diff --git a/cuda_core/tests/cython/build_tests.sh b/cuda_core/tests/cython/build_tests.sh
index 3e20136133..c92f3dd04e 100755
--- a/cuda_core/tests/cython/build_tests.sh
+++ b/cuda_core/tests/cython/build_tests.sh
@@ -15,4 +15,11 @@ else
   exit 1
 fi
 
+# pixi-build's editable install exposes the cuda namespace package via a
+# finder hook that Cython's filesystem .pxd resolver does not consult.
+# Surface the package's parent directory on PYTHONPATH so `cimport
+# cuda.bindings.*` can locate the .pxd files.
+CUDA_PKG_PARENT=$(python -c "import cuda.bindings as m, os; print(os.path.dirname(os.path.dirname(os.path.dirname(m.__file__))))")
+export PYTHONPATH="${CUDA_PKG_PARENT}${PYTHONPATH:+:${PYTHONPATH}}"
+
 cythonize -3 -i -Xfreethreading_compatible=True ${SCRIPTPATH}/test_*.pyx
diff --git a/pixi.toml b/pixi.toml
index 71d6b5d91b..d36e8f2298 100644
--- a/pixi.toml
+++ b/pixi.toml
@@ -19,29 +19,30 @@ PIXI_ENVIRONMENT_NAME = "${PIXI_ENVIRONMENT_NAME/default/cu13}"
 
 # Test Tasks
 # Runs tests across all sub-packages: pathfinder → bindings → core (dependency order)
-# Each sub-package has its own pixi.toml; the -e environment propagates via PIXI_ENVIRONMENT_NAME
+# Each sub-package has its own pixi.toml; the active environment is forwarded
+# explicitly via -e "$PIXI_ENVIRONMENT_NAME" in each inner pixi run.
 #
 # Usage: pixi run test | pixi run -e cu12 test | pixi run -e cu13 test
 [target.linux.tasks.test-pathfinder]
 cmd = [
-    "pixi",
-    "run",
-    "--manifest-path",
-    "$PIXI_PROJECT_ROOT/cuda_pathfinder",
-    "test",
+    "bash",
+    "-c",
+    'pixi run --manifest-path "$PIXI_PROJECT_ROOT/cuda_pathfinder" -e "$PIXI_ENVIRONMENT_NAME" test',
 ]
 
 [target.linux.tasks.test-bindings]
 cmd = [
-    "pixi",
-    "run",
-    "--manifest-path",
-    "$PIXI_PROJECT_ROOT/cuda_bindings",
-    "test",
+    "bash",
+    "-c",
+    'pixi run --manifest-path "$PIXI_PROJECT_ROOT/cuda_bindings" -e "$PIXI_ENVIRONMENT_NAME" test',
 ]
 
 [target.linux.tasks.test-core]
-cmd = ["pixi", "run", "--manifest-path", "$PIXI_PROJECT_ROOT/cuda_core", "test"]
+cmd = [
+    "bash",
+    "-c",
+    'pixi run --manifest-path "$PIXI_PROJECT_ROOT/cuda_core" -e "$PIXI_ENVIRONMENT_NAME" test',
+]
 
 [target.linux.tasks.test]
 depends-on = [