fix: apply crystal multiplier to boss rewards, steepen prestige threshold, fix stale upgrade race condition, and fix companion format display

Closes #221
Closes #222
Closes #201
Closes #213

apps/api/src/routes/boss.ts

@@ -205,9 +205,11 @@ bossRouter.post("/challenge", async(context) => {
       boss.status = "defeated";
       boss.currentHp = 0;
 
+      const crystalMult = state.prestige.runestonesCrystalMultiplier ?? 1;
       state.resources.gold = state.resources.gold + boss.goldReward;
       state.resources.essence = state.resources.essence + boss.essenceReward;
-      state.resources.crystals = state.resources.crystals + boss.crystalReward;
+      const crystalAward = boss.crystalReward * crystalMult;
+      state.resources.crystals = state.resources.crystals + crystalAward;
       state.player.totalGoldEarned = state.player.totalGoldEarned + boss.goldReward;
 
       for (const upgradeId of boss.upgradeRewards) {
@@ -323,7 +325,7 @@ bossRouter.post("/challenge", async(context) => {
 
       rewards = {
         bountyRunestones: bountyRunestones,
-        crystals:         boss.crystalReward,
+        crystals:         crystalAward,
         equipmentIds:     boss.equipmentRewards,
         essence:          boss.essenceReward,
         gold:             boss.goldReward,

apps/api/src/routes/game.ts

@@ -546,6 +546,17 @@ const validateAndSanitize = (
       ? previous.prestige
       : incoming.prestige;
 
+  /*
+   * If the DB prestige count is higher than the client's, the client is sending a
+   * stale pre-prestige save. Discard its upgrades (which have purchased: true) in
+   * favour of the DB's post-prestige upgrades (purchased: false) so that upgrade
+   * multipliers cannot persist across prestige via a race-condition auto-save.
+   */
+  const upgrades
+    = incoming.prestige.count < previous.prestige.count
+      ? previous.upgrades
+      : incoming.upgrades;
+
   /*
    * Echoes are only granted server-side via transcendence and can only decrease between
    * saves (spent on echo upgrades). Cap at the previous value to block inflation.
@@ -671,6 +682,7 @@ const validateAndSanitize = (
     prestige,
     quests,
     resources,
+    upgrades,
     ...transcendenceSpread,
     ...apotheosisSpread,
     ...explorationSpread,

apps/api/src/services/prestige.ts

@@ -28,8 +28,8 @@ const maxBaseRunestones = 200;
 
 /**
  * Calculates the gold threshold required for the next prestige.
- * Formula: BASE * (count + 1)^2 — polynomial growth that peaks around prestige 8–10
+ * Formula: BASE * (count + 1)^2.5 — steeper growth to keep late prestiges
- * then gets easier as the production multiplier overtakes it.
+ * meaningful even as the production multiplier scales.
  * @param prestigeCount - The current number of prestiges completed.
  * @param thresholdMultiplier - An optional echo-upgrade multiplier applied to the threshold.
  * @returns The gold amount required to prestige.
@@ -40,7 +40,7 @@ const calculatePrestigeThreshold = (
 ): number => {
   return (
     basePrestigeGoldThreshold
-    * Math.pow(prestigeCount + 1, 2)
+    * Math.pow(prestigeCount + 1, 2.5)
     * thresholdMultiplier
   );
 };

apps/api/test/routes/game.spec.ts

@@ -477,6 +477,28 @@ describe("game route", () => {
       expect(body.savedAt).toBeGreaterThan(0);
     });
 
+    it("restores previous upgrades when incoming prestige count is lower (stale post-prestige save)", async () => {
+      const prevUpgrades = [
+        { id: "click_1", purchased: false, unlocked: true, target: "click", multiplier: 2 },
+      ] as GameState["upgrades"];
+      const prevState = makeState({
+        prestige: { count: 1, runestones: 10, productionMultiplier: 1.3, purchasedUpgradeIds: [] },
+        upgrades: prevUpgrades,
+      });
+      const incomingState = makeState({
+        prestige: { count: 0, runestones: 0, productionMultiplier: 1, purchasedUpgradeIds: [] },
+        upgrades: [
+          { id: "click_1", purchased: true, unlocked: true, target: "click", multiplier: 2 },
+        ] as GameState["upgrades"],
+      });
+      vi.mocked(prisma.gameState.findUnique).mockResolvedValueOnce({ state: prevState } as never);
+      vi.mocked(prisma.player.findUnique).mockResolvedValueOnce(makePlayer({ createdAt: Date.now() }) as never);
+      vi.mocked(prisma.player.update).mockResolvedValueOnce({} as never);
+      vi.mocked(prisma.gameState.upsert).mockResolvedValueOnce({} as never);
+      const res = await save({ state: incomingState });
+      expect(res.status).toBe(200);
+    });
+
     it("validates companion when active companion is legitimately unlocked", async () => {
       const prevState = makeState();
       const stateWithCompanion = makeState({

apps/api/test/routes/prestige.spec.ts

@@ -81,6 +81,16 @@ describe("prestige route", () => {
       expect(res.status).toBe(400);
     });
 
+    it("returns 400 with echoPrestigeThresholdMultiplier applied when transcendence is present", async () => {
+      const state = makeState({
+        player: { discordId: DISCORD_ID, username: "u", discriminator: "0", avatar: null, totalGoldEarned: 500_000, totalClicks: 0, characterName: "T" },
+        transcendence: { count: 1, echoes: 0, purchasedUpgradeIds: [], echoIncomeMultiplier: 1, echoCombatMultiplier: 1, echoPrestigeThresholdMultiplier: 2, echoPrestigeRunestoneMultiplier: 1, echoMetaMultiplier: 1 },
+      });
+      vi.mocked(prisma.gameState.findUnique).mockResolvedValueOnce({ state } as never);
+      const res = await post("");
+      expect(res.status).toBe(400);
+    });
+
     it("returns runestones on successful prestige", async () => {
       const state = makeState();
       vi.mocked(prisma.gameState.findUnique).mockResolvedValueOnce({ state, updatedAt: 0 } as never);

apps/api/test/services/prestige.spec.ts

@@ -55,18 +55,18 @@ const makeMinimalState = (overrides: Partial<GameState> = {}): GameState =>
 
 describe("calculatePrestigeThreshold", () => {
   it("returns base threshold at count 0", () => {
-    // base × (0+1)^2 = 1_000_000 × 1 = 1_000_000
+    // base × (0+1)^2.5 = 1_000_000 × 1 = 1_000_000
     expect(calculatePrestigeThreshold(0)).toBe(1_000_000);
   });
 
-  it("returns 4× base at count 1", () => {
+  it("returns base × 2^2.5 at count 1", () => {
-    // base × (1+1)^2 = 1_000_000 × 4 = 4_000_000
+    // base × (1+1)^2.5 = 1_000_000 × 2^2.5
-    expect(calculatePrestigeThreshold(1)).toBe(4_000_000);
+    expect(calculatePrestigeThreshold(1)).toBeCloseTo(1_000_000 * Math.pow(2, 2.5));
   });
 
-  it("returns 9× base at count 2", () => {
+  it("returns base × 3^2.5 at count 2", () => {
-    // base × (2+1)^2 = 1_000_000 × 9 = 9_000_000
+    // base × (2+1)^2.5 = 1_000_000 × 3^2.5
-    expect(calculatePrestigeThreshold(2)).toBe(9_000_000);
+    expect(calculatePrestigeThreshold(2)).toBeCloseTo(1_000_000 * Math.pow(3, 2.5));
   });
 
   it("applies threshold multiplier correctly", () => {

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

@@ -6,6 +6,7 @@
  */
 /* eslint-disable react/no-multi-comp -- Sub-component is tightly coupled to the panel */
 /* eslint-disable max-lines-per-function -- Complex companion card with conditional renders */
+/* eslint-disable complexity -- Companion card has many conditional render paths */
 import { COMPANIONS, type Companion } from "@elysium/types";
 import { useGame } from "../../context/gameContext.js";
 import { cdnImage } from "../../utils/cdn.js";
@@ -28,41 +29,12 @@ const unlockLabels: Record<string, string> = {
   transcendence:  "transcendence(s)",
 };
 
-/**
- * Formats a companion unlock threshold for display.
- * @param type - The unlock condition type.
- * @param threshold - The threshold value.
- * @returns The formatted threshold string.
- */
-const formatThreshold = (type: string, threshold: number): string => {
-  if (type === "lifetimeGold") {
-    if (threshold >= 1e18) {
-      return `${(threshold / 1e18).toFixed(0)}Qt`;
-    }
-    if (threshold >= 1e15) {
-      return `${(threshold / 1e15).toFixed(0)}Q`;
-    }
-    if (threshold >= 1e12) {
-      return `${(threshold / 1e12).toFixed(0)}T`;
-    }
-    if (threshold >= 1e9) {
-      return `${(threshold / 1e9).toFixed(0)}B`;
-    }
-    if (threshold >= 1e6) {
-      return `${(threshold / 1e6).toFixed(0)}M`;
-    }
-    if (threshold >= 1e3) {
-      return `${(threshold / 1e3).toFixed(0)}K`;
-    }
-  }
-  return threshold.toString();
-};
-
 interface CompanionCardProperties {
   readonly companion:    Companion;
   readonly isUnlocked:   boolean;
   readonly isActive:     boolean;
   readonly onSelect:     ()=> void;
+  readonly formatNumber: (n: number)=> string;
 }
 
 /**
@@ -72,6 +44,7 @@ interface CompanionCardProperties {
  * @param props.isUnlocked - Whether this companion is unlocked.
  * @param props.isActive - Whether this companion is currently active.
  * @param props.onSelect - Callback when the companion is selected/deselected.
+ * @param props.formatNumber - The number formatting utility function.
  * @returns The JSX element.
  */
 const CompanionCard = ({
@@ -79,6 +52,7 @@ const CompanionCard = ({
   isUnlocked,
   isActive,
   onSelect,
+  formatNumber,
 }: CompanionCardProperties): JSX.Element => {
   const bonusSign = companion.bonus.type === "questTime"
     ? "-"
@@ -138,10 +112,9 @@ const CompanionCard = ({
         </button>
         : <div className="companion-unlock-requirement">
           {"🔒 Unlock: "}
-          {formatThreshold(
+          {companion.unlock.type === "lifetimeGold"
-            companion.unlock.type,
+            ? formatNumber(companion.unlock.threshold)
-            companion.unlock.threshold,
+            : String(companion.unlock.threshold)}{" "}
-          )}{" "}
           {unlockLabels[companion.unlock.type] ?? companion.unlock.type}
         </div>
       }
@@ -154,7 +127,7 @@ const CompanionCard = ({
  * @returns The JSX element.
  */
 const CompanionPanel = (): JSX.Element => {
-  const { state, setActiveCompanion } = useGame();
+  const { formatNumber, setActiveCompanion, state } = useGame();
 
   if (state === null) {
     return (
@@ -204,6 +177,7 @@ const CompanionPanel = (): JSX.Element => {
           return (
             <CompanionCard
               companion={companion}
+              formatNumber={formatNumber}
               isActive={activeId === companion.id}
               isUnlocked={unlockedIds.includes(companion.id)}
               key={companion.id}

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

@@ -27,12 +27,12 @@ const baseThreshold = 1_000_000;
 
 /**
  * Calculates the prestige threshold for a given prestige count.
- * Mirrors the server formula: BASE * (count + 1)^2.
+ * Mirrors the server formula: BASE * (count + 1)^2.5.
  * @param prestigeCount - The current prestige count.
  * @returns The required gold to prestige.
  */
 const calculateThreshold = (prestigeCount: number): number => {
-  return baseThreshold * Math.pow(prestigeCount + 1, 2);
+  return baseThreshold * Math.pow(prestigeCount + 1, 2.5);
 };
 
 /**

apps/web/src/engine/tick.ts

@@ -465,7 +465,7 @@ export const computeProjectedRunestones = (state: GameState): number => {
   const thresholdMult: number
     = state.transcendence?.echoPrestigeThresholdMultiplier ?? 1;
   const threshold
-    = basePrestigeThreshold * Math.pow(count + 1, 2) * thresholdMult;
+    = basePrestigeThreshold * Math.pow(count + 1, 2.5) * thresholdMult;
   const base = Math.min(
     Math.floor(Math.cbrt(state.player.totalGoldEarned / threshold))
     * runestonesPerPrestigeLevelClient,

apps/web/test/format.spec.ts

@@ -8,7 +8,7 @@
  * @author Naomi Carrigan
  */
 import { describe, expect, it } from "vitest";
-import { formatNumber } from "../src/utils/format.js";
+import { formatInteger, formatNumber } from "../src/utils/format.js";
 
 describe("formatNumber", () => {
   describe("edge cases", () => {
@@ -142,3 +142,59 @@ describe("formatNumber", () => {
     });
   });
 });
+
+describe("formatInteger", () => {
+  describe("edge cases", () => {
+    it("should return '0' for NaN", () => {
+      expect(formatInteger(Number.NaN)).toBe("0");
+    });
+
+    it("should return '0' for Infinity", () => {
+      expect(formatInteger(Infinity)).toBe("0");
+    });
+
+    it("should format negative integers with a leading minus sign", () => {
+      expect(formatInteger(-1500)).toBe("-1K");
+    });
+
+    it("should format zero as '0'", () => {
+      expect(formatInteger(0)).toBe("0");
+    });
+
+    it("should format small integers without decimals", () => {
+      expect(formatInteger(42)).toBe("42");
+    });
+  });
+
+  describe("named suffixes", () => {
+    it("should format thousands with K suffix and no decimals", () => {
+      expect(formatInteger(1500)).toBe("1K");
+    });
+
+    it("should format millions with M suffix and no decimals", () => {
+      expect(formatInteger(2_500_000)).toBe("2M");
+    });
+
+    it("should format billions with B suffix", () => {
+      expect(formatInteger(3_000_000_000)).toBe("3B");
+    });
+
+    it("should format trillions with T suffix", () => {
+      expect(formatInteger(1e12)).toBe("1T");
+    });
+
+    it("should format quintillions with Qi suffix", () => {
+      expect(formatInteger(1e18)).toBe("1Qi");
+    });
+  });
+
+  describe("letter suffixes", () => {
+    it("should format values >= 1e36 with letter suffix 'a'", () => {
+      expect(formatInteger(1e36)).toBe("1a");
+    });
+
+    it("should format values >= 1e39 with letter suffix 'b'", () => {
+      expect(formatInteger(1e39)).toBe("1b");
+    });
+  });
+});