fix(ci): fail cleanly on a malformed cuda.build.version instead of tracebacking

ci/tools/check_pixi_cuda_version.py

@@ -16,6 +16,24 @@
 PIXI_FILES = [ROOT / d / "pixi.toml" for d in ("cuda_bindings", "cuda_core")]
 
 
+def parse_build_version(build_version: object) -> tuple[str, str] | None:
+    """Split ``cuda.build.version`` into ``(major, minor)``, or ``None``.
+
+    Returns ``None`` for anything that is not a ``<major>.<minor>[.…]`` string
+    of digits. YAML makes this easy to get wrong: an unquoted ``13.3`` loads as
+    the float ``13.3`` and an unquoted ``13`` as the int ``13``, neither of
+    which has ``.split``. Without this check those -- and a quoted but
+    single-component ``"13"`` -- escaped as a raw traceback from a pre-commit
+    hook whose every other failure path returns a diagnostic exit code.
+    """
+    if not isinstance(build_version, str):
+        return None
+    parts = build_version.split(".")
+    if len(parts) < 2 or not all(part.isdigit() for part in parts[:2]):
+        return None
+    return parts[0], parts[1]
+
+
 def main() -> int:
     """Verify cuda_bindings/cuda_core pixi pins match ci/versions.yml."""
     if not VERSIONS_FILE_PATH.is_file():
@@ -27,7 +45,16 @@ def main() -> int:
         print(f"error: cuda.build.version not found in {VERSIONS_FILE_PATH}", file=sys.stderr)
         return 2
 
-    major, minor, *_ = build_version.split(".")
+    parsed = parse_build_version(build_version)
+    if parsed is None:
+        print(
+            f"error: cuda.build.version={build_version!r} in {VERSIONS_FILE_PATH} is not a "
+            f"'<major>.<minor>[.<patch>]' version string. Quote the value in YAML so it is "
+            f"not loaded as a number (13.3 becomes a float, 13 becomes an int).",
+            file=sys.stderr,
+        )
+        return 2
+    major, minor = parsed
     expected = f"{major}.{minor}.*"
     cuda_feature = f"cu{major}"
 

ci/tools/tests/test_check_pixi_cuda_version.py

@@ -0,0 +1,112 @@
+# SPDX-FileCopyrightText: Copyright (c) 2026 NVIDIA CORPORATION & AFFILIATES. All rights reserved.
+# SPDX-License-Identifier: Apache-2.0
+
+from __future__ import annotations
+
+import os
+import sys
+import textwrap
+
+import pytest
+
+# check_pixi_cuda_version imports PyYAML at module scope (the pre-commit hook
+# declares it via additional_dependencies), so skip rather than fail collection
+# when this module is exercised outside that environment.
+pytest.importorskip("yaml")
+
+sys.path.insert(0, os.path.join(os.path.dirname(__file__), ".."))
+import check_pixi_cuda_version as mod
+from check_pixi_cuda_version import parse_build_version
+
+PIXI_TOML = textwrap.dedent("""\
+    [workspace.build-variants]
+    cuda-version = ["12.*", "13.3.*"]
+
+    [feature.cu13.dependencies]
+    cuda-version = "13.3.*"
+    """)
+
+
+@pytest.mark.agent_authored(model="claude-opus-5")
+@pytest.mark.parametrize(
+    ("raw", "expected"),
+    [
+        pytest.param("13.3.0", ("13", "3"), id="three-part"),
+        pytest.param("12.9.1", ("12", "9"), id="three-part-other"),
+        pytest.param("13.3", ("13", "3"), id="two-part"),
+        pytest.param("13.3.0.1", ("13", "3"), id="four-part"),
+    ],
+)
+def test_parse_build_version_accepts_version_strings(raw, expected):
+    assert parse_build_version(raw) == expected
+
+
+@pytest.mark.agent_authored(model="claude-opus-5")
+@pytest.mark.parametrize(
+    "raw",
+    [
+        # YAML turns an unquoted `version: 13.3` into a float and an unquoted
+        # `version: 13` into an int. Neither has .split(), so the tool used to
+        # die with an AttributeError traceback.
+        pytest.param(13.3, id="float-from-unquoted-yaml"),
+        pytest.param(13, id="int-from-unquoted-yaml"),
+        pytest.param(None, id="none-from-empty-yaml-value"),
+        pytest.param(["13", "3"], id="list"),
+        # Quoted, but not a <major>.<minor> version: the tuple unpacking used
+        # to die with "not enough values to unpack".
+        pytest.param("13", id="single-component"),
+        pytest.param("", id="empty-string"),
+        pytest.param("13.", id="trailing-dot"),
+        pytest.param(".3", id="leading-dot"),
+        pytest.param("cuda.13", id="non-numeric-major"),
+    ],
+)
+def test_parse_build_version_rejects_everything_else(raw):
+    assert parse_build_version(raw) is None
+
+
+@pytest.mark.agent_authored(model="claude-opus-5")
+@pytest.mark.parametrize(
+    ("yaml_value", "note"),
+    [
+        pytest.param("13.3", "unquoted two-part version loads as a float", id="unquoted-float"),
+        pytest.param("13", "unquoted single number loads as an int", id="unquoted-int"),
+        pytest.param('"13"', "quoted but missing a minor component", id="quoted-single-component"),
+    ],
+)
+def test_main_reports_a_malformed_build_version(tmp_path, monkeypatch, capsys, yaml_value, note):
+    """A malformed ci/versions.yml must produce this tool's own diagnostic and
+    exit 2, not an uncaught traceback out of a pre-commit hook."""
+    (tmp_path / "ci").mkdir()
+    (tmp_path / "ci" / "versions.yml").write_text(f"cuda:\n  build:\n    version: {yaml_value}\n", encoding="utf-8")
+    pixi_files = []
+    for package in ("cuda_bindings", "cuda_core"):
+        (tmp_path / package).mkdir()
+        path = tmp_path / package / "pixi.toml"
+        path.write_text(PIXI_TOML, encoding="utf-8")
+        pixi_files.append(path)
+
+    monkeypatch.setattr(mod, "ROOT", tmp_path)
+    monkeypatch.setattr(mod, "VERSIONS_FILE_PATH", tmp_path / "ci" / "versions.yml")
+    monkeypatch.setattr(mod, "PIXI_FILES", pixi_files)
+
+    assert mod.main() == 2, note
+    assert "is not a '<major>.<minor>[.<patch>]' version string" in capsys.readouterr().err
+
+
+@pytest.mark.agent_authored(model="claude-opus-5")
+def test_main_accepts_a_well_formed_build_version(tmp_path, monkeypatch):
+    (tmp_path / "ci").mkdir()
+    (tmp_path / "ci" / "versions.yml").write_text('cuda:\n  build:\n    version: "13.3.0"\n', encoding="utf-8")
+    pixi_files = []
+    for package in ("cuda_bindings", "cuda_core"):
+        (tmp_path / package).mkdir()
+        path = tmp_path / package / "pixi.toml"
+        path.write_text(PIXI_TOML, encoding="utf-8")
+        pixi_files.append(path)
+
+    monkeypatch.setattr(mod, "ROOT", tmp_path)
+    monkeypatch.setattr(mod, "VERSIONS_FILE_PATH", tmp_path / "ci" / "versions.yml")
+    monkeypatch.setattr(mod, "PIXI_FILES", pixi_files)
+
+    assert mod.main() == 0