Mejoras de sesion: estabilizacion, IA, Nexus Yonke y marketplace B2B

- F0 blindaje: Redis/Celery, pg_hba sin trust LAN, secretos a env 600, backups, webhook auth, jobs muertos
- F1 caja: bugs POS, reembolsos al corte, apartados, CFDI, topes de descuento en cotizacion/apartado
- F2/F7 IA de catalogo: autocategorizacion, dedup de SKUs con embeddings, OCR de facturas, descripciones, claves SAT, limpieza de fitment
- F3 IA en el flujo: vision Yonke, preguntas MeLi, venta cruzada, anomalias, sinonimos, busqueda semantica (rerank/embeddings)
- F4/F8 escala y cartera: /metrics+Prometheus+Grafana, pool, score de credito, churn, metricas multi-tenant
- Nexus Yonke (M1-M6): modelo de datos 1-de-1, alta por donador, vitrina publica, MeLi usado, consignacion, garantia por dias, reportes, etiquetas
- Marketplace B2B entre yonkes (catalogo + pedidos cross-tenant)
- Seguridad: auth en /api/admin/* (35 endpoints), alertas por tenant
- Migraciones v4.27/v4.28; timers expire-demos y rollup-metrics

pos/blueprints/customers_bp.py

@@ -2,11 +2,14 @@
 """Customers blueprint: CRUD, credit management, vehicles, account statements."""
 
 import json
+import logging
 from flask import Blueprint, request, jsonify, g
 from middleware import require_auth, has_permission
 from tenant_db import get_tenant_conn
 from services.audit import log_action
 
+logger = logging.getLogger('pos')
+
 customers_bp = Blueprint('customers', __name__, url_prefix='/pos/api/customers')
 
 
@@ -155,6 +158,14 @@ def get_customer(customer_id):
 
     customer['created_at'] = str(customer['created_at']) if customer['created_at'] else None
 
+    # Credit risk score (A9). Never block customer detail on scoring errors.
+    try:
+        from services.credit_scoring import score_customer
+        customer['credit_score'] = score_customer(conn, customer_id)
+    except Exception as exc:
+        logger.warning('credit score for customer %s failed: %s', customer_id, exc)
+        customer['credit_score'] = None
+
     # Recent purchases (last 20)
     cur.execute("""
         SELECT s.id, s.total, s.payment_method, s.sale_type, s.status, s.created_at,
@@ -199,6 +210,28 @@ def get_customer(customer_id):
     return jsonify(customer)
 
 
+@customers_bp.route('/<int:customer_id>/credit-score', methods=['GET'])
+@require_auth()
+def get_customer_credit_score(customer_id):
+    """Credit risk score for a customer (A9).
+
+    Returns {score, tier, recommended_limit, reasons, data_points, ...}.
+    """
+    if not _can_view_customers():
+        return jsonify({'error': 'Missing permissions: customers.view'}), 403
+    conn = get_tenant_conn(g.tenant_id)
+    try:
+        from services.credit_scoring import score_customer
+        return jsonify(score_customer(conn, customer_id))
+    except ValueError as e:
+        return jsonify({'error': str(e)}), 404
+    except Exception as e:
+        logger.error('credit-score for customer %s failed: %s', customer_id, e)
+        return jsonify({'error': 'Could not compute credit score'}), 500
+    finally:
+        conn.close()
+
+
 @customers_bp.route('/<int:customer_id>/purchases', methods=['GET'])
 @require_auth()
 def get_customer_purchases(customer_id):
@@ -624,6 +657,24 @@ def record_customer_payment(customer_id):
                    new_value={'credit_balance': new_balance, 'payment': amount})
 
         conn.commit()
+
+        # Accounting entry (non-blocking): Cobro de credito
+        #   Debit Caja/Bancos, Credit Clientes
+        try:
+            from services.accounting_engine import record_credit_payment_entry
+            record_credit_payment_entry(conn, {
+                'customer_id': customer_id,
+                'customer_name': cust[0],
+                'amount': amount,
+                'payment_method': payment_method,
+            })
+            conn.commit()
+        except Exception as acc_err:
+            conn.rollback()
+            logger.error(
+                f'Accounting entry for customer payment #{payment_id} failed: {acc_err}'
+            )
+
         cur.close(); conn.close()
 
         return jsonify({