Is there an XSL “contains” directive?

Sure there is! For instance:

<xsl:if test="not(contains($hhref, '1234'))">
  <li>
    <a href="https://stackoverflow.com/questions/569908/{$hhref}" title="{$pdate}">
      <xsl:value-of select="title"/>
    </a>
  </li>
</xsl:if>

The syntax is: contains(stringToSearchWithin, stringToSearchFor)