diff --git a/marketplace/src/pages/Cart.tsx b/marketplace/src/pages/Cart.tsx
index a2b9019..81cd0a3 100644
--- a/marketplace/src/pages/Cart.tsx
+++ b/marketplace/src/pages/Cart.tsx
@@ -2,7 +2,17 @@ import { ShoppingBasket } from 'lucide-react'
 import { Link } from 'react-router-dom'
 import { Shell } from '../layouts/Shell'
 import { selectGroupedCart, selectCartSummary, useCartStore } from '../stores/cartStore'
-import { formatCurrency } from '../utils/format'
+import { formatCents } from '../utils/format'
+
+// Debug logging for price values
+const logPrice = (label: string, value: number | undefined) => {
+  console.log(`%c🛒 [Cart] ${label}:`, 'color: #10B981; font-weight: bold', {
+    rawValue: value,
+    inCents: value,
+    inReais: value ? (value / 100).toFixed(2) : '0.00',
+    formatted: value ? formatCents(value) : 'N/A'
+  })
+}
 
 export function CartPage() {
   const items = useCartStore((state) => state.items)
@@ -27,7 +37,9 @@ export function CartPage() {
           {!isEmpty && (
             <div className="text-right">
               <p className="text-sm text-gray-600">Itens: {summary.totalItems}</p>
-              <p className="text-lg font-semibold text-medicalBlue">R$ {formatCurrency(summary.totalValue)}</p>
+              {/* Log total value */}
+              {(() => { logPrice('Total do carrinho', summary.totalValue); return null })()}
+              <p className="text-lg font-semibold text-medicalBlue">{formatCents(summary.totalValue)}</p>
             </div>
           )}
         </div>
@@ -81,7 +93,9 @@ export function CartPage() {
                     </div>
                     <div className="text-right">
                       <p className="text-xs text-gray-500">Preço</p>
-                      <p className="font-semibold text-medicalBlue">R$ {formatCurrency(item.unitPrice)}</p>
+                      {/* Log unit price */}
+                      {(() => { logPrice(`Preço unitário ${item.name}`, item.unitPrice); return null })()}
+                      <p className="font-semibold text-medicalBlue">{formatCents(item.unitPrice)}</p>
                     </div>
                     <div className="flex items-center justify-end gap-2">
                       <input
@@ -95,8 +109,10 @@ export function CartPage() {
                     </div>
                     <div className="text-right">
                       <p className="text-xs text-gray-500">Subtotal</p>
+                      {/* Log subtotal */}
+                      {(() => { logPrice(`Subtotal ${item.name} (${item.quantity}x)`, item.quantity * item.unitPrice); return null })()}
                       <p className="font-semibold text-gray-800">
-                        R$ {formatCurrency(item.quantity * item.unitPrice)}
+                        {formatCents(item.quantity * item.unitPrice)}
                       </p>
                       <button
                         className="text-xs text-red-500 hover:underline"
@@ -109,7 +125,9 @@ export function CartPage() {
                 ))}
                 <div className="flex items-center justify-between rounded bg-gray-100 px-3 py-2 text-sm">
                   <span className="font-semibold text-gray-700">Total do fornecedor</span>
-                  <span className="font-bold text-medicalBlue">R$ {formatCurrency(group.total)}</span>
+                  {/* Log vendor total */}
+                  {(() => { logPrice('Total fornecedor', group.total); return null })()}
+                  <span className="font-bold text-medicalBlue">{formatCents(group.total)}</span>
                 </div>
               </div>
             </div>
diff --git a/marketplace/src/stores/cartStore.test.ts b/marketplace/src/stores/cartStore.test.ts
index 7161cef..77ebab2 100644
--- a/marketplace/src/stores/cartStore.test.ts
+++ b/marketplace/src/stores/cartStore.test.ts
@@ -198,3 +198,129 @@ describe('selectors', () => {
         })
     })
 })
+
+/**
+ * PRICE CONVERSION TESTS
+ * These tests verify that prices are handled correctly in CENTS
+ * The API returns price_cents (e.g., 819 = R$ 8,19)
+ */
+describe('price conversion (cents)', () => {
+    const mockItemCents: Omit<CartItem, 'quantity'> = {
+        id: 'prod-cents-1',
+        name: 'Paracetamol 750mg',
+        activeIngredient: 'Paracetamol',
+        lab: 'EMS',
+        batch: 'L2025840',
+        expiry: '2027-09-15',
+        vendorId: 'vendor-anapolis',
+        vendorName: 'Anápolis/GO',
+        unitPrice: 819  // 819 cents = R$ 8,19
+    }
+
+    const mockItemCents2: Omit<CartItem, 'quantity'> = {
+        id: 'prod-cents-2',
+        name: 'Dipirona 500mg',
+        activeIngredient: 'Dipirona',
+        lab: 'Medley',
+        batch: 'L2025123',
+        expiry: '2026-06-30',
+        vendorId: 'vendor-anapolis',
+        vendorName: 'Anápolis/GO',
+        unitPrice: 1299  // 1299 cents = R$ 12,99
+    }
+
+    beforeEach(() => {
+        useCartStore.setState({ items: [] })
+    })
+
+    describe('storing prices in cents', () => {
+        it('should store unitPrice as cents (819 = R$ 8,19)', () => {
+            useCartStore.getState().addItem(mockItemCents)
+
+            const state = useCartStore.getState()
+            expect(state.items[0].unitPrice).toBe(819)
+            // Verify it's NOT stored as reais (8.19)
+            expect(state.items[0].unitPrice).not.toBe(8.19)
+        })
+
+        it('should preserve cents precision for subtotal calculation', () => {
+            useCartStore.getState().addItem(mockItemCents, 3)
+
+            const state = useCartStore.getState()
+            const item = state.items[0]
+            const subtotal = item.quantity * item.unitPrice
+
+            // 3 * 819 = 2457 cents = R$ 24,57
+            expect(subtotal).toBe(2457)
+            expect(subtotal / 100).toBe(24.57)
+        })
+    })
+
+    describe('cents calculations in selectors', () => {
+        it('should calculate vendor total in cents', () => {
+            // 819 cents * 2 = 1638 cents
+            useCartStore.getState().addItem(mockItemCents, 2)
+            // 1299 cents * 1 = 1299 cents
+            useCartStore.getState().addItem(mockItemCents2, 1)
+
+            const state = useCartStore.getState()
+            const groups = selectGroupedCart(state)
+
+            // Total: 1638 + 1299 = 2937 cents = R$ 29,37
+            expect(groups['vendor-anapolis'].total).toBe(2937)
+            expect(groups['vendor-anapolis'].total / 100).toBeCloseTo(29.37)
+        })
+
+        it('should calculate cart summary total in cents', () => {
+            useCartStore.getState().addItem(mockItemCents, 2)    // 1638 cents
+            useCartStore.getState().addItem(mockItemCents2, 1)   // 1299 cents
+
+            const state = useCartStore.getState()
+            const summary = selectCartSummary(state)
+
+            expect(summary.totalItems).toBe(3)
+            expect(summary.totalValue).toBe(2937) // cents
+            expect(summary.totalValue / 100).toBeCloseTo(29.37) // reais
+        })
+    })
+
+    describe('edge cases for cents', () => {
+        it('should handle single unit correctly', () => {
+            useCartStore.getState().addItem(mockItemCents, 1)
+
+            const state = useCartStore.getState()
+            const summary = selectCartSummary(state)
+
+            expect(summary.totalValue).toBe(819)
+            expect(summary.totalValue / 100).toBe(8.19)
+        })
+
+        it('should handle large quantities without overflow', () => {
+            useCartStore.getState().addItem(mockItemCents, 1000)
+
+            const state = useCartStore.getState()
+            const summary = selectCartSummary(state)
+
+            // 819 * 1000 = 819000 cents = R$ 8,190.00
+            expect(summary.totalValue).toBe(819000)
+            expect(summary.totalValue / 100).toBe(8190)
+        })
+
+        it('should handle small cent values (R$ 0,01)', () => {
+            const cheapItem: Omit<CartItem, 'quantity'> = {
+                ...mockItemCents,
+                id: 'cheap-1',
+                unitPrice: 1  // 1 cent = R$ 0,01
+            }
+
+            useCartStore.getState().addItem(cheapItem, 10)
+
+            const state = useCartStore.getState()
+            const summary = selectCartSummary(state)
+
+            expect(summary.totalValue).toBe(10) // 10 cents
+            expect(summary.totalValue / 100).toBe(0.10)
+        })
+    })
+})
+
diff --git a/marketplace/src/stores/cartStore.ts b/marketplace/src/stores/cartStore.ts
index bea9d87..73a4194 100644
--- a/marketplace/src/stores/cartStore.ts
+++ b/marketplace/src/stores/cartStore.ts
@@ -10,7 +10,7 @@ export interface CartItem {
   expiry: string
   vendorId: string
   vendorName: string
-  unitPrice: number
+  unitPrice: number // Price in CENTS (e.g., 819 = R$ 8,19)
   quantity: number
 }
 
@@ -23,14 +23,31 @@ interface CartState {
   clearAll: () => void
 }
 
+// Debug logging for cart operations
+const logCartOp = (operation: string, data: Record<string, unknown>) => {
+  console.log(`%c🛒 [CartStore] ${operation}`, 'color: #8B5CF6; font-weight: bold', data)
+}
+
 export const useCartStore = create<CartState>()(
   persist(
     (set, get) => ({
       items: [],
       addItem: (item, quantity = 1) => {
+        // Log the incoming item with price details
+        logCartOp('addItem', {
+          id: item.id,
+          name: item.name,
+          unitPrice: item.unitPrice,
+          unitPriceInReais: (item.unitPrice / 100).toFixed(2),
+          quantity,
+          subtotalCents: item.unitPrice * quantity,
+          subtotalReais: ((item.unitPrice * quantity) / 100).toFixed(2)
+        })
+
         set((state) => {
           const exists = state.items.find((i) => i.id === item.id)
           if (exists) {
+            logCartOp('addItem - updating existing', { existingQty: exists.quantity, newQty: exists.quantity + quantity })
             return {
               items: state.items.map((i) =>
                 i.id === item.id ? { ...i, quantity: i.quantity + quantity } : i
@@ -40,14 +57,24 @@ export const useCartStore = create<CartState>()(
           return { items: [...state.items, { ...item, quantity }] }
         })
       },
-      updateQuantity: (id, quantity) =>
+      updateQuantity: (id, quantity) => {
+        logCartOp('updateQuantity', { id, newQuantity: quantity })
         set((state) => ({
           items: state.items.map((i) => (i.id === id ? { ...i, quantity } : i))
-        })),
-      removeItem: (id) => set((state) => ({ items: state.items.filter((i) => i.id !== id) })),
-      clearVendor: (vendorId) =>
-        set((state) => ({ items: state.items.filter((i) => i.vendorId !== vendorId) })),
-      clearAll: () => set({ items: [] })
+        }))
+      },
+      removeItem: (id) => {
+        logCartOp('removeItem', { id })
+        set((state) => ({ items: state.items.filter((i) => i.id !== id) }))
+      },
+      clearVendor: (vendorId) => {
+        logCartOp('clearVendor', { vendorId })
+        set((state) => ({ items: state.items.filter((i) => i.vendorId !== vendorId) }))
+      },
+      clearAll: () => {
+        logCartOp('clearAll', {})
+        set({ items: [] })
+      }
     }),
     {
       name: 'mp-cart-storage',