feat: add auto-prestige toggle via runestone shop upgrade

Adds a new Utility category to the prestige shop with the "Autonomous Ascension" upgrade (100 runestones). Once purchased, a toggle button appears in the shop that enables automatic prestige — the client RAF loop checks the threshold on each tick and fires the prestige API automatically using the current character name.

✨ This feature was implemented with help from Hikari~ 🌸

apps/web/src/context/GameContext.tsx

@@ -11,6 +11,7 @@ import {
   buyPrestigeUpgrade as buyPrestigeUpgradeApi,
   challengeBoss as challengeBossApi,
   loadGame,
+  prestige as prestigeApi,
   saveGame,
 } from "../api/client.js";
 import { RESOURCE_CAP, applyTick, calculateClickPower } from "../engine/tick.js";
@@ -73,11 +74,15 @@ interface GameContextValue {
   formatNumber: (value: number) => string;
   /** Buy a prestige upgrade from the runestone shop */
   buyPrestigeUpgrade: (upgradeId: string) => Promise<void>;
+  /** Toggle the auto-prestige setting on/off (requires auto_prestige upgrade) */
+  toggleAutoPrestige: () => void;
 }
 
 const GameContext = createContext<GameContextValue | null>(null);
 
 const AUTO_SAVE_INTERVAL_MS = 30_000;
+const AUTO_PRESTIGE_THRESHOLD_BASE = 1_000_000;
+const AUTO_PRESTIGE_THRESHOLD_SCALE = 5;
 
 export const GameProvider = ({ children }: { children: React.ReactNode }): React.JSX.Element => {
   const [state, setState] = useState<GameState | null>(null);
@@ -98,6 +103,8 @@ export const GameProvider = ({ children }: { children: React.ReactNode }): React
   const rafRef = useRef<number | null>(null);
   const newlyUnlockedRef = useRef<Achievement[]>([]);
   const signatureRef = useRef<string | null>(localStorage.getItem("elysium_save_signature"));
+  const isAutoPrestigingRef = useRef(false);
+  const reloadRef = useRef<() => Promise<void>>(() => Promise.resolve());
 
   stateRef.current = state;
 
@@ -136,6 +143,8 @@ export const GameProvider = ({ children }: { children: React.ReactNode }): React
     }
   }, []);
 
+  reloadRef.current = reload;
+
   useEffect(() => {
     void reload();
   }, [reload]);
@@ -191,6 +200,23 @@ export const GameProvider = ({ children }: { children: React.ReactNode }): React
         }
       }
 
+      // Auto-prestige: fire when unlocked, enabled, and threshold is met
+      const autoState = stateRef.current;
+      if (
+        !isAutoPrestigingRef.current &&
+        autoState?.prestige.purchasedUpgradeIds.includes("auto_prestige") &&
+        autoState.prestige.autoPrestigeEnabled &&
+        autoState.player.totalGoldEarned >=
+          AUTO_PRESTIGE_THRESHOLD_BASE *
+            Math.pow(AUTO_PRESTIGE_THRESHOLD_SCALE, autoState.prestige.count)
+      ) {
+        isAutoPrestigingRef.current = true;
+        void prestigeApi({ characterName: autoState.player.characterName })
+          .then(() => reloadRef.current())
+          .catch(() => { /* silently ignore — will retry next tick */ })
+          .finally(() => { isAutoPrestigingRef.current = false; });
+      }
+
       rafRef.current = requestAnimationFrame(tick);
     };
 
@@ -404,6 +430,19 @@ export const GameProvider = ({ children }: { children: React.ReactNode }): React
     }
   }, []);
 
+  const toggleAutoPrestige = useCallback(() => {
+    setState((prev) => {
+      if (!prev) return prev;
+      return {
+        ...prev,
+        prestige: {
+          ...prev.prestige,
+          autoPrestigeEnabled: !prev.prestige.autoPrestigeEnabled,
+        },
+      };
+    });
+  }, []);
+
   const challengeBoss = useCallback(async (bossId: string) => {
     if (!stateRef.current) return;
     const boss = stateRef.current.bosses.find((b) => b.id === bossId);
@@ -566,6 +605,7 @@ export const GameProvider = ({ children }: { children: React.ReactNode }): React
         setNumberFormat,
         formatNumber: boundFormatNumber,
         buyPrestigeUpgrade,
+        toggleAutoPrestige,
       }}
     >
       {children}