breaking: drop Python 3.9 (#5078)

Python 3.9 has gone to EOL. NumPy, TensorFlow, PyTorch, and JAX have
removed Python 3.9 support.

---------

Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>

Author: njzjz

.github/workflows/test_python.yml

@@ -19,7 +19,7 @@ jobs:
       fail-fast: false
       matrix:
         group: [1, 2, 3, 4, 5, 6]
-        python: ["3.9", "3.12"]
+        python: ["3.10", "3.12"]
 
     steps:
     - uses: actions/checkout@v6
@@ -85,7 +85,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        python: ["3.9", "3.12"]
+        python: ["3.10", "3.12"]
     needs: testpython
     steps:
     - name: Get durations from cache

AGENTS.md

@@ -94,7 +94,7 @@ source/               # C++ source code and tests
 
 ### Build Dependencies and Setup
 
-- **Python 3.9+** required
+- **Python 3.10+** required
 - **Virtual environment** strongly recommended: `uv venv venv && source venv/bin/activate`
 - **Backend dependencies**: TensorFlow, PyTorch, JAX, or Paddle (install before building)
 - **Build tools**: CMake, C++ compiler, scikit-build-core

backend/dynamic_metadata.py

@@ -3,9 +3,6 @@
 from pathlib import (
     Path,
 )
-from typing import (
-    Optional,
-)
 
 from .find_pytorch import (
     get_pt_requirement,
@@ -31,7 +28,7 @@ def __dir__() -> list[str]:
 
 def dynamic_metadata(
     field: str,
-    settings: Optional[dict[str, object]] = None,
+    settings: dict[str, object] | None = None,
 ):
     assert field in ["optional-dependencies", "entry-points", "scripts"]
     _, _, find_libpython_requires, extra_scripts, tf_version, pt_version = (

backend/find_paddle.py

@@ -17,14 +17,10 @@
 from sysconfig import (
     get_path,
 )
-from typing import (
-    Optional,
-    Union,
-)
 
 
 @lru_cache
-def find_paddle() -> tuple[Optional[str], list[str]]:
+def find_paddle() -> tuple[str | None, list[str]]:
     """Find PaddlePadle library.
 
     Tries to find PaddlePadle in the order of:
@@ -111,7 +107,7 @@ def get_pd_requirement(pd_version: str = "") -> dict:
 
 
 @lru_cache
-def get_pd_version(pd_path: Optional[Union[str, Path]]) -> str:
+def get_pd_version(pd_path: str | Path | None) -> str:
     """Get Paddle version from a Paddle Python library path.
 
     Parameters

backend/find_pytorch.py

@@ -17,10 +17,6 @@
 from sysconfig import (
     get_path,
 )
-from typing import (
-    Optional,
-    Union,
-)
 
 from packaging.specifiers import (
     SpecifierSet,
@@ -35,7 +31,7 @@
 
 
 @lru_cache
-def find_pytorch() -> tuple[Optional[str], list[str]]:
+def find_pytorch() -> tuple[str | None, list[str]]:
     """Find PyTorch library.
 
     Tries to find PyTorch in the order of:
@@ -150,7 +146,7 @@ def get_pt_requirement(pt_version: str = "") -> dict:
 
 
 @lru_cache
-def get_pt_version(pt_path: Optional[Union[str, Path]]) -> str:
+def get_pt_version(pt_path: str | Path | None) -> str:
     """Get TF version from a TF Python library path.
 
     Parameters

backend/find_tensorflow.py

@@ -17,10 +17,6 @@
 from sysconfig import (
     get_path,
 )
-from typing import (
-    Optional,
-    Union,
-)
 
 from packaging.specifiers import (
     SpecifierSet,
@@ -32,7 +28,7 @@
 
 
 @lru_cache
-def find_tensorflow() -> tuple[Optional[str], list[str]]:
+def find_tensorflow() -> tuple[str | None, list[str]]:
     """Find TensorFlow library.
 
     Tries to find TensorFlow in the order of:
@@ -208,7 +204,7 @@ def get_tf_requirement(tf_version: str = "") -> dict:
 
 
 @lru_cache
-def get_tf_version(tf_path: Optional[Union[str, Path]]) -> str:
+def get_tf_version(tf_path: str | Path | None) -> str:
     """Get TF version from a TF Python library path.
 
     Parameters

deepmd/backend/backend.py

@@ -2,13 +2,15 @@
 from abc import (
     abstractmethod,
 )
+from collections.abc import (
+    Callable,
+)
 from enum import (
     Flag,
     auto,
 )
 from typing import (
     TYPE_CHECKING,
-    Callable,
     ClassVar,
 )
 

deepmd/backend/dpmodel.py

@@ -1,7 +1,9 @@
 # SPDX-License-Identifier: LGPL-3.0-or-later
+from collections.abc import (
+    Callable,
+)
 from typing import (
     TYPE_CHECKING,
-    Callable,
     ClassVar,
 )
 

deepmd/backend/jax.py

@@ -1,10 +1,12 @@
 # SPDX-License-Identifier: LGPL-3.0-or-later
+from collections.abc import (
+    Callable,
+)
 from importlib.util import (
     find_spec,
 )
 from typing import (
     TYPE_CHECKING,
-    Callable,
     ClassVar,
 )
 

deepmd/backend/paddle.py

@@ -1,10 +1,12 @@
 # SPDX-License-Identifier: LGPL-3.0-or-later
+from collections.abc import (
+    Callable,
+)
 from importlib.util import (
     find_spec,
 )
 from typing import (
     TYPE_CHECKING,
-    Callable,
     ClassVar,
 )