diff --git a/app/(app)/shop/page.tsx b/app/(app)/shop/page.tsx
index 5a16088..7754210 100644
--- a/app/(app)/shop/page.tsx
+++ b/app/(app)/shop/page.tsx
@@ -1,34 +1,5 @@
 import { AppShell } from "@/components/layout/app-shell";
-import { Badge } from "@/components/ui/badge";
-import { Button } from "@/components/ui/button";
-import {
-  Card,
-  CardContent,
-  CardDescription,
-  CardHeader,
-  CardTitle,
-} from "@/components/ui/card";
-
-const shopItems = [
-  {
-    id: "hat",
-    name: "Pixel cap",
-    price: 50,
-    description: "A cozy cap for your habit pet.",
-  },
-  {
-    id: "bed",
-    name: "Cloud bed",
-    price: 120,
-    description: "Boost recovery after tough days.",
-  },
-  {
-    id: "snack",
-    name: "Berry snack",
-    price: 25,
-    description: "A small treat for good streaks.",
-  },
-];
+import { ShopContent } from "@/components/shop/shop-content";
 
 export default function ShopPage() {
   return (
@@ -36,31 +7,7 @@ export default function ShopPage() {
       title="Shop"
       description="Spend points earned from habits and daily check-ins."
     >
-      <div className="mb-4 flex items-center justify-between rounded-lg border bg-muted/40 px-4 py-3">
-        <span className="text-sm text-muted-foreground">Your balance</span>
-        <Badge variant="secondary">120 points</Badge>
-      </div>
-
-      <div className="grid gap-4">
-        {shopItems.map((item) => (
-          <Card key={item.id}>
-            <CardHeader>
-              <div className="flex items-start justify-between gap-3">
-                <div>
-                  <CardTitle className="text-base">{item.name}</CardTitle>
-                  <CardDescription>{item.description}</CardDescription>
-                </div>
-                <Badge>{item.price} pts</Badge>
-              </div>
-            </CardHeader>
-            <CardContent>
-              <Button className="w-full" variant="outline">
-                Buy
-              </Button>
-            </CardContent>
-          </Card>
-        ))}
-      </div>
+      <ShopContent />
     </AppShell>
   );
 }
diff --git a/components/habits/habit-tracker.tsx b/components/habits/habit-tracker.tsx
index 92dca98..6868c11 100644
--- a/components/habits/habit-tracker.tsx
+++ b/components/habits/habit-tracker.tsx
@@ -28,6 +28,7 @@ import {
   toggleHabitCompletion,
   type Habit,
 } from "@/lib/habits-storage";
+import { formatCoinsDelta } from "@/lib/coins";
 import { getProfilePreferences } from "@/lib/profile-preferences-storage";
 import { hasCompletedDailyQuizToday } from "@/lib/daily-quiz-storage";
 
@@ -187,6 +188,7 @@ export function HabitTracker({ mode = "daily" }: HabitTrackerProps) {
     () => new Set(),
   );
   const [toggleErrors, setToggleErrors] = useState<Record<string, string>>({});
+  const [coinMessage, setCoinMessage] = useState<string | null>(null);
 
   const getIsCompleted = useCallback(
     (habit: DailyTask) => {
@@ -231,6 +233,20 @@ export function HabitTracker({ mode = "daily" }: HabitTrackerProps) {
     }
   }, []);
 
+  useEffect(() => {
+    if (!coinMessage) {
+      return;
+    }
+
+    const timeoutId = window.setTimeout(() => {
+      setCoinMessage(null);
+    }, 3000);
+
+    return () => {
+      window.clearTimeout(timeoutId);
+    };
+  }, [coinMessage]);
+
   useEffect(() => {
     void refresh();
 
@@ -262,7 +278,8 @@ export function HabitTracker({ mode = "daily" }: HabitTrackerProps) {
 
     void (async () => {
       try {
-        const updatedHabits = await toggleHabitCompletion(habitId);
+        const { habits: updatedHabits, coinsDelta } =
+          await toggleHabitCompletion(habitId);
 
         setDailyTasks((current) =>
           current.map((task) => {
@@ -275,6 +292,7 @@ export function HabitTracker({ mode = "daily" }: HabitTrackerProps) {
           delete next[habitId];
           return next;
         });
+        setCoinMessage(formatCoinsDelta(coinsDelta));
       } catch (toggleError) {
         setOptimisticCompletion((current) => {
           const next = { ...current };
@@ -416,6 +434,9 @@ export function HabitTracker({ mode = "daily" }: HabitTrackerProps) {
       </CardHeader>
       <CardContent className="space-y-4">
         {error ? <p className="text-sm text-red-500">{error}</p> : null}
+        {coinMessage ? (
+          <p className="text-sm font-medium text-emerald-600">{coinMessage}</p>
+        ) : null}
         <DailyTaskList
           tasks={dailyTasks}
           getIsCompleted={getIsCompleted}
diff --git a/components/shop/shop-content.tsx b/components/shop/shop-content.tsx
new file mode 100644
index 0000000..66e1719
--- /dev/null
+++ b/components/shop/shop-content.tsx
@@ -0,0 +1,106 @@
+"use client";
+
+import { useCallback, useEffect, useState } from "react";
+
+import { Badge } from "@/components/ui/badge";
+import { Button } from "@/components/ui/button";
+import {
+  Card,
+  CardContent,
+  CardDescription,
+  CardHeader,
+  CardTitle,
+} from "@/components/ui/card";
+import { HABIT_PET_DATA_UPDATED_EVENT } from "@/lib/app-events";
+import { getCoins } from "@/lib/avatar-progression-storage";
+
+const shopItems = [
+  {
+    id: "hat",
+    name: "Pixel cap",
+    price: 50,
+    description: "A cozy cap for your habit pet.",
+  },
+  {
+    id: "bed",
+    name: "Cloud bed",
+    price: 120,
+    description: "Boost recovery after tough days.",
+  },
+  {
+    id: "snack",
+    name: "Berry snack",
+    price: 25,
+    description: "A small treat for good streaks.",
+  },
+];
+
+export function ShopContent() {
+  const [coins, setCoins] = useState<number | null>(null);
+  const [error, setError] = useState<string | null>(null);
+
+  const refreshCoins = useCallback(async () => {
+    try {
+      setError(null);
+      setCoins(await getCoins());
+    } catch (refreshError) {
+      setError(
+        refreshError instanceof Error
+          ? refreshError.message
+          : "Could not load your balance.",
+      );
+      setCoins(0);
+    }
+  }, []);
+
+  useEffect(() => {
+    void refreshCoins();
+
+    window.addEventListener(HABIT_PET_DATA_UPDATED_EVENT, refreshCoins);
+    return () => {
+      window.removeEventListener(HABIT_PET_DATA_UPDATED_EVENT, refreshCoins);
+    };
+  }, [refreshCoins]);
+
+  return (
+    <>
+      <div className="mb-4 flex items-center justify-between rounded-lg border bg-muted/40 px-4 py-3">
+        <span className="text-sm text-muted-foreground">Your balance</span>
+        <Badge variant="secondary">
+          {coins === null ? "..." : `${coins} points`}
+        </Badge>
+      </div>
+
+      {error ? <p className="mb-4 text-sm text-red-500">{error}</p> : null}
+
+      <div className="grid gap-4">
+        {shopItems.map((item) => {
+          const canAfford = coins !== null && coins >= item.price;
+
+          return (
+            <Card key={item.id}>
+              <CardHeader>
+                <div className="flex items-start justify-between gap-3">
+                  <div>
+                    <CardTitle className="text-base">{item.name}</CardTitle>
+                    <CardDescription>{item.description}</CardDescription>
+                  </div>
+                  <Badge>{item.price} pts</Badge>
+                </div>
+              </CardHeader>
+              <CardContent>
+                <Button
+                  className="w-full"
+                  variant="outline"
+                  disabled={coins === null || !canAfford}
+                >
+                  {canAfford ? "Buy" : "Not enough points"}
+                </Button>
+              </CardContent>
+            </Card>
+          );
+        })}
+      </div>
+    </>
+  );
+}
diff --git a/lib/avatar-progression-storage.ts b/lib/avatar-progression-storage.ts
new file mode 100644
index 0000000..d083bb4
--- /dev/null
+++ b/lib/avatar-progression-storage.ts
@@ -0,0 +1,74 @@
+import { createClient } from "@/lib/supabase/client";
+
+async function getAuthenticatedUserId() {
+  const supabase = createClient();
+  const {
+    data: { user },
+    error,
+  } = await supabase.auth.getUser();
+
+  if (error || !user) {
+    return null;
+  }
+
+  return user.id;
+}
+
+export async function getCoins(): Promise<number> {
+  const userId = await getAuthenticatedUserId();
+
+  if (!userId) {
+    return 0;
+  }
+
+  const supabase = createClient();
+  const { data, error } = await supabase
+    .from("avatar_state")
+    .select("coins")
+    .eq("user_id", userId)
+    .maybeSingle();
+
+  if (error) {
+    throw new Error(error.message);
+  }
+
+  if (!data) {
+    const { error: insertError } = await supabase
+      .from("avatar_state")
+      .insert({ user_id: userId, coins: 0 });
+
+    if (insertError) {
+      throw new Error(insertError.message);
+    }
+
+    return 0;
+  }
+
+  return data.coins ?? 0;
+}
+
+export async function adjustCoins(delta: number): Promise<number> {
+  const userId = await getAuthenticatedUserId();
+
+  if (!userId) {
+    throw new Error("You must be signed in to earn points.");
+  }
+
+  const currentCoins = await getCoins();
+  const nextCoins = Math.max(0, currentCoins + delta);
+
+  const supabase = createClient();
+  const { error } = await supabase
+    .from("avatar_state")
+    .update({
+      coins: nextCoins,
+      updated_at: new Date().toISOString(),
+    })
+    .eq("user_id", userId);
+
+  if (error) {
+    throw new Error(error.message);
+  }
+
+  return nextCoins;
+}
diff --git a/lib/coins.ts b/lib/coins.ts
new file mode 100644
index 0000000..8781247
--- /dev/null
+++ b/lib/coins.ts
@@ -0,0 +1,28 @@
+export const COINS_PER_TASK_COMPLETE = 50;
+export const COINS_PER_TASK_UNCHECK = -50;
+
+export const STREAK_MILESTONE_COINS: Record<number, number> = {
+  5: 50,
+  7: 75,
+  10: 100,
+  20: 150,
+  30: 200,
+  50: 350,
+  100: 750,
+};
+
+export const STREAK_MILESTONES = Object.keys(STREAK_MILESTONE_COINS)
+  .map(Number)
+  .sort((a, b) => a - b);
+
+export function getStreakMilestoneBonus(streak: number) {
+  return STREAK_MILESTONE_COINS[streak] ?? null;
+}
+
+export function formatCoinsDelta(delta: number) {
+  if (delta === 0) {
+    return "0 points";
+  }
+
+  return `${delta > 0 ? "+" : ""}${delta} points`;
+}
diff --git a/lib/daily-quiz-storage.ts b/lib/daily-quiz-storage.ts
index fa30185..b1df525 100644
--- a/lib/daily-quiz-storage.ts
+++ b/lib/daily-quiz-storage.ts
@@ -69,17 +69,20 @@ export async function getDailyEntryForToday(): Promise<DailyQuizSubmission | nul
     )
     .eq("user_id", userId)
     .eq("entry_date", entryDate)
-    .maybeSingle();
+    .order("created_at", { ascending: false })
+    .limit(1);
 
   if (error) {
     throw new Error(error.message);
   }
 
-  if (!data) {
+  const row = data?.[0];
+
+  if (!row) {
     return null;
   }
 
-  return mapRowToSubmission(data as DailyEntryRow);
+  return mapRowToSubmission(row as DailyEntryRow);
 }
 
 export async function getDailyQuizSubmission() {
diff --git a/lib/habits-storage.ts b/lib/habits-storage.ts
index 84662eb..824c5f0 100644
--- a/lib/habits-storage.ts
+++ b/lib/habits-storage.ts
@@ -4,7 +4,13 @@ import {
   getCatalogIdByLabel,
   isCatalogLabel,
 } from "@/lib/habit-catalog";
+import { adjustCoins } from "@/lib/avatar-progression-storage";
 import { notifyHabitPetDataUpdated } from "@/lib/app-events";
+import {
+  COINS_PER_TASK_COMPLETE,
+  COINS_PER_TASK_UNCHECK,
+  getStreakMilestoneBonus,
+} from "@/lib/coins";
 import { createClient } from "@/lib/supabase/client";
 
 export type Habit = {
@@ -16,13 +22,22 @@ export type Habit = {
   isCustom: boolean;
 };
 
+export type ToggleHabitResult = {
+  habits: Habit[];
+  coinsDelta: number;
+};
+
 type HabitRow = {
   id: string;
   name: string;
   streak: number;
   last_completed_on: string | null;
+  claimed_streak_milestones?: number[];
 };
 
+const habitSelectFields =
+  "id, name, streak, last_completed_on, claimed_streak_milestones";
+
 export function getTodayDateKey(date = new Date()) {
   return date.toISOString().slice(0, 10);
 }
@@ -50,12 +65,50 @@ function mapHabitRow(row: HabitRow): Habit {
     id: row.id,
     label: row.name,
     catalogId: getCatalogIdByLabel(row.name),
-    streak: row.streak,
-    lastCompletedDate: row.last_completed_on,
+    streak: row.streak ?? 0,
+    lastCompletedDate: row.last_completed_on ?? null,
     isCustom: !isCatalogLabel(row.name),
   };
 }
 
+function getFirstRow<T>(rows: T[] | null | undefined) {
+  return rows?.[0] ?? null;
+}
+
+function dedupeHabitsByName(rows: HabitRow[]) {
+  const seen = new Map<string, HabitRow>();
+
+  for (const row of rows) {
+    const key = row.name.trim().toLowerCase();
+
+    if (!seen.has(key)) {
+      seen.set(key, row);
+    }
+  }
+
+  return Array.from(seen.values());
+}
+
+async function findActiveHabitByName(
+  userId: string,
+  name: string,
+): Promise<HabitRow | null> {
+  const supabase = createClient();
+  const { data, error } = await supabase
+    .from("habits")
+    .select(habitSelectFields)
+    .eq("user_id", userId)
+    .eq("name", name)
+    .eq("active", true)
+    .order("created_at", { ascending: true });
+
+  if (error) {
+    throw new Error(error.message);
+  }
+
+  return getFirstRow(data as HabitRow[] | null);
+}
+
 async function getAuthenticatedUserId() {
   const supabase = createClient();
   const {
@@ -87,13 +140,16 @@ async function reconcileMissedDayStreaks(
 
   await Promise.all(
     habitsToReset.map((habit) =>
-      supabase.from("habits").update({ streak: 0 }).eq("id", habit.id),
+      supabase
+        .from("habits")
+        .update({ streak: 0, claimed_streak_milestones: [] })
+        .eq("id", habit.id),
     ),
   );
 
   return habits.map((habit) =>
     habitsToReset.some((item) => item.id === habit.id)
-      ? { ...habit, streak: 0 }
+      ? { ...habit, streak: 0, claimed_streak_milestones: [] }
       : habit,
   );
 }
@@ -111,14 +167,13 @@ async function getPreviousCompletedDate(
     .eq("habit_id", habitId)
     .neq("completed_on", today)
     .order("completed_on", { ascending: false })
-    .limit(1)
-    .maybeSingle();
+    .limit(1);
 
   if (error) {
     throw new Error(error.message);
   }
 
-  return data?.completed_on ?? null;
+  return getFirstRow(data as { completed_on: string }[] | null)?.completed_on ?? null;
 }
 
 export function isHabitCompletedToday(habit: Habit, today = getTodayDateKey()) {
@@ -135,7 +190,7 @@ export async function getHabits(): Promise<Habit[]> {
   const supabase = createClient();
   const { data, error } = await supabase
     .from("habits")
-    .select("id, name, streak, last_completed_on")
+    .select(habitSelectFields)
     .eq("user_id", userId)
     .eq("active", true)
     .order("created_at", { ascending: true });
@@ -144,7 +199,9 @@ export async function getHabits(): Promise<Habit[]> {
     throw new Error(error.message);
   }
 
-  const rows = await reconcileMissedDayStreaks((data ?? []) as HabitRow[]);
+  const rows = await reconcileMissedDayStreaks(
+    dedupeHabitsByName((data ?? []) as HabitRow[]),
+  );
 
   return rows.map(mapHabitRow);
 }
@@ -163,19 +220,7 @@ export async function ensureCatalogHabit(catalogId: string): Promise<Habit | nul
   }
 
   const supabase = createClient();
-  const { data: existing, error: existingError } = await supabase
-    .from("habits")
-    .select("id, name, streak, last_completed_on")
-    .eq("user_id", userId)
-    .eq("name", entry.label)
-    .eq("active", true)
-    .maybeSingle();
-
-  if (existingError) {
-    throw new Error(existingError.message);
-  }
-
-  let row = existing as HabitRow | null;
+  let row = await findActiveHabitByName(userId, entry.label);
 
   if (!row) {
     const { data: inserted, error: insertError } = await supabase
@@ -186,25 +231,31 @@ export async function ensureCatalogHabit(catalogId: string): Promise<Habit | nul
         active: true,
         streak: 0,
       })
-      .select("id, name, streak, last_completed_on")
+      .select(habitSelectFields)
       .single();
 
     if (insertError) {
-      throw new Error(insertError.message);
-    }
+      row = await findActiveHabitByName(userId, entry.label);
 
-    row = inserted as HabitRow;
+      if (!row) {
+        throw new Error(insertError.message);
+      }
+    } else {
+      row = inserted as HabitRow;
+    }
   }
 
   const [reconciledRow] = await reconcileMissedDayStreaks([row]);
   return mapHabitRow(reconciledRow);
 }
 
-export async function toggleHabitCompletion(habitId: string): Promise<Habit[]> {
+export async function toggleHabitCompletion(
+  habitId: string,
+): Promise<ToggleHabitResult> {
   const userId = await getAuthenticatedUserId();
 
   if (!userId) {
-    return [];
+    return { habits: [], coinsDelta: 0 };
   }
 
   const supabase = createClient();
@@ -212,7 +263,7 @@ export async function toggleHabitCompletion(habitId: string): Promise<Habit[]> {
 
   const { data: habit, error: habitError } = await supabase
     .from("habits")
-    .select("id, name, streak, last_completed_on")
+    .select(habitSelectFields)
     .eq("id", habitId)
     .eq("user_id", userId)
     .maybeSingle();
@@ -226,25 +277,29 @@ export async function toggleHabitCompletion(habitId: string): Promise<Habit[]> {
   }
 
   const [reconciledHabit] = await reconcileMissedDayStreaks([habit as HabitRow]);
-  let currentStreak = reconciledHabit.streak;
+  const currentStreak = reconciledHabit.streak;
 
-  const { data: existingLog, error: existingLogError } = await supabase
+  const { data: existingLogs, error: existingLogError } = await supabase
     .from("habit_logs")
     .select("id")
     .eq("user_id", userId)
     .eq("habit_id", habitId)
-    .eq("completed_on", today)
-    .maybeSingle();
+    .eq("completed_on", today);
 
   if (existingLogError) {
     throw new Error(existingLogError.message);
   }
 
+  const existingLog = getFirstRow(existingLogs as { id: string }[] | null);
+  let coinsDelta = 0;
+
   if (existingLog) {
     const { error: deleteError } = await supabase
       .from("habit_logs")
       .delete()
-      .eq("id", existingLog.id);
+      .eq("user_id", userId)
+      .eq("habit_id", habitId)
+      .eq("completed_on", today);
 
     if (deleteError) {
       throw new Error(deleteError.message);
@@ -265,6 +320,8 @@ export async function toggleHabitCompletion(habitId: string): Promise<Habit[]> {
     if (updateError) {
       throw new Error(updateError.message);
     }
+
+    coinsDelta = COINS_PER_TASK_UNCHECK;
   } else {
     const { error: insertError } = await supabase.from("habit_logs").insert({
       user_id: userId,
@@ -277,12 +334,20 @@ export async function toggleHabitCompletion(habitId: string): Promise<Habit[]> {
     }
 
     const nextStreak = currentStreak + 1;
+    const claimedMilestones = reconciledHabit.claimed_streak_milestones ?? [];
+    const milestoneBonus = getStreakMilestoneBonus(nextStreak);
+    const earnedMilestoneBonus =
+      milestoneBonus !== null && !claimedMilestones.includes(nextStreak);
+    const nextClaimedMilestones = earnedMilestoneBonus
+      ? [...claimedMilestones, nextStreak]
+      : claimedMilestones;
 
     const { error: updateError } = await supabase
       .from("habits")
       .update({
         streak: nextStreak,
         last_completed_on: today,
+        claimed_streak_milestones: nextClaimedMilestones,
       })
       .eq("id", habitId)
       .eq("user_id", userId);
@@ -290,10 +355,15 @@ export async function toggleHabitCompletion(habitId: string): Promise<Habit[]> {
     if (updateError) {
       throw new Error(updateError.message);
     }
+
+    coinsDelta =
+      COINS_PER_TASK_COMPLETE + (earnedMilestoneBonus ? milestoneBonus : 0);
   }
 
+  await adjustCoins(coinsDelta);
+
   notifyHabitPetDataUpdated();
-  return getHabits();
+  return { habits: await getHabits(), coinsDelta };
 }
 
 export async function addHabit(label: string): Promise<Habit[]> {
diff --git a/supabase/migrations/20260524160000_deduplicate_habits.sql b/supabase/migrations/20260524160000_deduplicate_habits.sql
new file mode 100644
index 0000000..4b7bbaa
--- /dev/null
+++ b/supabase/migrations/20260524160000_deduplicate_habits.sql
@@ -0,0 +1,13 @@
+-- Remove duplicate active habits with the same name for a user.
+delete from public.habits duplicate
+using public.habits keeper
+where duplicate.user_id = keeper.user_id
+  and duplicate.name = keeper.name
+  and duplicate.active = true
+  and keeper.active = true
+  and duplicate.id <> keeper.id
+  and duplicate.created_at > keeper.created_at;
+
+create unique index if not exists habits_user_id_name_active_unique
+  on public.habits (user_id, name)
+  where active = true;
diff --git a/supabase/migrations/20260524170000_habit_streak_milestones.sql b/supabase/migrations/20260524170000_habit_streak_milestones.sql
new file mode 100644
index 0000000..6aa7cfc
--- /dev/null
+++ b/supabase/migrations/20260524170000_habit_streak_milestones.sql
@@ -0,0 +1,2 @@
+alter table public.habits
+  add column if not exists claimed_streak_milestones int[] not null default '{}';