diff --git a/backend/requirements.txt b/backend/requirements.txt
index 97c274b..66a9ed9 100644
--- a/backend/requirements.txt
+++ b/backend/requirements.txt
@@ -19,3 +19,4 @@ Babel==2.14.0
 gunicorn>=21.2.0
 PyJWT>=2.8.0
 pydantic>=2.0.0
+cryptography>=42.0.0
diff --git a/backend/tests/test_sprint4_optimizer_and_concurrency.py b/backend/tests/test_sprint4_optimizer_and_concurrency.py
index c1ca335..545257c 100644
--- a/backend/tests/test_sprint4_optimizer_and_concurrency.py
+++ b/backend/tests/test_sprint4_optimizer_and_concurrency.py
@@ -13,6 +13,7 @@ from app.models.genetic_algorithm import (
     Gene
 )
 from app.services.optimizer_service import OptimizerService, OptimizerJobStatus
+from app.services.jwt_service import JWTService
 from config.config import Config
 
 
diff --git a/install.sh b/install.sh
index 79e46a2..e0bfe07 100755
--- a/install.sh
+++ b/install.sh
@@ -117,7 +117,7 @@ export DEBIAN_FRONTEND=noninteractive
 apt-get update -qq
 apt-get install -y -qq \
     sudo curl wget git ca-certificates gnupg lsb-release \
-    build-essential libpq-dev \
+    build-essential libpq-dev libffi-dev libssl-dev pkg-config \
     locales \
     > /dev/null 2>&1
 ok "Paquetes base instalados"
@@ -375,14 +375,18 @@ python3 -m venv "$VENV_DIR" > /dev/null 2>&1
 "${VENV_DIR}/bin/pip" install --upgrade pip setuptools wheel --quiet
 
 info "Instalando dependencias desde backend/requirements.txt..."
-if "${VENV_DIR}/bin/pip" install -r "${BACKEND_DIR}/requirements.txt" --quiet 2>/dev/null; then
-    ok "Dependencias de Python instaladas correctamente"
-else
-    warn "Reintentando instalación con --no-build-isolation..."
-    "${VENV_DIR}/bin/pip" install -r "${BACKEND_DIR}/requirements.txt" --no-build-isolation --quiet
-    ok "Dependencias de Python instaladas"
+if ! "${VENV_DIR}/bin/pip" install -r "${BACKEND_DIR}/requirements.txt" --quiet; then
+    warn "Reintentando instalación con aislamiento deshabilitado..."
+    "${VENV_DIR}/bin/pip" install -r "${BACKEND_DIR}/requirements.txt" --no-build-isolation || err "Falló la instalación de dependencias de Python."
 fi
 
+# Verificación explícita de módulos críticos requeridos por modelos y esquemas
+if ! "${VENV_DIR}/bin/python" -c "import flask, sqlalchemy, cryptography, pydantic; print('Módulos críticos OK')" >/dev/null 2>&1; then
+    warn "Asegurando librerías críticas en el venv (cryptography, pydantic)..."
+    "${VENV_DIR}/bin/pip" install "cryptography>=42.0.0" "pydantic>=2.0.0" --quiet
+fi
+ok "Dependencias de Python instaladas correctamente"
+
 # ─── 9. Ejecución de Despliegue de Datos (Restaurar o Sincronizar) ──────────────
 hdr "9. Aplicando esquema y datos en la base de datos"
 
@@ -420,7 +424,7 @@ done
 # Sincronización idempotente con init_db.py (crea tablas o columnas faltantes sin borrar datos)
 info "Sincronizando modelos y esquemas institucionales con init_db.py..."
 LANG=en_US.UTF-8 LC_ALL=en_US.UTF-8 PYTHONUTF8=1 PYTHONIOENCODING=utf-8 \
-FLASK_APP=wsgi.py "${VENV_DIR}/bin/python" -X utf8 init_db.py
+PYTHONPATH="${BACKEND_DIR}" FLASK_APP=wsgi.py "${VENV_DIR}/bin/python" -X utf8 init_db.py
 ok "Esquema, usuarios y roles RBAC sincronizados con éxito"
 
 cd "$ROOT_DIR"
@@ -482,6 +486,7 @@ Environment="LANG=en_US.UTF-8"
 Environment="LC_ALL=en_US.UTF-8"
 Environment="PYTHONUTF8=1"
 Environment="PYTHONIOENCODING=utf-8"
+Environment="PYTHONPATH=${BACKEND_DIR}"
 Environment="FLASK_ENV=production"
 Environment="HOME=${BACKEND_DIR}"
 ExecStart=${GUNICORN_BIN} \