PSA: if anyone is wondering to how to add debuggability to your Scalatags fragments to figure out where stuff comes from, you can do it with the SourceCode library (which is already pulled in by Scalatags):
def tagged(implicit name: sourcecode.Enclosing, line: sourcecode.Line) =
data.enclosing := (name.value + ":" + line.value)
Use e.g.
val searchForm = form(
tagged,