Hunch. All eight demands that Croatia sent to EU countries on 15 October are tied to chapters 23 and 31, the two chapters this question is about.
The chapters 23 and 31 market resolves on the same Commission pages: YES if both chapter 23, on courts and basic rights, and chapter 31, on foreign, security and defence policy, are provisionally closed by 31 December 2026, Brussels time. NO if either is still open then, with ANSA, Balkan Insight and RFE/RL as backups.
We looked for cases where the EU, or the European Economic Community before it, named a date in an official text by which entry talks with a country should or could end. We found seven such times since 1984, and talks ended on time in three. The four late ones ran over by two weeks, six months, six months and 18 months. (UK Parliament; European Parliament; European Parliament; European Parliament; EUR-Lex; UK Parliament)