feat: show default node/element names in table

src/otko/core/__init__.py

@@ -35,6 +35,7 @@ from otko.core.geometry import (
     DispBeamColumn,
     ElasticBeamColumn,
     Element,
+    ElementBase,
     ForceBeamColumn,
     GridLine,
     GridSystem,
@@ -114,6 +115,7 @@ __all__ = [
     "ensure_default_truss_material",
     "ensure_default_timeseries_and_pattern",
     "Element",
+    "ElementBase",
     "TrussElement",
     "CorotTrussElement",
     "ElasticBeamColumn",

src/otko/core/_base.py

@@ -16,11 +16,31 @@ class Entity(BaseModel):
     """Base class for every persisted domain object."""
 
     model_config = ConfigDict(
-        frozen=False,            # individual setters allowed; we lock at the Project boundary
-        extra="forbid",          # unknown JSON keys are an error, not a silent ignore
+        frozen=False,  # individual setters allowed; we lock at the Project boundary
+        extra="forbid",  # unknown JSON keys are an error, not a silent ignore
         validate_assignment=True,
         populate_by_name=True,
     )
 
-    id: PositiveInt = Field(..., description="Unique tag within its kind. Used as the OpenSees tag.")
+    id: PositiveInt = Field(
+        ..., description="Unique tag within its kind. Used as the OpenSees tag."
+    )
     name: str = Field(default="", description="Optional human-readable label.")
+
+    @property
+    def default_name(self) -> str:
+        """Fallback label used when ``name`` is blank.
+
+        Display-only — reading it never writes back into ``name`` and it
+        is never persisted. Subclasses override this with their prefix
+        (e.g. ``N<id>`` for nodes, ``E<id>`` for elements).
+        """
+        return ""
+
+    @property
+    def display_name(self) -> str:
+        """Explicit ``name`` stripped, or ``default_name`` when blank.
+
+        Display-only fallback — reading this never mutates ``name``.
+        """
+        return self.name.strip() or self.default_name

src/otko/core/geometry/__init__.py

@@ -6,6 +6,7 @@ from otko.core.geometry.elements import (
     DispBeamColumn,
     ElasticBeamColumn,
     Element,
+    ElementBase,
     ForceBeamColumn,
     QuadElement,
     TrussElement,
@@ -25,6 +26,7 @@ from otko.core.geometry.node import Node
 __all__ = [
     "Node",
     "Element",
+    "ElementBase",
     "TrussElement",
     "CorotTrussElement",
     "ElasticBeamColumn",

src/otko/core/geometry/elements.py

@@ -17,7 +17,21 @@ from pydantic import Field, PositiveFloat, PositiveInt
 from otko.core._base import Entity
 
 
-class TrussElement(Entity):
+class ElementBase(Entity):
+    """Shared base for all structural elements.
+
+    Carries the display-only ``E<id>`` fallback label so every element
+    type (including Quad) shows the same default name on the canvas
+    and in the table without persisting it into ``name``.
+    """
+
+    @property
+    def default_name(self) -> str:
+        """Fallback label for unnamed elements (``E<id>``)."""
+        return f"E{self.id}"
+
+
+class TrussElement(ElementBase):
     """Two-node truss with axial stiffness only — ``element truss``."""
 
     type: Literal["Truss"] = "Truss"
@@ -27,7 +41,7 @@ class TrussElement(Entity):
     rho: float = Field(default=0.0, ge=0.0, description="Mass per unit length.")
 
 
-class CorotTrussElement(Entity):
+class CorotTrussElement(ElementBase):
     """Co-rotational truss for large displacements — ``element corotTruss``."""
 
     type: Literal["CorotTruss"] = "CorotTruss"
@@ -37,7 +51,7 @@ class CorotTrussElement(Entity):
     rho: float = Field(default=0.0, ge=0.0)
 
 
-class ElasticBeamColumn(Entity):
+class ElasticBeamColumn(ElementBase):
     """Linear-elastic frame element — ``element elasticBeamColumn``.
 
     Pure-section style: provide section_id; OpenSees pulls EA, EI from
@@ -60,7 +74,7 @@ class ElasticBeamColumn(Entity):
     )
 
 
-class ForceBeamColumn(Entity):
+class ForceBeamColumn(ElementBase):
     """Force-based fibre frame element — ``element forceBeamColumn``."""
 
     type: Literal["ForceBeamColumn"] = "ForceBeamColumn"
@@ -72,7 +86,7 @@ class ForceBeamColumn(Entity):
     tolerance: float = Field(default=1e-12, gt=0.0)
 
 
-class DispBeamColumn(Entity):
+class DispBeamColumn(ElementBase):
     """Displacement-based fibre frame element — ``element dispBeamColumn``."""
 
     type: Literal["DispBeamColumn"] = "DispBeamColumn"
@@ -82,7 +96,7 @@ class DispBeamColumn(Entity):
     geom_transf: Literal["Linear", "PDelta", "Corotational"] = "Linear"
 
 
-class ZeroLengthElement(Entity):
+class ZeroLengthElement(ElementBase):
     """Two coincident nodes connected by uniaxial materials per DOF.
 
     Foundation building block for plastic hinges and isolators.
@@ -91,7 +105,9 @@ class ZeroLengthElement(Entity):
     type: Literal["ZeroLength"] = "ZeroLength"
     nodes: tuple[PositiveInt, PositiveInt]
     material_ids: tuple[PositiveInt, ...] = Field(..., min_length=1)
-    dofs: tuple[int, ...] = Field(..., min_length=1, description="DOF directions, 1-indexed (1..6).")
+    dofs: tuple[int, ...] = Field(
+        ..., min_length=1, description="DOF directions, 1-indexed (1..6)."
+    )
     do_rayleigh: bool = Field(
         default=False,
         description=(
@@ -104,7 +120,7 @@ class ZeroLengthElement(Entity):
     )
 
 
-class ZeroLengthSectionElement(Entity):
+class ZeroLengthSectionElement(ElementBase):
     """Two coincident nodes connected by a full :class:`Section` —
     OpenSees ``element zeroLengthSection``.
 
@@ -121,10 +137,12 @@ class ZeroLengthSectionElement(Entity):
 
     type: Literal["ZeroLengthSection"] = "ZeroLengthSection"
     nodes: tuple[PositiveInt, PositiveInt]
-    section_id: PositiveInt = Field(..., description="Section attached to the two coincident nodes.")
+    section_id: PositiveInt = Field(
+        ..., description="Section attached to the two coincident nodes."
+    )
 
 
-class BeamWithHingesElement(Entity):
+class BeamWithHingesElement(ElementBase):
     """Force-based beam with lumped plasticity at both ends —
     ``element beamWithHinges``.
 
@@ -156,7 +174,7 @@ class BeamWithHingesElement(Entity):
     geom_transf: Literal["Linear", "PDelta", "Corotational"] = "Linear"
 
 
-class QuadElement(Entity):
+class QuadElement(ElementBase):
     """Four-node 2D quadrilateral (plane-stress / plane-strain) —
     ``element quad`` / ``bbarQuad`` / ``enhancedQuad``.
 
@@ -179,7 +197,8 @@ class QuadElement(Entity):
         description="Surface pressure applied over the element (force / area).",
     )
     rho: float = Field(
-        default=0.0, ge=0.0,
+        default=0.0,
+        ge=0.0,
         description="Mass density override (kip·s²/in⁴). Leave 0 to use material rho.",
     )
     b1: float = Field(

src/otko/core/geometry/node.py

@@ -33,6 +33,11 @@ class Node(Entity):
     mass: Mass6 = (0.0, 0.0, 0.0, 0.0, 0.0, 0.0)
     restraint: Restraint6 = (False, False, False, False, False, False)
 
+    @property
+    def default_name(self) -> str:
+        """Fallback label for unnamed nodes (``N<id>``)."""
+        return f"N{self.id}"
+
     @property
     def is_restrained(self) -> bool:
         """True if any DOF is fixed."""

src/otko/views/canvas3d/model_renderer.py

@@ -1140,9 +1140,7 @@ class ModelRenderer:
         if self._node_pd is None or len(project.nodes) == 0:
             return None
         pts = np.asarray(self._node_pd.points)
-        labels = [
-            (node.name.strip() if node.name.strip() else f"N{node.id}") for node in project.nodes
-        ]
+        labels = [node.display_name for node in project.nodes]
         return self._plotter.add_point_labels(
             pts,
             labels,
@@ -1170,7 +1168,7 @@ class ModelRenderer:
             if i is None or j is None:
                 continue
             centers.append((pts[i] + pts[j]) / 2.0)
-            labels.append(el.name.strip() if el.name.strip() else f"E{el.id}")
+            labels.append(el.display_name)
         if not centers:
             return None
         return self._plotter.add_point_labels(

src/otko/views/docks/table_dock.py

@@ -492,7 +492,7 @@ class TableDock(QWidget):
         table.setRowCount(len(nodes))
         for r, n in enumerate(nodes):
             self._put(table, r, 0, str(n.id), editable=False, data=n.id)
-            self._put(table, r, 1, n.name, data=n.id)
+            self._put(table, r, 1, n.display_name, data=n.id)
             for c, v in enumerate(n.coords, start=2):
                 self._put(table, r, c, f"{v:g}", data=n.id)
             for c, v in enumerate(n.mass, start=5):
@@ -506,6 +506,12 @@ class TableDock(QWidget):
         nid = self._row_key(table, row)
         node = project.node(nid)
         if col == 1:
+            if not node.name.strip() and item.text().strip() == node.display_name:
+                # Confirmed the displayed fallback unchanged — not a real
+                # rename, so leave the stored name blank instead of
+                # persisting "N<id>" (and keep it off the undo stack).
+                self.refresh()
+                return
             updated = self._dry_run(node, {"name": item.text()})
             self._dispatch(UpdateNodeFieldsCommand(vm, nid, {"name": updated.name}))
         elif 2 <= col <= 4:
@@ -537,7 +543,7 @@ class TableDock(QWidget):
         table.setRowCount(len(elements))
         for r, el in enumerate(elements):
             self._put(table, r, 0, str(el.id), editable=False, data=el.id)
-            self._put(table, r, 1, el.name, data=el.id)
+            self._put(table, r, 1, el.display_name, data=el.id)
             self._put(table, r, 2, el.type, editable=False, data=el.id)
             self._put(table, r, 3, ", ".join(str(n) for n in el.nodes), data=el.id)
             self._put(
@@ -583,6 +589,12 @@ class TableDock(QWidget):
         eid = self._row_key(table, row)
         el = project.element(eid)
         if col == 1:
+            if not el.name.strip() and item.text().strip() == el.display_name:
+                # Confirmed the displayed fallback unchanged — not a real
+                # rename, so leave the stored name blank instead of
+                # persisting "E<id>" (and keep it off the undo stack).
+                self.refresh()
+                return
             updated = self._dry_run(el, {"name": item.text()})
             self._dispatch(UpdateElementFieldsCommand(vm, eid, {"name": updated.name}))
         elif col == 3:

tests/unit/test_display_name.py

@@ -0,0 +1,93 @@
+"""Unit tests for the display-only ``display_name`` fallback on entities."""
+
+from __future__ import annotations
+
+from otko.core import (
+    BeamWithHingesElement,
+    CorotTrussElement,
+    DispBeamColumn,
+    ElasticBeamColumn,
+    ElementBase,
+    ForceBeamColumn,
+    Node,
+    QuadElement,
+    TrussElement,
+    ZeroLengthElement,
+    ZeroLengthSectionElement,
+)
+from otko.core._base import Entity
+
+_ALL_ELEMENT_TYPES = (
+    TrussElement,
+    CorotTrussElement,
+    ElasticBeamColumn,
+    ForceBeamColumn,
+    DispBeamColumn,
+    ZeroLengthElement,
+    ZeroLengthSectionElement,
+    BeamWithHingesElement,
+    QuadElement,
+)
+
+
+class TestEntityBase:
+    def test_base_fallback_is_empty(self) -> None:
+        e = Entity(id=1)
+        assert e.default_name == ""
+        assert e.display_name == ""
+
+    def test_display_name_is_not_persisted(self) -> None:
+        assert "display_name" not in Entity(id=1).model_dump()
+        assert "default_name" not in Entity(id=1).model_dump()
+        assert "display_name" not in Node(id=1, coords=(0, 0, 0)).model_dump()
+
+
+class TestNodeDisplayName:
+    def test_blank_name_falls_back(self) -> None:
+        n = Node(id=1, coords=(0, 0, 0))
+        assert n.display_name == "N1"
+
+    def test_explicit_name_is_returned(self) -> None:
+        n = Node(id=1, name="Support A", coords=(0, 0, 0))
+        assert n.display_name == "Support A"
+
+    def test_whitespace_only_name_falls_back(self) -> None:
+        n = Node(id=2, name="   ", coords=(0, 0, 0))
+        assert n.display_name == "N2"
+
+    def test_explicit_name_is_stripped(self) -> None:
+        n = Node(id=1, name="  A1  ", coords=(0, 0, 0))
+        assert n.display_name == "A1"
+
+    def test_display_only_never_writes_back(self) -> None:
+        n = Node(id=1, coords=(0, 0, 0))
+        assert n.display_name == "N1"
+        assert n.name == ""
+
+
+class TestElementDisplayName:
+    def test_all_element_types_share_element_base(self) -> None:
+        for cls in _ALL_ELEMENT_TYPES:
+            assert issubclass(cls, ElementBase)
+
+    def test_blank_truss_name_falls_back(self) -> None:
+        t = TrussElement(id=1, nodes=(1, 2), area=0.01, material_id=1)
+        assert t.display_name == "E1"
+
+    def test_explicit_truss_name_is_returned(self) -> None:
+        t = TrussElement(id=1, name="Chord", nodes=(1, 2), area=0.01, material_id=1)
+        assert t.display_name == "Chord"
+
+    def test_whitespace_only_truss_name_falls_back(self) -> None:
+        t = TrussElement(id=3, name="  ", nodes=(1, 2), area=0.01, material_id=1)
+        assert t.display_name == "E3"
+
+    def test_blank_quad_name_falls_back(self) -> None:
+        q = QuadElement(id=1, nodes=(1, 2, 3, 4), thickness=0.1, material_id=1)
+        assert q.display_name == "E1"
+
+    def test_display_only_never_writes_back(self) -> None:
+        t = TrussElement(id=1, nodes=(1, 2), area=0.01, material_id=1)
+        assert t.display_name == "E1"
+        assert t.name == ""
+        assert "display_name" not in t.model_dump()