Update Notes v1.29 — Grand Strategy: The Three Kingdoms Steam update #5640555

## 🐛 Bug Fixes ### Diplomacy & Vassals - Fixed **vassal relationships that could not be released**. Once the relation data was corrupted (for example, your own nation appearing in your own vassal list, or an ally showing up in your enemy list), the entry could never be cleared and only a save edit could recover it. - Fixed **a nation being registered under multiple suzerains at the same time**, which left leftover vassal entries. - Fixed **diplomatic letters that sat in the mailbox for several turns** and were then accepted using the data from when they were sent, producing broken relations such as "a nation becoming its own vassal or ally" that could not be cleared through the UI. Acceptance now re-validates the current relationship first. - Diplomatic letters are now **automatically voided** in the following cases: - sender and recipient are the same nation; - either side has already b...