Read the CI Python versions from the recipes' conda_build_config.yaml

.github/AGENTS.md

@@ -14,16 +14,21 @@ All build/test workflows cover Python 3.10-3.15 plus free-threaded 3.14t and 3.1
 - **openssf-scorecard.yml** — security posture scanning
 - **coverity.yml** — weekly Coverity Scan static analysis of the C/Cython extensions (scan.coverity.com)
 
+## Actions
+- **actions/conda-python-matrix/** — composite action that reads the `python:` list of a recipe's `conda_build_config.yaml` and outputs the build/test matrix. `action.yml` and `conda_python_matrix.py` (standard library only) refer to nothing outside the directory, so it can move unchanged to a shared repository together with `conda-build-test.yml`. The `variants` job references it as `./.github/actions/conda-python-matrix`, which resolves against the caller's checkout; after the move that line must become `$/.github/actions/conda-python-matrix`, which resolves against the repository of the workflow file itself. It is not `$/` already because actionlint 1.7.12, used by pre-commit, rejects that syntax (rhysd/actionlint#711). Run it locally with `python .github/actions/conda-python-matrix/conda_python_matrix.py conda-recipe-cf/conda_build_config.yaml`
+
 ## CI/CD policy
-- Keep build matrix (Python versions, platforms) in workflow files only
+- Platforms are set in the caller workflows. The conda workflows read their Python versions from the `python:` list in the recipe's `conda_build_config.yaml`: the `variants` job of `conda-build-test.yml` turns it into the build/test matrix with the `.github/actions/conda-python-matrix` composite action. The other workflows keep their Python matrix in the workflow file
+- Every entry of a recipe's `python:` list is a full spec on its own line, without selectors (`3.12.* *_cpython`, `3.13.* *_cp313`, `3.14.* *_cp314`, `3.14.* *_cp314t`); the `variants` job rejects bare versions and selectors
+- The `variants` job keeps the check names of the former static matrix: `Build (3.12)` for a version with one build, `Build (3.14, 3.14.* *_cp314t, 3.14t)` for a version with GIL and free-threaded builds. The master ruleset requires the 3.14 `Test` checks by these exact names
 - Required checks: conda build + test on supported Python versions/platforms in CI
-- Python 3.14 is expressed as two `include` rows carrying `python_spec` (`3.14.* *_cp314` and `3.14.* *_cp314t`); a bare `--python 3.14` has been observed to select the free-threaded ABI and must not be relied on
+- In workflow-file matrices (`build_pip.yml`), Python 3.14 is expressed as two `include` rows carrying `python_spec` (`3.14.* *_cp314` and `3.14.* *_cp314t`); a bare `--python 3.14` has been observed to select the free-threaded ABI and must not be relied on
 - Python 3.15 follows the same pattern as 3.14: two `include` rows with `python_spec` `3.15.* *_cp315` and `3.15.* *_cp315t`
 - `include` rows create new matrix combinations and inherit nothing, so `experimental` must be repeated wherever the job reads them
-- Artifact naming: `$PACKAGE_NAME $OS Python $VERSION`, where `$VERSION` is `python_tag` (`3.14`, `3.14t`, `3.15`, or `3.15t`) when set, otherwise `python`
+- Artifact naming: `$PACKAGE_NAME $OS Python $VERSION`, where `$VERSION` is `python_tag`: the Python version, with a `t` suffix for free-threaded builds (`3.12`, `3.14`, `3.14t`)
 - Channels: `conda-forge`, Intel channel
 - Build jobs run `conda build --no-test`; test jobs run `conda build --test` on the built package on a fresh runner, so CI runs the test section of the recipe, as the feedstock does
-- `conda-package-cf.yml` and `conda-recipe-cf/` follow `conda-forge/mkl-service-feedstock`: when the feedstock is re-rendered with new pins (compiler versions, `mkl_devel`, Python versions), update `conda-recipe-cf/conda_build_config.yaml` and the `python-versions` input to match
+- `conda-package-cf.yml` and `conda-recipe-cf/` follow `conda-forge/mkl-service-feedstock`: when the feedstock is re-rendered with new pins (compiler versions, `mkl_devel`, Python versions), update `conda-recipe-cf/conda_build_config.yaml`, including its `python:` list, to match
 
 ## Security
 - OpenSSF Scorecard runs automatically

.github/actions/conda-python-matrix/action.yml

@@ -0,0 +1,24 @@
+name: Conda Python matrix
+description: >-
+  Build the conda build/test matrix from the python list of a recipe's
+  conda_build_config.yaml
+
+inputs:
+  recipe-dir:
+    description: Path to the conda recipe directory
+    required: true
+
+outputs:
+  matrix:
+    description: Matrix for strategy.matrix, as JSON
+    value: ${{ steps.read.outputs.matrix }}
+
+runs:
+  using: composite
+  steps:
+    - name: Read Python versions from conda_build_config.yaml
+      id: read
+      shell: bash
+      env:
+        CBC_PATH: ${{ inputs.recipe-dir }}/conda_build_config.yaml
+      run: python3 "${GITHUB_ACTION_PATH}/conda_python_matrix.py" "${CBC_PATH}"

.github/actions/conda-python-matrix/conda_python_matrix.py

@@ -0,0 +1,117 @@
+"""Build the conda CI matrix from the python list of a conda_build_config.yaml.
+
+Usage:
+  python conda_python_matrix.py RECIPE_DIR/conda_build_config.yaml
+
+Prints the matrix entries and, when $GITHUB_OUTPUT is set, writes
+matrix=<JSON> to it for strategy.matrix of later jobs. Standard library only,
+so it runs on any runner without conda.
+
+The python: key must hold full specs, one per line and without selectors,
+such as "3.12.* *_cpython", "3.13.* *_cp313" or "3.14.* *_cp314t", quoted or
+not, so that every job gets an explicit ABI. Each entry becomes one matrix
+entry with:
+- python: the version, e.g. "3.14"
+- python_spec: the entry itself, for conda build --python
+- python_tag: the version, with a "t" suffix for free-threaded builds, for
+  artifact names
+- label: the check name suffix. A version with a single build shows only the
+  version ("3.12"); a version with GIL and free-threaded builds shows the
+  version, spec and tag ("3.14, 3.14.* *_cp314t, 3.14t"). These are the
+  names of the former static matrix, which branch rulesets may require.
+"""
+
+import argparse
+import collections
+import json
+import os
+import re
+import sys
+
+SPEC_RE = re.compile(r"(\d+\.\d+)\.\* \*_(cpython|cp\d+t?)")
+
+
+class DeclarationError(Exception):
+    """The python: list cannot be turned into a matrix."""
+
+
+def read_specs(path):
+    """Return the entries of the python: key of a conda_build_config.yaml."""
+    specs, in_list = [], False
+    with open(path, encoding="utf-8") as f:
+        for line in f:
+            if line.startswith("python:"):
+                if specs or line.strip() != "python:":
+                    raise DeclarationError(
+                        "expected a single 'python:' key without selectors"
+                    )
+                in_list = True
+            elif in_list and re.match(r"\s+-", line):
+                if "#" in line:
+                    raise DeclarationError(
+                        "selectors on python entries are not supported: "
+                        + line.strip()
+                    )
+                spec = line.split("-", 1)[1].strip()
+                if len(spec) > 1 and spec[0] == spec[-1] and spec[0] in "'\"":
+                    spec = spec[1:-1]
+                specs.append(spec)
+            elif in_list and line.strip() and not line[0].isspace():
+                in_list = False
+    if not specs:
+        raise DeclarationError("no python entries found")
+    return specs
+
+
+def build_matrix(specs):
+    """Return the strategy.matrix for the given python entries."""
+    parsed = []
+    for spec in specs:
+        m = SPEC_RE.fullmatch(spec)
+        if not m:
+            raise DeclarationError(
+                f"unsupported python entry '{spec}', "
+                "expected e.g. '3.14.* *_cp314t'"
+            )
+        parsed.append((spec, m.group(1), m.group(2)))
+
+    builds = collections.Counter(version for _, version, _ in parsed)
+    include = []
+    for spec, version, abi in parsed:
+        tag = version + ("t" if abi.endswith("t") else "")
+        if builds[version] == 1:
+            label = version
+        else:
+            label = f"{version}, {spec}, {tag}"
+        include.append(
+            {
+                "python": version,
+                "python_spec": spec,
+                "python_tag": tag,
+                "label": label,
+            }
+        )
+    return {"include": include}
+
+
+def main(argv=None):
+    parser = argparse.ArgumentParser(description=__doc__.splitlines()[0])
+    parser.add_argument("cbc", help="path to conda_build_config.yaml")
+    args = parser.parse_args(argv)
+
+    try:
+        matrix = build_matrix(read_specs(args.cbc))
+    except DeclarationError as e:
+        print(f"{args.cbc}: {e}", file=sys.stderr)
+        return 1
+
+    print(json.dumps(matrix["include"], indent=2))
+    output = os.environ.get("GITHUB_OUTPUT")
+    if output:
+        with open(output, "a", encoding="utf-8") as f:
+            f.write("matrix=" + json.dumps(matrix) + "\n")
+    return 0
+
+
+if __name__ == "__main__":
+    sys.exit(main())

.github/workflows/conda-build-test.yml

@@ -24,11 +24,6 @@ on:
         required: false
         default: false
         type: boolean
-      python-versions:
-        description: JSON list of Python versions to build and test in addition to 3.14 and 3.15, which always get both the GIL and free-threaded builds
-        required: false
-        default: '["3.10", "3.11", "3.12", "3.13"]'
-        type: string
 
 permissions:
   contents: read
@@ -37,26 +32,34 @@ env:
   package-name: mkl-service
 
 jobs:
+  variants:
+    name: Variants
+
+    runs-on: ubuntu-latest
+    timeout-minutes: 5
+
+    outputs:
+      matrix: ${{ steps.matrix.outputs.matrix }}
+
+    steps:
+      - name: Checkout repo
+        uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
+        with:
+          persist-credentials: false
+
+      - name: Read Python versions from conda_build_config.yaml
+        id: matrix
+        uses: ./.github/actions/conda-python-matrix
+        with:
+          recipe-dir: ${{ inputs.recipe-dir }}
+
   build:
-    name: Build
+    name: Build (${{ matrix.label }})
+    needs: variants
 
     strategy:
       fail-fast: false
-      matrix:
-        python: ${{ fromJSON(inputs.python-versions) }}
-        include:
-          - python: '3.14'
-            python_spec: '3.14.* *_cp314'
-            python_tag: '3.14'
-          - python: '3.14'
-            python_spec: '3.14.* *_cp314t'
-            python_tag: '3.14t'
-          - python: '3.15'
-            python_spec: '3.15.* *_cp315'
-            python_tag: '3.15'
-          - python: '3.15'
-            python_spec: '3.15.* *_cp315t'
-            python_tag: '3.15t'
+      matrix: ${{ fromJSON(needs.variants.outputs.matrix) }}
 
     runs-on: ${{ inputs.runs-on }}
     timeout-minutes: 15
@@ -99,7 +102,7 @@ jobs:
         env:
           CHANNELS_LIST: ${{ inputs.channels-list }}
           RECIPE_DIR: ${{ inputs.recipe-dir }}
-          PYTHON_SPEC: ${{ matrix.python_spec || matrix.python }}
+          PYTHON_SPEC: ${{ matrix.python_spec }}
         run: |
           # CHANNELS_LIST intentionally word-splits into multiple -c args
           # shellcheck disable=SC2086
@@ -108,37 +111,23 @@ jobs:
       - name: Upload artifact
         uses: actions/upload-artifact@cf430e030ddbb5b0abf93d22962f4752f3646cd9 # v7.0.2
         with:
-          name: ${{ env.package-name }} ${{ runner.os }} Python ${{ matrix.python_tag || matrix.python }}
+          name: ${{ env.package-name }} ${{ runner.os }} Python ${{ matrix.python_tag }}
           path: ${{ env.CONDA_BLD }}/${{ env.package-name }}-*.conda
 
       - name: Upload wheels artifact
         if: ${{ inputs.build-wheels }}
         uses: actions/upload-artifact@cf430e030ddbb5b0abf93d22962f4752f3646cd9 # v7.0.2
         with:
-          name: ${{ env.package-name }} ${{ runner.os }} Wheels Python ${{ matrix.python_tag || matrix.python }}
+          name: ${{ env.package-name }} ${{ runner.os }} Wheels Python ${{ matrix.python_tag }}
           path: ${{ env.WHEELS_OUTPUT_FOLDER }}/mkl_service-*.whl
 
   test:
-    name: Test
-    needs: build
+    name: Test (${{ matrix.label }})
+    needs: [variants, build]
 
     strategy:
       fail-fast: false
-      matrix:
-        python: ${{ fromJSON(inputs.python-versions) }}
-        include:
-          - python: '3.14'
-            python_spec: '3.14.* *_cp314'
-            python_tag: '3.14'
-          - python: '3.14'
-            python_spec: '3.14.* *_cp314t'
-            python_tag: '3.14t'
-          - python: '3.15'
-            python_spec: '3.15.* *_cp315'
-            python_tag: '3.15'
-          - python: '3.15'
-            python_spec: '3.15.* *_cp315t'
-            python_tag: '3.15t'
+      matrix: ${{ fromJSON(needs.variants.outputs.matrix) }}
 
     runs-on: ${{ inputs.runs-on }}
     timeout-minutes: 15
@@ -154,7 +143,7 @@ jobs:
       - name: Download artifact
         uses: actions/download-artifact@9000827ccba6bdab643e8b6fd33ac0654aef8333 # v8.0.2
         with:
-          name: ${{ env.package-name }} ${{ runner.os }} Python ${{ matrix.python_tag || matrix.python }}
+          name: ${{ env.package-name }} ${{ runner.os }} Python ${{ matrix.python_tag }}
           path: ${{ env.pkg-dir }}
 
       - name: Setup miniconda

.github/workflows/conda-package-cf.yml

@@ -13,8 +13,8 @@ concurrency:
   group: ${{ github.workflow }}-${{ github.ref }}
   cancel-in-progress: true
 
-# Build like conda-forge/mkl-service-feedstock: same Python versions and
-# Visual Studio 2022 on Windows
+# Build like conda-forge/mkl-service-feedstock, whose Python versions are listed
+# in conda-recipe-cf/conda_build_config.yaml, with Visual Studio 2022 on Windows
 jobs:
   linux:
     name: linux
@@ -24,7 +24,6 @@ jobs:
       conda-subdir: linux-64
       channels-list: -c conda-forge --override-channels
       recipe-dir: conda-recipe-cf
-      python-versions: '["3.11", "3.12", "3.13"]'
 
   windows:
     name: windows
@@ -34,7 +33,6 @@ jobs:
       conda-subdir: win-64
       channels-list: -c conda-forge --override-channels
       recipe-dir: conda-recipe-cf
-      python-versions: '["3.11", "3.12", "3.13"]'
 
   osx:
     name: osx
@@ -44,4 +42,3 @@ jobs:
       conda-subdir: osx-64
       channels-list: -c conda-forge --override-channels
       recipe-dir: conda-recipe-cf
-      python-versions: '["3.11", "3.12", "3.13"]'

AGENTS.md

@@ -51,6 +51,7 @@ python -m pip install --no-deps --no-build-isolation .
 - **Python versions:** 3.10, 3.11, 3.12, 3.13, 3.14, 3.15, and free-threaded 3.14t and 3.15t (the conda-forge workflow starts at 3.11, like the feedstock)
 - **Python 3.14 ABI selection:** conda jobs must request an explicit ABI, `3.14.* *_cp314` (GIL) or `3.14.* *_cp314t` (free-threaded). Once the recipes stopped constraining `python-gil`, a bare `--python 3.14` was observed to resolve to the free-threaded build, so it must not be relied on.
 - **Python 3.15 ABI selection:** same as 3.14; conda jobs request `3.15.* *_cp315` (GIL) or `3.15.* *_cp315t` (free-threaded) explicitly.
+- **Where the conda jobs get Python versions:** from the `python:` list in the recipe's `conda_build_config.yaml` (`conda-recipe/` or `conda-recipe-cf/`), one build and one test job per entry
 - **Workflows:** `.github/workflows/`
   - `conda-package.yml` — main conda build/test pipeline
   - `conda-package-cf.yml` — conda build/test using only conda-forge channel, set up like `conda-forge/mkl-service-feedstock`

conda-recipe-cf/conda_build_config.yaml

@@ -22,3 +22,13 @@ c_compiler:                   # [win]
     - vs2022                  # [win]
 mkl_devel:                    # [not osx]
     - '2026'                  # [not osx]
+# Python versions of conda-forge/mkl-service-feedstock, plus 3.15t; CI builds
+# and tests one job per entry, see .github/workflows/conda-build-test.yml
+python:
+    - 3.11.* *_cpython
+    - 3.12.* *_cpython
+    - 3.13.* *_cp313
+    - 3.14.* *_cp314
+    - 3.14.* *_cp314t
+    - 3.15.* *_cp315
+    - 3.15.* *_cp315t

conda-recipe/AGENTS.md

@@ -6,11 +6,11 @@ Conda package build recipe for conda-forge and Intel channel distribution.
 - **meta.yaml** — package metadata, dependencies, build requirements
 - **build.sh** — Linux/macOS build script
 - **bld.bat** — Windows build script
-- **conda_build_config.yaml** — compiler / stdlib pinning used by conda-build variants
+- **conda_build_config.yaml** — compiler / stdlib pinning used by conda-build variants, and the `python:` list of versions that CI builds and tests (one job per entry)
 
 ## Build configuration
 - **Channels:** `conda-forge`, Intel channel
-- **Python versions in CI build matrix:** 3.10, 3.11, 3.12, 3.13, 3.14, 3.15, and free-threaded 3.14t and 3.15t (3.11+ for `conda-recipe-cf/`)
+- **Python versions in CI build matrix:** 3.10, 3.11, 3.12, 3.13, 3.14, 3.15, and free-threaded 3.14t and 3.15t (3.11+ for `conda-recipe-cf/`), from the `python:` list in each recipe's `conda_build_config.yaml`. A plain `conda build conda-recipe` therefore builds every listed version; pass `--python "3.12.* *_cpython"` to build one
 - **Compilers:** pinned via `conda_build_config.yaml` (GCC/GXX on Linux, VS2022 on Windows); `conda-recipe-cf/` also pins gcc 15, clang 21 and `mkl_devel` 2026, as the feedstock's conda-forge pinning does
 - **Dependencies:** `mkl` (runtime), `mkl-devel` (build), `cython >=3.1.0`
 

conda-recipe/conda_build_config.yaml

@@ -8,3 +8,13 @@ c_stdlib:                       # [win]
     - vs                        # [win]
 c_compiler:                     # [win]
     - vs2022                    # [win]
+# CI builds and tests one job per entry, see .github/workflows/conda-build-test.yml
+python:
+    - 3.10.* *_cpython
+    - 3.11.* *_cpython
+    - 3.12.* *_cpython
+    - 3.13.* *_cp313
+    - 3.14.* *_cp314
+    - 3.14.* *_cp314t
+    - 3.15.* *_cp315
+    - 3.15.* *_cp315t