diff --git a/pos/blueprints/catalog_bp.py b/pos/blueprints/catalog_bp.py
new file mode 100644
index 0000000..53bc103
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+++ b/pos/blueprints/catalog_bp.py
@@ -0,0 +1,265 @@
+# /home/Autopartes/pos/blueprints/catalog_bp.py
+"""Catalog blueprint: browsable inventory with cart, external availability lookup,
+and cross-reference queries."""
+
+from flask import Blueprint, request, jsonify, g
+from middleware import require_auth
+from tenant_db import get_tenant_conn
+from services.inventory_engine import get_stock_bulk
+
+catalog_bp = Blueprint('catalog', __name__, url_prefix='/pos/api/catalog')
+
+
+@catalog_bp.route('/search', methods=['GET'])
+@require_auth('catalog.view')
+def search_catalog():
+    """Search the tenant's inventory as a catalog. Returns items with stock and pricing.
+
+    Query params: q (search), category, brand, vehicle_brand, page, per_page
+
+    NOTE on filtering:
+    - `brand` filters by part manufacturer (Bosch, NGK, etc.) — the `brand` column.
+    - `vehicle_brand` filters by vehicle compatibility (Toyota, Nissan, etc.) — searches
+      inside the `vehicle_compatibility` JSON field via ILIKE on the cast text.
+    """
+    conn = get_tenant_conn(g.tenant_id)
+    cur = conn.cursor()
+
+    q = request.args.get('q', '')
+    category = request.args.get('category', '')
+    brand = request.args.get('brand', '')
+    vehicle_brand = request.args.get('vehicle_brand', '')
+    branch_id = request.args.get('branch_id', g.branch_id)
+    in_stock_only = request.args.get('in_stock', '') == 'true'
+    page = int(request.args.get('page', 1))
+    per_page = min(int(request.args.get('per_page', 30)), 100)
+
+    where = ["i.is_active = true"]
+    params = []
+
+    if branch_id:
+        where.append("i.branch_id = %s")
+        params.append(branch_id)
+    if q:
+        where.append("(i.part_number ILIKE %s OR i.name ILIKE %s OR i.barcode = %s)")
+        params.extend([f'%{q}%', f'%{q}%', q])
+    if category:
+        where.append("i.category_id = %s")
+        params.append(int(category))
+    if brand:
+        where.append("i.brand ILIKE %s")
+        params.append(f'%{brand}%')
+    if vehicle_brand:
+        where.append("i.vehicle_compatibility::text ILIKE %s")
+        params.append(f'%{vehicle_brand}%')
+
+    where_sql = " AND ".join(where)
+
+    cur.execute(f"SELECT count(*) FROM inventory i WHERE {where_sql}", params)
+    total = cur.fetchone()[0]
+
+    cur.execute(f"""
+        SELECT i.id, i.part_number, i.barcode, i.name, i.brand, i.unit,
+               i.price_1, i.price_2, i.price_3, i.tax_rate,
+               i.image_url, i.category_id, i.location, i.min_stock
+        FROM inventory i
+        WHERE {where_sql}
+        ORDER BY i.name
+        LIMIT %s OFFSET %s
+    """, params + [per_page, (page - 1) * per_page])
+
+    rows = cur.fetchall()
+    inv_ids = [r[0] for r in rows]
+
+    # Bulk stock lookup
+    stock_map = {}
+    if inv_ids:
+        cur.execute("""
+            SELECT inventory_id, COALESCE(SUM(quantity), 0)
+            FROM inventory_operations
+            WHERE inventory_id = ANY(%s)
+            GROUP BY inventory_id
+        """, (inv_ids,))
+        stock_map = {r[0]: r[1] for r in cur.fetchall()}
+
+    items = []
+    for r in rows:
+        stock = stock_map.get(r[0], 0)
+        if in_stock_only and stock <= 0:
+            continue
+        items.append({
+            'id': r[0], 'part_number': r[1], 'barcode': r[2], 'name': r[3],
+            'brand': r[4], 'unit': r[5],
+            'price_1': float(r[6]) if r[6] else 0,
+            'price_2': float(r[7]) if r[7] else 0,
+            'price_3': float(r[8]) if r[8] else 0,
+            'tax_rate': float(r[9]) if r[9] else 0.16,
+            'image_url': r[10], 'category_id': r[11], 'location': r[12],
+            'stock': stock,
+            'low_stock': r[13] and stock < r[13] if r[13] else False
+        })
+
+    cur.close(); conn.close()
+
+    total_pages = (total + per_page - 1) // per_page
+    return jsonify({
+        'data': items,
+        'pagination': {'page': page, 'per_page': per_page, 'total': total, 'total_pages': total_pages}
+    })
+
+
+@catalog_bp.route('/categories', methods=['GET'])
+@require_auth('catalog.view')
+def catalog_categories():
+    """Get categories with item counts for catalog navigation."""
+    conn = get_tenant_conn(g.tenant_id)
+    cur = conn.cursor()
+    branch_id = request.args.get('branch_id', g.branch_id)
+
+    where = "i.is_active = true"
+    params = []
+    if branch_id:
+        where += " AND i.branch_id = %s"
+        params.append(branch_id)
+
+    cur.execute(f"""
+        SELECT i.category_id, COUNT(*) as item_count
+        FROM inventory i
+        WHERE {where} AND i.category_id IS NOT NULL
+        GROUP BY i.category_id
+        ORDER BY item_count DESC
+    """, params)
+    categories = [{'id': r[0], 'count': r[1]} for r in cur.fetchall()]
+
+    cur.close(); conn.close()
+    return jsonify({'data': categories})
+
+
+@catalog_bp.route('/brands', methods=['GET'])
+@require_auth('catalog.view')
+def catalog_brands():
+    """Get part manufacturer brands with item counts for catalog navigation."""
+    conn = get_tenant_conn(g.tenant_id)
+    cur = conn.cursor()
+    branch_id = request.args.get('branch_id', g.branch_id)
+
+    where = "i.is_active = true"
+    params = []
+    if branch_id:
+        where += " AND i.branch_id = %s"
+        params.append(branch_id)
+
+    cur.execute(f"""
+        SELECT i.brand, COUNT(*) as item_count
+        FROM inventory i
+        WHERE {where} AND i.brand IS NOT NULL AND i.brand != ''
+        GROUP BY i.brand
+        ORDER BY item_count DESC
+    """, params)
+    brands = [{'name': r[0], 'count': r[1]} for r in cur.fetchall()]
+
+    cur.close(); conn.close()
+    return jsonify({'data': brands})
+
+
+@catalog_bp.route('/barcode/<barcode>', methods=['GET'])
+@require_auth('catalog.view')
+def lookup_barcode(barcode):
+    """Lookup a part by barcode (for scanner). Returns item with stock."""
+    conn = get_tenant_conn(g.tenant_id)
+    cur = conn.cursor()
+
+    cur.execute("""
+        SELECT i.id, i.part_number, i.barcode, i.name, i.brand, i.unit,
+               i.price_1, i.price_2, i.price_3, i.tax_rate, i.cost,
+               i.image_url, i.branch_id
+        FROM inventory i
+        WHERE (i.barcode = %s OR i.part_number = %s) AND i.is_active = true
+        LIMIT 1
+    """, (barcode, barcode))
+    row = cur.fetchone()
+
+    if not row:
+        cur.close(); conn.close()
+        return jsonify({'error': 'Part not found'}), 404
+
+    from services.inventory_engine import get_stock
+    item = {
+        'id': row[0], 'part_number': row[1], 'barcode': row[2], 'name': row[3],
+        'brand': row[4], 'unit': row[5],
+        'price_1': float(row[6]) if row[6] else 0,
+        'price_2': float(row[7]) if row[7] else 0,
+        'price_3': float(row[8]) if row[8] else 0,
+        'tax_rate': float(row[9]) if row[9] else 0.16,
+        'cost': float(row[10]) if row[10] else 0,
+        'image_url': row[11],
+        'stock': get_stock(conn, row[0], row[12])
+    }
+
+    cur.close(); conn.close()
+    return jsonify(item)
+
+
+@catalog_bp.route('/external-availability/<part_number>', methods=['GET'])
+@require_auth('catalog.view')
+def external_availability(part_number):
+    """Check part availability in external bodegas (Nexus marketplace).
+    Requires internet. Calls the main Nexus API.
+    """
+    import requests
+
+    try:
+        # Query the Nexus master API for warehouse inventory
+        # This calls the existing /api/search endpoint on the main Nexus server
+        resp = requests.get(
+            'http://localhost:5000/api/search',
+            params={'q': part_number},
+            timeout=5
+        )
+        if resp.status_code != 200:
+            return jsonify({'data': [], 'source': 'nexus', 'error': 'Catalog unavailable'}), 200
+
+        results = resp.json()
+        return jsonify({'data': results.get('results', []), 'source': 'nexus'})
+
+    except requests.RequestException:
+        return jsonify({'data': [], 'source': 'nexus', 'error': 'No internet connection'}), 200
+
+
+@catalog_bp.route('/cross-references/<part_number>', methods=['GET'])
+@require_auth('catalog.view')
+def cross_references(part_number):
+    """Get OEM <-> aftermarket cross-references for a part number.
+
+    Calls the Nexus master API which has the full cross-reference database
+    (part_cross_references table). Returns OEM equivalents and aftermarket
+    alternatives.
+
+    This follows the same pattern as external-availability: the tenant POS
+    calls the central Nexus server which holds the master catalog data.
+    """
+    import requests
+
+    try:
+        resp = requests.get(
+            'http://localhost:5000/api/cross-references',
+            params={'part_number': part_number},
+            timeout=5
+        )
+        if resp.status_code != 200:
+            return jsonify({'data': [], 'source': 'nexus', 'error': 'Cross-reference service unavailable'}), 200
+
+        results = resp.json()
+        return jsonify({
+            'part_number': part_number,
+            'cross_references': results.get('cross_references', []),
+            'source': 'nexus'
+        })
+
+    except requests.RequestException:
+        return jsonify({
+            'part_number': part_number,
+            'cross_references': [],
+            'source': 'nexus',
+            'error': 'No internet connection'
+        }), 200