diff --git a/.gitea/workflows/build.yml b/.gitea/workflows/build.yml
index 8816c42f..bd0bc66e 100644
--- a/.gitea/workflows/build.yml
+++ b/.gitea/workflows/build.yml
@@ -17,8 +17,45 @@ on:
             - main
 
 jobs:
+  # Ejecuta la suite de tests del backend antes de construir imágenes.
+  # Si falla, no se ejecuta build (ni push ni deploy).
+  test:
+    runs-on: self-hosted
+    steps:
+      - name: Checkout código
+        uses: actions/checkout@v4
+
+      - name: Configurar Python
+        uses: actions/setup-python@v5
+        with:
+          python-version: "3.11"
+          cache: "pip"
+          cache-dependency-path: backend/requirements.txt
+
+      - name: Instalar dependencias del backend
+        run: |
+          python -m pip install --upgrade pip
+          pip install -r backend/requirements.txt
+
+      - name: Comprobar TEST_DATABASE_URL
+        env:
+          TEST_DATABASE_URL: ${{ secrets.TEST_DATABASE_URL }}
+        run: |
+          if [ -z "$TEST_DATABASE_URL" ]; then
+            echo "::error::Define el secret TEST_DATABASE_URL en el repo (Gitea → Ajustes → Secretos)."
+            echo "Ejemplo: postgresql://usuario:clave@host:5432/nombre_bd"
+            exit 1
+          fi
+
+      - name: Ejecutar tests del backend
+        env:
+          TEST_DATABASE_URL: ${{ secrets.TEST_DATABASE_URL }}
+        working-directory: backend
+        run: pytest -q tests
+
   build:
     runs-on: self-hosted
+    needs: test
 
     steps:
       - name: Checkout código
diff --git a/backend/api/v1/modules/a24/fa/fa_item_lines/dto.py b/backend/api/v1/modules/a24/fa/fa_item_lines/dto.py
index 9c464513..34b8f35b 100644
--- a/backend/api/v1/modules/a24/fa/fa_item_lines/dto.py
+++ b/backend/api/v1/modules/a24/fa/fa_item_lines/dto.py
@@ -60,8 +60,7 @@ class FaLineItemCreateDTO(BaseModel):
     own_equipment: Optional[bool] = Field(None, description="Equipo propio")
     omit_annex31: Optional[bool] = Field(None, description="Omitir en Anexo 31")
 
-    class Config:
-        from_attributes = True
+    model_config = ConfigDict(from_attributes=True)
 
 
 class FaLineItemUpdateDTO(BaseModel):
@@ -112,8 +111,7 @@ class FaLineItemUpdateDTO(BaseModel):
     own_equipment: Optional[bool] = Field(None, description="Equipo propio")
     omit_annex31: Optional[bool] = Field(None, description="Omitir en Anexo 31")
 
-    class Config:
-        from_attributes = True
+    model_config = ConfigDict(from_attributes=True)
 
 
 class FaLineItemResponseDTO(BaseModel):
@@ -164,5 +162,4 @@ class FaLineItemResponseDTO(BaseModel):
     created_at: datetime = Field(..., description="Fecha de creación")
     updated_at: datetime = Field(..., description="Fecha de actualización")
 
-    class Config:
-        from_attributes = True
+    model_config = ConfigDict(from_attributes=True)
diff --git a/backend/api/v1/modules/a76/clients_and_providers/dto.py b/backend/api/v1/modules/a76/clients_and_providers/dto.py
index e461addd..fbe8d766 100644
--- a/backend/api/v1/modules/a76/clients_and_providers/dto.py
+++ b/backend/api/v1/modules/a76/clients_and_providers/dto.py
@@ -6,7 +6,7 @@ Reemplaza schemas.py siguiendo enfoque DDD y estilo NestJS
 from decimal import Decimal
 from typing import List, Literal, Optional
 
-from pydantic import BaseModel, Field, model_validator
+from pydantic import BaseModel, ConfigDict, Field, model_validator
 
 from .validators import is_valid_rfc, is_valid_tax_id
 
@@ -36,8 +36,7 @@ class ClientProviderAddressDTO(BaseModel):
     contact: Optional[str] = Field(None, max_length=50, description="Contact person")
     reference: Optional[str] = Field(None, max_length=250, description="Reference")
 
-    class Config:
-        from_attributes = True
+    model_config = ConfigDict(from_attributes=True)
 
 
 # DTOs para programas
@@ -86,8 +85,7 @@ class ClientProviderProgramsDTO(BaseModel):
         None, max_length=300, description="AUTSE number"
     )
 
-    class Config:
-        from_attributes = True
+    model_config = ConfigDict(from_attributes=True)
 
 
 # DTOs principales
@@ -145,8 +143,7 @@ class ClientProviderCreateDTO(BaseModel):
                 )
         return self
 
-    class Config:
-        from_attributes = True
+    model_config = ConfigDict(from_attributes=True)
 
 
 class ClientProviderUpdateDTO(BaseModel):
@@ -203,8 +200,7 @@ class ClientProviderUpdateDTO(BaseModel):
                 )
         return self
 
-    class Config:
-        from_attributes = True
+    model_config = ConfigDict(from_attributes=True)
 
 
 class ClientProviderResponseDTO(BaseModel):
@@ -232,8 +228,7 @@ class ClientProviderResponseDTO(BaseModel):
     address: Optional[ClientProviderAddressDTO] = None
     programs: Optional[ClientProviderProgramsDTO] = None
 
-    class Config:
-        from_attributes = True
+    model_config = ConfigDict(from_attributes=True)
 
 
 # DTOs para respuestas específicas
@@ -247,8 +242,7 @@ class ClientProviderBasicDTO(BaseModel):
     client_or_provider: Optional[str] = None
     is_active: Optional[bool] = None
 
-    class Config:
-        from_attributes = True
+    model_config = ConfigDict(from_attributes=True)
 
 
 class ClientProviderListDTO(BaseModel):
@@ -259,8 +253,7 @@ class ClientProviderListDTO(BaseModel):
     page: int
     size: int
 
-    class Config:
-        from_attributes = True
+    model_config = ConfigDict(from_attributes=True)
 
 
 class ClientProviderPaginatedResponseDTO(BaseModel):
@@ -271,5 +264,4 @@ class ClientProviderPaginatedResponseDTO(BaseModel):
     page: int
     page_size: int
 
-    class Config:
-        from_attributes = True
+    model_config = ConfigDict(from_attributes=True)
diff --git a/backend/api/v1/modules/a76/general_catalogs/company/dto.py b/backend/api/v1/modules/a76/general_catalogs/company/dto.py
index dff8a610..a83faf81 100644
--- a/backend/api/v1/modules/a76/general_catalogs/company/dto.py
+++ b/backend/api/v1/modules/a76/general_catalogs/company/dto.py
@@ -6,7 +6,7 @@ Reemplaza schemas.py siguiendo enfoque DDD y estilo NestJS
 from datetime import datetime
 from typing import Optional
 
-from pydantic import BaseModel, Field
+from pydantic import BaseModel, ConfigDict, Field
 
 
 class CompanyCreateDTO(BaseModel):
@@ -221,8 +221,7 @@ class CompanyCreateDTO(BaseModel):
     cancel_key_exp: Optional[int] = None
 
 
-    class Config:
-        from_attributes = True
+    model_config = ConfigDict(from_attributes=True)
 
 
 class CompanyUpdateDTO(CompanyCreateDTO):
@@ -417,5 +416,4 @@ class CompanyResponseDTO(BaseModel):
 
 
 
-    class Config:
-        from_attributes = True
+    model_config = ConfigDict(from_attributes=True)
diff --git a/backend/api/v1/modules/a76/general_catalogs/fractions/tariff_fractions/dto.py b/backend/api/v1/modules/a76/general_catalogs/fractions/tariff_fractions/dto.py
index 498d859a..16463397 100644
--- a/backend/api/v1/modules/a76/general_catalogs/fractions/tariff_fractions/dto.py
+++ b/backend/api/v1/modules/a76/general_catalogs/fractions/tariff_fractions/dto.py
@@ -19,8 +19,7 @@ class TariffFractionCreateDTO(BaseModel):
     adv_impo: Optional[str] = Field(None, max_length=20, description="Ad valorem importación")
     adv_expo: Optional[str] = Field(None, max_length=20, description="Ad valorem exportación")
 
-    class Config:
-        from_attributes = True
+    model_config = ConfigDict(from_attributes=True)
 
 
 class TariffFractionUpdateDTO(BaseModel):
@@ -33,8 +32,7 @@ class TariffFractionUpdateDTO(BaseModel):
     adv_impo: Optional[str] = Field(None, max_length=20, description="Ad valorem importación")
     adv_expo: Optional[str] = Field(None, max_length=20, description="Ad valorem exportación")
 
-    class Config:
-        from_attributes = True
+    model_config = ConfigDict(from_attributes=True)
 
 
 class TariffFractionResponseDTO(BaseModel):
@@ -66,8 +64,7 @@ class TariffFractionBasicDTO(BaseModel):
     adv_impo: Optional[str] = None
     adv_expo: Optional[str] = None
 
-    class Config:
-        from_attributes = True
+    model_config = ConfigDict(from_attributes=True)
 
 
 class TariffFractionListDTO(BaseModel):
@@ -79,8 +76,7 @@ class TariffFractionListDTO(BaseModel):
     page_size: int
     pages: int
 
-    class Config:
-        from_attributes = True
+    model_config = ConfigDict(from_attributes=True)
 
 
 class TariffFractionSearchDTO(BaseModel):
@@ -92,5 +88,4 @@ class TariffFractionSearchDTO(BaseModel):
     nico: Optional[str] = Field(None, description="Filtrar por NICO")
     umt: Optional[str] = Field(None, description="Filtrar por UMT")
 
-    class Config:
-        from_attributes = True
+    model_config = ConfigDict(from_attributes=True)
diff --git a/backend/api/v1/modules/core/tenants/dto.py b/backend/api/v1/modules/core/tenants/dto.py
index 46094676..d851a514 100644
--- a/backend/api/v1/modules/core/tenants/dto.py
+++ b/backend/api/v1/modules/core/tenants/dto.py
@@ -7,7 +7,7 @@ from datetime import datetime
 from enum import Enum
 from typing import Optional
 
-from pydantic import BaseModel, EmailStr, Field
+from pydantic import BaseModel, ConfigDict, EmailStr, Field
 
 
 class TenantTypeDTO(str, Enum):
@@ -41,8 +41,8 @@ class TenantCreateDTO(BaseModel):
         None, max_length=50, description="Teléfono de contacto"
     )
 
-    class Config:
-        json_schema_extra = {
+    model_config = ConfigDict(
+        json_schema_extra={
             "example": {
                 "name": "Empresa ABC S.A. de C.V.",
                 "slug": "empresa-abc",
@@ -53,6 +53,7 @@ class TenantCreateDTO(BaseModel):
                 "contact_phone": "+52 55 1234 5678",
             }
         }
+    )
 
 
 class TenantUpdateDTO(BaseModel):
@@ -64,13 +65,14 @@ class TenantUpdateDTO(BaseModel):
     contact_phone: Optional[str] = Field(None, max_length=50)
     is_active: Optional[bool] = None
 
-    class Config:
-        json_schema_extra = {
+    model_config = ConfigDict(
+        json_schema_extra={
             "example": {
                 "name": "Empresa ABC S.A. de C.V. - Actualizado",
                 "contact_email": "nuevo@empresa-abc.com",
             }
         }
+    )
 
 
 class TenantResponseDTO(BaseModel):
@@ -88,9 +90,9 @@ class TenantResponseDTO(BaseModel):
     created_at: datetime
     updated_at: datetime
 
-    class Config:
-        from_attributes = True
-        json_schema_extra = {
+    model_config = ConfigDict(
+        from_attributes=True,
+        json_schema_extra={
             "example": {
                 "id": 1,
                 "name": "Empresa ABC S.A. de C.V.",
@@ -104,7 +106,8 @@ class TenantResponseDTO(BaseModel):
                 "created_at": "2025-01-15T10:30:00Z",
                 "updated_at": "2025-01-15T10:30:00Z",
             }
-        }
+        },
+    )
 
 
 class TenantListResponseDTO(BaseModel):
diff --git a/backend/api/v1/modules/sitar/aladi2/schemas.py b/backend/api/v1/modules/sitar/aladi2/schemas.py
index 511ba5a8..ac136931 100644
--- a/backend/api/v1/modules/sitar/aladi2/schemas.py
+++ b/backend/api/v1/modules/sitar/aladi2/schemas.py
@@ -1,7 +1,7 @@
 """ALADI2 Schemas"""
 
 from typing import Optional
-from pydantic import BaseModel, Field
+from pydantic import BaseModel, ConfigDict, Field
 
 
 class Aladi2Response(BaseModel):
@@ -20,5 +20,4 @@ class Aladi2Response(BaseModel):
     NICO: Optional[str] = Field(None, max_length=2)
     SYSID: int
 
-    class Config:
-        from_attributes = True
+    model_config = ConfigDict(from_attributes=True)
diff --git a/backend/api/v1/modules/sitar/cuotas2/schemas.py b/backend/api/v1/modules/sitar/cuotas2/schemas.py
index d9c29164..74ca8ca2 100644
--- a/backend/api/v1/modules/sitar/cuotas2/schemas.py
+++ b/backend/api/v1/modules/sitar/cuotas2/schemas.py
@@ -1,7 +1,7 @@
 """Cuotas2 Schemas"""
 
 from typing import Optional
-from pydantic import BaseModel, Field
+from pydantic import BaseModel, ConfigDict, Field
 
 
 class Cuotas2Response(BaseModel):
@@ -26,5 +26,4 @@ class Cuotas2Response(BaseModel):
     NICO: Optional[str] = Field("", max_length=2)
     SYSID: int
 
-    class Config:
-        from_attributes = True
+    model_config = ConfigDict(from_attributes=True)
diff --git a/backend/api/v1/modules/sitar/cupos/schemas.py b/backend/api/v1/modules/sitar/cupos/schemas.py
index 4a6f652f..d607d6d5 100644
--- a/backend/api/v1/modules/sitar/cupos/schemas.py
+++ b/backend/api/v1/modules/sitar/cupos/schemas.py
@@ -1,7 +1,7 @@
 """Cupos Schemas"""
 
 from typing import Optional
-from pydantic import BaseModel, Field
+from pydantic import BaseModel, ConfigDict, Field
 
 
 class CuposResponse(BaseModel):
@@ -21,5 +21,4 @@ class CuposResponse(BaseModel):
     NICO: Optional[str] = Field("", max_length=2)
     SYSID: int
 
-    class Config:
-        from_attributes = True
+    model_config = ConfigDict(from_attributes=True)
diff --git a/backend/api/v1/modules/sitar/fracciones/schemas.py b/backend/api/v1/modules/sitar/fracciones/schemas.py
index a657c68b..1e01b4af 100644
--- a/backend/api/v1/modules/sitar/fracciones/schemas.py
+++ b/backend/api/v1/modules/sitar/fracciones/schemas.py
@@ -2,7 +2,7 @@
 
 from decimal import Decimal
 from typing import Optional
-from pydantic import BaseModel, Field
+from pydantic import BaseModel, ConfigDict, Field
 
 
 class FraccionesResponse(BaseModel):
@@ -35,5 +35,4 @@ class FraccionesResponse(BaseModel):
     NICO: Optional[str] = Field(None, max_length=14)
     SYSID: Optional[int] = None
 
-    class Config:
-        from_attributes = True
+    model_config = ConfigDict(from_attributes=True)
diff --git a/backend/api/v1/modules/sitar/fracciones_anteriores/schemas.py b/backend/api/v1/modules/sitar/fracciones_anteriores/schemas.py
index 9ddd8247..20b4757d 100644
--- a/backend/api/v1/modules/sitar/fracciones_anteriores/schemas.py
+++ b/backend/api/v1/modules/sitar/fracciones_anteriores/schemas.py
@@ -1,7 +1,7 @@
 """Fracciones Anteriores Schemas"""
 
 from typing import Optional
-from pydantic import BaseModel, Field
+from pydantic import BaseModel, ConfigDict, Field
 
 
 class FraccionesAnterioresResponse(BaseModel):
@@ -11,5 +11,4 @@ class FraccionesAnterioresResponse(BaseModel):
     FRACCIONANTERIOR: Optional[str] = Field(None, max_length=10)
     SYSID: int
 
-    class Config:
-        from_attributes = True
+    model_config = ConfigDict(from_attributes=True)
diff --git a/backend/api/v1/modules/sitar/fracciones_usa/schemas.py b/backend/api/v1/modules/sitar/fracciones_usa/schemas.py
index 1c5a8ba7..36e02fa3 100644
--- a/backend/api/v1/modules/sitar/fracciones_usa/schemas.py
+++ b/backend/api/v1/modules/sitar/fracciones_usa/schemas.py
@@ -1,7 +1,7 @@
 """Fracciones USA Schemas"""
 
 from typing import Optional
-from pydantic import BaseModel, Field
+from pydantic import BaseModel, ConfigDict, Field
 
 
 class FraccionesUSAResponse(BaseModel):
@@ -20,5 +20,4 @@ class FraccionesUSAResponse(BaseModel):
     NOTAS: Optional[str] = None
     CONSECUTIVO: int
 
-    class Config:
-        from_attributes = True
+    model_config = ConfigDict(from_attributes=True)
diff --git a/backend/api/v1/modules/sitar/fundamentos_tlc/schemas.py b/backend/api/v1/modules/sitar/fundamentos_tlc/schemas.py
index 2a2350b7..d05c328c 100644
--- a/backend/api/v1/modules/sitar/fundamentos_tlc/schemas.py
+++ b/backend/api/v1/modules/sitar/fundamentos_tlc/schemas.py
@@ -1,7 +1,7 @@
 """Fundamentos TLC Schemas"""
 
 from typing import Optional
-from pydantic import BaseModel, Field
+from pydantic import BaseModel, ConfigDict, Field
 
 
 class FundamentosTLCResponse(BaseModel):
@@ -23,5 +23,4 @@ class FundamentosTLCResponse(BaseModel):
     NICO: Optional[str] = Field("", max_length=2)
     SYSID: int
 
-    class Config:
-        from_attributes = True
+    model_config = ConfigDict(from_attributes=True)
diff --git a/backend/api/v1/modules/sitar/ieps/schemas.py b/backend/api/v1/modules/sitar/ieps/schemas.py
index f65e0def..2966f4ab 100644
--- a/backend/api/v1/modules/sitar/ieps/schemas.py
+++ b/backend/api/v1/modules/sitar/ieps/schemas.py
@@ -1,7 +1,7 @@
 """IEPS Schemas"""
 
 from typing import Optional
-from pydantic import BaseModel, Field
+from pydantic import BaseModel, ConfigDict, Field
 
 
 class IepsResponse(BaseModel):
@@ -16,5 +16,4 @@ class IepsResponse(BaseModel):
     NICO: Optional[str] = Field("", max_length=2)
     CONSECUTIVO: int
 
-    class Config:
-        from_attributes = True
+    model_config = ConfigDict(from_attributes=True)
diff --git a/backend/api/v1/modules/sitar/informacion_general/schemas.py b/backend/api/v1/modules/sitar/informacion_general/schemas.py
index 1b044670..b0c68238 100644
--- a/backend/api/v1/modules/sitar/informacion_general/schemas.py
+++ b/backend/api/v1/modules/sitar/informacion_general/schemas.py
@@ -1,7 +1,7 @@
 """Información General Schemas"""
 
 from typing import Optional
-from pydantic import BaseModel, Field
+from pydantic import BaseModel, ConfigDict, Field
 
 
 class InformacionGeneralResponse(BaseModel):
@@ -17,5 +17,4 @@ class InformacionGeneralResponse(BaseModel):
     NICO: Optional[str] = Field("", max_length=2)
     SYSID: int
 
-    class Config:
-        from_attributes = True
+    model_config = ConfigDict(from_attributes=True)
diff --git a/backend/api/v1/modules/sitar/noms/schemas.py b/backend/api/v1/modules/sitar/noms/schemas.py
index e02de133..e1ad6777 100644
--- a/backend/api/v1/modules/sitar/noms/schemas.py
+++ b/backend/api/v1/modules/sitar/noms/schemas.py
@@ -1,7 +1,7 @@
 """NOMs Schemas"""
 
 from typing import Optional
-from pydantic import BaseModel, Field
+from pydantic import BaseModel, ConfigDict, Field
 
 
 class NomsResponse(BaseModel):
@@ -23,5 +23,4 @@ class NomsResponse(BaseModel):
     PAIS: Optional[str] = Field("", max_length=3)
     SYSID: int
 
-    class Config:
-        from_attributes = True
+    model_config = ConfigDict(from_attributes=True)
diff --git a/backend/api/v1/modules/sitar/precios_estimados/schemas.py b/backend/api/v1/modules/sitar/precios_estimados/schemas.py
index 62753b6b..b3f18ed3 100644
--- a/backend/api/v1/modules/sitar/precios_estimados/schemas.py
+++ b/backend/api/v1/modules/sitar/precios_estimados/schemas.py
@@ -1,7 +1,7 @@
 """Precios Estimados Schemas"""
 
 from typing import Optional
-from pydantic import BaseModel, Field
+from pydantic import BaseModel, ConfigDict, Field
 
 
 class PreciosEstimados2Response(BaseModel):
@@ -14,5 +14,4 @@ class PreciosEstimados2Response(BaseModel):
     NICO: Optional[str] = Field("", max_length=2)
     SYSID: int
 
-    class Config:
-        from_attributes = True
+    model_config = ConfigDict(from_attributes=True)
diff --git a/backend/api/v1/modules/sitar/prosec/schemas.py b/backend/api/v1/modules/sitar/prosec/schemas.py
index 13d7b96c..0e798b99 100644
--- a/backend/api/v1/modules/sitar/prosec/schemas.py
+++ b/backend/api/v1/modules/sitar/prosec/schemas.py
@@ -1,7 +1,7 @@
 """PROSEC Schemas"""
 
 from typing import Optional
-from pydantic import BaseModel, Field
+from pydantic import BaseModel, ConfigDict, Field
 
 
 class ProsecResponse(BaseModel):
@@ -17,5 +17,4 @@ class ProsecResponse(BaseModel):
     NICO: Optional[str] = Field("", max_length=2)
     SYSID: int
 
-    class Config:
-        from_attributes = True
+    model_config = ConfigDict(from_attributes=True)
diff --git a/backend/api/v1/modules/sitar/rcg2/schemas.py b/backend/api/v1/modules/sitar/rcg2/schemas.py
index 977cb8af..3f90814b 100644
--- a/backend/api/v1/modules/sitar/rcg2/schemas.py
+++ b/backend/api/v1/modules/sitar/rcg2/schemas.py
@@ -1,7 +1,7 @@
 """RCG2 Schemas"""
 
 from typing import Optional
-from pydantic import BaseModel, Field
+from pydantic import BaseModel, ConfigDict, Field
 
 
 class Rcg2Response(BaseModel):
@@ -22,5 +22,4 @@ class Rcg2Response(BaseModel):
     NICO: Optional[str] = Field("", max_length=2)
     SYSID: int
 
-    class Config:
-        from_attributes = True
+    model_config = ConfigDict(from_attributes=True)
diff --git a/backend/api/v1/modules/sitar/regulaciones/schemas.py b/backend/api/v1/modules/sitar/regulaciones/schemas.py
index ddb6f4b3..c33387cf 100644
--- a/backend/api/v1/modules/sitar/regulaciones/schemas.py
+++ b/backend/api/v1/modules/sitar/regulaciones/schemas.py
@@ -1,7 +1,7 @@
 """Regulaciones Schemas"""
 
 from typing import Optional
-from pydantic import BaseModel, Field
+from pydantic import BaseModel, ConfigDict, Field
 
 
 class RegulacionesResponse(BaseModel):
@@ -15,5 +15,4 @@ class RegulacionesResponse(BaseModel):
     NICO: Optional[str] = Field("", max_length=2)
     SYSID: int
 
-    class Config:
-        from_attributes = True
+    model_config = ConfigDict(from_attributes=True)
diff --git a/backend/api/v1/modules/sitar/reit/schemas.py b/backend/api/v1/modules/sitar/reit/schemas.py
index 9d079198..bea940d6 100644
--- a/backend/api/v1/modules/sitar/reit/schemas.py
+++ b/backend/api/v1/modules/sitar/reit/schemas.py
@@ -1,7 +1,7 @@
 """REIT Schemas"""
 
 from typing import Optional
-from pydantic import BaseModel, Field
+from pydantic import BaseModel, ConfigDict, Field
 
 
 class ReitResponse(BaseModel):
@@ -21,5 +21,4 @@ class ReitResponse(BaseModel):
     NICO: Optional[str] = Field("", max_length=2)
     SYSID: int
 
-    class Config:
-        from_attributes = True
+    model_config = ConfigDict(from_attributes=True)
diff --git a/backend/api/v1/modules/sitar/requisito_previo/schemas.py b/backend/api/v1/modules/sitar/requisito_previo/schemas.py
index bc711e76..75082e71 100644
--- a/backend/api/v1/modules/sitar/requisito_previo/schemas.py
+++ b/backend/api/v1/modules/sitar/requisito_previo/schemas.py
@@ -1,7 +1,7 @@
 """Requisito Previo Schemas"""
 
 from typing import Optional
-from pydantic import BaseModel, Field
+from pydantic import BaseModel, ConfigDict, Field
 
 
 class RequisitoPrevioResponse(BaseModel):
@@ -24,5 +24,4 @@ class RequisitoPrevioResponse(BaseModel):
     NICO: Optional[str] = Field("", max_length=2)
     SYSID: int
 
-    class Config:
-        from_attributes = True
+    model_config = ConfigDict(from_attributes=True)
diff --git a/backend/api/v1/modules/sitar/tlcs/schemas.py b/backend/api/v1/modules/sitar/tlcs/schemas.py
index 944731ea..86a462ed 100644
--- a/backend/api/v1/modules/sitar/tlcs/schemas.py
+++ b/backend/api/v1/modules/sitar/tlcs/schemas.py
@@ -1,7 +1,7 @@
 """TLCS Schemas"""
 
 from typing import Optional
-from pydantic import BaseModel, Field
+from pydantic import BaseModel, ConfigDict, Field
 
 
 class TLCSResponse(BaseModel):
@@ -19,5 +19,4 @@ class TLCSResponse(BaseModel):
     NICO: Optional[str] = Field("", max_length=2)
     SYSID: int
 
-    class Config:
-        from_attributes = True
+    model_config = ConfigDict(from_attributes=True)
diff --git a/backend/api/v1/modules/sitar/vehiculos_marcas/schemas.py b/backend/api/v1/modules/sitar/vehiculos_marcas/schemas.py
index 979a8fba..0c3ea9b8 100644
--- a/backend/api/v1/modules/sitar/vehiculos_marcas/schemas.py
+++ b/backend/api/v1/modules/sitar/vehiculos_marcas/schemas.py
@@ -1,7 +1,7 @@
 """Vehiculos Marcas Schemas"""
 
 from typing import Optional
-from pydantic import BaseModel, Field
+from pydantic import BaseModel, ConfigDict, Field
 
 
 class VehiculosMarcasResponse(BaseModel):
@@ -11,5 +11,4 @@ class VehiculosMarcasResponse(BaseModel):
     MARCA: Optional[str] = Field(None, max_length=60)
     SYSID: int
 
-    class Config:
-        from_attributes = True
+    model_config = ConfigDict(from_attributes=True)
diff --git a/backend/api/v1/modules/sitar/vehiculos_modelos/schemas.py b/backend/api/v1/modules/sitar/vehiculos_modelos/schemas.py
index 0153c215..1fdb8d7a 100644
--- a/backend/api/v1/modules/sitar/vehiculos_modelos/schemas.py
+++ b/backend/api/v1/modules/sitar/vehiculos_modelos/schemas.py
@@ -1,7 +1,7 @@
 """Vehiculos Modelos Schemas"""
 
 from typing import Optional
-from pydantic import BaseModel, Field
+from pydantic import BaseModel, ConfigDict, Field
 
 
 class VehiculosModelosResponse(BaseModel):
@@ -34,5 +34,4 @@ class VehiculosModelosResponse(BaseModel):
     A1: Optional[str] = Field(None, max_length=19)
     SYSID: int
 
-    class Config:
-        from_attributes = True
+    model_config = ConfigDict(from_attributes=True)
diff --git a/backend/core/error_handlers.py b/backend/core/error_handlers.py
index 7a68ccb7..8423403d 100644
--- a/backend/core/error_handlers.py
+++ b/backend/core/error_handlers.py
@@ -159,11 +159,11 @@ async def validation_exception_handler(
     )
 
     response = JSONResponse(
-        status_code=status.HTTP_422_UNPROCESSABLE_ENTITY,
+        status_code=status.HTTP_422_UNPROCESSABLE_CONTENT,
         content={
             "error": "VALIDATION_ERROR",
             "message": summary,
-            "status_code": status.HTTP_422_UNPROCESSABLE_ENTITY,
+            "status_code": status.HTTP_422_UNPROCESSABLE_CONTENT,
             "errors": errors,
         },
     )
@@ -209,11 +209,11 @@ async def inner_validation_exception_handler(
     )
 
     response = JSONResponse(
-        status_code=status.HTTP_422_UNPROCESSABLE_ENTITY,
+        status_code=status.HTTP_422_UNPROCESSABLE_CONTENT,
         content={
             "error": "VALIDATION_ERROR",
             "message": summary,
-            "status_code": status.HTTP_422_UNPROCESSABLE_ENTITY,
+            "status_code": status.HTTP_422_UNPROCESSABLE_CONTENT,
             "errors": errors,
         },
     )
diff --git a/backend/core/exceptions.py b/backend/core/exceptions.py
index e53d20fe..1d457804 100644
--- a/backend/core/exceptions.py
+++ b/backend/core/exceptions.py
@@ -44,7 +44,7 @@ class ValidationException(BaseAPIException):
     ):
         super().__init__(
             message=message,
-            status_code=status.HTTP_422_UNPROCESSABLE_ENTITY,
+            status_code=status.HTTP_422_UNPROCESSABLE_CONTENT,
             errors=errors,
             error_code="VALIDATION_ERROR",
         )
diff --git a/backend/tests/README.md b/backend/tests/README.md
new file mode 100644
index 00000000..bfbab7c8
--- /dev/null
+++ b/backend/tests/README.md
@@ -0,0 +1,34 @@
+# Backend test strategy (Anexo24)
+
+## Test suites
+
+- `tests/e2e/`: full business flow (catalogs -> import -> export -> balances/discharges).
+- `tests/integration/`: process API behavior and edge cases.
+- `tests/unit/`: critical algorithms only (no trivial CRUD tests).
+
+## Prerequisites
+
+- PostgreSQL test database available.
+- Environment variable:
+  - `TEST_DATABASE_URL=postgresql://user:pass@host:5432/db_name`
+
+## Run commands
+
+- Fast subset (CI gate):
+  - `pytest -q tests/unit tests/integration`
+- Full suite:
+  - `pytest -q tests`
+  - `pytest tests -v -ra`
+  - `pytest tests -v -ra -s`
+- E2E only:
+  - `pytest -q tests/e2e`
+
+## CI recommendations
+
+- Pull request gate:
+  - Run unit + integration on every PR.
+- Nightly / main branch:
+  - Run full suite including E2E.
+- Keep Celery eager mode for deterministic process endpoint tests:
+  - `task_always_eager=True`
+  - `task_eager_propagates=True`
diff --git a/backend/tests/__init__.py b/backend/tests/__init__.py
new file mode 100644
index 00000000..8b137891
--- /dev/null
+++ b/backend/tests/__init__.py
@@ -0,0 +1 @@
+
diff --git a/backend/tests/conftest.py b/backend/tests/conftest.py
new file mode 100644
index 00000000..1be795d3
--- /dev/null
+++ b/backend/tests/conftest.py
@@ -0,0 +1,138 @@
+from collections.abc import Generator
+
+import pytest
+from fastapi import FastAPI
+from fastapi.testclient import TestClient
+from sqlalchemy import create_engine
+from sqlalchemy.orm import Session, sessionmaker
+
+# Importar modelos con relaciones string para registrar mappers antes de tests.
+# Evita errores tipo: expression 'Pedimentos' failed to locate a name.
+from api.v1.modules.a76.pedmientos.models.pedimentos import Pedimentos  # noqa: F401
+from api.v1.modules.a76.invoices.models import InvoiceHeader
+from api.v1.modules.a76.invoices.imports.process import routes as process_routes
+from api.v1.modules.a76.invoices.imports.process import main_process as import_main_process
+from api.v1.modules.a76.invoices.exports.process import main_process as export_main_process
+from core.celery_app import celery_app
+from core.config import settings
+from core.database import get_core_db
+from core.security import get_current_user
+
+
+TEST_DB_URL = (
+    __import__("os").environ.get("TEST_DATABASE_URL")
+    or __import__("os").environ.get("CORE_DATABASE_URL")
+    or settings.core_database_url
+)
+
+engine = create_engine(TEST_DB_URL, future=True)
+TestingSessionLocal = sessionmaker(
+    bind=engine,
+    autoflush=False,
+    autocommit=False,
+    expire_on_commit=False,
+    class_=Session,
+    join_transaction_mode="create_savepoint",
+)
+
+
+@pytest.fixture
+def db_session() -> Generator[Session, None, None]:
+    connection = engine.connect()
+    transaction = connection.begin()
+    session = TestingSessionLocal(bind=connection)
+    try:
+        yield session
+    finally:
+        session.close()
+        transaction.rollback()
+        connection.close()
+
+
+@pytest.fixture(autouse=True)
+def celery_eager() -> Generator[None, None, None]:
+    prev_broker = celery_app.conf.broker_url
+    prev_backend = celery_app.conf.result_backend
+    prev_always_eager = celery_app.conf.task_always_eager
+    prev_propagates = celery_app.conf.task_eager_propagates
+    prev_store_result = celery_app.conf.task_store_eager_result
+    prev_ignore_result = celery_app.conf.task_ignore_result
+
+    # Aislar Celery de infraestructura externa en tests (sin Redis/Valkey).
+    celery_app.conf.broker_url = "memory://"
+    celery_app.conf.result_backend = "cache+memory://"
+    celery_app.conf.task_always_eager = True
+    celery_app.conf.task_eager_propagates = True
+    celery_app.conf.task_store_eager_result = False
+    celery_app.conf.task_ignore_result = True
+    try:
+        yield
+    finally:
+        celery_app.conf.broker_url = prev_broker
+        celery_app.conf.result_backend = prev_backend
+        celery_app.conf.task_always_eager = prev_always_eager
+        celery_app.conf.task_eager_propagates = prev_propagates
+        celery_app.conf.task_store_eager_result = prev_store_result
+        celery_app.conf.task_ignore_result = prev_ignore_result
+
+
+@pytest.fixture
+def app(db_session: Session, monkeypatch: pytest.MonkeyPatch) -> FastAPI:
+    test_app = FastAPI()
+    test_app.include_router(process_routes.router, prefix="/api/v1/a76")
+
+    def _override_get_db() -> Generator[Session, None, None]:
+        yield db_session
+
+    async def _override_current_user():
+        return {"sub": "test-user", "tenant_id": 1}
+
+    # validate_access_to_resource is imported directly in the routes module.
+    monkeypatch.setattr(
+        process_routes,
+        "validate_access_to_resource",
+        lambda db, company_id, current_user: int(current_user["tenant_id"]),
+    )
+
+    class _InlineResult:
+        def __init__(self, task_id: str):
+            self.id = task_id
+
+    def _run_import_inline(*, args=None, **kwargs):
+        if args is None:
+            args = []
+        invoice_id, tenant_id, company_id = args
+        invoice = db_session.get(InvoiceHeader, int(invoice_id))
+        if invoice is None:
+            return _InlineResult("missing-import-invoice")
+        import_main_process.main_process(db_session, invoice, str(tenant_id), str(company_id))
+        db_session.flush()
+        return _InlineResult(f"inline-import-{invoice_id}")
+
+    def _run_export_inline(*, args=None, **kwargs):
+        if args is None:
+            args = []
+        invoice_id, tenant_id, company_id = args
+        invoice = db_session.get(InvoiceHeader, int(invoice_id))
+        if invoice is None:
+            return _InlineResult("missing-export-invoice")
+        export_main_process.main_process(db_session, invoice, str(tenant_id), str(company_id))
+        db_session.flush()
+        return _InlineResult(f"inline-export-{invoice_id}")
+
+    class _InlineTask:
+        def __init__(self, runner):
+            self.apply_async = runner
+
+    # Evita worker/redis y obliga ejecución inline con la misma sesión.
+    monkeypatch.setattr(process_routes, "process_invoice_task", _InlineTask(_run_import_inline))
+    monkeypatch.setattr(process_routes, "process_export_invoice_task", _InlineTask(_run_export_inline))
+
+    test_app.dependency_overrides[get_core_db] = _override_get_db
+    test_app.dependency_overrides[get_current_user] = _override_current_user
+    return test_app
+
+
+@pytest.fixture
+def client(app: FastAPI) -> TestClient:
+    return TestClient(app)
diff --git a/backend/tests/e2e/test_inventory_flow_anexo24.py b/backend/tests/e2e/test_inventory_flow_anexo24.py
new file mode 100644
index 00000000..19be14b6
--- /dev/null
+++ b/backend/tests/e2e/test_inventory_flow_anexo24.py
@@ -0,0 +1,113 @@
+from decimal import Decimal
+
+from api.v1.modules.a24.balance_movements.models import BalanceMovement, MovementType
+from api.v1.modules.a24.discharges.models import DischargeDetail, DischargeHeader
+from api.v1.modules.a76.invoices.imports.process import main_process as import_main
+from api.v1.modules.a76.invoices.exports.process import main_process as export_main
+from api.v1.modules.a76.invoices.exports.process import task as export_task
+from tests.fixtures.builders import (
+    create_business_catalogs,
+    create_export_invoice_with_line,
+    create_import_invoice_with_line,
+    ensure_reference_data,
+    ensure_tenant_company,
+)
+
+
+def _patch_import_pipeline(monkeypatch, import_line):
+    monkeypatch.setattr(import_main, "pre_validators", lambda *args, **kwargs: [import_line])
+    monkeypatch.setattr(import_main, "review_classes", lambda *args, **kwargs: None)
+    monkeypatch.setattr(import_main, "review_exchange_rate", lambda *args, **kwargs: None)
+    monkeypatch.setattr(import_main, "review_weights_kgs", lambda *args, **kwargs: None)
+    monkeypatch.setattr(import_main, "review_weights_lbs", lambda *args, **kwargs: None)
+    monkeypatch.setattr(import_main, "_validate_sisimp_limits", lambda *args, **kwargs: None)
+    monkeypatch.setattr(import_main, "_validate_lines", lambda *args, **kwargs: ([], {}))
+
+
+def _patch_export_pipeline(monkeypatch, export_line):
+    monkeypatch.setattr(export_main, "pre_validators", lambda *args, **kwargs: [export_line])
+    monkeypatch.setattr(export_main, "review_class", lambda *args, **kwargs: None)
+    monkeypatch.setattr(export_main, "review_exchange_rate", lambda *args, **kwargs: None)
+    monkeypatch.setattr(export_main, "assign_values", lambda *args, **kwargs: None)
+    monkeypatch.setattr(export_main, "review_qty_vs_weight", lambda *args, **kwargs: None)
+    monkeypatch.setattr(export_main, "review_unit_cost", lambda *args, **kwargs: None)
+    monkeypatch.setattr(export_main, "review_qty_series", lambda *args, **kwargs: None)
+
+
+def test_e2e_inventory_flow_import_then_export(client, db_session, monkeypatch):
+    """
+    E2E principal:
+    - Alta catálogos/base
+    - Procesa factura IMP -> genera entry
+    - Procesa factura EXP -> genera consumo/descarga
+    - Valida decremento de saldo sin negativos
+    """
+    ensure_reference_data(db_session)
+    ensure_tenant_company(db_session, tenant_id=1, company_id=1)
+    catalogs = create_business_catalogs(db_session, tenant_id=1, company_id=1)
+
+    import_invoice, import_line = create_import_invoice_with_line(
+        db_session, 1, 1, catalogs, invoice_type="TEM", invoice_number="IMP-E2E-01", qty=Decimal("10")
+    )
+    _patch_import_pipeline(monkeypatch, import_line)
+
+    response = client.post(f"/api/v1/a76/invoices/{import_invoice.id}/process?company_id=1")
+    assert response.status_code == 200
+
+    entry_movements = (
+        db_session.query(BalanceMovement)
+        .filter(
+            BalanceMovement.import_invoice_id == import_invoice.id,
+            BalanceMovement.import_item_line_id == import_line.id,
+            BalanceMovement.movement_type == MovementType.ENTRY,
+        )
+        .all()
+    )
+    assert entry_movements
+    assert sum(Decimal(str(m.quantity or 0)) for m in entry_movements) > 0
+
+    export_invoice, export_line = create_export_invoice_with_line(
+        db_session, 1, 1, catalogs, import_invoice, import_line, qty=Decimal("4")
+    )
+    _patch_export_pipeline(monkeypatch, export_line)
+
+    response = client.post(f"/api/v1/a76/invoices/{export_invoice.id}/process?company_id=1")
+    assert response.status_code == 200
+
+    consumptions = (
+        db_session.query(BalanceMovement)
+        .filter(
+            BalanceMovement.source_invoice_id == export_invoice.id,
+            BalanceMovement.movement_type == MovementType.CONSUMPTION,
+        )
+        .all()
+    )
+    assert consumptions, "El proceso de exportación debe generar consumos"
+
+    discharge_headers = (
+        db_session.query(DischargeHeader)
+        .filter(DischargeHeader.source_invoice_id == export_invoice.id)
+        .all()
+    )
+    assert discharge_headers
+
+    discharge_details = (
+        db_session.query(DischargeDetail)
+        .filter(DischargeDetail.export_item_line_id == export_line.id)
+        .all()
+    )
+    assert discharge_details
+    assert all(detail.movement_id is not None for detail in discharge_details)
+
+    net_balance = db_session.query(BalanceMovement).filter(
+        BalanceMovement.import_item_line_id == import_line.id
+    ).all()
+    signed = Decimal("0")
+    for mov in net_balance:
+        qty = Decimal(str(mov.quantity or 0))
+        if mov.movement_type in {MovementType.CONSUMPTION, MovementType.WASTE, MovementType.SCRAP, MovementType.DESTRUCTION}:
+            signed -= qty
+        else:
+            signed += qty
+    assert signed >= 0
+    assert signed < Decimal("10")
diff --git a/backend/tests/fixtures/__init__.py b/backend/tests/fixtures/__init__.py
new file mode 100644
index 00000000..8b137891
--- /dev/null
+++ b/backend/tests/fixtures/__init__.py
@@ -0,0 +1 @@
+
diff --git a/backend/tests/fixtures/builders.py b/backend/tests/fixtures/builders.py
new file mode 100644
index 00000000..2c4e5cbf
--- /dev/null
+++ b/backend/tests/fixtures/builders.py
@@ -0,0 +1,396 @@
+from __future__ import annotations
+
+from datetime import date, datetime
+from decimal import Decimal
+
+from sqlalchemy.orm import Session
+
+from api.v1.modules.a24.fa.fa_item_lines.models import FaLineItem
+from api.v1.modules.a76.clients_and_providers.models import (
+    ClientOrProviderEnum,
+    ClientProvider,
+    ClientProviderAddress,
+)
+from api.v1.modules.a76.customs_brokers.models import CustomsBroker
+from api.v1.modules.a76.general_catalogs.company.models import Company
+from api.v1.modules.a76.general_catalogs.exchange_rate.models import ExchangeRate
+from api.v1.modules.a76.general_catalogs.units_of_measure.models import UnitOfMeasure
+from api.v1.modules.a76.invoices.models import (
+    Currency,
+    InvoiceComplianceMx,
+    InvoiceFinancials,
+    InvoiceHeader,
+    InvoiceLogistics,
+    InvoiceStatus,
+    OperationType,
+)
+from api.v1.modules.a76.items.line_customs.models import LineCustom
+from api.v1.modules.a76.items.line_descriptions.models import LineDescription
+from api.v1.modules.a76.items.line_financials.models import LineFinancial
+from api.v1.modules.a76.items.line_quantities.models import LineQuantity
+from api.v1.modules.a76.items.models import LineItem
+from api.v1.modules.core.tenants.models import Tenant, TenantType
+from api.v1.modules.public.reference_data.invoice_types.models import InvoiceType
+from api.v1.modules.public.reference_data.pedimento_regimens.models import RegimenPedimento
+
+
+def ensure_reference_data(db: Session) -> None:
+    for key, desc in [
+        ("TEM", "IMPORTACION TEMPORAL"),
+        ("DEF", "IMPORTACION DEFINITIVA"),
+        ("MEX", "COMPRAS MEXICANAS"),
+        ("DONAC", "DONACION"),
+    ]:
+        if db.get(InvoiceType, key) is None:
+            operation = "exp" if key == "DONAC" else "imp"
+            db.add(
+                InvoiceType(
+                    key=key,
+                    description=desc,
+                    note="seed for tests",
+                    type="both",
+                    operation=operation,
+                )
+            )
+
+    if db.get(RegimenPedimento, "A1") is None:
+        db.add(
+            RegimenPedimento(
+                code="A1",
+                description="Regimen de prueba",
+            )
+        )
+    db.flush()
+
+
+def ensure_tenant_company(db: Session, tenant_id: int = 1, company_id: int = 1) -> Company:
+    tenant = db.get(Tenant, tenant_id)
+    if tenant is None:
+        tenant = Tenant(
+            id=tenant_id,
+            name=f"Tenant {tenant_id}",
+            slug=f"tenant-{tenant_id}",
+            type=TenantType.SHARED,
+            keycloak_realm="test",
+            is_active=True,
+        )
+        db.add(tenant)
+
+    company = db.get(Company, company_id)
+    if company is None:
+        company = Company(
+            id=company_id,
+            tenant_id=tenant_id,
+            name=f"Company {company_id}",
+            rfc="TST010101AAA",
+            prosec=False,
+        )
+        db.add(company)
+    db.flush()
+    return company
+
+
+def create_business_catalogs(db: Session, tenant_id: int, company_id: int) -> dict:
+    provider = (
+        db.query(ClientProvider)
+        .filter(
+            ClientProvider.tenant_id == tenant_id,
+            ClientProvider.company_id == company_id,
+            ClientProvider.name == "Proveedor Test",
+        )
+        .first()
+    )
+    if provider is None:
+        provider = ClientProvider(
+            tenant_id=tenant_id,
+            company_id=company_id,
+            name="Proveedor Test",
+            client_or_provider=ClientOrProviderEnum.BOTH,
+            is_active=True,
+        )
+        db.add(provider)
+        db.flush()
+    if provider.address is None:
+        provider.address = ClientProviderAddress(
+            id=provider.id,
+            client_id=provider.id,
+            tenant_id=tenant_id,
+            company_id=company_id,
+            country="MEX",
+        )
+
+    sold_to = (
+        db.query(ClientProvider)
+        .filter(
+            ClientProvider.tenant_id == tenant_id,
+            ClientProvider.company_id == company_id,
+            ClientProvider.name == "Cliente Test",
+        )
+        .first()
+    )
+    if sold_to is None:
+        sold_to = ClientProvider(
+            tenant_id=tenant_id,
+            company_id=company_id,
+            name="Cliente Test",
+            client_or_provider=ClientOrProviderEnum.BOTH,
+            is_active=True,
+        )
+        db.add(sold_to)
+        db.flush()
+    if sold_to.address is None:
+        sold_to.address = ClientProviderAddress(
+            id=sold_to.id,
+            client_id=sold_to.id,
+            tenant_id=tenant_id,
+            company_id=company_id,
+            country="USA",
+        )
+
+    shipped_to = (
+        db.query(ClientProvider)
+        .filter(
+            ClientProvider.tenant_id == tenant_id,
+            ClientProvider.company_id == company_id,
+            ClientProvider.name == "Destinatario Test",
+        )
+        .first()
+    )
+    if shipped_to is None:
+        shipped_to = ClientProvider(
+            tenant_id=tenant_id,
+            company_id=company_id,
+            name="Destinatario Test",
+            client_or_provider=ClientOrProviderEnum.BOTH,
+            is_active=True,
+        )
+        db.add(shipped_to)
+        db.flush()
+    if shipped_to.address is None:
+        shipped_to.address = ClientProviderAddress(
+            id=shipped_to.id,
+            client_id=shipped_to.id,
+            tenant_id=tenant_id,
+            company_id=company_id,
+            country="USA",
+        )
+
+    broker = (
+        db.query(CustomsBroker)
+        .filter(
+            CustomsBroker.tenant_id == tenant_id,
+            CustomsBroker.company_id == company_id,
+            CustomsBroker.broker_key == "A1234",
+        )
+        .first()
+    )
+    if broker is None:
+        broker = CustomsBroker(
+            tenant_id=tenant_id,
+            company_id=company_id,
+            broker_key="A1234",
+            name="Agente Test",
+        )
+        db.add(broker)
+        db.flush()
+
+    uom = (
+        db.query(UnitOfMeasure)
+        .filter(
+            UnitOfMeasure.tenant_id == tenant_id,
+            UnitOfMeasure.company_id == company_id,
+            UnitOfMeasure.code == "PZA",
+        )
+        .first()
+    )
+    if uom is None:
+        uom = UnitOfMeasure(
+            tenant_id=tenant_id,
+            company_id=company_id,
+            code="PZA",
+            description="Pieza",
+        )
+        db.add(uom)
+        db.flush()
+
+    exr = (
+        db.query(ExchangeRate)
+        .filter(
+            ExchangeRate.tenant_id == tenant_id,
+            ExchangeRate.company_id == company_id,
+            ExchangeRate.date == datetime(2026, 3, 17, 0, 0, 0),
+        )
+        .first()
+    )
+    if exr is None:
+        exr = ExchangeRate(
+            tenant_id=tenant_id,
+            company_id=company_id,
+            date=datetime(2026, 3, 17, 0, 0, 0),
+            value=Decimal("17.250000"),
+            local_currency="MN",
+            foreign_currency="ME",
+        )
+        db.add(exr)
+
+    db.flush()
+    return {
+        "provider_id": provider.id,
+        "sold_to_id": sold_to.id,
+        "shipped_to_id": shipped_to.id,
+        "broker_id": broker.id,
+        "uom_id": uom.id,
+    }
+
+
+def create_import_invoice_with_line(
+    db: Session,
+    tenant_id: int,
+    company_id: int,
+    catalogs: dict,
+    invoice_type: str = "TEM",
+    invoice_number: str = "IMP-0001",
+    qty: Decimal = Decimal("10"),
+) -> tuple[InvoiceHeader, LineItem]:
+    invoice = InvoiceHeader(
+        tenant_id=tenant_id,
+        company_id=company_id,
+        system="fixed_asset",
+        operation_type=OperationType.IMP,
+        invoice_type=invoice_type,
+        document_type="A1",
+        invoice_number=invoice_number,
+        invoice_date=date(2026, 3, 17),
+        status=InvoiceStatus.PENDING,
+    )
+    invoice.compliance_mx = InvoiceComplianceMx(
+        tenant_id=tenant_id,
+        company_id=company_id,
+        provider_id=catalogs["provider_id"],
+        sold_to_id=catalogs["sold_to_id"],
+        shipped_to_id=catalogs["shipped_to_id"],
+        customs_broker_id=catalogs["broker_id"],
+        is_pedimento_pending=True,
+        was_reviewed_by_company=True,
+    )
+    invoice.financials = InvoiceFinancials(
+        tenant_id=tenant_id,
+        company_id=company_id,
+        currency=Currency.FOREIGN,
+        exchange_rate=Decimal("17.250000"),
+        iva_factor="16",
+    )
+    invoice.logistics = InvoiceLogistics(
+        tenant_id=tenant_id,
+        company_id=company_id,
+        weight_type="kgs",
+    )
+    db.add(invoice)
+    db.flush()
+
+    line = LineItem(
+        tenant_id=tenant_id,
+        company_id=company_id,
+        invoice_id=invoice.id,
+        line_number=1,
+        unit_of_measure=catalogs["uom_id"],
+    )
+    line.quantity = LineQuantity(
+        quantity=qty,
+        net_weight=Decimal("50"),
+        gross_weight=Decimal("55"),
+        package_quantity=1,
+    )
+    line.financial = LineFinancial(
+        unit_cost_capture=Decimal("10"),
+        value_usd=Decimal("100"),
+        value_mxn=Decimal("1725"),
+    )
+    line.customs = LineCustom(origin_country="MEX", fraction_type="GENERAL")
+    line.description = LineDescription(has_serial=False)
+    db.add(line)
+    db.flush()
+    return invoice, line
+
+
+def create_export_invoice_with_line(
+    db: Session,
+    tenant_id: int,
+    company_id: int,
+    catalogs: dict,
+    source_import_invoice: InvoiceHeader,
+    source_import_line: LineItem,
+    qty: Decimal = Decimal("4"),
+) -> tuple[InvoiceHeader, LineItem]:
+    invoice = InvoiceHeader(
+        tenant_id=tenant_id,
+        company_id=company_id,
+        system="fixed_asset",
+        operation_type=OperationType.EXP,
+        invoice_type="DONAC",
+        document_type="A1",
+        invoice_number="EXP-0001",
+        invoice_date=date(2026, 3, 18),
+        status=InvoiceStatus.PENDING,
+    )
+    invoice.compliance_mx = InvoiceComplianceMx(
+        tenant_id=tenant_id,
+        company_id=company_id,
+        provider_id=catalogs["provider_id"],
+        sold_to_id=catalogs["sold_to_id"],
+        shipped_to_id=catalogs["shipped_to_id"],
+        customs_broker_id=catalogs["broker_id"],
+        is_pedimento_pending=True,
+        was_reviewed_by_company=True,
+    )
+    invoice.financials = InvoiceFinancials(
+        tenant_id=tenant_id,
+        company_id=company_id,
+        currency=Currency.FOREIGN,
+        exchange_rate=Decimal("17.250000"),
+        iva_factor="16",
+    )
+    invoice.logistics = InvoiceLogistics(
+        tenant_id=tenant_id,
+        company_id=company_id,
+        weight_type="kgs",
+    )
+    db.add(invoice)
+    db.flush()
+
+    line = LineItem(
+        tenant_id=tenant_id,
+        company_id=company_id,
+        invoice_id=invoice.id,
+        line_number=1,
+        unit_of_measure=catalogs["uom_id"],
+    )
+    line.quantity = LineQuantity(
+        quantity=qty,
+        net_weight=Decimal("20"),
+        gross_weight=Decimal("22"),
+        package_quantity=1,
+    )
+    line.financial = LineFinancial(
+        unit_cost_capture=Decimal("12"),
+        value_usd=Decimal("48"),
+        value_mxn=Decimal("828"),
+    )
+    line.customs = LineCustom(origin_country="MEX", origin_procedure="TEM", fraction_type="GENERAL")
+    line.description = LineDescription(has_serial=False)
+    db.add(line)
+    db.flush()
+
+    db.add(
+        FaLineItem(
+            id=line.id,
+            tenant_id=tenant_id,
+            company_id=company_id,
+            discharge=True,
+            search_invoice=source_import_invoice.invoice_number,
+            search_line=source_import_line.line_number,
+            is_subitem=False,
+        )
+    )
+    db.flush()
+    return invoice, line
diff --git a/backend/tests/integration/test_export_process_api.py b/backend/tests/integration/test_export_process_api.py
new file mode 100644
index 00000000..411a894c
--- /dev/null
+++ b/backend/tests/integration/test_export_process_api.py
@@ -0,0 +1,127 @@
+from decimal import Decimal
+
+import pytest
+
+from api.v1.modules.a24.balance_movements.models import BalanceMovement, MovementType
+from api.v1.modules.a76.invoices.exports.process import main_process as export_main
+from api.v1.modules.a76.invoices.imports.process import main_process as import_main
+from core.exceptions import ValidationException
+from tests.fixtures.builders import (
+    create_business_catalogs,
+    create_export_invoice_with_line,
+    create_import_invoice_with_line,
+    ensure_reference_data,
+    ensure_tenant_company,
+)
+
+
+def _patch_import_pipeline(monkeypatch, import_line):
+    monkeypatch.setattr(import_main, "pre_validators", lambda *args, **kwargs: [import_line])
+    monkeypatch.setattr(import_main, "review_classes", lambda *args, **kwargs: None)
+    monkeypatch.setattr(import_main, "review_exchange_rate", lambda *args, **kwargs: None)
+    monkeypatch.setattr(import_main, "review_weights_kgs", lambda *args, **kwargs: None)
+    monkeypatch.setattr(import_main, "review_weights_lbs", lambda *args, **kwargs: None)
+    monkeypatch.setattr(import_main, "_validate_sisimp_limits", lambda *args, **kwargs: None)
+    monkeypatch.setattr(import_main, "_validate_lines", lambda *args, **kwargs: ([], {}))
+
+
+def _patch_import_pipeline_without_prevalidators(monkeypatch):
+    monkeypatch.setattr(import_main, "review_classes", lambda *args, **kwargs: None)
+    monkeypatch.setattr(import_main, "review_exchange_rate", lambda *args, **kwargs: None)
+    monkeypatch.setattr(import_main, "review_weights_kgs", lambda *args, **kwargs: None)
+    monkeypatch.setattr(import_main, "review_weights_lbs", lambda *args, **kwargs: None)
+    monkeypatch.setattr(import_main, "_validate_sisimp_limits", lambda *args, **kwargs: None)
+    monkeypatch.setattr(import_main, "_validate_lines", lambda *args, **kwargs: ([], {}))
+
+
+def _patch_export_pipeline(monkeypatch, export_line):
+    monkeypatch.setattr(export_main, "pre_validators", lambda *args, **kwargs: [export_line])
+    monkeypatch.setattr(export_main, "review_class", lambda *args, **kwargs: None)
+    monkeypatch.setattr(export_main, "review_exchange_rate", lambda *args, **kwargs: None)
+    monkeypatch.setattr(export_main, "assign_values", lambda *args, **kwargs: None)
+    monkeypatch.setattr(export_main, "review_qty_vs_weight", lambda *args, **kwargs: None)
+    monkeypatch.setattr(export_main, "review_unit_cost", lambda *args, **kwargs: None)
+    monkeypatch.setattr(export_main, "review_qty_series", lambda *args, **kwargs: None)
+
+
+def _prepare_inventory(client, db_session, monkeypatch):
+    ensure_reference_data(db_session)
+    ensure_tenant_company(db_session, tenant_id=1, company_id=1)
+    catalogs = create_business_catalogs(db_session, tenant_id=1, company_id=1)
+    import_invoice, import_line = create_import_invoice_with_line(
+        db_session, 1, 1, catalogs, invoice_type="TEM", invoice_number="IMP-EXP-01", qty=Decimal("10")
+    )
+    _patch_import_pipeline(monkeypatch, import_line)
+    resp = client.post(f"/api/v1/a76/invoices/{import_invoice.id}/process?company_id=1")
+    assert resp.status_code == 200
+    return catalogs, import_invoice, import_line
+
+
+def test_process_export_endpoint_consumes_existing_balances(client, db_session, monkeypatch):
+    catalogs, import_invoice, import_line = _prepare_inventory(client, db_session, monkeypatch)
+    export_invoice, export_line = create_export_invoice_with_line(
+        db_session, 1, 1, catalogs, import_invoice, import_line, qty=Decimal("3")
+    )
+    _patch_export_pipeline(monkeypatch, export_line)
+
+    resp = client.post(f"/api/v1/a76/invoices/{export_invoice.id}/process?company_id=1")
+    assert resp.status_code == 200
+
+    consumptions = (
+        db_session.query(BalanceMovement)
+        .filter(
+            BalanceMovement.source_invoice_id == export_invoice.id,
+            BalanceMovement.movement_type == MovementType.CONSUMPTION,
+        )
+        .all()
+    )
+    assert consumptions
+
+
+def test_process_export_prevents_negative_balance(client, db_session, monkeypatch):
+    catalogs, import_invoice, import_line = _prepare_inventory(client, db_session, monkeypatch)
+    export_invoice, export_line = create_export_invoice_with_line(
+        db_session, 1, 1, catalogs, import_invoice, import_line, qty=Decimal("99")
+    )
+    _patch_export_pipeline(monkeypatch, export_line)
+
+    with pytest.raises(ValidationException):
+        client.post(f"/api/v1/a76/invoices/{export_invoice.id}/process?company_id=1")
+
+    # Debe no crear consumos al existir insuficiencia de saldo.
+    consumptions = (
+        db_session.query(BalanceMovement)
+        .filter(
+            BalanceMovement.source_invoice_id == export_invoice.id,
+            BalanceMovement.movement_type == MovementType.CONSUMPTION,
+        )
+        .all()
+    )
+    assert consumptions == []
+
+
+def test_process_endpoint_prevents_double_processing_import(client, db_session, monkeypatch):
+    ensure_reference_data(db_session)
+    ensure_tenant_company(db_session, tenant_id=1, company_id=1)
+    catalogs = create_business_catalogs(db_session, tenant_id=1, company_id=1)
+    invoice, line = create_import_invoice_with_line(
+        db_session, 1, 1, catalogs, invoice_type="TEM", invoice_number="IMP-DOUBLE-01", qty=Decimal("5")
+    )
+    _patch_import_pipeline_without_prevalidators(monkeypatch)
+
+    first = client.post(f"/api/v1/a76/invoices/{invoice.id}/process?company_id=1")
+    assert first.status_code == 200
+    with pytest.raises(ValidationException):
+        client.post(f"/api/v1/a76/invoices/{invoice.id}/process?company_id=1")
+
+    # No debe duplicar entradas para la misma factura/línea procesada.
+    entries = (
+        db_session.query(BalanceMovement)
+        .filter(
+            BalanceMovement.import_invoice_id == invoice.id,
+            BalanceMovement.import_item_line_id == line.id,
+            BalanceMovement.movement_type == MovementType.ENTRY,
+        )
+        .all()
+    )
+    assert len(entries) == 1
diff --git a/backend/tests/integration/test_import_process_api.py b/backend/tests/integration/test_import_process_api.py
new file mode 100644
index 00000000..fd0aadaa
--- /dev/null
+++ b/backend/tests/integration/test_import_process_api.py
@@ -0,0 +1,64 @@
+from decimal import Decimal
+
+from api.v1.modules.a24.balance_movements.models import BalanceMovement, MovementType
+from api.v1.modules.a76.invoices.imports.process import main_process as import_main
+from tests.fixtures.builders import (
+    create_business_catalogs,
+    create_import_invoice_with_line,
+    ensure_reference_data,
+    ensure_tenant_company,
+)
+
+
+def _patch_import_pipeline(monkeypatch, import_line):
+    monkeypatch.setattr(import_main, "pre_validators", lambda *args, **kwargs: [import_line])
+    monkeypatch.setattr(import_main, "review_classes", lambda *args, **kwargs: None)
+    monkeypatch.setattr(import_main, "review_exchange_rate", lambda *args, **kwargs: None)
+    monkeypatch.setattr(import_main, "review_weights_kgs", lambda *args, **kwargs: None)
+    monkeypatch.setattr(import_main, "review_weights_lbs", lambda *args, **kwargs: None)
+    monkeypatch.setattr(import_main, "_validate_sisimp_limits", lambda *args, **kwargs: None)
+    monkeypatch.setattr(import_main, "_validate_lines", lambda *args, **kwargs: ([], {}))
+
+
+def test_process_import_endpoint_creates_balance_entries(client, db_session, monkeypatch):
+    ensure_reference_data(db_session)
+    ensure_tenant_company(db_session, tenant_id=1, company_id=1)
+    catalogs = create_business_catalogs(db_session, tenant_id=1, company_id=1)
+    invoice, line = create_import_invoice_with_line(
+        db_session, 1, 1, catalogs, invoice_type="TEM", invoice_number="IMP-INT-01", qty=Decimal("7")
+    )
+    _patch_import_pipeline(monkeypatch, line)
+
+    resp = client.post(f"/api/v1/a76/invoices/{invoice.id}/process?company_id=1")
+    assert resp.status_code == 200
+
+    entries = (
+        db_session.query(BalanceMovement)
+        .filter(
+            BalanceMovement.import_invoice_id == invoice.id,
+            BalanceMovement.import_item_line_id == line.id,
+            BalanceMovement.movement_type == MovementType.ENTRY,
+        )
+        .all()
+    )
+    assert len(entries) >= 1
+
+
+def test_process_import_def_does_not_create_balance_entries(client, db_session, monkeypatch):
+    ensure_reference_data(db_session)
+    ensure_tenant_company(db_session, tenant_id=1, company_id=1)
+    catalogs = create_business_catalogs(db_session, tenant_id=1, company_id=1)
+    invoice, line = create_import_invoice_with_line(
+        db_session, 1, 1, catalogs, invoice_type="DEF", invoice_number="IMP-DEF-01", qty=Decimal("7")
+    )
+    _patch_import_pipeline(monkeypatch, line)
+
+    resp = client.post(f"/api/v1/a76/invoices/{invoice.id}/process?company_id=1")
+    assert resp.status_code == 200
+
+    entries = (
+        db_session.query(BalanceMovement)
+        .filter(BalanceMovement.import_invoice_id == invoice.id)
+        .all()
+    )
+    assert entries == []
diff --git a/backend/tests/unit/invoices/test_balance_algorithm.py b/backend/tests/unit/invoices/test_balance_algorithm.py
new file mode 100644
index 00000000..a158ed06
--- /dev/null
+++ b/backend/tests/unit/invoices/test_balance_algorithm.py
@@ -0,0 +1,121 @@
+from datetime import date
+from decimal import Decimal
+
+from api.v1.modules.a24.balance_movements.models import BalanceMovement, MovementType
+from api.v1.modules.a76.invoices.exports.process.sub_process.compare_balances import compare_balances
+from api.v1.modules.a76.invoices.exports.process.sub_process.discharge_types import (
+    AvailableLot,
+    DownloadEntry,
+)
+from api.v1.modules.a76.invoices.exports.process.sub_process.fill_available_balances import (
+    _net_balance_for_lot,
+)
+from core.exceptions import ErrorCollector
+from tests.fixtures.builders import (
+    create_business_catalogs,
+    create_import_invoice_with_line,
+    ensure_reference_data,
+    ensure_tenant_company,
+)
+
+
+def test_net_balance_accounts_for_returns_and_entry_void(db_session):
+    """
+    Balance neto esperado:
+      entry 10 - consumption 4 + return 1 - entry_void 2 = 5
+    """
+    ensure_reference_data(db_session)
+    ensure_tenant_company(db_session, tenant_id=1, company_id=1)
+    catalogs = create_business_catalogs(db_session, tenant_id=1, company_id=1)
+    import_invoice, import_line = create_import_invoice_with_line(
+        db_session,
+        1,
+        1,
+        catalogs,
+        invoice_type="TEM",
+        invoice_number="IMP-UNIT-01",
+        qty=Decimal("10"),
+    )
+
+    line_id = import_line.id
+    tenant_id = import_invoice.tenant_id
+    company_id = import_invoice.company_id
+    import_invoice_id = import_invoice.id
+    for idx, (mtype, qty) in enumerate(
+        [
+            (MovementType.ENTRY, Decimal("10")),
+            (MovementType.CONSUMPTION, Decimal("4")),
+            (MovementType.RETURN, Decimal("1")),
+            (MovementType.ENTRY_VOID, Decimal("2")),
+        ],
+        start=1,
+    ):
+        db_session.add(
+            BalanceMovement(
+                id=10000 + idx,
+                tenant_id=tenant_id,
+                company_id=company_id,
+                import_invoice_id=import_invoice_id,
+                import_item_line_id=line_id,
+                movement_type=mtype,
+                quantity=qty,
+                order_peps=10000 + idx,
+                operation_date=date(2026, 3, 20),
+            )
+        )
+    db_session.flush()
+
+    balance = _net_balance_for_lot(db_session, line_id, date(2026, 3, 21))
+    assert balance == Decimal("5")
+
+
+def test_fifo_consumption_algorithm_uses_oldest_lots_first(db_session, monkeypatch):
+    """
+    Verifica distribución FIFO (PEPS):
+    - lote1 (order=1, qty=3), lote2 (order=2, qty=5), demanda=6
+    - resultado: lote1 consume 3, lote2 consume 3, faltante 0
+    """
+    monkeypatch.setattr(
+        "api.v1.modules.a76.invoices.exports.process.sub_process.compare_balances._resolve_import_uom",
+        lambda db, import_item_line_id: "PZA",
+    )
+
+    entry = DownloadEntry(
+        origin_procedure="TEM",
+        export_line=1,
+        part_number="PN-1",
+        class_code="CLS",
+        quantity=Decimal("6"),
+        quantity_used=Decimal("0"),
+        unit_of_measure="PZA",
+        import_invoice="IMP-1",
+        import_line=1,
+        line_item_id=1,
+        available_lots=[
+            AvailableLot(
+                import_item_line_id=11,
+                import_invoice_id=101,
+                part_number_id=None,
+                available_qty=Decimal("3"),
+                value_me=Decimal("0"),
+                value_mn=Decimal("0"),
+                order_peps=1,
+            ),
+            AvailableLot(
+                import_item_line_id=12,
+                import_invoice_id=101,
+                part_number_id=None,
+                available_qty=Decimal("5"),
+                value_me=Decimal("0"),
+                value_mn=Decimal("0"),
+                order_peps=2,
+            ),
+        ],
+    )
+
+    errors = ErrorCollector()
+    compare_balances(db_session, export_invoice=None, to_discharge=[entry], errors=errors)  # type: ignore[arg-type]
+    assert not errors.has_errors()
+    assert entry.quantity_used == Decimal("6")
+    assert entry.available_lots[0].consumed_qty == Decimal("3")
+    assert entry.available_lots[1].consumed_qty == Decimal("3")
diff --git a/backend/tests/unit/invoices/test_currency_conversion_imports.py b/backend/tests/unit/invoices/test_currency_conversion_imports.py
new file mode 100644
index 00000000..aac88f8e
--- /dev/null
+++ b/backend/tests/unit/invoices/test_currency_conversion_imports.py
@@ -0,0 +1,72 @@
+from decimal import Decimal
+from types import SimpleNamespace
+
+from api.v1.modules.a76.invoices.models import Currency
+from api.v1.modules.a76.invoices.imports.process.sub_process.assing_values_def_mex import (
+    assign_values_iva_lines,
+)
+
+
+def _mk_line(qty: str, capture: str):
+    return SimpleNamespace(
+        quantity=SimpleNamespace(quantity=Decimal(qty)),
+        financial=SimpleNamespace(
+            unit_cost_capture=Decimal(capture),
+            unit_cost_usd=None,
+            unit_cost_mxn=None,
+            unit_cost_mc=None,
+            sub_import_value_usd=None,
+            sub_import_value_mxn=None,
+            sub_import_value_mc=None,
+            vat_usd=None,
+            vat_mxn=None,
+            vat_mc=None,
+            value_usd=None,
+            value_mxn=None,
+            value_mc=None,
+        ),
+    )
+
+
+def _mk_invoice(currency: Currency):
+    return SimpleNamespace(
+        financials=SimpleNamespace(
+            currency=currency,
+            exchange_rate=Decimal("17.25"),
+            exchange_rate_mm=Decimal("1.10"),
+            iva_factor="16",
+        )
+    )
+
+
+def test_assign_values_iva_lines_currency_me():
+    invoice = _mk_invoice(Currency.FOREIGN)
+    line = _mk_line("10", "2")
+    assign_values_iva_lines(invoice, [line])
+
+    assert line.financial.sub_import_value_usd == Decimal("20")
+    assert line.financial.vat_usd == Decimal("3.2")
+    assert line.financial.value_usd == Decimal("23.2")
+    assert line.financial.unit_cost_mxn == Decimal("34.50")
+
+
+def test_assign_values_iva_lines_currency_mn():
+    invoice = _mk_invoice(Currency.LOCAL)
+    line = _mk_line("5", "100")
+    assign_values_iva_lines(invoice, [line])
+
+    assert line.financial.sub_import_value_mxn == Decimal("500")
+    assert line.financial.vat_mxn == Decimal("80")
+    assert line.financial.value_mxn == Decimal("580")
+    assert line.financial.unit_cost_usd == Decimal("5.797101449275362318840579710")
+
+
+def test_assign_values_iva_lines_currency_mc():
+    invoice = _mk_invoice(Currency.MANUAL)
+    line = _mk_line("4", "3")
+    assign_values_iva_lines(invoice, [line])
+
+    assert line.financial.sub_import_value_mc == Decimal("12")
+    assert line.financial.vat_mc == Decimal("1.92")
+    assert line.financial.value_mc == Decimal("13.92")
+    assert line.financial.unit_cost_usd == Decimal("3.30")