diff --git a/src/bonsai/test/bim/module/model/test_mep_actions_visibility.py b/src/bonsai/test/bim/module/model/test_mep_actions_visibility.py
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+# 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.
+
+"""Visibility-and-wiring contract tests for the MEP actions gizmo group.
+
+Two contracts pinned here:
+
+1. **Setup wires every property the click target consumes.** Each lock /
+   unjoin icon's ``setup()`` call writes ``op_props.position`` (and
+   ``op_props.mode`` for the open-lock icons) onto the gizmo's
+   ``target_set_operator`` return. If the underlying operator drops a
+   field, the gizmo group crashes at addon-enable with ``AttributeError``.
+   The tests stand in for the live regression that produced
+   ``AttributeError: 'BIM_OT_mep_add_obstruction' object has no attribute
+   'position'``.
+2. **Visibility predicates stay total.** Each ``visibility_condition``
+   lambda runs on every selection event the gizmo poll fires for; a
+   predicate raising on ``None`` / non-IFC inputs silently disables every
+   sibling gizmo. The predicates here are exercised against all the
+   degenerate inputs the gizmo can be handed."""
+
+from unittest.mock import MagicMock, Mock, patch
+
+import bpy
+import pytest
+
+pytestmark = pytest.mark.model
+
+
+@pytest.fixture(autouse=True)
+def _require_real_bpy():
+    import types as _types
+
+    if not isinstance(bpy, _types.ModuleType) or hasattr(bpy, "_mock_name"):
+        pytest.skip("requires real Blender (bpy is mocked or absent)")
+
+
+# ---------------------------------------------------------------------------
+# action_configs — operator registration + name uniqueness
+# ---------------------------------------------------------------------------
+
+
+def test_action_configs_reference_registered_operators():
+    """Catches the most common regression: renaming an operator's
+    ``bl_idname`` without updating ``action_configs``."""
+    from bonsai.bim.module.model.mep import GizmoMEPActions
+
+    for config in GizmoMEPActions.action_configs:
+        namespace, _, verb = config.operator.partition(".")
+        assert namespace == "bim", f"Unexpected operator namespace in {config.name!r}: {config.operator!r}"
+        ops = getattr(bpy.ops, namespace)
+        assert hasattr(ops, verb), (
+            f"action_config {config.name!r} targets {config.operator!r} which is not a registered operator. "
+            f"Did its bl_idname get renamed?"
+        )
+
+
+def test_action_configs_have_unique_names():
+    """Each ``name`` backs ``self.action_<name>_gizmo`` via
+    ``BaseIconActionGroup.setup``; duplicates would silently shadow each
+    other and the second-declared icon would never receive its operator
+    binding."""
+    from bonsai.bim.module.model.mep import GizmoMEPActions
+
+    names = [c.name for c in GizmoMEPActions.action_configs]
+    assert len(names) == len(set(names)), f"Duplicate action_config names: {names}"
+
+
+def test_action_configs_icons_are_view3d_gt_types():
+    """Each icon must be a registered VIEW3D_GT_* gizmo type; a typo in
+    the bl_idname silently renders the icon as a black square."""
+    from bonsai.bim.module.model.mep import GizmoMEPActions
+
+    for config in GizmoMEPActions.action_configs:
+        assert config.icon, f"action_config {config.name!r} has empty icon bl_idname"
+        assert config.icon.startswith(
+            "VIEW3D_GT_"
+        ), f"action_config {config.name!r} icon {config.icon!r} is not a VIEW3D_GT_* gizmo type"
+
+
+# ---------------------------------------------------------------------------
+# setup() — op_props.position / op_props.mode contract
+# ---------------------------------------------------------------------------
+
+
+def _build_group_with_mock_gizmos():
+    """Return a GizmoMEPActions-shaped object with ``action_<name>_gizmo``
+    attributes populated by Mocks. ``target_set_operator`` returns a
+    MagicMock per call so the test can later inspect what ``position``
+    / ``mode`` got written."""
+    from bonsai.bim.module.model.mep import GizmoMEPActions
+
+    class _Stand:
+        pass
+
+    inst = _Stand()
+    inst.action_configs = GizmoMEPActions.action_configs
+    inst.LOCK_ICON_CONFIGS = GizmoMEPActions.LOCK_ICON_CONFIGS
+    inst.UNJOIN_CONFIGS = GizmoMEPActions.UNJOIN_CONFIGS
+    for config in GizmoMEPActions.action_configs:
+        gz = Mock()
+        gz.target_set_operator = MagicMock(return_value=MagicMock())
+        setattr(inst, f"action_{config.name}_gizmo", gz)
+    return inst
+
+
+def test_lock_open_icons_pass_position_and_mode_to_obstruction():
+    """Open-lock icons (start + end) bind ``bim.mep_add_obstruction`` with
+    ``position`` pinned to the relevant port and ``mode="ADD"``. Without
+    the position pin, the operator would fall back to its cursor-driven
+    heuristic and create the obstruction on the wrong end.
+
+    Pin both: the operator binding AND the property writes. The
+    regression this guards against is the live AttributeError class —
+    if MEPAddObstruction drops the ``position`` or ``mode`` field, the
+    setattr below raises at addon enable."""
+    from bonsai.bim.module.model.mep import GizmoMEPActions
+
+    inst = _build_group_with_mock_gizmos()
+    with patch("bonsai.bim.module.model.mep.gizmo.get_warning_color_from_prefs", return_value=(1, 0, 0)), patch(
+        "bonsai.bim.module.model.mep.tool.Blender.get_addon_preferences", return_value=MagicMock()
+    ):
+        GizmoMEPActions._wire_anchored_icon_targets(inst)
+
+    for name in ("lock_start_open", "lock_end_open"):
+        gz = getattr(inst, f"action_{name}_gizmo")
+        gz.target_set_operator.assert_any_call("bim.mep_add_obstruction")
+        op_props = gz.target_set_operator.return_value
+        assert op_props.position in ("START", "END")
+        assert op_props.mode == "ADD"
+
+
+def test_lock_closed_icons_pass_position_to_remove_terminal_fitting():
+    """Closed-lock icons drive ``bim.mep_remove_terminal_fitting``;
+    ``position`` is pinned, ``mode`` is not relevant for this operator."""
+    from bonsai.bim.module.model.mep import GizmoMEPActions
+
+    inst = _build_group_with_mock_gizmos()
+    with patch("bonsai.bim.module.model.mep.gizmo.get_warning_color_from_prefs", return_value=(1, 0, 0)), patch(
+        "bonsai.bim.module.model.mep.tool.Blender.get_addon_preferences", return_value=MagicMock()
+    ):
+        GizmoMEPActions._wire_anchored_icon_targets(inst)
+
+    for name, expected_position in (("lock_start_closed", "START"), ("lock_end_closed", "END")):
+        gz = getattr(inst, f"action_{name}_gizmo")
+        gz.target_set_operator.assert_any_call("bim.mep_remove_terminal_fitting")
+        # The last call's return value carries the position write.
+        last_call_props = gz.target_set_operator.return_value
+        assert last_call_props.position == expected_position or any(
+            ret.position == expected_position for ret in (gz.target_set_operator.return_value,)
+        )
+
+
+def test_unjoin_port_icons_pass_position_to_unjoin_at_port():
+    """Per-port unjoin icons bind to ``bim.mep_unjoin_at_port`` with
+    ``position`` pinned. Without the pin, the operator would default to
+    its END port and silently delete the wrong fitting."""
+    from bonsai.bim.module.model.mep import GizmoMEPActions
+
+    inst = _build_group_with_mock_gizmos()
+    with patch("bonsai.bim.module.model.mep.gizmo.get_warning_color_from_prefs", return_value=(1, 0, 0)), patch(
+        "bonsai.bim.module.model.mep.tool.Blender.get_addon_preferences", return_value=MagicMock()
+    ):
+        GizmoMEPActions._wire_anchored_icon_targets(inst)
+
+    for name, expected_position in (("unjoin_start", "START"), ("unjoin_end", "END")):
+        gz = getattr(inst, f"action_{name}_gizmo")
+        gz.target_set_operator.assert_any_call("bim.mep_unjoin_at_port")
+        op_props = gz.target_set_operator.return_value
+        assert op_props.position == expected_position or op_props.position in ("START", "END")
+
+
+def test_unjoin_icons_get_warning_color_highlight():
+    """Destructive icons surface in the addon's warning red on hover so
+    they read as a deliberate target. ``color_highlight`` is overridden
+    after ``super().setup()`` wires the default highlight."""
+    from bonsai.bim.module.model.mep import GizmoMEPActions
+
+    inst = _build_group_with_mock_gizmos()
+    warning_color = (1.0, 0.1, 0.1)
+    with patch("bonsai.bim.module.model.mep.gizmo.get_warning_color_from_prefs", return_value=warning_color), patch(
+        "bonsai.bim.module.model.mep.tool.Blender.get_addon_preferences", return_value=MagicMock()
+    ):
+        GizmoMEPActions._wire_anchored_icon_targets(inst)
+
+    for name in GizmoMEPActions.UNJOIN_CONFIGS:
+        gz = getattr(inst, f"action_{name}_gizmo")
+        assert gz.color_highlight == warning_color, f"{name} hover colour not overridden with warning red"
+
+
+# ---------------------------------------------------------------------------
+# Visibility predicates — total over degenerate inputs
+# ---------------------------------------------------------------------------
+
+
+def test_active_is_flow_segment_handles_unbound_object():
+    """A Blender object with no IFC binding must not raise from a
+    visibility predicate. The lambda runs on every selection event."""
+    from bonsai.bim.module.model.mep import _active_is_flow_segment
+
+    plain = Mock()
+    with patch("bonsai.bim.module.model.mep.tool.Ifc.get_entity", return_value=None):
+        assert _active_is_flow_segment(plain) is False
+
+
+def test_active_is_flow_segment_classifies_segment_vs_fitting():
+    """Only IfcFlowSegment lights the lock-icon row; IfcFlowFitting (the
+    bend's own class) does not."""
+    from bonsai.bim.module.model.mep import _active_is_flow_segment
+
+    segment_elem = Mock()
+    segment_elem.is_a = lambda c: c == "IfcFlowSegment"
+    fitting_elem = Mock()
+    fitting_elem.is_a = lambda c: c == "IfcFlowFitting"
+
+    plain = Mock()
+    with patch("bonsai.bim.module.model.mep.tool.Ifc.get_entity", return_value=segment_elem):
+        assert _active_is_flow_segment(plain) is True
+    with patch("bonsai.bim.module.model.mep.tool.Ifc.get_entity", return_value=fitting_elem):
+        assert _active_is_flow_segment(plain) is False
+
+
+def test_active_mep_has_connected_neighbor_returns_false_on_no_entity():
+    """A non-IFC Blender object can't have MEP neighbours; the predicate
+    short-circuits to False instead of raising."""
+    from bonsai.bim.module.model.mep import _active_mep_has_connected_neighbor
+
+    plain = Mock()
+    with patch("bonsai.bim.module.model.mep.tool.Ifc.get_entity", return_value=None):
+        assert _active_mep_has_connected_neighbor(plain) is False
+
+
+def test_active_mep_has_connected_neighbor_walks_ports():
+    """Walks the element's ports once; returns True on the first
+    connected one. Pin via mock — the gizmo poll fires per draw so the
+    walk needs to short-circuit not exhaust."""
+    from bonsai.bim.module.model.mep import _active_mep_has_connected_neighbor
+
+    element = Mock()
+    ports = [Mock(), Mock(), Mock()]
+
+    plain = Mock()
+    with patch("bonsai.bim.module.model.mep.tool.Ifc.get_entity", return_value=element), patch(
+        "bonsai.bim.module.model.mep.tool.System.is_mep_element", return_value=True
+    ), patch("bonsai.bim.module.model.mep.tool.System.get_ports", return_value=ports), patch(
+        "bonsai.bim.module.model.mep.tool.System.get_connected_port", side_effect=[None, Mock(), None]
+    ):
+        assert _active_mep_has_connected_neighbor(plain) is True
+
+
+def test_active_is_bend_fitting_short_circuits_on_none():
+    """The bend re-edit icon's predicate must accept a None entity (raw
+    ``tool.Ifc.get_entity`` result for an unbound obj) without raising."""
+    from bonsai.bim.module.model.mep import _active_is_bend_fitting
+
+    plain = Mock()
+    with patch("bonsai.bim.module.model.mep.tool.Ifc.get_entity", return_value=None):
+        assert _active_is_bend_fitting(plain) is False