统一 2D/3D 深度色条为同一量程。

将 2D 闩锁的深度色彩区间推给 3D 自动着色，固定量程仍跟旋钮。用 test_shared_depth_scale 与深度闩锁冒烟用例验证。

apps/studio/tests/test_shared_depth_scale.py

@@ -0,0 +1,62 @@
+"""2D and 3D depth colour bars name one interval."""
+
+from __future__ import annotations
+
+from types import SimpleNamespace
+
+import numpy as np
+from orisys_app_shared.scene3d.contracts import FieldDescriptor
+from orisys_studio.scene3d.gl_backend import _field_scalar_range
+
+
+def _field(quantity: str, values, *, signed: bool = False) -> SimpleNamespace:
+    arr = np.asarray(values, dtype=np.float32)
+    return SimpleNamespace(
+        descriptor=FieldDescriptor(quantity, "1", "approximate", signed),
+        scalar=arr,
+        valid=np.isfinite(arr),
+    )
+
+
+def test_depth_automatic_scale_uses_the_shared_2d_span() -> None:
+    field = _field("depth_response", np.linspace(0.0, 9.0, 16).reshape(4, 4))
+    assert _field_scalar_range(
+        field,
+        previous=(0.0, 2.0),
+        shared_depth_scale=(0.0, 1.0),
+    ) == (0.0, 1.0)
+
+
+def test_flow_ignores_the_shared_depth_span() -> None:
+    field = _field("flow_magnitude", np.linspace(0.0, 9.0, 16).reshape(4, 4))
+    span = _field_scalar_range(
+        field,
+        previous=None,
+        shared_depth_scale=(0.0, 1.0),
+    )
+    assert span is not None
+    assert span != (0.0, 1.0)
+    assert span[1] > span[0]
+
+
+def test_depth_without_a_shared_span_still_measures_the_field() -> None:
+    field = _field("depth_response", np.linspace(0.0, 9.0, 16).reshape(4, 4))
+    span = _field_scalar_range(
+        field,
+        previous=None,
+        shared_depth_scale=None,
+    )
+    assert span is not None
+    assert span[0] == 0.0
+    assert span[1] > 1.0
+
+
+def test_a_degenerate_shared_span_falls_back_to_the_measurement() -> None:
+    field = _field("depth_response", np.linspace(0.0, 9.0, 16).reshape(4, 4))
+    span = _field_scalar_range(
+        field,
+        previous=None,
+        shared_depth_scale=(1.0, 1.0),
+    )
+    assert span is not None
+    assert span != (1.0, 1.0)