Fixed. The issue was that _merge_frames and _merge_secondary_y_frames weren't preserving the layout property of animation frames (which contains range_y).

  Changes:
  - figures.py: Added layout=base_frame.layout to go.Frame() in both merge functions
  - test_figures.py: Added 2 new tests for frame layout preservation

Author: FBumann

tests/test_figures.py

@@ -232,6 +232,20 @@ def test_frame_names_preserved(self) -> None:
         combined_names = {frame.name for frame in combined.frames}
         assert original_names == combined_names
 
+    def test_frame_layout_preserved(self) -> None:
+        """Test that frame layout (e.g., axis range) is preserved."""
+        fig = xpx(self.da_3d).line(animation_frame="time", range_y=[0, 10])
+        overlay_fig = xpx(self.da_3d).scatter(animation_frame="time")
+
+        # Verify base has frame layout
+        assert fig.frames[0].layout is not None
+
+        combined = overlay(fig, overlay_fig)
+
+        # Frame layout should be preserved
+        for i, frame in enumerate(combined.frames):
+            assert frame.layout == fig.frames[i].layout
+
 
 class TestOverlayFacetsAndAnimation:
     """Tests for overlay with both facets and animation."""
@@ -560,6 +574,20 @@ def test_mismatched_animation_frames_raises(self) -> None:
         with pytest.raises(ValueError, match="frame names don't match"):
             add_secondary_y(fig1, fig2)
 
+    def test_frame_layout_preserved(self) -> None:
+        """Test that frame layout (e.g., axis range) is preserved."""
+        base = xpx(self.da_2d).line(animation_frame="time", range_y=[0, 10])
+        secondary = xpx(self.da_2d).bar(animation_frame="time")
+
+        # Verify base has frame layout
+        assert base.frames[0].layout is not None
+
+        combined = add_secondary_y(base, secondary)
+
+        # Frame layout should be preserved
+        for i, frame in enumerate(combined.frames):
+            assert frame.layout == base.frames[i].layout
+
 
 class TestAddSecondaryYDeepCopy:
     """Tests to ensure add_secondary_y creates deep copies."""

xarray_plotly/figures.py

@@ -142,6 +142,7 @@ def _merge_frames(
                 data=merged_data,
                 name=frame_name,
                 traces=list(range(base_trace_count + sum(overlay_trace_counts))),
+                layout=base_frame.layout,
             )
         )
 
@@ -403,6 +404,7 @@ def _merge_secondary_y_frames(
                 data=merged_data,
                 name=frame_name,
                 traces=list(range(base_trace_count + secondary_trace_count)),
+                layout=base_frame.layout,
             )
         )