Support group Harkonnen traitor calls

docs/OPTIONAL_ALLIANCE_VICTORY.md

@@ -83,6 +83,16 @@ single-ally wording to both group members is provisional. Advanced, expansion
 factions and optional modules remain outside this prototype, and normal
 group starts are not yet available.
 
+## Group Harkonnen traitor support — 28 October 2026
+
+In the unexposed Basic classic group prototype, Harkonnen may call its held
+traitor against the opponent of either allied combatant. The choice remains
+Harkonnen's, and the native allied-call Karama response, other combatants'
+votes, mutual calls and battle resolution continue through the existing
+windows. Applying the printed single-ally power to both group members is a
+provisional interpretation. Other profiles and normal lobby access remain
+separate; the remaining group abilities and interactions are unfinished.
+
 ## Group Nexus negotiation — 28 October 2026
 
 **Integrated groundwork, not a selectable game mode.** In a staged Basic