diff --git a/src/lib/shopifySync.ts b/src/lib/shopifySync.ts
new file mode 100644
index 0000000..3c6fd2a
--- /dev/null
+++ b/src/lib/shopifySync.ts
@@ -0,0 +1,171 @@
+import type { ShopifyProductFull, SyncProduct } from '@/types/sync'
+
+const API_VERSION = '2024-01'
+
+function getConfig() {
+  const domain = process.env.SHOPIFY_STORE_DOMAIN
+  const token = process.env.SHOPIFY_ADMIN_API_TOKEN
+  if (!domain || !token) {
+    throw new Error('SHOPIFY_STORE_DOMAIN et SHOPIFY_ADMIN_API_TOKEN requis')
+  }
+  return {
+    baseUrl: `https://${domain}/admin/api/${API_VERSION}`,
+    headers: {
+      'X-Shopify-Access-Token': token,
+      'Content-Type': 'application/json',
+    },
+  }
+}
+
+interface ShopifyVariant {
+  id: number
+  price: string
+  sku: string
+  inventory_quantity: number
+}
+
+interface ShopifyAPIProduct {
+  id: number
+  title: string
+  handle: string
+  body_html: string
+  status: string
+  variants: ShopifyVariant[]
+}
+
+function toSyncProduct(p: ShopifyAPIProduct): ShopifyProductFull {
+  return {
+    shopifyId: String(p.id),
+    ref: p.variants[0]?.sku || p.handle,
+    handle: p.handle,
+    title: p.title,
+    description: p.body_html ?? '',
+    price: p.variants[0]?.price ?? '0.00',
+    stock: p.variants[0]?.inventory_quantity ?? 0,
+    status: p.status === 'active' ? 'active' : 'draft',
+  }
+}
+
+function extractNextUrl(linkHeader: string | null): string | null {
+  if (!linkHeader) return null
+  const match = linkHeader.match(/<([^>]+)>;\s*rel="next"/)
+  return match ? match[1] : null
+}
+
+/**
+ * Récupère tous les produits Shopify (actifs + drafts), en paginant.
+ * Limite : 250 par page via cursor-based pagination.
+ */
+export async function fetchAllShopifyProducts(): Promise<ShopifyProductFull[]> {
+  const { baseUrl, headers } = getConfig()
+  const all: ShopifyProductFull[] = []
+
+  let url: string | null =
+    `${baseUrl}/products.json?limit=250&fields=id,title,handle,status,body_html,variants&status=any`
+
+  while (url) {
+    const res = await fetch(url, { headers })
+    if (!res.ok) throw new Error(`Shopify fetch error: ${res.status}`)
+    const data = await res.json()
+    all.push(...(data.products as ShopifyAPIProduct[]).map(toSyncProduct))
+    url = extractNextUrl(res.headers.get('Link'))
+  }
+
+  return all
+}
+
+/**
+ * Crée un nouveau produit Shopify depuis un SyncProduct.
+ * Retourne l'ID Shopify créé.
+ */
+export async function createShopifyProduct(product: SyncProduct): Promise<string> {
+  const { baseUrl, headers } = getConfig()
+
+  const body = {
+    product: {
+      title: product.title,
+      body_html: product.description,
+      handle: product.handle,
+      status: product.status,
+      variants: [{ price: product.price, sku: product.ref }],
+    },
+  }
+
+  const res = await fetch(`${baseUrl}/products.json`, {
+    method: 'POST',
+    headers,
+    body: JSON.stringify(body),
+  })
+
+  if (!res.ok) {
+    const err = await res.text()
+    throw new Error(`Shopify createProduct error: ${res.status} — ${err}`)
+  }
+
+  const data = await res.json()
+  return String(data.product.id)
+}
+
+/**
+ * Met à jour un produit Shopify existant (titre, description, prix, statut).
+ */
+export async function updateShopifyProduct(
+  shopifyId: string,
+  product: SyncProduct,
+  variantId: string,
+): Promise<void> {
+  const { baseUrl, headers } = getConfig()
+
+  const body = {
+    product: {
+      id: shopifyId,
+      title: product.title,
+      body_html: product.description,
+      status: product.status,
+      variants: [{ id: variantId, price: product.price }],
+    },
+  }
+
+  const res = await fetch(`${baseUrl}/products/${shopifyId}.json`, {
+    method: 'PUT',
+    headers,
+    body: JSON.stringify(body),
+  })
+
+  if (!res.ok) {
+    const err = await res.text()
+    throw new Error(`Shopify updateProduct error: ${res.status} — ${err}`)
+  }
+}
+
+/**
+ * Passe un produit Shopify en draft (désactivation — jamais de suppression).
+ */
+export async function deactivateShopifyProduct(shopifyId: string): Promise<void> {
+  const { baseUrl, headers } = getConfig()
+
+  const res = await fetch(`${baseUrl}/products/${shopifyId}.json`, {
+    method: 'PUT',
+    headers,
+    body: JSON.stringify({ product: { id: shopifyId, status: 'draft' } }),
+  })
+
+  if (!res.ok) {
+    const err = await res.text()
+    throw new Error(`Shopify deactivateProduct error: ${res.status} — ${err}`)
+  }
+}
+
+/**
+ * Récupère l'ID de la première variante d'un produit Shopify.
+ * Nécessaire pour mettre à jour le prix (update variant).
+ */
+export async function getFirstVariantId(shopifyId: string): Promise<string> {
+  const { baseUrl, headers } = getConfig()
+  const res = await fetch(`${baseUrl}/products/${shopifyId}/variants.json?limit=1`, { headers })
+  if (!res.ok) throw new Error(`Shopify getVariants error: ${res.status}`)
+  const data = await res.json()
+  const variant = data.variants?.[0]
+  if (!variant) throw new Error(`Aucune variante pour le produit ${shopifyId}`)
+  return String(variant.id)
+}