From f0754ec7f006c67573b799f2fd0776cc0f821353 Mon Sep 17 00:00:00 2001
From: Sam Goldman <samgoldman@meta.com>
Date: Wed, 23 Sep 2026 10:58:50 -0700
Subject: [PATCH] GH-51474: [Python][Annotations] Add pyrefly check to CI

Run pyrefly alongside mypy, pyright, and ty in
ci/scripts/python_test_type_annotations.sh, with a [tool.pyrefly] section in
python/pyproject.toml that mirrors the existing checkers (check only
pyarrow-stubs, resolve pyarrow from pyarrow-stubs first, Python 3.11), and
document it in the developer guide.
---
 ci/scripts/python_test_type_annotations.sh    |  3 ++-
 docs/source/developers/python/development.rst | 11 +++++++++++
 python/pyproject.toml                         | 13 +++++++++++++
 3 files changed, 26 insertions(+), 1 deletion(-)

diff --git a/ci/scripts/python_test_type_annotations.sh b/ci/scripts/python_test_type_annotations.sh
index 092bedf3f5ea..9c4ca3dd9731 100755
--- a/ci/scripts/python_test_type_annotations.sh
+++ b/ci/scripts/python_test_type_annotations.sh
@@ -29,10 +29,11 @@ fi
 pip install fsspec pandas-stubs scipy-stubs types-cffi types-psutil types-requests types-python-dateutil
 
 # Install type checkers
-pip install mypy pyright ty
+pip install mypy pyrefly pyright ty
 
 # Run type checkers
 cd "${pyarrow_dir}"
 mypy
 pyright --stats
 ty check --verbose --output-format concise
+pyrefly check --summarize-errors
diff --git a/docs/source/developers/python/development.rst b/docs/source/developers/python/development.rst
index 91f98cab060b..a6fdf4d1c2f2 100644
--- a/docs/source/developers/python/development.rst
+++ b/docs/source/developers/python/development.rst
@@ -145,6 +145,17 @@ To run ty (note: currently only partially configured):
    $ cd arrow/python
    $ ty check
 
+**pyrefly**
+
+To run pyrefly:
+
+.. code-block::
+
+   $ cd arrow/python
+   $ pyrefly check
+
+The pyrefly configuration is in the ``[tool.pyrefly]`` section of ``pyproject.toml``.
+
 Maintaining Type Stubs
 -----------------------
 
diff --git a/python/pyproject.toml b/python/pyproject.toml
index 68c1a807dd51..f98ed3fed899 100644
--- a/python/pyproject.toml
+++ b/python/pyproject.toml
@@ -137,6 +137,19 @@ exclude = [
 stubPath = "pyarrow-stubs"
 typeCheckingMode = "basic"
 
+# TODO: Enable type checking once stubs are merged
+[tool.pyrefly]
+project-includes = ["pyarrow-stubs"]
+project-excludes = [
+    "pyarrow",
+    "benchmarks",
+    "examples",
+    "scripts",
+    "build",
+]
+search-path = ["pyarrow-stubs"]
+python-version = "3.11"
+
 # TODO: Enable type checking once stubs are merged
 [tool.ty.environment]
 extra-paths = ["pyarrow-stubs"]