fix(pathfinder): anchor canary probe import root

Run the canary subprocess from the parent package's import root so wheel-based CI tests do not accidentally resolve `cuda.pathfinder` from the checkout tree and fail on missing generated files.

Made-with: Cursor

Author: cpcloud

cuda_pathfinder/cuda/pathfinder/_dynamic_libs/load_nvidia_dynamic_lib.py

@@ -8,6 +8,7 @@
 import struct
 import subprocess
 import sys
+from pathlib import Path
 from typing import TYPE_CHECKING
 
 from cuda.pathfinder._dynamic_libs.lib_descriptor import LIB_DESCRIPTORS
@@ -41,6 +42,7 @@
 _PLATFORM_NAME = "Windows" if IS_WINDOWS else "Linux"
 _CANARY_PROBE_MODULE = "cuda.pathfinder._dynamic_libs.canary_probe_subprocess"
 _CANARY_PROBE_TIMEOUT_SECONDS = 10.0
+_CANARY_PROBE_IMPORT_ROOT = Path(__file__).resolve().parents[3]
 
 # Driver libraries: shipped with the NVIDIA display driver, always on the
 # system linker path.  These skip all CTK search steps (site-packages,
@@ -102,6 +104,7 @@ def _resolve_system_loaded_abs_path_in_subprocess(libname: str) -> str | None:
             text=True,
             timeout=_CANARY_PROBE_TIMEOUT_SECONDS,
             check=False,
+            cwd=_CANARY_PROBE_IMPORT_ROOT,
         )
     except subprocess.TimeoutExpired as exc:
         _raise_canary_probe_child_process_error(timeout=exc.timeout, stderr=exc.stderr)

cuda_pathfinder/tests/test_ctk_root_discovery.py

@@ -30,7 +30,7 @@
 
 _MODULE = "cuda.pathfinder._dynamic_libs.load_nvidia_dynamic_lib"
 _STEPS_MODULE = "cuda.pathfinder._dynamic_libs.search_steps"
-_PACKAGE_ROOT = Path(__file__).resolve().parents[1]
+_PACKAGE_ROOT = Path(load_mod.__file__).resolve().parents[3]
 
 
 def _ctx(libname: str = "nvvm") -> SearchContext:
@@ -206,6 +206,7 @@ def test_subprocess_probe_returns_abs_path_on_string_payload(mocker):
         text=True,
         timeout=10.0,
         check=False,
+        cwd=_PACKAGE_ROOT,
     )