diff --git a/test/test_uv_env_setup.py b/test/test_uv_env_setup.py
new file mode 100644
index 000000000..6ef79e1b9
--- /dev/null
+++ b/test/test_uv_env_setup.py
@@ -0,0 +1,26 @@
+"""Tests for uv_env_setup.sh error handling."""
+
+import subprocess
+from pathlib import Path
+
+
+def test_source_invalid_platform_does_not_kill_shell():
+    """Verify sourcing with invalid platform does not kill the shell.
+
+    If the script uses bare `exit 1`, sourcing it kills the shell
+    (subshell exits). If it uses `return 1`, the subshell survives
+    and the sentinel `STILL_ALIVE` is printed.
+    """
+    script = Path(__file__).parents[1] / "uv_env_setup.sh"
+    result = subprocess.run(
+        [
+            "bash",
+            "-c",
+            f"source {script} INVALID 2>/dev/null; echo STILL_ALIVE",
+        ],
+        capture_output=True,
+        text=True,
+    )
+    assert "STILL_ALIVE" in result.stdout, (
+        "Shell was killed by `exit 1` instead of `return 1`"
+    )
diff --git a/uv_env_setup.sh b/uv_env_setup.sh
index 820a2bc81..d49d86fac 100644
--- a/uv_env_setup.sh
+++ b/uv_env_setup.sh
@@ -30,7 +30,7 @@ elif [ "$PLATFORM" == "cu121" ]; then
     PYG_URL="https://data.pyg.org/whl/torch-${TORCH_VER}+cu121.html"
 else
     echo "❌ Error: Invalid platform '$PLATFORM'. Use: cpu, cu118, or cu121."
-    exit 1
+    return 1 2>/dev/null || exit 1
 fi
 
 echo "⚙️  Updating pyproject.toml..."