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
- * then gets easier as the production multiplier overtakes it.
+ * Formula: BASE * (count + 1)^2.5 — steeper growth to keep late prestiges
+ * 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", () => {
-    // base × (1+1)^2 = 1_000_000 × 4 = 4_000_000
-    expect(calculatePrestigeThreshold(1)).toBe(4_000_000);
+  it("returns base × 2^2.5 at count 1", () => {
+    // base × (1+1)^2.5 = 1_000_000 × 2^2.5
+    expect(calculatePrestigeThreshold(1)).toBeCloseTo(1_000_000 * Math.pow(2, 2.5));
   });
 
-  it("returns 9× base at count 2", () => {
-    // base × (2+1)^2 = 1_000_000 × 9 = 9_000_000
-    expect(calculatePrestigeThreshold(2)).toBe(9_000_000);
+  it("returns base × 3^2.5 at count 2", () => {
+    // base × (2+1)^2.5 = 1_000_000 × 3^2.5
+    expect(calculatePrestigeThreshold(2)).toBeCloseTo(1_000_000 * Math.pow(3, 2.5));
   });
 
   it("applies threshold multiplier correctly", () => {