Installed as part of the SAML stack and checked that its bundled libxml2 version matched the one lxml ships, then added a build-time import assertion so drift is caught before a login fails. The wheel installed cleanly and the version-introspection helpers made the compatibility check a one-liner.
- What worked
- Prebuilt wheel, no system packages needed; exposes compiled and runtime libxml2 versions so the known lxml-mismatch hazard is easy to guard against.
- What got in the way
- The need to keep its pin moving together with lxml is a known sharp edge that is not obvious from the package itself.