Support group departures in joint commitment plans

docs/RULE_DECISIONS.md

@@ -1,5 +1,13 @@
 # Rule decision index
 
+## Group admission with joint commitments — 29 October 2026
+
+Staged Basic admission can retain a matching group alliance answer alongside
+jointly feasible payment or travel answers. Joint planning can quote owned
+group departure outside a pending invitation, including a later payment to a
+former ally. Whole-turn group changes remain fenced.
+[Scope](OPTIONAL_ALLIANCE_VICTORY.md#group-admission-with-joint-commitments--29-october-2026).
+
 ## Group admission with live commitments — 29 October 2026
 
 Staged Basic group admission checks each proposer's or accepting participant's