feat: add daily challenges system

Three PST-midnight-resetting challenges generated deterministically per
day from click, boss, quest, and prestige types. Progress tracked
server-side for bosses and prestige, client-side for clicks and quests.
Crystal rewards awarded on completion and preserved through prestige resets.

IDEAS.md

@@ -10,7 +10,7 @@ A running list of planned features and content additions. Strike through items a
 
 - [ ] **Second prestige layer (Transcendence)** — Unlocked after ~10 prestiges. Sacrifice all runestones for a new currency ("Echoes"?). Echoes are permanent account-wide currency that persist across prestiges. Has its own upgrade tree with truly game-changing bonuses. Gives endgame players a long-term goal.
 
-- [ ] **Daily challenges** — Three rotating objectives each day (e.g. kill X boss, earn X gold this run, complete X quests). Reward bonus runestones. Encourages daily logins even when idling comfortably.
+- [x] **Daily challenges** — Three rotating objectives each day (e.g. kill X boss, earn X gold this run, complete X quests). Reward bonus crystals. Encourages daily logins even when idling comfortably.
 
 - [ ] **Boss first-kill bounties** — Defeating a boss for the very first time grants a one-time runestone bonus. Rewards exploration and makes conquering a new zone feel extra satisfying.
 
@@ -30,7 +30,7 @@ A running list of planned features and content additions. Strike through items a
 
 ## 📊 UI / Statistics
 
-- [ ] **Statistics panel** — All-time totals: gold earned across all runs, total prestiges, bosses defeated, quests completed, time played. Idle game players love seeing big numbers about their big numbers.
+- [x] **Statistics panel** — All-time totals: gold earned across all runs, total prestiges, bosses defeated, quests completed, time played. Idle game players love seeing big numbers about their big numbers.
 
 - [ ] **Last cloud save date + Force cloud save button** — Display when the last cloud save occurred (always visible, e.g. in the ResourceBar). Include a manual "Force Save" button for peace of mind.
 
@@ -39,8 +39,8 @@ A running list of planned features and content additions. Strike through items a
 ## 💜 Priority Order (Suggested)
 
 1. ~~Offline earnings~~ ✅
-2. Statistics panel (low effort, high satisfaction)
+2. ~~Statistics panel~~ ✅
-3. Daily challenges (retention driver)
+3. ~~Daily challenges~~ ✅
 4. Boss first-kill bounties (easy content win)
 5. Milestone prestige bonuses (easy content win)
 6. Equipment set bonuses (medium effort)

apps/api/src/data/dailyChallenges.ts

@@ -0,0 +1,25 @@
+import type { DailyChallengeType } from "@elysium/types";
+
+interface DailyChallengeTemplate {
+  type: DailyChallengeType;
+  label: string;
+  target: number;
+  rewardCrystals: number;
+}
+
+export const DAILY_CHALLENGE_TEMPLATES: DailyChallengeTemplate[] = [
+  // Clicks — always requires active play
+  { type: "clicks", label: "Click 500 times", target: 500, rewardCrystals: 50 },
+  { type: "clicks", label: "Click 1,000 times", target: 1_000, rewardCrystals: 100 },
+  { type: "clicks", label: "Click 5,000 times", target: 5_000, rewardCrystals: 300 },
+  // Boss defeats — requires active combat
+  { type: "bossesDefeated", label: "Defeat 1 boss", target: 1, rewardCrystals: 75 },
+  { type: "bossesDefeated", label: "Defeat 3 bosses", target: 3, rewardCrystals: 200 },
+  { type: "bossesDefeated", label: "Defeat 5 bosses", target: 5, rewardCrystals: 400 },
+  // Quest completions — requires starting quests
+  { type: "questsCompleted", label: "Complete 3 quests", target: 3, rewardCrystals: 100 },
+  { type: "questsCompleted", label: "Complete 5 quests", target: 5, rewardCrystals: 200 },
+  { type: "questsCompleted", label: "Complete 10 quests", target: 10, rewardCrystals: 400 },
+  // Prestige — the big one
+  { type: "prestige", label: "Prestige once", target: 1, rewardCrystals: 750 },
+];

apps/api/src/routes/boss.ts

@@ -2,6 +2,7 @@ import type { BossChallengeResponse, GameState } from "@elysium/types";
 import { Hono } from "hono";
 import { prisma } from "../db/client.js";
 import { authMiddleware } from "../middleware/auth.js";
+import { updateChallengeProgress } from "../services/dailyChallenges.js";
 
 export const bossRouter = new Hono();
 
@@ -173,6 +174,17 @@ bossRouter.post("/challenge", async (context) => {
       }
     }
 
+    // Update daily boss challenge progress
+    if (state.dailyChallenges) {
+      const { updatedChallenges, crystalsAwarded } = updateChallengeProgress(
+        state.dailyChallenges,
+        "bossesDefeated",
+        1,
+      );
+      state.dailyChallenges = updatedChallenges;
+      state.resources.crystals += crystalsAwarded;
+    }
+
     rewards = {
       gold: boss.goldReward,
       essence: boss.essenceReward,

apps/api/src/routes/game.ts

@@ -6,6 +6,7 @@ import { DEFAULT_ACHIEVEMENTS } from "../data/achievements.js";
 import { DEFAULT_ADVENTURERS } from "../data/adventurers.js";
 import { DEFAULT_EQUIPMENT } from "../data/equipment.js";
 import { authMiddleware } from "../middleware/auth.js";
+import { getOrResetDailyChallenges } from "../services/dailyChallenges.js";
 import { calculateOfflineEarnings } from "../services/offlineProgress.js";
 
 const RESOURCE_CAP = 1e300;
@@ -327,6 +328,9 @@ gameRouter.get("/load", async (context) => {
     state.resources.essence += offlineEssence;
   }
 
+  // Generate or reset daily challenges if a new day has begun
+  state.dailyChallenges = getOrResetDailyChallenges(state);
+
   state.lastTickAt = now;
 
   if (needsBackfill || offlineGold > 0 || offlineEssence > 0) {

apps/api/src/routes/prestige.ts

@@ -3,6 +3,7 @@ import { Hono } from "hono";
 import { prisma } from "../db/client.js";
 import { authMiddleware } from "../middleware/auth.js";
 import { DEFAULT_PRESTIGE_UPGRADES } from "../data/prestigeUpgrades.js";
+import { updateChallengeProgress } from "../services/dailyChallenges.js";
 import {
   buildPostPrestigeState,
   computeRunestoneMultipliers,
@@ -37,15 +38,34 @@ prestigeRouter.post("/", async (context) => {
     );
   }
 
+  // Update daily prestige challenge progress before resetting the run
+  let updatedDailyChallenges = state.dailyChallenges;
+  let challengeCrystals = 0;
+  if (updatedDailyChallenges) {
+    const result = updateChallengeProgress(updatedDailyChallenges, "prestige", 1);
+    updatedDailyChallenges = result.updatedChallenges;
+    challengeCrystals = result.crystalsAwarded;
+  }
+
   const { newState, newPrestigeData, runestonesEarned } = buildPostPrestigeState(
     state,
     characterName,
   );
 
+  // Preserve daily challenges across the prestige reset and apply any crystal rewards
+  const finalState: GameState = {
+    ...newState,
+    dailyChallenges: updatedDailyChallenges,
+    resources: {
+      ...newState.resources,
+      crystals: newState.resources.crystals + challengeCrystals,
+    },
+  };
+
   const now = Date.now();
   await prisma.gameState.update({
     where: { discordId },
-    data: { state: newState as object, updatedAt: now },
+    data: { state: finalState as object, updatedAt: now },
   });
 
   await prisma.player.update({

apps/api/src/services/dailyChallenges.ts

@@ -0,0 +1,103 @@
+import type {
+  DailyChallenge,
+  DailyChallengeState,
+  DailyChallengeType,
+  GameState,
+} from "@elysium/types";
+import { DAILY_CHALLENGE_TEMPLATES } from "../data/dailyChallenges.js";
+
+// Use the server's PST/PDT timezone so challenges roll over at PST midnight
+const getTodayString = (): string =>
+  new Intl.DateTimeFormat("en-CA", { timeZone: "America/Los_Angeles" }).format(new Date());
+
+/** Simple deterministic pseudo-random based on a numeric seed. */
+const seededRandom = (seed: number): number => {
+  const x = Math.sin(seed + 1) * 10_000;
+  return x - Math.floor(x);
+};
+
+/** Converts a date string into a stable numeric seed. */
+const dateSeed = (dateStr: string): number =>
+  dateStr.split("").reduce((acc, char, i) => acc + char.charCodeAt(0) * (i + 1), 0);
+
+/** Deterministically shuffles an array using a numeric seed. */
+const shuffleWithSeed = <T>(arr: T[], seed: number): T[] => {
+  const result = [...arr];
+  for (let i = result.length - 1; i > 0; i--) {
+    const j = Math.floor(seededRandom(seed + i) * (i + 1));
+    [result[i], result[j]] = [result[j], result[i]];
+  }
+  return result;
+};
+
+const CHALLENGE_TYPES: DailyChallengeType[] = [
+  "clicks",
+  "bossesDefeated",
+  "questsCompleted",
+  "prestige",
+];
+
+/**
+ * Generates 3 daily challenges for the given date string, deterministically.
+ * Picks one challenge from 3 different randomly-selected types.
+ */
+export const generateDailyChallenges = (dateStr: string): DailyChallenge[] => {
+  const seed = dateSeed(dateStr);
+  const selectedTypes = shuffleWithSeed([...CHALLENGE_TYPES], seed).slice(0, 3);
+
+  return selectedTypes.map((type, index) => {
+    const templates = DAILY_CHALLENGE_TEMPLATES.filter((t) => t.type === type);
+    const templateIndex = Math.floor(seededRandom(seed + index * 100) * templates.length);
+    const template = templates[templateIndex];
+
+    return {
+      id: `${dateStr}_${type}`,
+      type: template.type,
+      label: template.label,
+      target: template.target,
+      progress: 0,
+      completed: false,
+      rewardCrystals: template.rewardCrystals,
+    };
+  });
+};
+
+/**
+ * Returns the current daily challenge state, generating fresh challenges if
+ * the stored date doesn't match today (i.e. a new day has begun).
+ */
+export const getOrResetDailyChallenges = (state: GameState): DailyChallengeState => {
+  const today = getTodayString();
+  if (state.dailyChallenges?.date === today) {
+    return state.dailyChallenges;
+  }
+  return { date: today, challenges: generateDailyChallenges(today) };
+};
+
+/**
+ * Increments progress for challenges matching the given type.
+ * Returns the updated challenge state and total crystals awarded for newly completed challenges.
+ */
+export const updateChallengeProgress = (
+  challengeState: DailyChallengeState,
+  type: DailyChallengeType,
+  amount: number,
+): { updatedChallenges: DailyChallengeState; crystalsAwarded: number } => {
+  let crystalsAwarded = 0;
+
+  const updatedChallenges: DailyChallengeState = {
+    ...challengeState,
+    challenges: challengeState.challenges.map((challenge) => {
+      if (challenge.type !== type || challenge.completed) return challenge;
+
+      const newProgress = Math.min(challenge.progress + amount, challenge.target);
+      const nowCompleted = newProgress >= challenge.target;
+
+      if (nowCompleted) crystalsAwarded += challenge.rewardCrystals;
+
+      return { ...challenge, progress: newProgress, completed: nowCompleted };
+    }),
+  };
+
+  return { updatedChallenges, crystalsAwarded };
+};

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

@@ -0,0 +1,91 @@
+import { useGame } from "../../context/GameContext.js";
+
+const formatTimeUntilReset = (): string => {
+  const now = new Date();
+  // Mirror the server's PST/PDT-based rollover: challenges reset at PST midnight
+  const nowAsPST = new Date(now.toLocaleString("en-US", { timeZone: "America/Los_Angeles" }));
+  const tomorrowMidnightPST = new Date(nowAsPST);
+  tomorrowMidnightPST.setDate(tomorrowMidnightPST.getDate() + 1);
+  tomorrowMidnightPST.setHours(0, 0, 0, 0);
+  const pstOffset = nowAsPST.getTime() - now.getTime();
+  const resetAt = new Date(tomorrowMidnightPST.getTime() - pstOffset);
+  const msRemaining = resetAt.getTime() - now.getTime();
+  const hoursRemaining = Math.floor(msRemaining / (1000 * 60 * 60));
+  const minutesRemaining = Math.floor((msRemaining % (1000 * 60 * 60)) / (1000 * 60));
+  return `${String(hoursRemaining)}h ${String(minutesRemaining)}m`;
+};
+
+export const DailyChallengePanel = (): React.JSX.Element => {
+  const { state, formatNumber } = useGame();
+
+  if (!state) return <section className="panel"><p>Loading...</p></section>;
+
+  const { dailyChallenges } = state;
+
+  if (!dailyChallenges) {
+    return (
+      <section className="panel daily-challenge-panel">
+        <h2>📅 Daily Challenges</h2>
+        <p className="daily-challenge-subtitle">Load the game to generate today's challenges!</p>
+      </section>
+    );
+  }
+
+  const completedCount = dailyChallenges.challenges.filter((c) => c.completed).length;
+
+  return (
+    <section className="panel daily-challenge-panel">
+      <h2>📅 Daily Challenges</h2>
+      <div className="daily-challenge-header">
+        <p className="daily-challenge-subtitle">
+          Complete challenges for bonus 💎 crystals! Resets in{" "}
+          <strong>{formatTimeUntilReset()}</strong> (PST midnight).
+        </p>
+        <p className="daily-challenge-progress">
+          {completedCount} / {dailyChallenges.challenges.length} completed
+        </p>
+      </div>
+
+      <div className="daily-challenge-list">
+        {dailyChallenges.challenges.map((challenge) => {
+          const progressPercent = Math.min(
+            100,
+            Math.floor((challenge.progress / challenge.target) * 100),
+          );
+
+          return (
+            <div
+              key={challenge.id}
+              className={`daily-challenge-card ${challenge.completed ? "completed" : ""}`}
+            >
+              <div className="daily-challenge-info">
+                <h3 className="daily-challenge-label">{challenge.label}</h3>
+                <p className="daily-challenge-reward">
+                  Reward: <strong>💎 {formatNumber(challenge.rewardCrystals)} crystals</strong>
+                </p>
+              </div>
+
+              <div className="daily-challenge-right">
+                {challenge.completed ? (
+                  <span className="daily-challenge-done">✅ Complete!</span>
+                ) : (
+                  <>
+                    <p className="daily-challenge-count">
+                      {formatNumber(challenge.progress)} / {formatNumber(challenge.target)}
+                    </p>
+                    <div className="daily-challenge-bar-track">
+                      <div
+                        className="daily-challenge-bar-fill"
+                        style={{ width: `${String(progressPercent)}%` }}
+                      />
+                    </div>
+                  </>
+                )}
+              </div>
+            </div>
+          );
+        })}
+      </div>
+    </section>
+  );
+};

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

@@ -14,8 +14,9 @@ import { PrestigePanel } from "./PrestigePanel.js";
 import { QuestPanel } from "./QuestPanel.js";
 import { StatisticsPanel } from "./StatisticsPanel.js";
 import { UpgradePanel } from "./UpgradePanel.js";
+import { DailyChallengePanel } from "./DailyChallengePanel.js";
 
-type Tab = "adventurers" | "upgrades" | "quests" | "bosses" | "equipment" | "achievements" | "prestige" | "statistics";
+type Tab = "adventurers" | "upgrades" | "quests" | "bosses" | "equipment" | "achievements" | "prestige" | "statistics" | "daily";
 
 const TABS: { id: Tab; label: string }[] = [
   { id: "adventurers", label: "⚔️ Adventurers" },
@@ -26,6 +27,7 @@ const TABS: { id: Tab; label: string }[] = [
   { id: "achievements", label: "🏆 Achievements" },
   { id: "prestige", label: "⭐ Prestige" },
   { id: "statistics", label: "📊 Statistics" },
+  { id: "daily", label: "📅 Daily" },
 ];
 
 export const GameLayout = (): React.JSX.Element => {
@@ -101,6 +103,7 @@ export const GameLayout = (): React.JSX.Element => {
             {activeTab === "achievements" && <AchievementPanel />}
             {activeTab === "prestige" && <PrestigePanel />}
             {activeTab === "statistics" && <StatisticsPanel />}
+            {activeTab === "daily" && <DailyChallengePanel />}
           </div>
         </main>
       </div>

apps/web/src/context/GameContext.tsx

@@ -14,6 +14,7 @@ import {
   saveGame,
 } from "../api/client.js";
 import { RESOURCE_CAP, applyTick, calculateClickPower } from "../engine/tick.js";
+import { updateChallengeProgress } from "../utils/dailyChallenges.js";
 import { formatNumber as formatNumberUtil } from "../utils/format.js";
 
 
@@ -245,14 +246,28 @@ export const GameProvider = ({ children }: { children: React.ReactNode }): React
       if (!prev) return prev;
       const clickPower = calculateClickPower(prev);
       const newGold = Math.min(prev.resources.gold + clickPower, RESOURCE_CAP);
+
+      let updatedDailyChallenges = prev.dailyChallenges;
+      let challengeCrystals = 0;
+      if (updatedDailyChallenges) {
+        const result = updateChallengeProgress(updatedDailyChallenges, "clicks", 1);
+        updatedDailyChallenges = result.updatedChallenges;
+        challengeCrystals = result.crystalsAwarded;
+      }
+
       return {
         ...prev,
-        resources: { ...prev.resources, gold: newGold },
+        resources: {
+          ...prev.resources,
+          gold: newGold,
+          crystals: Math.min(prev.resources.crystals + challengeCrystals, RESOURCE_CAP),
+        },
         player: {
           ...prev.player,
           totalGoldEarned: prev.player.totalGoldEarned + clickPower,
           totalClicks: prev.player.totalClicks + 1,
         },
+        dailyChallenges: updatedDailyChallenges,
       };
     });
   }, []);

apps/web/src/engine/tick.ts

@@ -1,4 +1,5 @@
 import type { Achievement, Equipment, GameState } from "@elysium/types";
+import { updateChallengeProgress } from "../utils/dailyChallenges.js";
 
 /**
  * Checks all achievements against the current game state and returns an updated
@@ -198,6 +199,23 @@ export const applyTick = (state: GameState, deltaSeconds: number): GameState =>
     });
   }
 
+  // Count quests newly completed this tick and update daily challenge progress
+  const newlyCompletedQuestCount = updatedQuests.filter(
+    (q, i) => q.status === "completed" && state.quests[i]?.status !== "completed",
+  ).length;
+
+  let updatedDailyChallenges = state.dailyChallenges;
+  let challengeCrystals = 0;
+  if (updatedDailyChallenges && newlyCompletedQuestCount > 0) {
+    const result = updateChallengeProgress(
+      updatedDailyChallenges,
+      "questsCompleted",
+      newlyCompletedQuestCount,
+    );
+    updatedDailyChallenges = result.updatedChallenges;
+    challengeCrystals = result.crystalsAwarded;
+  }
+
   const newGold = capResource(state.resources.gold + goldGained + questGold);
   const newEssence = capResource(state.resources.essence + essenceGained + questEssence);
   const newTotalGoldEarned = state.player.totalGoldEarned + goldGained + questGold;
@@ -208,8 +226,9 @@ export const applyTick = (state: GameState, deltaSeconds: number): GameState =>
       ...state.resources,
       gold: newGold,
       essence: newEssence,
-      crystals: capResource(state.resources.crystals + questCrystals),
+      crystals: capResource(state.resources.crystals + questCrystals + challengeCrystals),
     },
+    dailyChallenges: updatedDailyChallenges,
     player: {
       ...state.player,
       totalGoldEarned: newTotalGoldEarned,

apps/web/src/styles.css

@@ -1837,3 +1837,108 @@ body {
   height: 100vh;
   justify-content: center;
 }
+
+/* ===================== DAILY CHALLENGES ===================== */
+
+.daily-challenge-panel {
+  display: flex;
+  flex-direction: column;
+  gap: 1rem;
+}
+
+.daily-challenge-header {
+  display: flex;
+  align-items: flex-start;
+  justify-content: space-between;
+  flex-wrap: wrap;
+  gap: 0.5rem;
+}
+
+.daily-challenge-subtitle {
+  color: var(--colour-text-muted);
+  font-size: 0.85rem;
+  margin: 0;
+}
+
+.daily-challenge-progress {
+  color: var(--colour-accent);
+  font-size: 0.85rem;
+  font-weight: bold;
+  white-space: nowrap;
+  margin: 0;
+}
+
+.daily-challenge-list {
+  display: flex;
+  flex-direction: column;
+  gap: 0.75rem;
+}
+
+.daily-challenge-card {
+  background: var(--colour-bg-secondary);
+  border: 1px solid var(--colour-border);
+  border-radius: 8px;
+  display: flex;
+  align-items: center;
+  justify-content: space-between;
+  gap: 1rem;
+  padding: 0.75rem 1rem;
+  transition: border-color 0.2s ease;
+}
+
+.daily-challenge-card.completed {
+  border-color: var(--colour-success, #4caf50);
+  opacity: 0.8;
+}
+
+.daily-challenge-info {
+  flex: 1;
+  min-width: 0;
+}
+
+.daily-challenge-label {
+  font-size: 0.95rem;
+  font-weight: bold;
+  margin: 0 0 0.25rem;
+}
+
+.daily-challenge-reward {
+  color: var(--colour-text-muted);
+  font-size: 0.8rem;
+  margin: 0;
+}
+
+.daily-challenge-right {
+  display: flex;
+  flex-direction: column;
+  align-items: flex-end;
+  gap: 0.25rem;
+  min-width: 120px;
+}
+
+.daily-challenge-done {
+  color: var(--colour-success, #4caf50);
+  font-size: 0.9rem;
+  font-weight: bold;
+}
+
+.daily-challenge-count {
+  color: var(--colour-text-muted);
+  font-size: 0.8rem;
+  margin: 0;
+}
+
+.daily-challenge-bar-track {
+  background: var(--colour-bg-primary, #1a1a2e);
+  border-radius: 4px;
+  height: 6px;
+  width: 120px;
+  overflow: hidden;
+}
+
+.daily-challenge-bar-fill {
+  background: var(--colour-accent);
+  border-radius: 4px;
+  height: 100%;
+  transition: width 0.3s ease;
+}

apps/web/src/utils/dailyChallenges.ts

@@ -0,0 +1,32 @@
+import type { DailyChallengeState, DailyChallengeType } from "@elysium/types";
+
+/**
+ * Increments progress for daily challenges matching the given type.
+ * Returns the updated challenge state and any crystals awarded for newly-completed challenges.
+ *
+ * Note: challenge generation and daily resets are handled server-side only.
+ * This utility is purely for client-side progress tracking.
+ */
+export const updateChallengeProgress = (
+  challengeState: DailyChallengeState,
+  type: DailyChallengeType,
+  amount: number,
+): { updatedChallenges: DailyChallengeState; crystalsAwarded: number } => {
+  let crystalsAwarded = 0;
+
+  const updatedChallenges: DailyChallengeState = {
+    ...challengeState,
+    challenges: challengeState.challenges.map((challenge) => {
+      if (challenge.type !== type || challenge.completed) return challenge;
+
+      const newProgress = Math.min(challenge.progress + amount, challenge.target);
+      const nowCompleted = newProgress >= challenge.target;
+
+      if (nowCompleted) crystalsAwarded += challenge.rewardCrystals;
+
+      return { ...challenge, progress: newProgress, completed: nowCompleted };
+    }),
+  };
+
+  return { updatedChallenges, crystalsAwarded };
+};

packages/types/src/index.ts

@@ -22,6 +22,11 @@ export type {
   UpdateProfileResponse,
 } from "./interfaces/Api.js";
 export type { Boss, BossStatus } from "./interfaces/Boss.js";
+export type {
+  DailyChallenge,
+  DailyChallengeState,
+  DailyChallengeType,
+} from "./interfaces/DailyChallenge.js";
 export type {
   Equipment,
   EquipmentBonus,

packages/types/src/interfaces/DailyChallenge.ts

@@ -0,0 +1,17 @@
+export type DailyChallengeType = "clicks" | "bossesDefeated" | "questsCompleted" | "prestige";
+
+export interface DailyChallenge {
+  id: string;
+  type: DailyChallengeType;
+  label: string;
+  target: number;
+  progress: number;
+  completed: boolean;
+  rewardCrystals: number;
+}
+
+export interface DailyChallengeState {
+  /** ISO date string (e.g. "2026-03-06") used to detect when to reset */
+  date: string;
+  challenges: DailyChallenge[];
+}

packages/types/src/interfaces/GameState.ts

@@ -1,6 +1,7 @@
 import type { Achievement } from "./Achievement.js";
 import type { Adventurer } from "./Adventurer.js";
 import type { Boss } from "./Boss.js";
+import type { DailyChallengeState } from "./DailyChallenge.js";
 import type { Equipment } from "./Equipment.js";
 import type { Player } from "./Player.js";
 import type { PrestigeData } from "./Prestige.js";
@@ -24,4 +25,6 @@ export interface GameState {
   baseClickPower: number;
   /** Unix timestamp of the last client-side tick */
   lastTickAt: number;
+  /** Daily challenge progress — optional for backwards compatibility with old saves */
+  dailyChallenges?: DailyChallengeState;
 }