feat: persist zone selection across panel navigation in sessionStorage

Both the boss panel and the quest panel now read their active zone from
sessionStorage on mount and write back to it whenever the user selects
a new zone. The stored selections are cleared automatically when the
session ends, and fall back to verdant_vale when no stored value exists.

Closes #36

apps/web/src/components/game/adventurerPanel.tsx

@@ -16,6 +16,31 @@ import type { Adventurer } from "@elysium/types";
 type BatchSize = 1 | 5 | 10 | 25 | 100 | "max";
 const batchOptions: Array<BatchSize> = [ 1, 5, 10, 25, 100, "max" ];
 
+/**
+ * Parses a localStorage string back into a valid BatchSize, defaulting to 1.
+ * @param stored - The raw string from localStorage (or null if absent).
+ * @returns A valid BatchSize value.
+ */
+const parseBatchSize = (stored: string | null): BatchSize => {
+  if (stored === "max") {
+    return "max";
+  }
+  const numeric = Number(stored);
+  if (numeric === 5) {
+    return 5;
+  }
+  if (numeric === 10) {
+    return 10;
+  }
+  if (numeric === 25) {
+    return 25;
+  }
+  if (numeric === 100) {
+    return 100;
+  }
+  return 1;
+};
+
 /**
  * Computes the total cost to buy a batch of adventurers.
  * @param adventurer - The adventurer to buy.
@@ -148,7 +173,9 @@ const AdventurerCard = ({
 const AdventurerPanel = (): JSX.Element => {
   const { state, formatNumber } = useGame();
   const [ showLocked, setShowLocked ] = useState(true);
-  const [ batchSize, setBatchSize ] = useState<BatchSize>(1);
+  const [ batchSize, setBatchSize ] = useState<BatchSize>(() => {
+    return parseBatchSize(localStorage.getItem("elysium_batch_size"));
+  });
 
   if (state === null) {
     return (
@@ -196,6 +223,7 @@ const AdventurerPanel = (): JSX.Element => {
         {batchOptions.map((option) => {
           function handleBatchSelect(): void {
             setBatchSize(option);
+            localStorage.setItem("elysium_batch_size", String(option));
           }
           return (
             <button

apps/web/src/components/game/bossPanel.tsx

@@ -239,7 +239,9 @@ const BossPanel = (): JSX.Element => {
   const [ challengingBossId, setChallengingBossId ] = useState<string | null>(
     null,
   );
-  const [ activeZoneId, setActiveZoneId ] = useState("verdant_vale");
+  const [ activeZoneId, setActiveZoneId ] = useState(() => {
+    return sessionStorage.getItem("elysium_boss_zone") ?? "verdant_vale";
+  });
   const [ showLocked, setShowLocked ] = useState(true);
 
   if (state === null) {
@@ -317,6 +319,11 @@ const BossPanel = (): JSX.Element => {
     }
   }
 
+  function handleZoneSelect(zoneId: string): void {
+    setActiveZoneId(zoneId);
+    sessionStorage.setItem("elysium_boss_zone", zoneId);
+  }
+
   function handleToggle(): void {
     setShowLocked((current) => {
       return !current;
@@ -374,7 +381,7 @@ const BossPanel = (): JSX.Element => {
 
       <ZoneSelector
         activeZoneId={activeZoneId}
-        onSelectZone={setActiveZoneId}
+        onSelectZone={handleZoneSelect}
         zones={zones}
       />
 

apps/web/src/components/game/questPanel.tsx

@@ -184,7 +184,9 @@ const QuestCard = ({
  */
 const QuestPanel = (): JSX.Element => {
   const { state, toggleAutoQuest } = useGame();
-  const [ activeZoneId, setActiveZoneId ] = useState("verdant_vale");
+  const [ activeZoneId, setActiveZoneId ] = useState(() => {
+    return sessionStorage.getItem("elysium_quest_zone") ?? "verdant_vale";
+  });
   const [ showLocked, setShowLocked ] = useState(true);
 
   if (state === null) {
@@ -243,6 +245,11 @@ const QuestPanel = (): JSX.Element => {
     }
   }
 
+  function handleZoneSelect(zoneId: string): void {
+    setActiveZoneId(zoneId);
+    sessionStorage.setItem("elysium_quest_zone", zoneId);
+  }
+
   function handleToggle(): void {
     setShowLocked((current) => {
       return !current;
@@ -285,7 +292,7 @@ const QuestPanel = (): JSX.Element => {
 
       <ZoneSelector
         activeZoneId={activeZoneId}
-        onSelectZone={setActiveZoneId}
+        onSelectZone={handleZoneSelect}
         zones={zones}
       />