FASE 4-5-6: Infraestructura, CRM, Service Orders, Notificaciones, Ahorro, Logistica, API Publica

FASE 4:
- Redis cache de stock con fallback graceful
- Multi-moneda (MXN/USD) con contabilidad en MXN
- Proveedores y ordenes de compra completo
- Meilisearch 1.5M+ partes indexadas
- Metabase KPIs con dashboard auto-generado

FASE 5:
- CRM mejorado: activities, tags, loyalty program, analytics
- Imagenes de partes: upload, resize, thumbnails WebP
- Ordenes de servicio Kanban: received->diagnosis->repair->ready->delivered
- Garantias/RMA, alertas de reorden, multi-sucursal
- Stubs BNPL (APLAZO) y ERP Sync (Aspel/Contpaqi)

FASE 6:
- Notificaciones automaticas: push/WhatsApp/email/in-app
- Reportes de ahorro vs retail_price
- Logistica + tracking: DHL, FedEx, Estafeta, 99min, Uber
- API Publica: API keys, rate limiting, catalog search

Migraciones: v1.9-v3.0
Tests: 93/93 pasando
Backup: nexus_backup_20260427_045859.tar.gz

pos/blueprints/pos_bp.py

@@ -22,8 +22,29 @@ pos_bp = Blueprint('pos', __name__, url_prefix='/pos/api')
 def _enrich_items(cur, items, customer_id=None):
     """Look up inventory data for items that lack unit_price/tax_rate.
 
+    Uses batch queries to avoid N+1 performance issues.
     Returns list of dicts with all fields needed by calculate_totals.
     """
+    inv_ids = [item.get('inventory_id') for item in items if item.get('inventory_id')]
+    if not inv_ids:
+        raise ValueError("No valid inventory items provided")
+
+    # Batch fetch all inventory items in one query
+    cur.execute("""
+        SELECT id, part_number, name, cost, price_1, price_2, price_3,
+               tax_rate, branch_id
+        FROM inventory WHERE id = ANY(%s) AND is_active = true
+    """, (inv_ids,))
+    inv_map = {r[0]: r for r in cur.fetchall()}
+
+    # Fetch customer price tier once (if provided)
+    price_tier = 1
+    if customer_id:
+        cur.execute("SELECT price_tier FROM customers WHERE id = %s", (customer_id,))
+        cust = cur.fetchone()
+        if cust and cust[0]:
+            price_tier = int(cust[0])
+
     enriched = []
     for item in items:
         inv_id = item.get('inventory_id')
@@ -31,23 +52,10 @@ def _enrich_items(cur, items, customer_id=None):
         if qty <= 0:
             raise ValueError(f"Invalid quantity for inventory_id {inv_id}")
 
-        cur.execute("""
-            SELECT id, part_number, name, cost, price_1, price_2, price_3,
-                   tax_rate, branch_id
-            FROM inventory WHERE id = %s AND is_active = true
-        """, (inv_id,))
-        inv = cur.fetchone()
+        inv = inv_map.get(inv_id)
         if not inv:
             raise ValueError(f"Inventory item {inv_id} not found or inactive")
 
-        # Determine price tier from customer if provided
-        price_tier = 1
-        if customer_id:
-            cur.execute("SELECT price_tier FROM customers WHERE id = %s", (customer_id,))
-            cust = cur.fetchone()
-            if cust and cust[0]:
-                price_tier = int(cust[0])
-
         # price_1=inv[4], price_2=inv[5], price_3=inv[6]
         tier_prices = {1: inv[4], 2: inv[5], 3: inv[6]}
         default_price = float(tier_prices.get(price_tier, inv[4]) or inv[4])
@@ -85,7 +93,9 @@ def create_sale():
         register_id: int,
         amount_paid: float,
         payment_details: [{method, amount, reference}],  (for mixed payments)
-        notes: str
+        notes: str,
+        currency: 'MXN' | 'USD' (default 'MXN'),
+        exchange_rate: float (optional, auto-fetched from tenant config if omitted)
     }
     """
     data = request.get_json() or {}
@@ -402,7 +412,9 @@ def create_quotation():
         items: [{inventory_id, quantity, unit_price, discount_pct, tax_rate}],
         customer_id: int | null,
         valid_days: int (default 7),
-        notes: str
+        notes: str,
+        currency: 'MXN' | 'USD' (default 'MXN'),
+        exchange_rate: float (optional, auto-fetched if not provided)
     }
     """
     data = request.get_json() or {}
@@ -426,17 +438,29 @@ def create_quotation():
     valid_days = int(data.get('valid_days', 7))
     valid_until = (date.today() + timedelta(days=valid_days)).isoformat()
 
+        # Multi-currency for quotations
+        from services.currency import get_exchange_rate
+        currency = data.get('currency', 'MXN')
+        if currency not in ('MXN', 'USD'):
+            cur.close(); conn.close()
+            return jsonify({'error': f'Unsupported currency: {currency}'}), 400
+        exchange_rate = data.get('exchange_rate')
+        if currency != 'MXN' and exchange_rate is None:
+            exchange_rate = float(get_exchange_rate(conn, currency, 'MXN'))
+        exchange_rate = float(exchange_rate) if exchange_rate else 1.0
+
     try:
         cur.execute("""
             INSERT INTO quotations
                 (branch_id, customer_id, employee_id, subtotal,
-                 tax_total, total, status, valid_until, notes)
-            VALUES (%s,%s,%s,%s,%s,%s,'active',%s,%s)
+                 tax_total, total, status, valid_until, notes, currency, exchange_rate)
+            VALUES (%s,%s,%s,%s,%s,%s,'active',%s,%s,%s,%s)
             RETURNING id, created_at
         """, (
             g.branch_id, data.get('customer_id'), g.employee_id,
             totals['subtotal'], totals['tax_total'],
-            totals['total'], valid_until, data.get('notes')
+            totals['total'], valid_until, data.get('notes'),
+            currency, exchange_rate
         ))
         quot_id, created_at = cur.fetchone()
 
@@ -452,12 +476,13 @@ def create_quotation():
             cur.execute("""
                 INSERT INTO quotation_items
                     (quotation_id, inventory_id, part_number, name, quantity,
-                     unit_price, discount_pct, tax_rate, subtotal)
-                VALUES (%s,%s,%s,%s,%s,%s,%s,%s,%s)
+                     unit_price, discount_pct, tax_rate, subtotal, currency, exchange_rate)
+                VALUES (%s,%s,%s,%s,%s,%s,%s,%s,%s,%s,%s)
             """, (
                 quot_id, item['inventory_id'], part_number, name,
                 item['quantity'], item['unit_price'], item['discount_pct'],
-                item['tax_rate'], line_subtotal
+                item['tax_rate'], line_subtotal,
+                currency, exchange_rate
             ))
 
         log_action(conn, 'QUOTATION_CREATE', 'quotation', quot_id,
@@ -930,8 +955,8 @@ def convert_quotation(quot_id):
     conn = get_tenant_conn(g.tenant_id)
     cur = conn.cursor()
 
-    # Get quotation
-    cur.execute("SELECT id, customer_id, status FROM quotations WHERE id = %s", (quot_id,))
+    # Get quotation (include currency)
+    cur.execute("SELECT id, customer_id, status, currency, exchange_rate FROM quotations WHERE id = %s", (quot_id,))
     quot = cur.fetchone()
     if not quot:
         cur.close(); conn.close()
@@ -940,6 +965,9 @@ def convert_quotation(quot_id):
         cur.close(); conn.close()
         return jsonify({'error': f'Quotation is {quot[2]}, cannot convert'}), 400
 
+    quot_currency = quot[3] or 'MXN'
+    quot_rate = quot[4] or 1.0
+
     # Get quotation items
     cur.execute("""
         SELECT inventory_id, quantity, unit_price, discount_pct, tax_rate
@@ -953,7 +981,7 @@ def convert_quotation(quot_id):
             'tax_rate': float(r[4]) if r[4] else 0.16,
         })
 
-    # Build sale_data
+    # Build sale_data (preserve quotation currency)
     sale_data = {
         'items': items,
         'customer_id': quot[1],
@@ -963,6 +991,8 @@ def convert_quotation(quot_id):
         'amount_paid': data.get('amount_paid', 0),
         'payment_details': data.get('payment_details', []),
         'notes': f'Convertida de cotizacion #{quot_id}',
+        'currency': quot_currency,
+        'exchange_rate': quot_rate,
     }
 
     try: