Add Python 3.14 support (pytorch#20452)

### Summary
Raise requires-python upper bound from <3.14 to <3.15 and add 3.14 to
wheel build matrices and the pull request test matrix.

coremltools has no cp314 wheels yet, so its dependency gets a
python_version < '3.14' marker — the CoreML backend is unavailable on
3.14 until Apple ships compatible wheels. scikit-learn is loosened from
==1.7.1 to >=1.7.1 since 1.7.2+ has cp314 wheels.

Bump black from 24.4.2 to 26.3.0 so the linter recognizes py314 as a
valid target-version in pyproject.toml.

Fixes pytorch#16750

This PR was authored with Claude.

### Test Plan
- Built portable_lib, data_loader, selective_build, _llm_runner
pybinding targets — all compiled clean on Python 3.13/macOS
- Verified black 26.3.0 recognizes py314 target-version
- lintrunner passes with updated black
- Full CI validation on Python 3.14 will run via the updated wheel build
and pull.yml workflows

Author: rascani

.claude/skills/building/SKILL.md

@@ -23,17 +23,16 @@ conda activate executorch
 
 **Path B — no conda (fall back to venv):**
 ```bash
-# Find a compatible Python (3.10–3.13). On macOS with only Homebrew Python 3.14+,
-# install a compatible version first: brew install python@3.12
-python3.12 -m venv .executorch-venv   # or python3.11, python3.10, python3.13
+# Find a compatible Python (3.10–3.14).
+python3.12 -m venv .executorch-venv   # or python3.11, python3.10, python3.13, python3.14
 source .executorch-venv/bin/activate
 pip install --upgrade pip
 ```
 
 **Then verify (either path):**
 
 Run `python --version` and `cmake --version`. Fix automatically:
-- **Python not 3.10–3.13**: recreate the env with a correct Python version.
+- **Python not 3.10–3.14**: recreate the env with a correct Python version.
 - **cmake missing or < 3.24**: run `pip install 'cmake>=3.24'` inside the env.
 - **cmake >= 4.0**: works in practice, no action needed.
 

.github/workflows/build-wheels-aarch64-linux.yml

@@ -30,7 +30,7 @@ jobs:
       test-infra-ref: main
       with-cuda: disabled
       with-rocm: disabled
-      python-versions: '["3.10", "3.11", "3.12", "3.13"]'
+      python-versions: '["3.10", "3.11", "3.12", "3.13", "3.14"]'
 
   build:
     needs: generate-matrix

.github/workflows/build-wheels-linux.yml

@@ -30,7 +30,7 @@ jobs:
       test-infra-ref: main
       with-cuda: disabled
       with-rocm: disabled
-      python-versions: '["3.10", "3.11", "3.12", "3.13"]'
+      python-versions: '["3.10", "3.11", "3.12", "3.13", "3.14"]'
 
   build:
     needs: generate-matrix

.github/workflows/build-wheels-macos.yml

@@ -30,7 +30,7 @@ jobs:
       test-infra-ref: main
       with-cuda: disabled
       with-rocm: disabled
-      python-versions: '["3.10", "3.11", "3.12", "3.13"]'
+      python-versions: '["3.10", "3.11", "3.12", "3.13", "3.14"]'
 
   build:
     needs: generate-matrix

.github/workflows/build-wheels-windows.yml

@@ -33,7 +33,7 @@ jobs:
       test-infra-ref: main
       with-cuda: disabled
       with-rocm: disabled
-      python-versions: '["3.10", "3.11", "3.12", "3.13"]'
+      python-versions: '["3.10", "3.11", "3.12", "3.13", "3.14"]'
 
   build:
     needs: generate-matrix

pyproject.toml

@@ -51,9 +51,10 @@ classifiers = [
     "Programming Language :: Python :: 3.11",
     "Programming Language :: Python :: 3.12",
     "Programming Language :: Python :: 3.13",
+    "Programming Language :: Python :: 3.14",
 ]
 
-requires-python = ">=3.10,<3.14"
+requires-python = ">=3.10,<3.15"
 
 # Runtime dependencies are declared dynamically (see `dynamic` above) and
 # computed in setup.py, so the EXECUTORCH_BUILD_MINIMAL wheel can ship a slimmer
@@ -139,7 +140,7 @@ first_party_detection = false
 # Emit syntax compatible with older versions of python instead of only the range
 # specified by `requires-python`. TODO: Remove this once we support these older
 # versions of python and can expand the `requires-python` range.
-target-version = ["py38", "py39", "py310", "py311", "py312", "py313"]
+target-version = ["py38", "py39", "py310", "py311", "py312", "py313", "py314"]
 
 [tool.docformatter]
 black = true

requirements-lintrunner.txt

@@ -9,7 +9,7 @@ pycodestyle==2.11.1
 torchfix==0.6.0
 
 # UFMT
-black==24.4.2
+black==26.3.0
 ufmt==2.8.0
 usort==1.0.8.post1
 

setup.py

@@ -192,9 +192,9 @@ def _base_dependencies() -> List[str]:
         # See also third-party/TARGETS for buck's typing-extensions version.
         "typing-extensions>=4.10.0",
         # Keep this version in sync with: ./backends/apple/coreml/scripts/install_requirements.sh
-        "coremltools==9.0; platform_system == 'Darwin' or platform_system == 'Linux'",
+        "coremltools==9.0; (platform_system == 'Darwin' or platform_system == 'Linux') and python_version < '3.14'",
         # scikit-learn is used to support palettization in the coreml backend.
-        "scikit-learn==1.7.1",
+        "scikit-learn>=1.7.1",
         "hydra-core>=1.3.0",
         "omegaconf>=2.3.0",
     ]