fix: Installation flag (#5842)

## 📝 Summary

`UV_TARGET` does not exist

Author: dmadisetti

marimo/_runtime/packages/pypi_package_manager.py

@@ -152,8 +152,14 @@ async def _install(self, package: str, *, upgrade: bool) -> bool:
             install_cmd = [self._uv_bin, "add"]
         else:
             LOGGER.info(f"Installing in {package} with 'uv pip install'")
+
             install_cmd = [self._uv_bin, "pip", "install"]
 
+            # Allow for explicit site directory location if needed
+            target = os.environ.get("MARIMO_UV_TARGET", None)
+            if target:
+                install_cmd.append(f"--target={target}")
+
         if upgrade:
             install_cmd.append("--upgrade")
 

tests/_runtime/packages/test_pypi_package_manager.py

@@ -216,6 +216,37 @@ async def test_uv_install_not_in_project(mock_run: MagicMock):
     assert result is True
 
 
+@patch("subprocess.run")
+@patch.object(UvPackageManager, "is_in_uv_project", False)
+async def test_uv_install_not_in_project_with_target(mock_run: MagicMock):
+    """Test UV install uses pip with target"""
+    mock_run.return_value = MagicMock(returncode=0)
+    mgr = UvPackageManager()
+
+    # Explicitly set environ, since patch doesn't work in an asynchronous
+    # context.
+    import os
+
+    os.environ["MARIMO_UV_TARGET"] = "target_path"
+    result = await mgr._install("package1 package2", upgrade=False)
+    del os.environ["MARIMO_UV_TARGET"]
+
+    mock_run.assert_called_once_with(
+        [
+            "uv",
+            "pip",
+            "install",
+            "--target=target_path",
+            "--compile",
+            "package1",
+            "package2",
+            "-p",
+            PY_EXE,
+        ],
+    )
+    assert result is True
+
+
 @patch("subprocess.run")
 @patch.object(UvPackageManager, "is_in_uv_project", True)
 async def test_uv_install_in_project(mock_run: MagicMock):