From a1966ddd6eeca5d25781b1f88bdf4d6f16b8abea Mon Sep 17 00:00:00 2001
From: zacharyburnett <zburnett@stsci.edu>
Date: Tue, 23 Jun 2026 14:22:35 -0400
Subject: [PATCH 1/6] py_limited_api

---
 pyproject.toml | 4 ++++
 setup.py       | 5 +++++
 2 files changed, 9 insertions(+)

diff --git a/pyproject.toml b/pyproject.toml
index 92fea03..346041a 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -37,6 +37,10 @@ requires = [
 ]
 build-backend = "setuptools.build_meta"
 
+[tool.cibuildwheel]
+build = "cp311-*"  # build for CPython 3.11 Stable API
+skip = ["cp314t-*"]  # explicitly skip free-threaded builds
+
 [tool.setuptools]
 include-package-data = false
 
diff --git a/setup.py b/setup.py
index 4c74b93..f7062e3 100755
--- a/setup.py
+++ b/setup.py
@@ -23,6 +23,9 @@ def c_includes(parent: str, depth: int = 1):
 PACKAGENAME = "calcos"
 SOURCES = c_sources("src")
 INCLUDES = c_includes("src") + [numpy_includes()]
+MACROS = [
+    ("Py_LIMITED_API", 0x030B0000),  # PY_VERSION_HEX for 3.11
+]
 
 
 setup(
@@ -31,6 +34,8 @@ def c_includes(parent: str, depth: int = 1):
             PACKAGENAME + ".ccos",
             sources=SOURCES,
             include_dirs=INCLUDES,
+            define_macros=MACROS,
+            py_limited_api=True,
         ),
     ],
 )

From c2456f737570e4b2da9cf5a312a8b1d132f2f11f Mon Sep 17 00:00:00 2001
From: zacharyburnett <zburnett@stsci.edu>
Date: Tue, 30 Jun 2026 16:02:15 -0400
Subject: [PATCH 2/6] use template build workflow

---
 .github/workflows/build.yml | 77 +++++++++++++++++++++++++++++--------
 pyproject.toml              |  1 +
 2 files changed, 61 insertions(+), 17 deletions(-)

diff --git a/.github/workflows/build.yml b/.github/workflows/build.yml
index a51954b..5c3fb72 100644
--- a/.github/workflows/build.yml
+++ b/.github/workflows/build.yml
@@ -1,28 +1,71 @@
 name: build
 
 on:
-  release:
-    types: [ released ]
   pull_request:
+  release:
+    types: [released]
   workflow_dispatch:
 
 concurrency:
-  group: ${{ github.workflow }}-${{ github.ref }}
+  group: ${{ github.workflow }}-${{ github.event.pull_request.number || github.ref }}
   cancel-in-progress: true
 
+permissions: {}
+
 jobs:
   build:
-    uses: OpenAstronomy/github-actions-workflows/.github/workflows/publish.yml@9f1fedda61294df4c004c05519a3fbf3b8e1f32f # v2.3.1
-    with:
-      targets: |
-        # Linux wheels
-        - cp3*-manylinux_x86_64
-        # MacOS wheels
-        - cp3*-macosx_x86_64
-        # Until we have arm64 runners, we can't automatically test arm64 wheels
-        - cp3*-macosx_arm64
-      sdist: true
-      test_command: python -c "from calcos import ccos"
-      upload_to_pypi: ${{ (github.event_name == 'release') && (github.event.action == 'released') }}
-    secrets:
-      pypi_token: ${{ secrets.PYPI_PASSWORD_STSCI_MAINTAINER }}
+    strategy:
+      matrix:
+        runs-on:
+          - ubuntu-latest
+          - macos-latest
+    runs-on: ${{ matrix.runs-on }}
+    steps:
+      - uses: actions/checkout@9c091bb21b7c1c1d1991bb908d89e4e9dddfe3e0 # v7.0.0
+        with:
+          fetch-tags: true
+          fetch-depth: 0
+          persist-credentials: false
+      - uses: actions/setup-python@ece7cb06caefa5fff74198d8649806c4678c61a1 # v6.3.0
+        with:
+          python-version: "3"
+      - if: ${{ runner.os == 'Linux' }}
+        uses: docker/setup-qemu-action@96fe6ef7f33517b61c61be40b68a1882f3264fb8 # v4.2.0
+        with:
+          platforms: all
+      - uses: pypa/cibuildwheel@294735312765b09d24a2fbec22660ce817587d55 # v4.1.0
+        with:
+          package-dir: ./
+          output-dir: dist/
+      - run: pip install build
+      - run: python -m build --sdist
+      - uses: actions/upload-artifact@043fb46d1a93c77aae656e7c1c64a875d1fc6a0a # v7.0.1
+        with:
+          name: dist-${{ runner.os }}-${{ runner.arch }}
+          path: ./dist/
+  publish:
+    if: (github.event_name == 'release') && (github.event.action == 'released')
+    needs: [build]
+    runs-on: ubuntu-latest
+    permissions:
+      id-token: write
+      attestations: write
+    # To add required reviewers before deployment,
+    # edit the protection rules in GitHub Settings:
+    # Settings > Environments > pypi > Add required reviewers
+    environment:
+      name: pypi
+      url: https://pypi.org/p/calcos
+    steps:
+      - uses: actions/download-artifact@3e5f45b2cfb9172054b4087a40e8e0b5a5461e7c # v8.0.1
+        with:
+          pattern: dist*
+          path: dist/
+          merge-multiple: true
+      - uses: actions/attest@a1948c3f048ba23858d222213b7c278aabede763 # v4.1.1
+        with:
+          subject-path: "dist/*"
+      # To upload to PyPI without a token, add this workflow file as a Trusted Publisher in the project settings on the PyPI website
+      - uses: pypa/gh-action-pypi-publish@cef221092ed1bacb1cc03d23a2d87d1d172e277b # v1.14.0
+        with:
+          password: ${{ secrets.PYPI_PASSWORD_STSCI_MAINTAINER }}
diff --git a/pyproject.toml b/pyproject.toml
index 346041a..c2e2087 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -40,6 +40,7 @@ build-backend = "setuptools.build_meta"
 [tool.cibuildwheel]
 build = "cp311-*"  # build for CPython 3.11 Stable API
 skip = ["cp314t-*"]  # explicitly skip free-threaded builds
+test-command = "python -c 'from calcos import ccos'"
 
 [tool.setuptools]
 include-package-data = false

From 9c6b9f65c0b2db77f3f1175a24cd52100eeabb56 Mon Sep 17 00:00:00 2001
From: zacharyburnett <zburnett@stsci.edu>
Date: Wed, 1 Jul 2026 10:10:01 -0400
Subject: [PATCH 3/6] tell setuptools to build with py_limited_api

---
 setup.py | 1 +
 1 file changed, 1 insertion(+)

diff --git a/setup.py b/setup.py
index f7062e3..7032ec4 100755
--- a/setup.py
+++ b/setup.py
@@ -38,4 +38,5 @@ def c_includes(parent: str, depth: int = 1):
             py_limited_api=True,
         ),
     ],
+    options={'bdist_wheel': {'py_limited_api': 'cp311'}},
 )

From faa6ec15c2fb0fb189051e21e3bb282672cfee69 Mon Sep 17 00:00:00 2001
From: zacharyburnett <zburnett@stsci.edu>
Date: Tue, 7 Jul 2026 13:01:03 -0400
Subject: [PATCH 4/6] conditional on GIL

---
 pyproject.toml |  2 +-
 setup.py       | 17 ++++++++++++-----
 2 files changed, 13 insertions(+), 6 deletions(-)

diff --git a/pyproject.toml b/pyproject.toml
index c2e2087..fa97953 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -39,7 +39,7 @@ build-backend = "setuptools.build_meta"
 
 [tool.cibuildwheel]
 build = "cp311-*"  # build for CPython 3.11 Stable API
-skip = ["cp314t-*"]  # explicitly skip free-threaded builds
+skip = ["cp3*t-*"]  # explicitly skip free-threaded builds
 test-command = "python -c 'from calcos import ccos'"
 
 [tool.setuptools]
diff --git a/setup.py b/setup.py
index 7032ec4..9369464 100755
--- a/setup.py
+++ b/setup.py
@@ -3,6 +3,10 @@
 from setuptools import setup, Extension
 from numpy import get_include as numpy_includes
 from pathlib import Path
+import sysconfig
+
+
+FREE_THREADED_PYTHON = sysconfig.get_config_var("Py_GIL_DISABLED") == 1
 
 
 def c_sources(parent: str) -> list[str]:
@@ -23,10 +27,13 @@ def c_includes(parent: str, depth: int = 1):
 PACKAGENAME = "calcos"
 SOURCES = c_sources("src")
 INCLUDES = c_includes("src") + [numpy_includes()]
-MACROS = [
-    ("Py_LIMITED_API", 0x030B0000),  # PY_VERSION_HEX for 3.11
-]
+MACROS = []
+if not FREE_THREADED_PYTHON:
+    MACROS.append(("Py_LIMITED_API", 0x030B0000))  # PY_VERSION_HEX for 3.11
 
+SETUPTOOLS_OPTIONS = {}
+if not FREE_THREADED_PYTHON:
+    SETUPTOOLS_OPTIONS["bdist_wheel"] = {"py_limited_api": "cp311"}
 
 setup(
     ext_modules=[
@@ -35,8 +42,8 @@ def c_includes(parent: str, depth: int = 1):
             sources=SOURCES,
             include_dirs=INCLUDES,
             define_macros=MACROS,
-            py_limited_api=True,
+            py_limited_api=not FREE_THREADED_PYTHON,
         ),
     ],
-    options={'bdist_wheel': {'py_limited_api': 'cp311'}},
+    options=SETUPTOOLS_OPTIONS,
 )

From 4fe49109d98be18d04ec1bee06f854ac1b0fdb13 Mon Sep 17 00:00:00 2001
From: zacharyburnett <zburnett@stsci.edu>
Date: Tue, 7 Jul 2026 13:02:03 -0400
Subject: [PATCH 5/6] try free-threaded

---
 pyproject.toml | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/pyproject.toml b/pyproject.toml
index fa97953..13ae927 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -38,8 +38,10 @@ requires = [
 build-backend = "setuptools.build_meta"
 
 [tool.cibuildwheel]
-build = "cp311-*"  # build for CPython 3.11 Stable API
-skip = ["cp3*t-*"]  # explicitly skip free-threaded builds
+build = [
+  "cp311-*",  # build for CPython 3.11 Stable API
+  "cp3*t-*",  # build for free-threaded Python
+]
 test-command = "python -c 'from calcos import ccos'"
 
 [tool.setuptools]

From 7c0548a5cbe5cf7674b8b879fff22e7d29712356 Mon Sep 17 00:00:00 2001
From: zacharyburnett <zburnett@stsci.edu>
Date: Tue, 7 Jul 2026 13:20:19 -0400
Subject: [PATCH 6/6] align with build workflow template

---
 .github/workflows/build.yml | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/.github/workflows/build.yml b/.github/workflows/build.yml
index 5c3fb72..43c1a81 100644
--- a/.github/workflows/build.yml
+++ b/.github/workflows/build.yml
@@ -29,6 +29,7 @@ jobs:
       - uses: actions/setup-python@ece7cb06caefa5fff74198d8649806c4678c61a1 # v6.3.0
         with:
           python-version: "3"
+          pip-install: build
       - if: ${{ runner.os == 'Linux' }}
         uses: docker/setup-qemu-action@96fe6ef7f33517b61c61be40b68a1882f3264fb8 # v4.2.0
         with:
@@ -37,7 +38,6 @@ jobs:
         with:
           package-dir: ./
           output-dir: dist/
-      - run: pip install build
       - run: python -m build --sdist
       - uses: actions/upload-artifact@043fb46d1a93c77aae656e7c1c64a875d1fc6a0a # v7.0.1
         with: