diff --git a/src/bonsai/bonsai/bim/module/drawing/gizmos.py b/src/bonsai/bonsai/bim/module/drawing/gizmos.py
index 3c03e9db49..6028ac055d 100644
--- a/src/bonsai/bonsai/bim/module/drawing/gizmos.py
+++ b/src/bonsai/bonsai/bim/module/drawing/gizmos.py
@@ -4877,7 +4877,14 @@ class GizmoDimension(GizmoMovable):
 
         self.init_value = click_distance
 
-        if self.initial_snap_state and self.active_obj:
+        # Schematic gizmos opt out of dimension snap. Force the header
+        # indicator to ``off`` for the drag's duration so the user sees the
+        # state matches behaviour; ``exit`` restores ``initial_snap_state``.
+        # Skipping the snap cache here also avoids the per-drag mesh probe.
+        snap_supported = getattr(self.gizmo_group, "snap_enabled_on_dimensions", True)
+        if not snap_supported:
+            context.scene.tool_settings.use_snap = False
+        elif self.initial_snap_state and self.active_obj:
             build_snap_cache(context, self.active_obj)
             self._snap_cache_built = True
 
@@ -4919,11 +4926,18 @@ class GizmoDimension(GizmoMovable):
         if not region or not rv3d:
             return {"RUNNING_MODAL"}
 
-        tool_settings.use_snap = not self.initial_snap_state if event.ctrl else self.initial_snap_state
+        # Group-level opt-out: schematic gizmos float in viewport space, so
+        # global-snap-to-scene-vertices would produce spurious value jumps.
+        # The fallback (``True``) covers any gizmo whose group is not a
+        # ``BaseParametricGizmoGroup``.
+        snap_supported = getattr(self.gizmo_group, "snap_enabled_on_dimensions", True)
 
-        if tool_settings.use_snap and not self._snap_cache_built and self.active_obj:
-            build_snap_cache(context, self.active_obj)
-            self._snap_cache_built = True
+        if snap_supported:
+            tool_settings.use_snap = not self.initial_snap_state if event.ctrl else self.initial_snap_state
+
+            if tool_settings.use_snap and not self._snap_cache_built and self.active_obj:
+                build_snap_cache(context, self.active_obj)
+                self._snap_cache_built = True
 
         current_coord = (event.mouse_region_x, event.mouse_region_y)
 
@@ -4947,7 +4961,7 @@ class GizmoDimension(GizmoMovable):
 
         delta = (current_3d - self.start_location).dot(axis_direction)
 
-        if tool_settings.use_snap and self.active_obj:
+        if snap_supported and tool_settings.use_snap and self.active_obj:
             # Snap the dimension tip (not mouse position) to target
             # Calculate where the dimension tip would be with current delta
             # The tip is at: gizmo_origin + axis * (init_value + delta)
@@ -5320,6 +5334,13 @@ class BaseParametricGizmoGroup:
     # Pre-computed flip matrix for negative value handling (180° rotation around Z)
     FLIP_MATRIX = Matrix.Rotation(math.pi, 4, "Z")
 
+    # Default: dimension drags respect Blender's global snap (Ctrl-toggleable
+    # during drag). Subclasses whose dimensions float in viewport space rather
+    # than aligning to real-world geometry should override to ``False`` —
+    # snapping to scene vertices in that case produces spurious value jumps
+    # as the mouse crosses unrelated meshes.
+    snap_enabled_on_dimensions: bool = True
+
     # === Icon Gizmo Layout (meters) ===
     # Icons are positioned in a horizontal row above the element:
     #   [Validate] [Cancel] [Cycle]
@@ -6580,6 +6601,11 @@ class BaseSchematicGizmoGroup(BaseParametricGizmoGroup):
     # list and become no-ops. The schematic equivalents below take their place.
     dimension_gizmo_props: list[DimensionGizmoConfig] = []
 
+    # Schematic dimensions float in billboarded viewport space, not aligned to
+    # real-world geometry. Snapping the dragged tip to scene vertices would
+    # produce nonsensical value jumps as the mouse crosses unrelated meshes.
+    snap_enabled_on_dimensions: bool = False
+
     # Declarative dimension configuration consumed by ``setup_schematic_dimensions``
     # and ``update_schematic_dimensions``. Each config produces one
     # ``BIM_GT_gizmo_dimension`` instance positioned at a schematic-local
diff --git a/src/bonsai/bonsai/bim/module/model/__init__.py b/src/bonsai/bonsai/bim/module/model/__init__.py
index b30fb17896..08806ad8fb 100644
--- a/src/bonsai/bonsai/bim/module/model/__init__.py
+++ b/src/bonsai/bonsai/bim/module/model/__init__.py
@@ -246,9 +246,13 @@ classes = (
     railing.CopyRailingParameters,
     railing.AddRailing,
     railing.CancelEditingRailing,
+    railing.CycleRailingType,
     railing.FinishEditingRailing,
+    railing.PickRailingTerminalType,
     railing.FlipRailingPathOrder,
     railing.EnableEditingRailing,
+    railing.GizmoRailingSchematic,
+    railing.ToggleRailingUseManualSupports,
     railing.CancelEditingRailingPath,
     railing.FinishEditingRailingPath,
     railing.EnableEditingRailingPath,
diff --git a/src/bonsai/bonsai/bim/module/model/prop.py b/src/bonsai/bonsai/bim/module/model/prop.py
index b9709c067a..ebafafda6d 100644
--- a/src/bonsai/bonsai/bim/module/model/prop.py
+++ b/src/bonsai/bonsai/bim/module/model/prop.py
@@ -228,11 +228,7 @@ def update_wall_offset_baseline(self: "BIMWallProperties", context: bpy.types.Co
 def update_railing(self: "BIMRailingProperties", context: bpy.types.Context) -> None:
     """Regenerate railing mesh when property changes."""
     if self.is_editing:
-        # Only FRAMELESS_PANEL can update live via bmesh.
-        # WALL_MOUNTED_HANDRAIL geometry is generated from IFC representation,
-        # so it only updates on "Finish Editing" to avoid modifying IFC during preview.
-        if self.railing_type == "FRAMELESS_PANEL":
-            _get_updater("railing", "update_railing_modifier_bmesh")(context)
+        _get_updater("railing", "update_railing_modifier_bmesh")(context)
 
 
 def update_roof(self: "BIMRoofProperties", context: bpy.types.Context) -> None:
diff --git a/src/bonsai/bonsai/bim/module/model/railing.py b/src/bonsai/bonsai/bim/module/model/railing.py
index 6f3697d51d..825cc339ac 100644
--- a/src/bonsai/bonsai/bim/module/model/railing.py
+++ b/src/bonsai/bonsai/bim/module/model/railing.py
@@ -18,6 +18,7 @@
 
 
 import json
+import math
 from typing import Any
 
 import bmesh
@@ -27,14 +28,24 @@ import ifcopenshell.api.geometry
 import ifcopenshell.api.pset
 import ifcopenshell.util.representation
 import ifcopenshell.util.unit
-from mathutils import Vector
+from mathutils import Matrix, Vector
 
 import bonsai.core.geometry
 import bonsai.core.root
 import bonsai.tool as tool
+from bonsai.bim.module.drawing import gizmos as gizmo
+from bonsai.bim.module.drawing.gizmos import DimensionGizmoConfig
+from bonsai.bim.module.model import prop
 from bonsai.bim.module.model.data import RailingData, refresh
 from bonsai.bim.module.model.decorator import ProfileDecorator
-from bonsai.bim.parametric_lifecycle import PathPreservingEditMixin
+from bonsai.bim.parametric_lifecycle import (
+    CycleTypeMixin,
+    PathPreservingEditMixin,
+    PickTypeMixin,
+)
+from bonsai.tool.cad import WELD_TOLERANCE
+
+V_ = tool.Blender.V_
 
 # reference:
 # https://ifc43-docs.standards.buildingsmart.org/IFC/RELEASE/IFC4x3/HTML/lexical/IfcRailing.htm
@@ -125,6 +136,56 @@ def update_bbim_railing_pset(element: ifcopenshell.entity_instance, railing_data
     ifcopenshell.api.pset.edit_pset(tool.Ifc.get(), pset=pset, properties={"Data": railing_data})
 
 
+def generate_wall_mounted_handrail_preview(
+    obj: bpy.types.Object,
+    props: "BIMRailingProperties",
+    path_data: dict[str, Any],
+    si_conversion: float,
+) -> None:
+    """Viewport-only WALL_MOUNTED_HANDRAIL preview: rebuild ``obj.data`` from the same
+    geometry helper the IFC representation builder uses, without writing any IFC."""
+    railing_path = [Vector(v) * si_conversion for v in path_data["verts"]]
+    looped_path = path_data["edges"][-1][-1] == path_data["edges"][0][0]
+
+    geom = ifcopenshell.api.geometry.compute_wall_mounted_handrail_geometry(
+        railing_path=railing_path,
+        support_spacing=props.support_spacing,
+        railing_diameter=props.railing_diameter,
+        clear_width=props.clear_width,
+        height=props.height,
+        use_manual_supports=props.use_manual_supports,
+        terminal_type=props.terminal_type,
+        looped_path=looped_path,
+        unit_scale=1.0,  # props are already SI; bypass the IFC project-units conversion
+    )
+
+    bm = tool.Blender.get_bmesh_for_mesh(obj.data, clean=True)
+
+    tool.Cad.sweep_disk_along_polyline(
+        bm,
+        [Vector(p) for p in geom.handrail_polyline],
+        geom.handrail_radius,
+        arc_indices=geom.handrail_arc_point_indices,
+    )
+
+    for support in geom.supports:
+        tool.Cad.sweep_disk_along_polyline(
+            bm,
+            [Vector(p) for p in support.arc_polyline],
+            support.arc_radius,
+        )
+        tool.Cad.add_disk_extrusion(
+            bm,
+            Vector(support.disk_position),
+            support.disk_radius,
+            support.disk_depth,
+            support.disk_z_rotation,
+        )
+
+    bmesh.ops.recalc_face_normals(bm, faces=bm.faces[:])
+    tool.Blender.apply_bmesh(obj.data, bm)
+
+
 def update_railing_modifier_bmesh(context: bpy.types.Context) -> None:
     """before using should make sure that Data contains up-to-date information.
     If BBIM Pset just changed should call refresh() before updating bmesh
@@ -140,6 +201,13 @@ def update_railing_modifier_bmesh(context: bpy.types.Context) -> None:
     path_data = RailingData.data["path_data"]
 
     si_conversion = ifcopenshell.util.unit.calculate_unit_scale(tool.Ifc.get())
+
+    # WALL_MOUNTED_HANDRAIL renders the preview from the compute helper; IFC stays
+    # untouched until Finish Editing rebuilds the representation.
+    if not props.is_editing_path and props.railing_type == "WALL_MOUNTED_HANDRAIL":
+        generate_wall_mounted_handrail_preview(obj, props, path_data, si_conversion)
+        return
+
     # need to make sure we support edit mode
     # since users will probably be in edit mode when they'll be changing railing path
     bm = tool.Blender.get_bmesh_for_mesh(obj.data, clean=True)
@@ -165,8 +233,6 @@ def update_railing_modifier_bmesh(context: bpy.types.Context) -> None:
         thickness = props.thickness
         spacing = props.spacing
 
-        # spacing
-        # split each edge in 3 segments by 0.5 * spacing by x-y plane
         main_edges = bm.edges[:]
         for main_edge in main_edges:
             bm_split_edge_at_offset(main_edge, spacing)
@@ -211,7 +277,7 @@ def update_railing_modifier_bmesh(context: bpy.types.Context) -> None:
         bmesh.ops.dissolve_edges(bm, edges=edges_to_dissolve)
         bmesh.ops.dissolve_verts(bm, verts=verts_to_dissolve)
         # to remove unnecessary verts in 0 spacing case
-        bmesh.ops.remove_doubles(bm, verts=bm.verts, dist=0.0001)
+        bmesh.ops.remove_doubles(bm, verts=bm.verts, dist=WELD_TOLERANCE)
 
         bmesh.ops.recalc_face_normals(bm, faces=bm.faces[:])
 
@@ -271,8 +337,8 @@ def get_path_data(obj: bpy.types.Object) -> dict[str, Any]:
             segments.append((i - 1, 0))
             break
 
-        # skip path verts if they just go vertical to avoid errors
-        if (v.co.xy - prev_v.co.xy).length <= 0.0001:
+        # Vertical-only segments project to a degenerate XY edge; skip to avoid divide-by-zero downstream.
+        if (v.co.xy - prev_v.co.xy).length <= WELD_TOLERANCE:
             continue
 
         points.append(v.co)
@@ -407,9 +473,8 @@ class CopyRailingParameters(bpy.types.Operator, tool.Ifc.Operator):
 
 
 class _RailingEditMixin(PathPreservingEditMixin):
-    """Type-specific hooks for railing parametric-edit operators. Single-object
-    (active_object). ``path_data`` is preserved through the edit; the separate
-    ``Enable/Finish/CancelEditingRailingPath`` operators handle path editing."""
+    """Single-object (active_object) railing-edit hooks; path_data is preserved
+    through the edit (path editing is a separate operator family)."""
 
     pset_name = "BBIM_Railing"
 
@@ -436,7 +501,21 @@ class _RailingEditMixin(PathPreservingEditMixin):
         update_railing_modifier_ifc_data(context)
 
     @classmethod
-    def _update_modifier_bmesh(cls, obj: bpy.types.Object, context: bpy.types.Context) -> None:
+    def _restore_viewport_after_cancel(cls, obj: bpy.types.Object, context: bpy.types.Context) -> None:
+        """WALL_MOUNTED_HANDRAIL reloads the committed Body; others rebuild the preview bmesh."""
+        props = tool.Model.get_railing_props(obj)
+        if props.railing_type == "WALL_MOUNTED_HANDRAIL":
+            element = tool.Ifc.get_entity(obj)
+            assert element
+            body = ifcopenshell.util.representation.get_representation(element, "Model", "Body", "MODEL_VIEW")
+            if body:
+                bonsai.core.geometry.switch_representation(
+                    tool.Ifc,
+                    tool.Geometry,
+                    obj=obj,
+                    representation=body,
+                )
+            return
         update_railing_modifier_bmesh(context)
 
 
@@ -467,6 +546,554 @@ class FinishEditingRailing(_RailingEditMixin, bpy.types.Operator, tool.Ifc.Opera
         return self._finish_targets(context)
 
 
+class CycleRailingType(bpy.types.Operator, tool.Ifc.Operator, CycleTypeMixin):
+    """Cycle railing_type (FRAMELESS_PANEL ↔ WALL_MOUNTED_HANDRAIL). Shift+click reverses."""
+
+    bl_idname = "bim.cycle_railing_type"
+    bl_label = "Cycle Railing Type"
+    bl_options = {"REGISTER", "UNDO"}
+
+    element_checker = tool.Parametric.is_railing
+    props_getter = tool.Model.get_railing_props
+    type_literal = tool.Model.RailingType
+    type_attr = "railing_type"
+
+    def _execute(self, context: bpy.types.Context) -> set[str]:
+        return self._cycle_type(context)
+
+
+class ToggleRailingUseManualSupports(bpy.types.Operator):
+    """Flip use_manual_supports on the active WALL_MOUNTED_HANDRAIL railing.
+
+    No-op unless a parametric edit is active and the railing is wall-mounted.
+    """
+
+    bl_idname = "bim.toggle_railing_use_manual_supports"
+    bl_label = "Toggle Railing Manual Supports"
+    bl_description = "Switch between automatic support spacing and manual per-vertex placement"
+    bl_options = {"REGISTER", "UNDO"}
+
+    def execute(self, context):
+        resolved = tool.Model.resolve_active_props_for_edit(
+            context,
+            tool.Model.get_railing_props,
+            subtype=("railing_type", "WALL_MOUNTED_HANDRAIL"),
+        )
+        if resolved is None:
+            return {"CANCELLED"}
+        _obj, props = resolved
+        props.use_manual_supports = not props.use_manual_supports
+        return {"FINISHED"}
+
+
+class PickRailingTerminalType(bpy.types.Operator, tool.Ifc.Operator, PickTypeMixin):
+    """Pick ``terminal_type`` for the active WALL_MOUNTED_HANDRAIL railing."""
+
+    bl_idname = "bim.pick_railing_terminal_type"
+    bl_label = "Pick Railing Terminal Type"
+    bl_description = "Pick the cap geometry applied at the rail ends"
+    bl_options = {"REGISTER", "UNDO"}
+
+    skip_element_check = True
+    props_getter = tool.Model.get_railing_props
+    type_literal = prop.CapType
+    type_attr = "terminal_type"
+
+    def _execute(self, context: bpy.types.Context) -> set[str]:
+        if (
+            tool.Model.resolve_active_props_for_edit(
+                context,
+                tool.Model.get_railing_props,
+                subtype=("railing_type", "WALL_MOUNTED_HANDRAIL"),
+            )
+            is None
+        ):
+            return {"CANCELLED"}
+        return self._pick_type(context)
+
+
+def _format_attr_distance(attr_name: str):
+    """text_formatter that renders the named property as a distance, ignoring the
+    dimension's visible-length argument (which is fixed for schematic gizmos)."""
+    return lambda p, _v: tool.Unit.format_distance(getattr(p, attr_name))
+
+
+class GizmoRailingSchematic(bpy.types.GizmoGroup, gizmo.BaseSchematicGizmoGroup):
+    """Schematic-frame parametric editor for railings. Mutually exclusive with path-edit mode."""
+
+    bl_idname = "OBJECT_GGT_bim_railing_edition"
+    bl_label = "Railing Editing Gizmo"
+    bl_space_type = "VIEW_3D"
+    bl_region_type = "WINDOW"
+    bl_options = {"3D", "PERSISTENT"}
+
+    enable_editing_operator = "bim.enable_editing_railing"
+    finish_editing_operator = "bim.finish_editing_railing"
+    cancel_editing_operator = "bim.cancel_editing_railing"
+    cycle_type_operator = "bim.cycle_railing_type"
+
+    props_getter = tool.Model.get_railing_props
+    gizmo_pref_name = "railing"
+
+    # Schematic-local layout. +X → screen RIGHT, +Y → screen UP, +Z → toward viewer
+    # (post billboard rotation). Each dimension is anchored alongside the feature it
+    # measures so the label, not the bar length, carries the value.
+    SCHEMATIC_MESH_HEIGHT_FRAC = 0.9  # Mesh top edge in schematic-local +Y
+    SCHEMATIC_MESH_WIDTH_FRAC = 0.7  # Mesh side edges in schematic-local ±X
+    SCHEMATIC_MESH_RAIL_Y_FRAC = SCHEMATIC_MESH_HEIGHT_FRAC / 2  # WALL_MOUNTED_HANDRAIL rail centreline
+    SCHEMATIC_MESH_DEPTH_FRAC = 0.06  # Panel depth — small so the schematic reads as slabs not boxes
+    # WALL_MOUNTED_HANDRAIL dimensions — fractions of schematic_box_size so they
+    # scale with the host group's box size.
+    SCHEMATIC_RAIL_RADIUS_FRAC = 0.05
+    SCHEMATIC_RAIL_CLEAR_FRAC = 0.5  # Stylised — wider than real-world for visible bracket arm
+    SCHEMATIC_RAIL_INSET_FRAC = 0.08  # Wall extends past the outermost support on both sides
+
+    @classmethod
+    def schematic_rail_radius(cls) -> float:
+        return cls.schematic_box_size * cls.SCHEMATIC_RAIL_RADIUS_FRAC
+
+    @classmethod
+    def schematic_rail_clear(cls) -> float:
+        return cls.schematic_box_size * cls.SCHEMATIC_RAIL_CLEAR_FRAC
+
+    # Axonometric 3/4 view: +Z projects down-and-left so the depth axis
+    # is visibly separated from the back face. Without the X tilt, panel
+    # thickness (schematic-local Z) collapses to a near-horizontal bar.
+    schematic_view_rotation = Matrix.Rotation(math.radians(20), 4, "X") @ Matrix.Rotation(math.radians(-25), 4, "Y")
+
+    # Hover a dimension → highlight the schematic edges tagged with the matching feature.
+    # Tags are written by the mesh builders. "spacing" is empty space (no edges) so it's
+    # absent from this map and gracefully no-ops on hover.
+    schematic_attr_to_feature = {
+        "height": "panel_height",
+        "thickness": "panel_thickness",
+        "railing_diameter": "rail_tube",
+        "clear_width": "bracket",
+        "support_spacing": "bracket",
+    }
+
+    schematic_dimension_props = [
+        # ── FRAMELESS_PANEL ─────────────────────────────────────────────
+        DimensionGizmoConfig(
+            attr_name="height",
+            axis=(0, 1, 0),
+            min_value=0.01,
+            # Gated to FRAMELESS_PANEL: in WALL_MOUNTED_HANDRAIL, height only
+            # feeds TO_FLOOR / TO_END_POST_AND_FLOOR terminals so dragging it
+            # is a no-op under the default "180" terminal.
+            visibility_condition=lambda p: p.railing_type == "FRAMELESS_PANEL",
+            matrix_position=lambda p: Vector((-GizmoRailingSchematic.SCHEMATIC_MESH_WIDTH_FRAC / 2 - 0.08, 0.0, 0.0)),
+            schematic_visible_length=SCHEMATIC_MESH_HEIGHT_FRAC,
+            text_formatter=_format_attr_distance("height"),
+        ),
+        DimensionGizmoConfig(
+            attr_name="thickness",
+            axis=(0, 0, 1),  # panel depth — projects to a true depth direction under the 3/4 tilt
+            min_value=0.005,
+            visibility_condition=lambda p: p.railing_type == "FRAMELESS_PANEL",
+            matrix_position=lambda p: Vector(
+                (
+                    (
+                        -GizmoRailingSchematic.SCHEMATIC_MESH_WIDTH_FRAC / 2
+                        - GizmoRailingSchematic.SCHEMATIC_MESH_GAP_HALF_WIDTH
+                    )
+                    / 2,
+                    GizmoRailingSchematic.SCHEMATIC_MESH_HEIGHT_FRAC + 0.05,
+                    -GizmoRailingSchematic.SCHEMATIC_MESH_DEPTH_FRAC / 2,
+                )
+            ),
+            schematic_visible_length=0.4,  # longer than default to survive depth foreshortening
+            text_formatter=_format_attr_distance("thickness"),
+        ),
+        DimensionGizmoConfig(
+            attr_name="spacing",
+            axis=(1, 0, 0),
+            min_value=0.0,  # zero-spacing collapses the picket gap into a single continuous panel
+            visibility_condition=lambda p: p.railing_type == "FRAMELESS_PANEL",
+            matrix_position=lambda p: Vector((0.0, -0.1, 0.0)),
+            text_formatter=_format_attr_distance("spacing"),
+        ),
+        # ── WALL_MOUNTED_HANDRAIL ──────────────────────────────────────
+        DimensionGizmoConfig(
+            attr_name="railing_diameter",
+            axis=(0, 1, 0),
+            min_value=0.001,
+            visibility_condition=lambda p: p.railing_type == "WALL_MOUNTED_HANDRAIL",
+            matrix_position=lambda p: Vector(
+                (
+                    -GizmoRailingSchematic.SCHEMATIC_MESH_WIDTH_FRAC / 2 - 0.05,
+                    GizmoRailingSchematic.SCHEMATIC_MESH_RAIL_Y_FRAC - 0.09,
+                    GizmoRailingSchematic.schematic_rail_clear(),
+                )
+            ),
+            text_formatter=_format_attr_distance("railing_diameter"),
+        ),
+        DimensionGizmoConfig(
+            attr_name="clear_width",
+            axis=(0, 0, 1),  # +Z is the wall-to-rail perpendicular axis under the 3/4 tilt
+            min_value=0.001,
+            visibility_condition=lambda p: p.railing_type == "WALL_MOUNTED_HANDRAIL",
+            matrix_position=lambda p: Vector(
+                (
+                    0.0,
+                    GizmoRailingSchematic.SCHEMATIC_MESH_RAIL_Y_FRAC,
+                    0.0,
+                )
+            ),
+            schematic_visible_length=0.36,  # 2× default so the call-out survives depth projection
+            text_formatter=_format_attr_distance("clear_width"),
+        ),
+        DimensionGizmoConfig(
+            attr_name="support_spacing",
+            axis=(1, 0, 0),
+            min_value=0.05,
+            visibility_condition=lambda p: (p.railing_type == "WALL_MOUNTED_HANDRAIL" and not p.use_manual_supports),
+            matrix_position=lambda p: Vector(
+                (
+                    -GizmoRailingSchematic.SCHEMATIC_MESH_WIDTH_FRAC / 2
+                    + GizmoRailingSchematic.SCHEMATIC_RAIL_INSET_FRAC,
+                    -0.18,
+                    0.0,
+                )
+            ),
+            # Bare names (not Gizmo…SCHEMATIC_…) because the class is still under construction here.
+            schematic_visible_length=SCHEMATIC_MESH_WIDTH_FRAC - 2 * SCHEMATIC_RAIL_INSET_FRAC,
+            text_formatter=_format_attr_distance("support_spacing"),
+        ),
+    ]
+
+    @classmethod
+    def is_element_type(cls, element: ifcopenshell.entity_instance) -> bool:
+        return tool.Parametric.is_railing(element)
+
+    @classmethod
+    def schematic_cache_key(cls, props) -> tuple:
+        """Cache the schematic mesh by ``railing_type`` — proportions are fixed
+        per type, so the bmesh build runs at most twice across a session
+        (once for ``FRAMELESS_PANEL``, once for ``WALL_MOUNTED_HANDRAIL``)
+        rather than once per draw call."""
+        return (props.railing_type,)
+
+    def setup_element_specific_gizmos(self, context: bpy.types.Context) -> None:
+        """Create the WALL_MOUNTED_HANDRAIL-only affordances on the schematic.
+
+        Two static lock glyphs (open/closed) for toggling
+        ``use_manual_supports``: instantiate both and let the per-frame state
+        query pick which one to show. State-aware icons use a static pair
+        rather than a single dynamic gizmo to avoid ``prop_path`` resolution
+        in the render path.
+
+        Plus a cycle-glyph at the rail end that opens the ``terminal_type``
+        popup when clicked.
+        """
+        default_color, highlight_color = self.get_decoration_colors()
+
+        self.lock_open_gizmo, self.lock_closed_gizmo = self.create_icon_gizmo_lock_pair(
+            "bim.toggle_railing_use_manual_supports",
+            open_color=default_color,
+        )
+
+        self.terminal_gizmo = self.gizmos.new("VIEW3D_GT_menu")
+        self.terminal_gizmo.color = default_color
+        self.terminal_gizmo.color_highlight = highlight_color
+        self.terminal_gizmo.use_draw_scale = False
+        self.terminal_gizmo.alpha = 0.8
+        self.terminal_gizmo.target_set_operator("bim.pick_railing_terminal_type")
+
+    def _refresh_element_specific(self, context: bpy.types.Context, mw: "Matrix", props) -> None:
+        """Position and gate the WALL_MOUNTED_HANDRAIL-only gizmos.
+
+        - Lock glyphs: only WALL_MOUNTED_HANDRAIL while editing. Show
+          ``lock_open`` when ``use_manual_supports`` is True, the closed
+          padlock when False ("auto-spacing is locked to support_spacing").
+        - Terminal gizmo: same gating, positioned just past the right rail
+          end so it reads as "configure the rail's end cap".
+        """
+        super()._refresh_element_specific(context, mw, props)
+
+        # ``draw_prepare`` can fire on a freshly recreated GizmoGroup instance
+        # before ``setup_element_specific_gizmos`` has populated the lock /
+        # terminal attributes (Blender 5.x recreates per-region groups on
+        # reload). Bail out cheaply; the next refresh after setup completes
+        # will reposition them correctly.
+        if not hasattr(self, "lock_open_gizmo"):
+            return
+
+        # Single gate for all WALL_MOUNTED_HANDRAIL extras.
+        active = props.is_editing and not props.is_editing_path and props.railing_type == "WALL_MOUNTED_HANDRAIL"
+
+        if not active:
+            self.lock_open_gizmo.hide = True
+            self.lock_closed_gizmo.hide = True
+            self.terminal_gizmo.hide = True
+            return
+
+        billboard_rot = self._frame_billboard_rot
+        view_rotation = self.schematic_view_rotation
+        anchor = self._compute_schematic_anchor(props, mw, billboard_rot)
+
+        # ── Lock glyphs for use_manual_supports ──────────────────────────
+        # Sit just above the wall's bottom line, near the centre of the
+        # schematic — visually grouped with the dimension it controls
+        # (support_spacing) without overlapping the arrow tail below.
+        is_manual = bool(props.use_manual_supports)
+        self.lock_open_gizmo.hide = not is_manual
+        self.lock_closed_gizmo.hide = is_manual
+        lock_local = Vector((0.0, 0.05, 0.0))
+        lock_world = anchor + billboard_rot @ view_rotation @ lock_local
+        lock_matrix = gizmo.billboarded_at(lock_world, billboard_rot, 0.09)
+        self.lock_open_gizmo.matrix_basis = lock_matrix
+        self.lock_closed_gizmo.matrix_basis = lock_matrix
+
+        # ── Terminal-type popup gizmo at the right rail end ──────────────
+        # Pushed well past the right wall edge so the icon doesn't crowd
+        # the wall outline or the bracket attach point. At rail height and
+        # rail depth so it reads as "attached to the rail terminal".
+        self.terminal_gizmo.hide = False
+        terminal_local = Vector(
+            (
+                self.SCHEMATIC_MESH_WIDTH_FRAC / 2 + 0.25,
+                self.SCHEMATIC_MESH_RAIL_Y_FRAC,
+                self.schematic_rail_clear(),
+            )
+        )
+        terminal_world = anchor + billboard_rot @ view_rotation @ terminal_local
+        self.terminal_gizmo.matrix_basis = gizmo.billboarded_at(terminal_world, billboard_rot, 0.18)
+
+    def update_editing_gizmos(self, context: bpy.types.Context, mw: "Matrix", props: "BIMRailingProperties") -> None:
+        """Hide the pen gizmo while polyline path-edit is active; reposition the cycle icon.
+
+        The base class shows the pen gizmo whenever ``is_editing`` is False,
+        which is the case during path-edit too. Allowing the user to click
+        through into parametric edit while the polyline mesh is open in EDIT
+        mode mixes two distinct editing states and leaves a stale draft if
+        they cancel out — block the entry point instead. The operator itself
+        is intentionally not guarded (callers via scripting can still invoke
+        it); this is the UX-level enforcement.
+
+        The cycle icon defaults to the editing icon row (next to validate /
+        cancel) via the parent's positioning. We move it to just above the
+        schematic mesh so it reads as "cycle the railing type *shown here*"
+        — associated with the preview the user is interacting with, not a
+        generic editing button at the bottom of the schematic.
+        """
+        super().update_editing_gizmos(context, mw, props)
+        if props.is_editing_path:
+            self.pen_gizmo.hide = True
+
+        if props.is_editing and not props.is_editing_path:
+            billboard_rot = self._frame_billboard_rot
+            view_rotation = self.schematic_view_rotation
+            anchor = self._compute_schematic_anchor(props, mw, billboard_rot)
+            # Comfortably above the mesh top edge so the icon doesn't crowd
+            # the ``thickness`` / ``clear_width`` dimension callouts that
+            # already sit just above the panel/wall.
+            cycle_local = Vector((0.0, self.SCHEMATIC_MESH_HEIGHT_FRAC + 0.25, 0.0))
+            world_pos = anchor + billboard_rot @ view_rotation @ cycle_local
+            # 30% smaller than the editing-icon-row default (0.30 → 0.21):
+            # the cycle is a tertiary affordance compared to pen/validate/cancel.
+            self.cycle_gizmo.matrix_basis = gizmo.billboarded_at(world_pos, billboard_rot, 0.21)
+
+    @classmethod
+    def build_schematic_mesh(cls, props) -> "bmesh.types.BMesh":
+        """Build a wireframe preview of the railing in schematic-local coordinates.
+
+        FRAMELESS_PANEL renders as a box whose proportions track the bound
+        properties (height / thickness / spacing); WALL_MOUNTED_HANDRAIL
+        renders as a horizontal tube with two L-shaped supports whose
+        proportions track railing_diameter / clear_width / support_spacing.
+        Both are scaled to fit inside ``[-schematic_box_size, +schematic_box_size]``
+        on each axis so the schematic reads the same regardless of absolute
+        property values.
+
+        The mesh is decorative — clicks land on the labeled sliders, not on
+        the preview geometry. See ``BaseSchematicGizmoGroup`` for the
+        draw-handler lifecycle.
+        """
+        bm = bmesh.new()
+        if props.railing_type == "FRAMELESS_PANEL":
+            cls._build_frameless_panel_schematic(bm, props)
+        else:
+            cls._build_wall_mounted_handrail_schematic(bm, props)
+        return bm
+
+    # Schematic-local half-width of the visible gap between the two panel boxes.
+    # Conveys the "spacing" semantic at a glance — the user sees two pickets
+    # separated by air, with the spacing dimension emerging from that gap.
+    SCHEMATIC_MESH_GAP_HALF_WIDTH = 0.05
+
+    @classmethod
+    def _build_frameless_panel_schematic(cls, bm: "bmesh.types.BMesh", props) -> None:
+        """Stylised panel: two wireframe boxes with a visible gap between them.
+
+        The box edges sit at the ``SCHEMATIC_MESH_*_FRAC`` positions
+        (matching where the dimension gizmos anchor), so each dimension line
+        visually starts at the geometry feature it measures. Internal
+        proportions are stable across drags — the actual values are shown
+        through the dimension labels, while the schematic communicates
+        which feature each label refers to. The gap between the two boxes
+        (set by ``SCHEMATIC_MESH_GAP_HALF_WIDTH``) gives the "spacing"
+        dimension a real visual referent.
+
+        Edges are tagged on a string layer so hover-highlight can colour
+        the geometric feature being measured: vertical edges → height,
+        depth edges → thickness. The X-aligned edges along the panel
+        width are untagged (they don't correspond to a single dimension).
+        """
+        hw = cls.SCHEMATIC_MESH_WIDTH_FRAC / 2
+        hd = cls.SCHEMATIC_MESH_DEPTH_FRAC / 2
+        h_top = cls.SCHEMATIC_MESH_HEIGHT_FRAC
+        gap = cls.SCHEMATIC_MESH_GAP_HALF_WIDTH
+
+        layer_name = cls.SCHEMATIC_FEATURE_LAYER_NAME
+        feat_layer = bm.edges.layers.string.get(layer_name) or bm.edges.layers.string.new(layer_name)
+
+        # Edge index → feature tag for one box. Order matches the (a, b)
+        # tuple order below: bottom ring (4) + top ring (4) + verticals (4).
+        edge_tags_per_box = (
+            b"",  # (0,1) bottom-back, X-aligned
+            b"panel_thickness",  # (1,2) bottom-right, Z-aligned
+            b"",  # (2,3) bottom-front, X-aligned
+            b"panel_thickness",  # (3,0) bottom-left, Z-aligned
+            b"",  # (4,5) top-back, X-aligned
+            b"panel_thickness",  # (5,6) top-right, Z-aligned
+            b"",  # (6,7) top-front, X-aligned
+            b"panel_thickness",  # (7,4) top-left, Z-aligned
+            b"panel_height",  # (0,4) vertical back-left
+            b"panel_height",  # (1,5) vertical back-right
+            b"panel_height",  # (2,6) vertical front-right
+            b"panel_height",  # (3,7) vertical front-left
+        )
+
+        # Build two separate wireframe boxes — one on each side of the central
+        # gap. The boxes share the same Y range (0..h_top) and Z range (±hd)
+        # but split the X range so the gap from -gap to +gap stays empty.
+        for x_left, x_right in ((-hw, -gap), (gap, hw)):
+            corners = [
+                bm.verts.new((x_left, 0.0, -hd)),
+                bm.verts.new((x_right, 0.0, -hd)),
+                bm.verts.new((x_right, 0.0, hd)),
+                bm.verts.new((x_left, 0.0, hd)),
+                bm.verts.new((x_left, h_top, -hd)),
+                bm.verts.new((x_right, h_top, -hd)),
+                bm.verts.new((x_right, h_top, hd)),
+                bm.verts.new((x_left, h_top, hd)),
+            ]
+            for tag, (a, b) in zip(
+                edge_tags_per_box,
+                (
+                    (0, 1),
+                    (1, 2),
+                    (2, 3),
+                    (3, 0),  # bottom ring
+                    (4, 5),
+                    (5, 6),
+                    (6, 7),
+                    (7, 4),  # top ring
+                    (0, 4),
+                    (1, 5),
+                    (2, 6),
+                    (3, 7),  # vertical edges
+                ),
+            ):
+                edge = bm.edges.new((corners[a], corners[b]))
+                if tag:
+                    edge[feat_layer] = tag
+
+    @classmethod
+    def _build_wall_mounted_handrail_schematic(cls, bm: "bmesh.types.BMesh", props) -> None:
+        """Stylised wall-mounted handrail: wall outline, hex tube, two L-brackets.
+
+        Three visual elements convey "rail mounted on a wall":
+
+        - **Wall outline** — a wireframe rectangle in the YZ plane at ``z=0``,
+          extending slightly past the rail ends so the wall reads as a
+          surface the rail is *attached to* rather than a coincident frame.
+        - **Handrail tube** — a hexagonal cross-section extruded along ±X
+          at ``z=+clear_s`` (in front of the wall), at ``y=rail_y``.
+        - **L-shaped brackets** at each rail end — from the rail centreline
+          drop a short distance, then run perpendicular back to the wall
+          plane. Mirrors the standard wall-mount bracket geometry: a
+          horizontal arm holding the rail off the wall, a vertical drop
+          attaching to the rail.
+
+        Like ``_build_frameless_panel_schematic``, the schematic uses fixed
+        proportions so the dimension gizmos' anchor points stay aligned
+        with the geometry features regardless of property values.
+        """
+        half_len = cls.SCHEMATIC_MESH_WIDTH_FRAC / 2
+        wall_top = cls.SCHEMATIC_MESH_HEIGHT_FRAC
+        rail_y = cls.SCHEMATIC_MESH_RAIL_Y_FRAC  # rail sits at half wall height
+        radius_s = cls.schematic_rail_radius()
+        clear_s = cls.schematic_rail_clear()
+
+        layer_name = cls.SCHEMATIC_FEATURE_LAYER_NAME
+        feat_layer = bm.edges.layers.string.get(layer_name) or bm.edges.layers.string.new(layer_name)
+
+        # ── Wall outline (rectangle at z=0, slightly wider than the rail) ──
+        # Spans the full schematic height; the rail attaches in the middle,
+        # so the wall reads as "continuing past the rail above and below".
+        # Wall edges stay untagged — they're background context, not a
+        # feature any dimension measures.
+        wall_extra = 0.08
+        wall_x_left = -half_len - wall_extra
+        wall_x_right = half_len + wall_extra
+        wall_corners = [
+            bm.verts.new((wall_x_left, 0.0, 0.0)),
+            bm.verts.new((wall_x_right, 0.0, 0.0)),
+            bm.verts.new((wall_x_right, wall_top, 0.0)),
+            bm.verts.new((wall_x_left, wall_top, 0.0)),
+        ]
+        for a, b in ((0, 1), (1, 2), (2, 3), (3, 0)):
+            bm.edges.new((wall_corners[a], wall_corners[b]))
+
+        # ── Handrail tube (hex cross-section in YZ, extruded along X) ──────
+        # Centred on the rail centreline at (±(half_len - rail_inset),
+        # rail_y, +clear_s) — in front of the wall plane at z=0. The tube
+        # is shorter than the wall so the wall visibly extends past it on
+        # both sides; the L-brackets sit at the tube ends, so the leftmost
+        # bracket no longer coincides with the wall's left edge.
+        rail_inset = cls.SCHEMATIC_RAIL_INSET_FRAC
+        rail_x_left = -half_len + rail_inset
+        rail_x_right = half_len - rail_inset
+        segments = 6
+        ring_left, ring_right = [], []
+        for i in range(segments):
+            theta = 2 * math.pi * i / segments
+            dy = math.cos(theta) * radius_s
+            dz = math.sin(theta) * radius_s
+            ring_left.append(bm.verts.new((rail_x_left, rail_y + dy, clear_s + dz)))
+            ring_right.append(bm.verts.new((rail_x_right, rail_y + dy, clear_s + dz)))
+        # All hex-tube edges tagged "rail_tube" so they highlight together
+        # when the railing_diameter dimension is hovered.
+        for i in range(segments):
+            j = (i + 1) % segments
+            e_left = bm.edges.new((ring_left[i], ring_left[j]))
+            e_right = bm.edges.new((ring_right[i], ring_right[j]))
+            e_axial = bm.edges.new((ring_left[i], ring_right[i]))
+            e_left[feat_layer] = b"rail_tube"
+            e_right[feat_layer] = b"rail_tube"
+            e_axial[feat_layer] = b"rail_tube"
+
+        # ── L-brackets at each rail end (rail → drop → wall) ───────────────
+        # Bracket attach points follow the rail ends, so they're pulled
+        # inward by ``rail_inset`` from the wall edges. From the rail
+        # centreline, drop ``bracket_drop`` in Y, then run perpendicular
+        # back to the wall plane (z=0). The L shape reads as a wall-mount
+        # bracket under the 3/4 tilt. Both bracket segments tagged
+        # "bracket" so they highlight when clear_width OR support_spacing
+        # is hovered (both dimensions measure features of the supports).
+        bracket_drop = 0.06
+        for x in (rail_x_left, rail_x_right):
+            v_rail = bm.verts.new((x, rail_y, clear_s))
+            v_corner = bm.verts.new((x, rail_y - bracket_drop, clear_s))
+            v_wall = bm.verts.new((x, rail_y - bracket_drop, 0.0))
+            e1 = bm.edges.new((v_rail, v_corner))
+            e2 = bm.edges.new((v_corner, v_wall))
+            e1[feat_layer] = b"bracket"
+            e2[feat_layer] = b"bracket"
+
+
 class FlipRailingPathOrder(bpy.types.Operator, tool.Ifc.Operator):
     bl_idname = "bim.flip_railing_path_order"
     bl_label = "Flip Railing Path Order"
@@ -510,6 +1137,16 @@ class EnableEditingRailingPath(bpy.types.Operator, tool.Ifc.Operator):
         [o.select_set(False) for o in context.selected_objects if o != obj]
         assert obj
         props = tool.Model.get_railing_props(obj)
+
+        # Auto-commit any in-progress parametric draft before switching to
+        # path-edit. ``set_props_kwargs_from_ifc_data`` a few lines below
+        # overwrites props with the pset's stored values — without committing
+        # first, anything the user dragged on a dimension gizmo (height,
+        # diameter, …) would be silently discarded the moment path-edit
+        # starts.
+        if props.is_editing:
+            tool.Parametric.commit_object_draft(obj, "bim.finish_editing_railing")
+
         data = tool.Model.get_modeling_bbim_pset_data(obj, "BBIM_Railing")["data_dict"]
         # required since we could load pset from .ifc and BIMRoofProperties won't be set
         props.set_props_kwargs_from_ifc_data(data)
diff --git a/src/bonsai/test/bim/conftest.py b/src/bonsai/test/bim/conftest.py
index 2d69fe415a..a957b479ba 100644
--- a/src/bonsai/test/bim/conftest.py
+++ b/src/bonsai/test/bim/conftest.py
@@ -1,5 +1,46 @@
 import pytest
 
+
+class _FakePropsBase:
+    """Base for parametric-edit PropertyGroup stand-ins used in lifecycle tests.
+
+    The parametric-edit lifecycle mixins read/write a common contract:
+    ``is_editing`` (bool), ``last_kwargs`` (dict | None — capture of the last
+    data written via ``set_props_kwargs_from_ifc_data``),
+    ``set_props_kwargs_from_ifc_data(data)``, and
+    ``get_general_kwargs(convert_to_project_units=True)``. Per-type stand-ins
+    (door, railing, roof) subclass this and add their own kwargs accessors
+    and per-type fields."""
+
+    def __init__(self, general: dict | None = None):
+        self.is_editing = False
+        self.last_kwargs: dict | None = None
+        self.general = dict(general) if general is not None else {}
+
+    def set_props_kwargs_from_ifc_data(self, data):
+        self.last_kwargs = dict(data)
+
+    def get_general_kwargs(self, convert_to_project_units=True):
+        return dict(self.general)
+
+
+def make_lifecycle_obj(props, *, name="obj"):
+    """Build a ``bpy.types.Object`` stand-in for parametric-lifecycle tests.
+
+    The mixin code under test reads ``obj.props`` (the PropertyGroup
+    stand-in) and ``obj.name`` (used in error reports). ``spec=bpy.types.Object``
+    catches typo'd attribute access at test time. ``bpy`` is imported inside
+    the function so this conftest stays importable when bpy is absent."""
+    from unittest import mock
+
+    import bpy
+
+    obj = mock.Mock(spec=bpy.types.Object, name=name)
+    obj.props = props
+    obj.name = name
+    return obj
+
+
 # pytest by default doesn't print steps and where it failed. Let's fix that.
 
 
diff --git a/src/bonsai/test/bim/module/drawing/test_gizmos.py b/src/bonsai/test/bim/module/drawing/test_gizmos.py
index cc781cd118..18f640549b 100644
--- a/src/bonsai/test/bim/module/drawing/test_gizmos.py
+++ b/src/bonsai/test/bim/module/drawing/test_gizmos.py
@@ -24,7 +24,11 @@ from types import SimpleNamespace
 import bpy
 import pytest
 
-from bonsai.bim.module.drawing.gizmos import DimensionGizmoConfig
+from bonsai.bim.module.drawing.gizmos import (
+    BaseParametricGizmoGroup,
+    BaseSchematicGizmoGroup,
+    DimensionGizmoConfig,
+)
 
 pytestmark = pytest.mark.drawing
 
@@ -52,3 +56,19 @@ def test_text_formatter_receives_props_and_value():
     config = DimensionGizmoConfig(attr_name="length", axis=(1, 0, 0), text_formatter=formatter)
     props = SimpleNamespace(label="L")
     assert config.text_formatter(props, 3.14) == "L=3.14"
+
+
+def test_parametric_base_enables_dimension_snap_by_default():
+    """In-place parametric gizmos align to real-world geometry, so dragging
+    must respect the global snap toggle (Ctrl-flip during drag) — same
+    contract every door / window / wall / stair / roof / mep dimension
+    has shipped with."""
+    assert BaseParametricGizmoGroup.snap_enabled_on_dimensions is True
+
+
+def test_schematic_base_disables_dimension_snap():
+    """Schematic dimensions float in viewport space; snapping the dragged
+    tip to scene vertices would produce spurious value jumps as the
+    mouse crosses unrelated geometry. The opt-out lives on the base so
+    every schematic subclass inherits it without per-class wiring."""
+    assert BaseSchematicGizmoGroup.snap_enabled_on_dimensions is False
diff --git a/src/bonsai/test/bim/module/model/test_railing_lifecycle.py b/src/bonsai/test/bim/module/model/test_railing_lifecycle.py
new file mode 100644
index 0000000000..0aad3534b7
--- /dev/null
+++ b/src/bonsai/test/bim/module/model/test_railing_lifecycle.py
@@ -0,0 +1,300 @@
+# Bonsai - OpenBIM Blender Add-on
+# Copyright (C) 2026
+#
+# This file is part of Bonsai.
+#
+# Bonsai is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# Bonsai is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with Bonsai.  If not, see <http://www.gnu.org/licenses/>.
+#
+# This file was generated with the assistance of an AI coding tool.
+
+"""Unit coverage for the ``_RailingEditMixin`` overrides and the lifecycle
+behaviour railing inherits from ``PathPreservingEditMixin``.
+
+The parent short-circuit (skip the IFC commit / viewport rebuild when the
+draft is identical to the stored pset) lives in
+``PathPreservingEditMixin``; the tests below verify railing's subclass
+honours that contract by inheritance, then pin the railing-specific
+viewport-restore dispatch:
+
+- Finish / Cancel no-op short-circuit: inherited from the parent — verified
+  here because railing was the original consumer that motivated the
+  optimisation.
+- ``_RailingEditMixin._restore_viewport_after_cancel`` dispatch: WALL_MOUNTED_HANDRAIL
+  reloads the high-poly Body representation via ``switch_representation``;
+  FRAMELESS_PANEL rebuilds the bmesh preview via
+  ``update_railing_modifier_bmesh``. This is the per-type branch that used
+  to live in ``_cancel_one`` and now lives in the viewport-restore hook the
+  parent's ``_cancel_one`` calls.
+"""
+
+from unittest import mock
+
+import pytest
+
+from test.bim.conftest import _FakePropsBase
+from test.bim.conftest import make_lifecycle_obj as _make_obj
+
+pytestmark = pytest.mark.model
+
+
+# ---------------------------------------------------------------------------
+# Helpers
+# ---------------------------------------------------------------------------
+
+
+class _FakeRailingProps(_FakePropsBase):
+    """Stand-in for ``BIMRailingProperties`` — adds ``railing_type`` on top of
+    the shared parametric-edit contract. Starts in ``is_editing=True`` because
+    the railing-specific overrides under test only fire on Finish / Cancel,
+    not on Enable."""
+
+    def __init__(self, railing_type: str = "WALL_MOUNTED_HANDRAIL", general: dict | None = None):
+        super().__init__(general=general if general is not None else {"railing_type": railing_type, "height": 1.0})
+        self.railing_type = railing_type
+        self.is_editing = True
+
+
+@pytest.fixture
+def patched_railing():
+    """Patch the railing module's external references for unit testing.
+
+    ``_RailingEditMixin`` and the parent lifecycle reach for
+    ``tool.Model.get_modeling_bbim_pset_data``, ``tool.Ifc.get_entity``,
+    ``ifcopenshell.util.representation.get_representation``,
+    ``bonsai.core.geometry.switch_representation``, and the module-level
+    ``update_railing_modifier_bmesh`` — each looked up through the railing
+    module's own bindings, so we patch them there.
+
+    ``parametric_lifecycle.tool`` is patched separately so the parent's
+    ``_resolve`` and ``_cancel_one`` can read ``tool.Model.get_modeling_bbim_pset_data``
+    without falling through to the real Blender bindings.
+
+    Uses ``mock.patch.object`` with a direct module reference rather than
+    the dotted-string form: ``mock.patch("bonsai.bim.module.model.railing.bonsai")``
+    needs ``pkgutil.resolve_name`` to traverse ``bonsai → bim → module → …``,
+    which fails at the ``bonsai.bim`` step until that subpackage has been
+    imported elsewhere. The direct-object form sidesteps the resolution.
+
+    Returns a dict for tests to seed return values and assert call sites.
+    """
+    from bonsai.bim import parametric_lifecycle
+    from bonsai.bim.module.model import railing
+
+    with (
+        mock.patch.object(railing, "tool") as mock_tool,
+        mock.patch.object(railing, "ifcopenshell") as mock_ifc,
+        mock.patch.object(railing, "bonsai") as mock_bonsai,
+        mock.patch.object(railing, "update_railing_modifier_bmesh") as mock_update_bmesh,
+        mock.patch.object(parametric_lifecycle, "tool") as mock_pl_tool,
+    ):
+        # _resolve will be overridden on the test subclass below so the
+        # parametric_lifecycle.tool patch isn't needed for that path, but the
+        # parent's _cancel_one / _finish_one still call
+        # tool.Model.get_modeling_bbim_pset_data and would otherwise miss.
+        mock_tool.Ifc.get_entity.return_value = mock.Mock(name="entity")
+        yield {
+            "tool": mock_tool,
+            "ifcopenshell": mock_ifc,
+            "bonsai": mock_bonsai,
+            "update_bmesh": mock_update_bmesh,
+            "pl_tool": mock_pl_tool,
+        }
+
+
+def _railing_test_subclass(props):
+    """Build a ``_RailingEditMixin`` subclass that bypasses ``_resolve``.
+
+    The base ``_resolve`` reads ``tool.Ifc.get_entity`` from
+    ``parametric_lifecycle.tool`` (a separate import from the railing
+    module's ``tool``). Overriding it here keeps the test patches local
+    to the railing module and the hook closures local to the test."""
+    from bonsai.bim.module.model.railing import _RailingEditMixin
+
+    test_element = mock.Mock(name="ifc_element")
+
+    class _TestRailingMixin(_RailingEditMixin):
+        pset_updates: mock.MagicMock = mock.MagicMock(name="_update_pset")
+        ifc_data_updates: mock.MagicMock = mock.MagicMock(name="_update_modifier_ifc_data")
+        bmesh_updates: mock.MagicMock = mock.MagicMock(name="_restore_viewport_after_cancel")
+
+        @classmethod
+        def _resolve(cls, obj):
+            return test_element, props
+
+        @classmethod
+        def _update_pset(cls, element, data):
+            cls.pset_updates(element, data)
+
+        @classmethod
+        def _update_modifier_ifc_data(cls, obj, context):
+            cls.ifc_data_updates(obj, context)
+
+        @classmethod
+        def _restore_viewport_after_cancel(cls, obj, context):
+            cls.bmesh_updates(obj, context)
+
+        # The base _post_load_data JSON-serialises path_data; bypass that
+        # here so the round-trip stays a plain dict and tests can compare
+        # by reference / equality without re-parsing.
+        @classmethod
+        def _post_load_data(cls, data):
+            return dict(data)
+
+    return _TestRailingMixin, test_element
+
+
+# ---------------------------------------------------------------------------
+# _RailingEditMixin._finish_one
+# ---------------------------------------------------------------------------
+
+
+def test_finish_one_short_circuits_when_draft_matches_stored(patched_railing):
+    """Enable → Finish without any property edit must NOT write to IFC.
+
+    Without this, every "open Edit, click Validate immediately" cycle
+    would create a fresh ``IfcShapeRepresentation``, pollute the file's
+    representation list, and burn an undo entry — the user-visible
+    regression that motivated the short-circuit.
+
+    Behaviour now inherited from ``PathPreservingEditMixin``; railing keeps
+    the coverage as the original consumer of the contract.
+    """
+    stored = {"railing_type": "WALL_MOUNTED_HANDRAIL", "height": 1.0}
+    props = _FakeRailingProps(general=dict(stored))
+    obj = _make_obj(props)
+    patched_railing["pl_tool"].Model.get_modeling_bbim_pset_data.return_value = {
+        "data_dict": {**stored, "path_data": {"verts": [], "edges": []}},
+    }
+
+    cls, _element = _railing_test_subclass(props)
+    cls._finish_one(obj, mock.Mock(name="context"))
+
+    assert props.is_editing is False, "is_editing must still flip even on no-op"
+    cls.pset_updates.assert_not_called()
+    cls.ifc_data_updates.assert_not_called()
+
+
+def test_finish_one_writes_when_draft_differs(patched_railing):
+    """The complement of the short-circuit: a real property change must
+    flow through to ``_update_pset`` + ``_update_modifier_ifc_data``."""
+    stored = {"railing_type": "WALL_MOUNTED_HANDRAIL", "height": 1.0}
+    # Draft height differs: simulating a user edit.
+    props = _FakeRailingProps(general={"railing_type": "WALL_MOUNTED_HANDRAIL", "height": 1.5})
+    obj = _make_obj(props)
+    patched_railing["pl_tool"].Model.get_modeling_bbim_pset_data.return_value = {
+        "data_dict": {**stored, "path_data": {"verts": [], "edges": []}},
+    }
+
+    cls, element = _railing_test_subclass(props)
+    cls._finish_one(obj, mock.Mock(name="context"))
+
+    assert props.is_editing is False
+    cls.pset_updates.assert_called_once()
+    # The pset must receive the DRAFT data, not the stored data — that's the
+    # whole point of Finish committing the user's edits.
+    written = cls.pset_updates.call_args[0][1]
+    assert written["height"] == 1.5
+    cls.ifc_data_updates.assert_called_once_with(obj, mock.ANY)
+
+
+# ---------------------------------------------------------------------------
+# _RailingEditMixin._cancel_one
+# ---------------------------------------------------------------------------
+
+
+def test_cancel_one_short_circuits_when_draft_matches_stored(patched_railing):
+    """Cancel-without-changes is asymmetrically expensive without this guard:
+    ``switch_representation`` re-tessellates the IfcSweptDiskSolid and is
+    visibly slow on a long handrail. When nothing changed, the mesh on
+    screen is still the committed IFC representation (the preview only
+    builds on a property change) — skip the reload entirely.
+
+    Behaviour now inherited from ``PathPreservingEditMixin``; railing keeps
+    the coverage as the original consumer of the contract.
+    """
+    stored = {"railing_type": "WALL_MOUNTED_HANDRAIL", "height": 1.0}
+    props = _FakeRailingProps(general=dict(stored))
+    obj = _make_obj(props)
+    patched_railing["pl_tool"].Model.get_modeling_bbim_pset_data.return_value = {
+        "data_dict": {**stored, "path_data": {"verts": [], "edges": []}},
+    }
+
+    cls, _element = _railing_test_subclass(props)
+    cls._cancel_one(obj, mock.Mock(name="context"))
+
+    assert props.is_editing is False
+    patched_railing["bonsai"].core.geometry.switch_representation.assert_not_called()
+    patched_railing["update_bmesh"].assert_not_called()
+    cls.bmesh_updates.assert_not_called()
+
+
+# ---------------------------------------------------------------------------
+# _RailingEditMixin._restore_viewport_after_cancel — per-type viewport-restore dispatch
+#
+# The parent's _cancel_one calls cls._restore_viewport_after_cancel whenever
+# the draft differs from the stored pset. Railing's override branches on
+# railing_type so WALL_MOUNTED_HANDRAIL reloads the high-poly Body
+# representation rather than rebuilding the low-poly cylinder-segment preview.
+# ---------------------------------------------------------------------------
+
+
+def test_restore_viewport_wall_mounted_handrail_switches_representation(patched_railing):
+    """WALL_MOUNTED_HANDRAIL restore must call ``switch_representation`` with
+    the Body representation — the preview is viewport-only (low-poly cylinder)
+    and would persist visibly without the reload."""
+    from bonsai.bim.module.model.railing import _RailingEditMixin
+
+    props = _FakeRailingProps(railing_type="WALL_MOUNTED_HANDRAIL")
+    obj = _make_obj(props)
+    patched_railing["tool"].Model.get_railing_props.return_value = props
+    body_repr = mock.Mock(name="body_representation")
+    patched_railing["ifcopenshell"].util.representation.get_representation.return_value = body_repr
+
+    _RailingEditMixin._restore_viewport_after_cancel(obj, mock.Mock(name="context"))
+
+    patched_railing["bonsai"].core.geometry.switch_representation.assert_called_once()
+    kwargs = patched_railing["bonsai"].core.geometry.switch_representation.call_args.kwargs
+    assert kwargs["obj"] is obj
+    assert kwargs["representation"] is body_repr
+    # Must NOT fall through to the FRAMELESS bmesh-rebuild path.
+    patched_railing["update_bmesh"].assert_not_called()
+
+
+def test_restore_viewport_frameless_panel_calls_module_bmesh_rebuild(patched_railing):
+    """FRAMELESS_PANEL's bmesh IS the canonical mesh — there's no IFC
+    swept-disk solid to reload. The restore must delegate to the module-level
+    ``update_railing_modifier_bmesh`` rebuilder rather than swap representations."""
+    from bonsai.bim.module.model.railing import _RailingEditMixin
+
+    props = _FakeRailingProps(railing_type="FRAMELESS_PANEL")
+    obj = _make_obj(props)
+    patched_railing["tool"].Model.get_railing_props.return_value = props
+    ctx = mock.Mock(name="context")
+
+    _RailingEditMixin._restore_viewport_after_cancel(obj, ctx)
+
+    patched_railing["update_bmesh"].assert_called_once_with(ctx)
+    patched_railing["bonsai"].core.geometry.switch_representation.assert_not_called()
+
+
+# ---------------------------------------------------------------------------
+# _get_railing_path_anchor: tests removed.
+#
+# The schematic-redesign branch replaced ``GizmoRailingEdition`` with
+# ``GizmoRailingSchematic``, which anchors via the schematic frame rather
+# than the polyline's first vertex. ``_get_railing_path_anchor`` was the
+# helper for the old anchor strategy and has been deleted along with the
+# old gizmo group. If schematic-mode gains a similar path-derived helper,
+# new tests should land here.
+# ---------------------------------------------------------------------------
diff --git a/src/bonsai/test/bim/module/model/test_railing_schematic.py b/src/bonsai/test/bim/module/model/test_railing_schematic.py
new file mode 100644
index 0000000000..7ba12a7a70
--- /dev/null
+++ b/src/bonsai/test/bim/module/model/test_railing_schematic.py
@@ -0,0 +1,270 @@
+# Bonsai - OpenBIM Blender Add-on
+# Copyright (C) 2026
+#
+# This file is part of Bonsai.
+#
+# Bonsai is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# Bonsai is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with Bonsai.  If not, see <http://www.gnu.org/licenses/>.
+#
+# This file was generated with the assistance of an AI coding tool.
+
+import types
+from types import SimpleNamespace
+
+import bmesh
+import bpy
+import pytest
+
+from bonsai import tool
+from bonsai.bim.module.drawing.gizmos import (
+    BaseSchematicGizmoGroup,
+    DimensionGizmoConfig,
+)
+from bonsai.bim.module.model.railing import GizmoRailingSchematic
+
+pytestmark = pytest.mark.model
+
+
+@pytest.fixture(autouse=True)
+def _require_real_bpy():
+    """Skip the file when ``bpy`` is mocked or absent.
+
+    Without this guard, mis-routed test runs (e.g. ``pytest test/bim/...``
+    invoked outside Blender) crash at module-collection time on the chain of
+    ``bonsai.tool`` imports below, instead of producing a clean ``skipped``.
+    """
+    if not isinstance(bpy, types.ModuleType) or hasattr(bpy, "_mock_name"):
+        pytest.skip("requires real Blender (bpy is mocked or absent)")
+
+
+# ── Class shape ──────────────────────────────────────────────────────────────
+
+
+def test_railing_schematic_inherits_base():
+    """GizmoRailingSchematic plugs into the schematic framework, not the
+    in-place dimension framework. If a future refactor breaks this lineage
+    the schematic-specific machinery (sliders, draw handler) silently goes
+    dormant."""
+    assert issubclass(GizmoRailingSchematic, BaseSchematicGizmoGroup)
+
+
+def test_railing_schematic_bl_idname_preserved():
+    """``OBJECT_GGT_bim_railing_edition`` is the user-facing identifier and
+    is referenced by keymaps and persistence. Preserve it across the class
+    rename — see the migration note in the class docstring."""
+    assert GizmoRailingSchematic.bl_idname == "OBJECT_GGT_bim_railing_edition"
+
+
+def test_railing_schematic_props_getter_pairing():
+    """``gizmo_pref_name = "railing"`` and ``props_getter = tool.Model.get_railing_props``
+    are the pairing test_parametric_registry depends on. If either drifts,
+    the addon-preferences gizmo toggle silently stops controlling this group."""
+    assert GizmoRailingSchematic.gizmo_pref_name == "railing"
+    assert GizmoRailingSchematic.props_getter == tool.Model.get_railing_props
+
+
+def test_railing_schematic_disables_in_place_dimension_props():
+    """The schematic owns the value-input surface — no in-place dimensions on the actual geometry."""
+    assert GizmoRailingSchematic.dimension_gizmo_props == []
+
+
+# ── Dimension configuration ─────────────────────────────────────────────────
+
+
+def test_railing_schematic_has_six_dimensions():
+    """One dimension per parametric property — three for each railing_type."""
+    assert len(GizmoRailingSchematic.schematic_dimension_props) == 6
+
+
+def test_railing_schematic_dimension_attr_names_complete():
+    """The six bound attributes match the parametric properties that
+    ``update_railing_modifier_bmesh`` reads when regenerating the live preview."""
+    attr_names = {c.attr_name for c in GizmoRailingSchematic.schematic_dimension_props}
+    assert attr_names == {
+        "height",
+        "thickness",
+        "spacing",
+        "railing_diameter",
+        "clear_width",
+        "support_spacing",
+    }
+
+
+def test_railing_schematic_dimensions_are_dimension_configs():
+    """The dimension-line aesthetic depends on ``DimensionGizmoConfig`` (with
+    arrows + label), not the abstract slider widget."""
+    for config in GizmoRailingSchematic.schematic_dimension_props:
+        assert isinstance(config, DimensionGizmoConfig)
+
+
+def test_railing_schematic_dimensions_have_text_formatters():
+    """Each dimension must format the label from the actual property value,
+    not from the visually-scaled value the gizmo's getter returns. Without a
+    formatter the label would show the schematic-scaled length, which is
+    meaningless to the user."""
+    for config in GizmoRailingSchematic.schematic_dimension_props:
+        assert config.text_formatter is not None, f"{config.attr_name} missing text_formatter"
+
+
+@pytest.mark.parametrize(
+    "attr_name,railing_type,expected",
+    [
+        ("height", "FRAMELESS_PANEL", True),
+        ("height", "WALL_MOUNTED_HANDRAIL", False),
+        ("thickness", "FRAMELESS_PANEL", True),
+        ("spacing", "FRAMELESS_PANEL", True),
+        ("railing_diameter", "WALL_MOUNTED_HANDRAIL", True),
+        ("railing_diameter", "FRAMELESS_PANEL", False),
+        ("clear_width", "WALL_MOUNTED_HANDRAIL", True),
+    ],
+)
+def test_railing_schematic_dimension_visibility_gated_by_railing_type(attr_name, railing_type, expected):
+    """The two railing types are mutually exclusive — height/thickness/spacing
+    belong to FRAMELESS_PANEL; railing_diameter/clear_width/support_spacing
+    belong to WALL_MOUNTED_HANDRAIL. The visibility lambdas enforce that."""
+    config = next(c for c in GizmoRailingSchematic.schematic_dimension_props if c.attr_name == attr_name)
+    props = SimpleNamespace(railing_type=railing_type, use_manual_supports=False)
+    assert config.visibility_condition(props) is expected
+
+
+def test_railing_schematic_support_spacing_hidden_for_manual_supports():
+    """``support_spacing`` only drives auto-positioned supports — when the
+    user has switched to manual supports the dimension should disappear."""
+    config = next(c for c in GizmoRailingSchematic.schematic_dimension_props if c.attr_name == "support_spacing")
+    auto = SimpleNamespace(railing_type="WALL_MOUNTED_HANDRAIL", use_manual_supports=False)
+    manual = SimpleNamespace(railing_type="WALL_MOUNTED_HANDRAIL", use_manual_supports=True)
+    assert config.visibility_condition(auto) is True
+    assert config.visibility_condition(manual) is False
+
+
+# ── Fixed-length tag rendering ─────────────────────────────────────────────
+
+
+def test_schematic_dim_visible_length_is_constant():
+    """Every schematic dimension tag renders at the same width — the bar is a
+    UI affordance, not a proportional measurement. The constant ratio keeps
+    tiny (5 mm thickness) and huge (5 m height) values equally clickable; the
+    real value lives in the dimension label.
+
+    Regression guard: if value-proportional scaling is reintroduced, this
+    contract breaks silently — small dimensions start collapsing into stacked
+    arrows again.
+    """
+    cls = GizmoRailingSchematic
+    ratio = cls.SCHEMATIC_DIM_VISIBLE_LENGTH_RATIO
+    assert ratio > 0
+    assert ratio <= 1.0  # bar must fit within the schematic box
+
+
+def test_schematic_no_compute_schematic_scale_override():
+    """The constant-length schematic must not reintroduce scale-based
+    proportional sizing via a ``_compute_schematic_scale`` override."""
+    assert "_compute_schematic_scale" not in GizmoRailingSchematic.__dict__
+
+
+# ── Path-edit guard ─────────────────────────────────────────────────────────
+
+
+def test_update_editing_gizmos_override_defined_on_subclass():
+    """``GizmoRailingSchematic`` must own the override that hides the pen
+    icon during path-edit. The parent's version shows the pen whenever
+    ``is_editing`` is False, which includes path-edit; that would let the
+    user open two editing modes at once."""
+    assert "update_editing_gizmos" in GizmoRailingSchematic.__dict__
+
+
+# ── Schematic mesh building ─────────────────────────────────────────────────
+
+
+def test_build_schematic_mesh_frameless_panel_returns_bmesh_with_edges():
+    """FRAMELESS_PANEL renders as two separated wireframe boxes — 8 corners
+    per box × 2 = 16 verts; 12 edges per box × 2 = 24 edges. The visible
+    gap between the two boxes is the "spacing" semantic made literal.
+
+    The mesh proportions are fixed (independent of property values) so the
+    dimension gizmos can anchor to known feature positions; the property
+    values are shown through dimension labels, not the mesh size."""
+    props = SimpleNamespace(
+        railing_type="FRAMELESS_PANEL",
+        height=1.0,
+        thickness=0.05,
+        spacing=0.5,
+    )
+    bm = GizmoRailingSchematic.build_schematic_mesh(props)
+    try:
+        assert isinstance(bm, bmesh.types.BMesh)
+        assert len(bm.verts) == 16
+        assert len(bm.edges) == 24
+    finally:
+        bm.free()
+
+
+def test_build_schematic_mesh_wall_mounted_handrail_returns_bmesh_with_edges():
+    """WALL_MOUNTED_HANDRAIL renders as three visual elements:
+
+    - **Wall outline** — 4 corner verts, 4 edges (rectangle at z=0).
+    - **Hex tube** — 12 verts (6 per ring × 2 ends), 18 edges
+      (6 left ring + 6 right ring + 6 axial).
+    - **L-brackets** at each rail end — 3 verts per bracket (rail centre,
+      corner, wall attach) × 2 brackets = 6 verts; 2 edges per bracket
+      (rail→corner, corner→wall) × 2 = 4 edges.
+
+    Total: 22 verts, 26 edges.
+    """
+    props = SimpleNamespace(
+        railing_type="WALL_MOUNTED_HANDRAIL",
+        railing_diameter=0.05,
+        clear_width=0.04,
+        support_spacing=1.0,
+    )
+    bm = GizmoRailingSchematic.build_schematic_mesh(props)
+    try:
+        assert isinstance(bm, bmesh.types.BMesh)
+        assert len(bm.verts) == 22
+        assert len(bm.edges) == 26
+    finally:
+        bm.free()
+
+
+def test_build_schematic_mesh_proportions_independent_of_props():
+    """The mesh uses fixed proportions so dimension gizmo anchor points stay
+    aligned with the geometry — extreme prop ratios don't change the mesh."""
+    small = SimpleNamespace(railing_type="FRAMELESS_PANEL", height=0.01, thickness=0.005, spacing=0.05)
+    large = SimpleNamespace(railing_type="FRAMELESS_PANEL", height=10.0, thickness=0.5, spacing=2.0)
+    bm_small = GizmoRailingSchematic.build_schematic_mesh(small)
+    bm_large = GizmoRailingSchematic.build_schematic_mesh(large)
+    try:
+        # Same vert count regardless of prop magnitude.
+        assert len(bm_small.verts) == len(bm_large.verts)
+        # Same bounding box in each axis (within floating-point noise).
+        for axis in range(3):
+            small_coords = [v.co[axis] for v in bm_small.verts]
+            large_coords = [v.co[axis] for v in bm_large.verts]
+            assert min(small_coords) == pytest.approx(min(large_coords))
+            assert max(small_coords) == pytest.approx(max(large_coords))
+    finally:
+        bm_small.free()
+        bm_large.free()
+
+
+def test_build_schematic_mesh_panel_top_matches_height_frac():
+    """The panel's top edge sits at exactly ``SCHEMATIC_MESH_HEIGHT_FRAC``,
+    which is also where the ``thickness`` dimension anchors above the box.
+    If this drifts, the dimension labels float disconnected from the mesh."""
+    props = SimpleNamespace(railing_type="FRAMELESS_PANEL", height=1.0, thickness=0.05, spacing=0.3)
+    bm = GizmoRailingSchematic.build_schematic_mesh(props)
+    try:
+        max_y = max(v.co.y for v in bm.verts)
+        assert max_y == pytest.approx(GizmoRailingSchematic.SCHEMATIC_MESH_HEIGHT_FRAC)
+    finally:
+        bm.free()