Publication Manager should have an xref tab that would attempt to resolve xrefs in a publication. The xrefs tab would be similar to the Variables tab, and it should show broken xrefs while a publication is being constructed, just like the variables tab displays missing variables.
This would enable users to more easily detect and proactively resolve broken xrefs before an output is published.
Currently, the system attempts to resolve xrefs in a publication only when an output is published.