diff --git a/pos/static/js/catalog.js b/pos/static/js/catalog.js
index 68f04dc..059950d 100644
--- a/pos/static/js/catalog.js
+++ b/pos/static/js/catalog.js
@@ -62,6 +62,44 @@
     var currentDetailPart = null;
     var detailQty = 1;
     var isOffline = false;
+    var skipPush = false; // flag to avoid pushing state on popstate
+
+    // ─── Browser History Management ───
+    function pushNavState() {
+        if (skipPush) return;
+        var s = JSON.parse(JSON.stringify(nav));
+        s.page = currentPage;
+        history.pushState(s, '', '/pos/catalog');
+    }
+
+    window.addEventListener('popstate', function (e) {
+        if (e.state) {
+            skipPush = true;
+            nav.level = e.state.level || 'brands';
+            nav.brand = e.state.brand;
+            nav.model = e.state.model;
+            nav.year = e.state.year;
+            nav.engine = e.state.engine;
+            nav.category = e.state.category;
+            nav.group = e.state.group;
+            currentPage = e.state.page || 1;
+
+            // Reload the correct level
+            if (nav.level === 'brands') loadBrands();
+            else if (nav.level === 'models') loadModels();
+            else if (nav.level === 'years') loadYears();
+            else if (nav.level === 'engines') loadEngines();
+            else if (nav.level === 'categories') loadCategories();
+            else if (nav.level === 'groups') loadGroups();
+            else if (nav.level === 'parts') loadParts(currentPage);
+            else loadBrands();
+
+            skipPush = false;
+        }
+    });
+
+    // Push initial state
+    history.replaceState(JSON.parse(JSON.stringify(nav)), '', '/pos/catalog');
 
     // ─── Cart State ───
     var cartItems = JSON.parse(localStorage.getItem('pos_cart') || '[]');
@@ -143,6 +181,7 @@
 
     function resetNav() {
         nav.level = 'brands';
+        pushNavState();
         nav.brand = nav.model = nav.year = nav.engine = nav.category = nav.group = null;
     }
 
@@ -176,6 +215,7 @@
 
     function loadBrands() {
         nav.level = 'brands';
+        pushNavState();
         updateBreadcrumb();
         levelTitle.textContent = 'Selecciona una marca';
         setupLevelFilter(true);
@@ -209,6 +249,7 @@
 
     function loadModels() {
         nav.level = 'models';
+        pushNavState();
         updateBreadcrumb();
         levelTitle.textContent = 'Modelos de ' + nav.brand.name;
         setupLevelFilter(true);
@@ -235,6 +276,7 @@
 
     function loadYears() {
         nav.level = 'years';
+        pushNavState();
         updateBreadcrumb();
         levelTitle.textContent = nav.brand.name + ' ' + nav.model.name + ' — Anios';
         setupLevelFilter(false);
@@ -261,6 +303,7 @@
 
     function loadEngines() {
         nav.level = 'engines';
+        pushNavState();
         updateBreadcrumb();
         levelTitle.textContent = nav.brand.name + ' ' + nav.model.name + ' ' + nav.year.year + ' — Motor';
         setupLevelFilter(false);
@@ -298,6 +341,7 @@
 
     function loadCategories() {
         nav.level = 'categories';
+        pushNavState();
         updateBreadcrumb();
         levelTitle.textContent = 'Categorias de partes';
         setupLevelFilter(true);
@@ -325,6 +369,7 @@
 
     function loadGroups() {
         nav.level = 'groups';
+        pushNavState();
         updateBreadcrumb();
         levelTitle.textContent = nav.category.name;
         setupLevelFilter(true);
@@ -352,6 +397,7 @@
 
     function loadParts(page) {
         nav.level = 'parts';
+        pushNavState();
         currentPage = page || 1;
         updateBreadcrumb();
         levelTitle.textContent = nav.group.name;
@@ -932,6 +978,7 @@
         nav.year = { id: parseInt(vsYear.value), year: yearText };
         nav.engine = { id_mye: parseInt(myeId), name: engineText };
         nav.level = 'categories';
+        pushNavState();
 
         loadCategories();
 
@@ -953,6 +1000,7 @@
         vsClear.style.display = 'none';
 
         nav.level = 'brands'; nav.brand = null; nav.model = null; nav.year = null; nav.engine = null; nav.category = null; nav.group = null; currentPage = 1;
+        pushNavState();
         loadBrands();
     }