chore(dpa4): clear CodeQL notes/warning (cyclic-import, unnecessary-delete, import-and-import-from)

- Break the base_model<->dpa4_native_spin_model static import cycle by making
  the BaseModel import lazy inside deserialize (its only use).
- Drop an unnecessary 'del keepalive' at end of a test.
- Align a mixed 'import module' with the file's 'import from' style.
Leaves only the py/inheritance/signature-mismatch warnings, a pre-existing
repo-wide pattern on descriptor .call() overrides (present on unmodified
descriptors too).

Author: Han Wang

deepmd/dpmodel/model/dpa4_native_spin_model.py

@@ -12,13 +12,14 @@
 from deepmd.dpmodel.common import (
     NativeOP,
 )
-from deepmd.dpmodel.model.base_model import (
-    BaseModel,
-)
 from deepmd.dpmodel.output_def import (
     FittingOutputDef,
     ModelOutputDef,
 )
+
+# NOTE: ``BaseModel`` is imported lazily inside ``deserialize`` (its only use).
+# ``base_model`` dispatches to this module in its own ``deserialize``, so a
+# top-level import here would form a static import cycle (py/cyclic-import).
 from deepmd.utils.spin import (
     Spin,
 )
@@ -264,6 +265,12 @@ def serialize(self) -> dict:
 
     @classmethod
     def deserialize(cls, data: dict) -> "DPA4NativeSpinModel":
+        # Lazy import to avoid a static import cycle with ``base_model`` (which
+        # dispatches to this module in its own ``deserialize``).
+        from deepmd.dpmodel.model.base_model import (
+            BaseModel,
+        )
+
         data = data.copy()
         data.pop("@class", None)
         data.pop("@version", None)

source/tests/pt_expt/model/test_dpa4_graph_lower.py

@@ -220,7 +220,6 @@ def test_dpa4_exchange_border_op_self_communication() -> None:
     torch.testing.assert_close(out[:nlocal], x_in[:nlocal])  # owned untouched
     for gi, owner in enumerate(owners):
         torch.testing.assert_close(out[nlocal + gi], x_in[int(owner)])
-    del keepalive
 
 
 def test_dpa4_exchange_schedule_counts() -> None:
@@ -242,7 +241,7 @@ def test_dpa4_exchange_schedule_counts() -> None:
     ``use_env_seed`` attributes below, not hardcoded (it would differ for a
     fixture with an SO2-free block, which this one does not have).
     """
-    import deepmd.pt_expt.descriptor.dpa4_nn.block as blk_mod
+    from deepmd.pt_expt.descriptor.dpa4_nn import block as blk_mod
 
     device = env.DEVICE
     dd = _make_message_sensitive_model(device).atomic_model.descriptor