Validate battle save unit roster

src/game/state/battleSaveState.ts

@@ -71,6 +71,7 @@ type BattleSaveValidationOptions = {
   expectedBattleId?: string;
   mapWidth?: number;
   mapHeight?: number;
+  validUnitIds?: ReadonlySet<string>;
 };
 
 const unitDirections = new Set<UnitDirection>(['south', 'east', 'north', 'west']);
@@ -118,7 +119,7 @@ export function isValidBattleSaveState(state: unknown, options: BattleSaveValida
     !isStringArray(state.actedUnitIds) ||
     !isBattleLog(state.battleLog) ||
     !isAttackIntentArray(state.attackIntents) ||
-    !state.units.every((unit) => isSavedBattleUnitState(unit, options)) ||
+    !areSavedBattleUnitsValid(state.units, options) ||
     !isBondArray(state.bonds)
   ) {
     return false;
@@ -185,7 +186,29 @@ function isAttackIntentArray(value: unknown) {
   );
 }
 
-function isSavedBattleUnitState(value: unknown, options: BattleSaveValidationOptions) {
+function areSavedBattleUnitsValid(units: unknown[], options: BattleSaveValidationOptions) {
+  const seenUnitIds = new Set<string>();
+
+  for (const unit of units) {
+    if (!isSavedBattleUnitState(unit, options) || seenUnitIds.has(unit.id)) {
+      return false;
+    }
+
+    seenUnitIds.add(unit.id);
+  }
+
+  if (!options.validUnitIds) {
+    return true;
+  }
+
+  if (seenUnitIds.size !== options.validUnitIds.size) {
+    return false;
+  }
+
+  return [...seenUnitIds].every((unitId) => options.validUnitIds?.has(unitId));
+}
+
+function isSavedBattleUnitState(value: unknown, options: BattleSaveValidationOptions): value is SavedBattleUnitState {
   if (!isRecord(value) || typeof value.id !== 'string' || value.id.length === 0 || !isRecord(value.equipment)) {
     return false;
   }