths", "CIRCLE")
+        node_c.add_in(in_c)
+        node_c.add_out(out_c)
+
+        # Link A -> B and B -> C
+        link_ab = DummyLink(out_a, in_b)
+        in_b.is_linked = True
+        in_b.links = [link_ab]
+
+        link_bc = DummyLink(out_b, in_c)
+        in_c.is_linked = True
+        in_c.links = [link_bc]
+
+        tree = type("DummyTree", (), {})()
+        tree.nodes = [node_a, node_b, node_c]
+
+        sync_tree_socket_shapes(tree)
+
+        # Both B and C should have LIST shapes
+        self.assertEqual(out_a.display_shape, "LIST")
+        self.assertEqual(in_b.display_shape, "LIST")
+        self.assertEqual(out_b.display_shape, "LIST")
+        self.assertEqual(in_c.display_shape, "LIST")
+        self.assertEqual(out_c.display_shape, "LIST")
+
+        # Disconnect A -> B: everything down the chain should revert to CIRCLE
+        in_b.is_linked = False
+        in_b.links = []
+
+        sync_tree_socket_shapes(tree)
+
+        self.assertEqual(out_a.display_shape, "LIST")
+        self.assertEqual(in_b.display_shape, "CIRCLE")
+        self.assertEqual(out_b.display_shape, "CIRCLE")
+        self.assertEqual(in_c.display_shape, "CIRCLE")
+        self.assertEqual(out_c.display_shape, "CIRCLE")
+
+
+if __name__ == "__main__":
+    unittest.main()

tests/test_lists.py

@@ -58,7 +58,6 @@ from NodeSlicer.infra.blender.list_utils import (
 )
 from NodeSlicer.core.slice import SlicePaths
 from NodeSlicer.infra.blender.blender_mesh_capture import SlicingObject, SlicingCollection, SlicingGroup
-from NodeSlicer.core.nodeslicer.tree import SLICETREE_NodeTree
 
 
 class TestListUtils(unittest.TestCase):
@@ -185,56 +184,6 @@ class TestSocketShapesAndLinks(unittest.TestCase):
         self.assertEqual(out_path.display_shape, "LIST")
 
 
-class TestTreeValidLinkRules(unittest.TestCase):
-    def setUp(self):
-        self.tree = SLICETREE_NodeTree()
-
-    def test_valid_link_start_print_rejects_list(self):
-        list_out = DummySocket("Gcode", "NodeSocketString", display_shape="LIST")
-        start_print = DummyNode("SLICENODE_StartPrint")
-        sp_in = DummySocket("Gcode", "NodeSocketString")
-        start_print.add_in(sp_in)
-
-        # Connection should be rejected
-        self.assertFalse(self.tree.valid_link(list_out, sp_in))
-
-        # Standard non-list connection should be allowed
-        normal_out = DummySocket("Gcode", "NodeSocketString", display_shape="CIRCLE")
-        self.assertTrue(self.tree.valid_link(normal_out, sp_in))
-
-    def test_valid_link_printer_list_rejects_list(self):
-        list_out = DummySocket("Gcode", "NodeSocketString", display_shape="LIST")
-        printer_list = DummyNode("SLICENODE_PrinterList")
-        pl_in = DummySocket("Printer1", "NodeSocketString")
-        printer_list.add_in(pl_in)
-
-        self.assertFalse(self.tree.valid_link(list_out, pl_in))
-
-    def test_valid_link_path_operations_secondary_inputs_accept_list(self):
-        list_out = DummySocket("Paths", "SLICESOCK_Paths", display_shape="LIST")
-        path_ops = DummyNode("SLICENODE_PathOperations")
-        p0 = DummySocket("Paths", "SLICESOCK_Paths")
-        p1 = DummySocket("Paths", "SLICESOCK_Paths")
-        path_ops.add_in(p0)
-        path_ops.add_in(p1)
-
-        # Primary input p0 accepts list
-        self.assertTrue(self.tree.valid_link(list_out, p0))
-        # Secondary input p1 also accepts list (matched index per index)
-        self.assertTrue(self.tree.valid_link(list_out, p1))
-
-    def test_valid_link_seam_placement_cutting_mesh_accepts_list(self):
-        list_mesh_out = DummySocket("Mesh", "SLICESOCK_Mesh", display_shape="LIST")
-        seam_node = DummyNode("SLICENODE_SeamPlacement")
-        p_in = DummySocket("Paths", "SLICESOCK_Paths")
-        m_in = DummySocket("Mesh", "SLICESOCK_Mesh")
-        seam_node.add_in(p_in)
-        seam_node.add_in(m_in)
-
-        # Secondary cutting mesh accepts list (matched index per index)
-        self.assertTrue(self.tree.valid_link(list_mesh_out, m_in))
-
-
 class TestNodeEvaluationsWithLists(unittest.TestCase):
     def test_path_operations_with_first_input_list(self):
         from NodeSlicer.core.nodeslicer.nodes.path import SLICENODE_PathOperations
@@ -669,86 +618,7 @@ class TestGroupNodeListShapes(unittest.TestCase):
         self.assertEqual(grp_in.display_shape, "LIST")
         self.assertEqual(grp_out.display_shape, "LIST")
 
-    def test_valid_link_with_group_nodes(self):
-        item_paths = DummyInterfaceItem("Paths", "sock_paths", in_out="INPUT", socket_type="SLICESOCK_Paths")
-        item_float = DummyInterfaceItem("FloatVal", "sock_float", in_out="INPUT", socket_type="NodeSocketFloat")
-
-        gin = DummyNode("NodeGroupInput")
-        gin_out_paths = DummySocket("Paths", "SLICESOCK_Paths")
-        gin_out_paths.identifier = "sock_paths"
-        gin_out_float = DummySocket("FloatVal", "NodeSocketFloat")
-        gin_out_float.identifier = "sock_float"
-        gin.add_out(gin_out_paths)
-        gin.add_out(gin_out_float)
-
-        target_node = DummyNode("SLICENODE_BufferShells")
-        target_node.list_socket_mapping = [("Paths", "Paths")]
-        target_in_paths = DummySocket("Paths", "SLICESOCK_Paths")
-        target_node.add_in(target_in_paths)
-
-        link = DummyLink(gin_out_paths, target_in_paths)
-        gin_out_paths.is_linked = True
-        gin_out_paths.links = [link]
-
-        tree = DummyGroupTree([item_paths, item_float], [gin, target_node])
-
-        grp_node = DummyGroupNode("Group", tree)
-        grp_in_paths = DummySocket("Paths", "SLICESOCK_Paths")
-        grp_in_paths.identifier = "sock_paths"
-        grp_in_float = DummySocket("FloatVal", "NodeSocketFloat")
-        grp_in_float.identifier = "sock_float"
-        grp_node.add_in(grp_in_paths)
-        grp_node.add_in(grp_in_float)
-
-        list_out = DummySocket("Paths", "SLICESOCK_Paths", display_shape="LIST")
-        validator = SLICETREE_NodeTree()
-
-        # Linking list to Paths group input (which accepts list): allowed
-        self.assertTrue(validator.valid_link(list_out, grp_in_paths))
-
-        # Linking list to FloatVal group input: rejected
-        self.assertFalse(validator.valid_link(list_out, grp_in_float))
-
-
 class TestImplicitGetMesh(unittest.TestCase):
-    def setUp(self):
-        self.tree = SLICETREE_NodeTree()
-
-    def test_valid_link_object_to_mesh(self):
-        obj_out = DummySocket("Object", "NodeSocketObject")
-        obj_out.is_output = True
-        mesh_in = DummySocket("Mesh", "SLICESOCK_Mesh")
-        mesh_in.is_output = False
-        mesh_in.node = DummyNode("SLICENODE_SliceShells")
-        mesh_in.node.list_socket_mapping = [("Mesh", "Paths")]
-
-        # Object output to Mesh input is valid
-        self.assertTrue(self.tree.valid_link(obj_out, mesh_in))
-
-        # Reverse: Mesh output to Object input is NOT valid
-        mesh_out = DummySocket("Mesh", "SLICESOCK_Mesh")
-        mesh_out.is_output = True
-        obj_in = DummySocket("Object", "NodeSocketObject")
-        obj_in.is_output = False
-        self.assertFalse(self.tree.valid_link(mesh_out, obj_in))
-
-    def test_valid_link_object_list_to_mesh(self):
-        list_obj_out = DummySocket("Objects", "NodeSocketObject", display_shape="LIST")
-        list_obj_out.is_output = True
-        mesh_in = DummySocket("Mesh", "SLICESOCK_Mesh")
-        mesh_in.is_output = False
-        mesh_in.node = DummyNode("SLICENODE_SliceShells")
-        mesh_in.node.list_socket_mapping = [("Mesh", "Paths")]
-
-        # Target accepts lists -> allowed
-        self.assertTrue(self.tree.valid_link(list_obj_out, mesh_in))
-
-        # SeamPlacement cutting mesh accepts lists
-        seam_mesh_in = DummySocket("Mesh", "SLICESOCK_Mesh")
-        seam_mesh_in.is_output = False
-        seam_mesh_in.node = DummyNode("SLICENODE_SeamPlacement")
-        self.assertTrue(self.tree.valid_link(list_obj_out, seam_mesh_in))
-
     def test_resolve_input_implicit_get_mesh_single_object(self):
         from NodeSlicer.infra.blender.blender_slice_nodes_generic import resolve_input, execution_cache
 

tests/test_transform.py

@@ -739,14 +739,29 @@ class TestTransform(unittest.TestCase):
 
         # 9. Blender Object fallback
         class MockBpyObject:
-            location = (11.0, 22.0, 33.0)
-            rotation_euler = (0.4, 0.5, 0.6)
-            scale = (1.1, 2.2, 3.3)
+            def __init__(self, loc=(11.0, 22.0, 33.0), rot=(0.4, 0.5, 0.6), sc=(1.1, 2.2, 3.3)):
+                self.location = loc
+                self.rotation_euler = rot
+                self.scale = sc
         node.resolve = lambda s: MockBpyObject()
         self.assertEqual(node.evaluate_output("Translation"), (11.0, 22.0, 33.0))
         self.assertEqual(node.evaluate_output("Rotation"), (0.4, 0.5, 0.6))
         self.assertEqual(node.evaluate_output("Scale"), (1.1, 2.2, 3.3))
 
+        # 10. List of Blender Objects
+        obj1 = MockBpyObject((1.0, 2.0, 3.0), (0.0, 0.0, 0.0), (1.0, 1.0, 1.0))
+        obj2 = MockBpyObject((4.0, 5.0, 6.0), (0.1, 0.2, 0.3), (2.0, 2.0, 2.0))
+        node.resolve = lambda s: [obj1, obj2]
+        self.assertEqual(node.evaluate_output("Translation"), [(1.0, 2.0, 3.0), (4.0, 5.0, 6.0)])
+        self.assertEqual(node.evaluate_output("Rotation"), [(0.0, 0.0, 0.0), (0.1, 0.2, 0.3)])
+        self.assertEqual(node.evaluate_output("Scale"), [(1.0, 1.0, 1.0), (2.0, 2.0, 2.0)])
+
+        # 11. Empty list
+        node.resolve = lambda s: []
+        self.assertEqual(node.evaluate_output("Translation"), [])
+        self.assertEqual(node.evaluate_output("Rotation"), [])
+        self.assertEqual(node.evaluate_output("Scale"), [])
+
     def test_path_operations_acquire_transforms(self):
         """Tests Acquire Transforms checkbox and behavior on SLICENODE_PathOperations."""
         from NodeSlicer.core.nodeslicer.nodes.path import SLICENODE_PathOperations