Support whole and mixed final Nexus alliance questions

game/mixed-alliance-question.ts

@@ -0,0 +1,14 @@
+import { AlliancePromiseError, parseAllianceClaim } from './alliance-promises';
+import type { MixedActionExpression } from './mixed-action-question';
+
+export type AllianceActionClaim = { partner: string };
+export type MixedAllianceClaim = { turn: number; mixed: MixedActionExpression<AllianceActionClaim> };
+
+/** One exact final partner only. Turn/source/compiled metadata belong to the
+ * outer current-Nexus question or its private answer-time binding. */
+export function parseAllianceActionClaim(value: unknown): AllianceActionClaim {
+  if (!value || typeof value !== 'object' || Array.isArray(value) || Object.keys(value).join(',') !== 'partner')
+    throw new AlliancePromiseError('Supply one exact final alliance partner without turn or Nexus metadata.');
+  const { partner } = parseAllianceClaim({ turn: 1, partner: (value as Record<string, unknown>).partner });
+  return { partner };
+}