diff --git a/src/chrome/src/agent/adapters.js b/src/chrome/src/agent/adapters.js
index 86edbfe1f..c271c50c4 100644
--- a/src/chrome/src/agent/adapters.js
+++ b/src/chrome/src/agent/adapters.js
@@ -16279,6 +16279,21 @@ const ADAPTERS = [
 - Pre-orders / "Made to order" listings have a longer ship date — surface that to the user before buying.`,
   },
 
+  // ─── Regional — Mercado Libre / Mercado Livre (LATAM) ────────────────
+  // Start with the AR, MX, and BR storefronts requested in CONTRIBUTING.md.
+  // Other country sites need separate localization research before inclusion.
+  {
+    name: 'mercado-libre',
+    category: 'general',
+    matches: (url) => /^https?:\/\/(?:[a-z0-9-]+\.)*(?:mercadolibre\.com\.(?:ar|mx)|mercadolivre\.com\.br)\//.test(url),
+    notes: `
+- Multi-seller MARKETPLACE. As of 2026-07 the buy controls are AR/MX "Comprar ahora" / "Agregar al carrito" / "Otras opciones de compra"; BR "Comprar agora" / "Adicionar ao carrinho" / "Outras opções de compra". Use one locale's labels, never a blend of the two.
+- Catalog pages (path contains /p/MLA…, /p/MLM…, /p/MLB…) group MANY sellers under one product: the buy box is ONE offer, and "Otras opciones de compra"/"Outras opções de compra" lists the rest at different prices and arrival dates — open it before quoting a price. Single-seller listings (articulo.mercadolibre.com.*, produto.mercadolivre.com.br, paths ending -_JM) have no such list.
+- Shipping cost and arrival date are computed from the destination "código postal" (AR/MX) / "CEP" (BR) and differ per seller. Set it before stating either, and re-check in the cart.
+- Buy-now hands off to a Mercado Pago host where this guidance stops applying — confirm the final total there.
+- Search hosts (listado.mercadolibre.com.ar, listado.mercadolibre.com.mx, lista.mercadolivre.com.br) can redirect automation to /gz/account-verification. If that wall appears, STOP and ask the user to complete it manually — do not retry, bypass, or claim results were read.`,
+  },
+
   // ─── Regional — Türkiye (TR) ──────────────────────────────────────────
   // Regional adapters are the project's #1 wanted contribution (CONTRIBUTING.md);
   // Türkiye is top of the priority list. Add more TR sites (trendyol,
diff --git a/src/firefox/src/agent/adapters.js b/src/firefox/src/agent/adapters.js
index eede90d57..2f58e93a0 100644
--- a/src/firefox/src/agent/adapters.js
+++ b/src/firefox/src/agent/adapters.js
@@ -16277,6 +16277,21 @@ const ADAPTERS = [
 - Pre-orders / "Made to order" listings have a longer ship date — surface that to the user before buying.`,
   },
 
+  // ─── Regional — Mercado Libre / Mercado Livre (LATAM) ────────────────
+  // Start with the AR, MX, and BR storefronts requested in CONTRIBUTING.md.
+  // Other country sites need separate localization research before inclusion.
+  {
+    name: 'mercado-libre',
+    category: 'general',
+    matches: (url) => /^https?:\/\/(?:[a-z0-9-]+\.)*(?:mercadolibre\.com\.(?:ar|mx)|mercadolivre\.com\.br)\//.test(url),
+    notes: `
+- Multi-seller MARKETPLACE. As of 2026-07 the buy controls are AR/MX "Comprar ahora" / "Agregar al carrito" / "Otras opciones de compra"; BR "Comprar agora" / "Adicionar ao carrinho" / "Outras opções de compra". Use one locale's labels, never a blend of the two.
+- Catalog pages (path contains /p/MLA…, /p/MLM…, /p/MLB…) group MANY sellers under one product: the buy box is ONE offer, and "Otras opciones de compra"/"Outras opções de compra" lists the rest at different prices and arrival dates — open it before quoting a price. Single-seller listings (articulo.mercadolibre.com.*, produto.mercadolivre.com.br, paths ending -_JM) have no such list.
+- Shipping cost and arrival date are computed from the destination "código postal" (AR/MX) / "CEP" (BR) and differ per seller. Set it before stating either, and re-check in the cart.
+- Buy-now hands off to a Mercado Pago host where this guidance stops applying — confirm the final total there.
+- Search hosts (listado.mercadolibre.com.ar, listado.mercadolibre.com.mx, lista.mercadolivre.com.br) can redirect automation to /gz/account-verification. If that wall appears, STOP and ask the user to complete it manually — do not retry, bypass, or claim results were read.`,
+  },
+
   // ─── Regional — Türkiye (TR) ──────────────────────────────────────────
   // Regional adapters are the project's #1 wanted contribution (CONTRIBUTING.md);
   // Türkiye is top of the priority list. Add more TR sites (trendyol,
diff --git a/test/run.js b/test/run.js
index c99a712d8..c617a5486 100644
--- a/test/run.js
+++ b/test/run.js
@@ -2387,6 +2387,50 @@ test('matches apple store pages', () => {
   assert.equal(getActiveAdapter('https://secure.store.apple.com/shop/checkout')?.name, 'apple');
 });
 
+test('matches Mercado Libre LATAM storefronts and includes marketplace guidance', () => {
+  const trustedUrls = [
+    'https://mercadolibre.com.ar/',
+    'https://www.mercadolibre.com.ar/notebook/p/MLA123',
+    'https://listado.mercadolibre.com.ar/notebook',
+    'https://articulo.mercadolibre.com.ar/MLA-123-notebook-_JM',
+    'https://www.mercadolibre.com.mx/notebook/p/MLM123',
+    'https://listado.mercadolibre.com.mx/notebook',
+    'https://mercadolivre.com.br/',
+    'https://www.mercadolivre.com.br/notebook/p/MLB123',
+    'https://lista.mercadolivre.com.br/notebook',
+    'https://produto.mercadolivre.com.br/MLB-123-notebook-_JM',
+  ];
+  for (const url of trustedUrls) {
+    assert.equal(getActiveAdapter(url)?.name, 'mercado-libre');
+    assert.equal(getActiveAdapterFx(url)?.name, 'mercado-libre');
+  }
+
+  const rejectedUrls = [
+    'https://mercadolibre.com.ar.phishing.example/notebook',
+    'https://mercadolivre.com.br.evil.example/notebook',
+    'https://example.com/mercadolibre.com.mx/notebook',
+    // Other country storefronts need their own localized research before inclusion.
+    'https://www.mercadolibre.cl/notebook',
+  ];
+  for (const url of rejectedUrls) {
+    assert.notEqual(getActiveAdapter(url)?.name, 'mercado-libre');
+    assert.notEqual(getActiveAdapterFx(url)?.name, 'mercado-libre');
+  }
+
+  const adapter = getActiveAdapter('https://www.mercadolibre.com.mx/notebook/p/MLM123');
+  const firefoxAdapter = getActiveAdapterFx('https://www.mercadolivre.com.br/notebook/p/MLB123');
+  assert.match(adapter?.notes || '', /MARKETPLACE/);
+  assert.match(adapter?.notes || '', /Otras opciones de compra/);
+  assert.match(adapter?.notes || '', /Outras opções de compra/);
+  assert.match(adapter?.notes || '', /CEP/);
+  assert.match(adapter?.notes || '', /account-verification/);
+  // Checkout leaves the matched hosts, so the notes must hand the total off.
+  assert.match(adapter?.notes || '', /Mercado Pago/);
+  // Blended ES/PT labels match no real control on either storefront.
+  assert.doesNotMatch(adapter?.notes || '', /Agregar\/Adicionar|ahora\/agora|carrito\/carrinho/);
+  assert.equal(firefoxAdapter?.notes, adapter?.notes);
+});
+
 test('matches sahibinden.com and includes anti-bot guidance', () => {
   assert.equal(getActiveAdapter('https://www.sahibinden.com/')?.name, 'sahibinden');
   assert.equal(getActiveAdapter('https://sahibinden.com/kategori/vasita')?.name, 'sahibinden');