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/notification_bp.py

@@ -0,0 +1,136 @@
+"""Notification Blueprint: templates, logs, preferences.
+
+Prefix: /pos/api/notifications
+"""
+
+from flask import Blueprint, request, jsonify, g
+from middleware import require_auth
+from tenant_db import get_tenant_conn
+from services.notification_engine import (
+    get_templates, create_template, update_template,
+    dispatch_notification, get_notification_logs, mark_as_read,
+    notify_low_stock, notify_order_ready, notify_maintenance_due,
+    notify_new_sale, notify_po_received,
+)
+
+notification_bp = Blueprint('notifications', __name__, url_prefix='/pos/api/notifications')
+
+
+@notification_bp.route('/templates', methods=['GET'])
+@require_auth()
+def list_templates():
+    event_type = request.args.get('event_type')
+    channel = request.args.get('channel')
+    conn = get_tenant_conn(g.tenant_id)
+    try:
+        templates = get_templates(conn, g.tenant_id, event_type=event_type, channel=channel)
+        return jsonify({'templates': templates})
+    finally:
+        conn.close()
+
+
+@notification_bp.route('/templates', methods=['POST'])
+@require_auth()
+def create_new_template():
+    data = request.get_json() or {}
+    required = ['event_type', 'channel', 'name', 'body_template']
+    for field in required:
+        if not data.get(field):
+            return jsonify({'error': f'{field} is required'}), 400
+    conn = get_tenant_conn(g.tenant_id)
+    try:
+        tid = create_template(
+            conn, g.tenant_id, data['event_type'], data['channel'], data['name'],
+            data['body_template'], subject_template=data.get('subject_template'),
+            is_active=data.get('is_active', True),
+        )
+        return jsonify({'id': tid, 'message': 'Template created'}), 201
+    finally:
+        conn.close()
+
+
+@notification_bp.route('/templates/<int:template_id>', methods=['PUT'])
+@require_auth()
+def update_existing_template(template_id):
+    data = request.get_json() or {}
+    conn = get_tenant_conn(g.tenant_id)
+    try:
+        ok = update_template(conn, template_id, data)
+        if not ok:
+            return jsonify({'error': 'No fields to update'}), 400
+        return jsonify({'message': 'Template updated'})
+    finally:
+        conn.close()
+
+
+@notification_bp.route('/logs', methods=['GET'])
+@require_auth()
+def list_logs():
+    recipient_type = request.args.get('recipient_type')
+    recipient_id = request.args.get('recipient_id', type=int)
+    status = request.args.get('status')
+    limit = min(int(request.args.get('limit', 50)), 200)
+    conn = get_tenant_conn(g.tenant_id)
+    try:
+        logs = get_notification_logs(
+            conn, g.tenant_id, recipient_type=recipient_type,
+            recipient_id=recipient_id, status=status, limit=limit,
+        )
+        return jsonify({'logs': logs})
+    finally:
+        conn.close()
+
+
+@notification_bp.route('/logs/<int:log_id>/read', methods=['PUT'])
+@require_auth()
+def mark_log_read(log_id):
+    conn = get_tenant_conn(g.tenant_id)
+    try:
+        mark_as_read(conn, log_id)
+        return jsonify({'message': 'Marked as read'})
+    finally:
+        conn.close()
+
+
+@notification_bp.route('/dispatch', methods=['POST'])
+@require_auth()
+def manual_dispatch():
+    """Manually dispatch a notification."""
+    data = request.get_json() or {}
+    event_type = data.get('event_type')
+    context = data.get('context', {})
+    if not event_type:
+        return jsonify({'error': 'event_type is required'}), 400
+
+    conn = get_tenant_conn(g.tenant_id)
+    try:
+        log_ids = dispatch_notification(
+            conn, g.tenant_id, event_type, context,
+            recipient_type=data.get('recipient_type', 'owner'),
+            recipient_id=data.get('recipient_id'),
+            channels=data.get('channels'),
+        )
+        return jsonify({'log_ids': log_ids, 'message': 'Notification dispatched'})
+    finally:
+        conn.close()
+
+
+# ─── Convenience endpoints ─────────────────────────────
+
+@notification_bp.route('/test/low-stock', methods=['POST'])
+@require_auth()
+def test_low_stock():
+    data = request.get_json() or {}
+    inventory_id = data.get('inventory_id')
+    if not inventory_id:
+        return jsonify({'error': 'inventory_id required'}), 400
+    conn = get_tenant_conn(g.tenant_id)
+    try:
+        log_ids = notify_low_stock(
+            conn, g.tenant_id, inventory_id,
+            stock=data.get('stock', 0),
+            reorder_point=data.get('reorder_point', 5),
+        )
+        return jsonify({'log_ids': log_ids, 'message': 'Low stock notification sent'})
+    finally:
+        conn.close()