diff --git a/frontend/src/components/editor/Step2FuzzyModeling.jsx b/frontend/src/components/editor/Step2FuzzyModeling.jsx
index 34ba6f8..dcc3d18 100644
--- a/frontend/src/components/editor/Step2FuzzyModeling.jsx
+++ b/frontend/src/components/editor/Step2FuzzyModeling.jsx
@@ -11,7 +11,8 @@ export default function Step2FuzzyModeling({
   handleFinalSubmit, 
   onBack, 
   subscales, 
-  onOpenSubscale
+  onOpenSubscale,
+  submitError
 }) {
   const scaleKeys = Object.keys(baseScale);
   
@@ -51,6 +52,20 @@ export default function Step2FuzzyModeling({
             colors={CHART_COLORS} 
         />
 
+        {submitError && (
+          <div className="bg-red-50 mb-6 border-red-500 p-4 rounded-xl shadow-sm animate-fade-in mx-2">
+            <div className="flex items-center">
+              <span className="text-red-500 text-xl mr-3">⚠️</span>
+              <div>
+                <h3 className="text-sm font-bold text-red-800">Error de validación al generar la gráfica</h3>
+                <div className="mt-1 text-sm text-red-700 whitespace-pre-line font-medium">
+                  {submitError}
+                </div>
+              </div>
+            </div>
+          </div>
+        )}
+
         <Controls 
             selectedTerm={selectedTerm} 
             currentMf={mfDefinitions[selectedTerm]} 
diff --git a/frontend/src/components/editor/Step3FinalGraph.jsx b/frontend/src/components/editor/Step3FinalGraph.jsx
index 45c9d27..99884dd 100644
--- a/frontend/src/components/editor/Step3FinalGraph.jsx
+++ b/frontend/src/components/editor/Step3FinalGraph.jsx
@@ -1,78 +1,84 @@
-import { useMemo } from 'react';
-import { LineChart, Line, XAxis, YAxis, CartesianGrid, Tooltip, ResponsiveContainer } from 'recharts';
+import React, { useMemo } from 'react';
+import { ComposedChart, Area, Line, XAxis, YAxis, CartesianGrid, Tooltip, ResponsiveContainer } from 'recharts';
 import { CHART_COLORS } from '../../config';
 
-const Step3FinalGraph = ({ data }) => {
+const Step3FinalGraph = ({ data, criterionName }) => {
   const sortedResults = useMemo(() => {
-    if (!data || !data.results) return [];
+    const rawItems = data?.levels || data?.results || [];
 
-    const withPermanentColors = data.results.map((item, index) => ({
-      ...item,
-      color: CHART_COLORS[index % CHART_COLORS.length]
-    }));
+    const processed = rawItems.map((item, index) => {
+      const isType2 = !!item.lower && !!item.upper;
+      const color = CHART_COLORS[index % CHART_COLORS.length] || '#333';
 
-    return withPermanentColors.sort((a, b) => {
-      const coreA = Array.isArray(a.core) ? Number(a.core[0]) : 0;
-      const coreB = Array.isArray(b.core) ? Number(b.core[0]) : 0;
-      return coreA - coreB;
+      let lineData = [];
+      let coreVal = 0;
+      let termName = item.term || (item.lower && item.lower.term) || `Termino ${index}`;
+
+      if (isType2) {
+        const lowerNodes = [...(item.lower.left_nodes || []), ...(item.lower.right_nodes || [])];
+        const upperNodes = [...(item.upper.left_nodes || []), ...(item.upper.right_nodes || [])];
+
+        lineData = lowerNodes.map((lNode, i) => {
+          const uNode = upperNodes[i];
+          const lowerY = Number(lNode[1]);
+          const upperY = Number(uNode ? uNode[1] : lNode[1]);
+          return { x: Number(lNode[0]), lowerY, upperY, range: [lowerY, upperY] };
+        });
+        coreVal = Array.isArray(item.lower.core) ? Number(item.lower.core[0]) : 0;
+      } else {
+        const nodes = [...(item.left_nodes || []), ...(item.right_nodes || [])];
+        lineData = nodes.map(node => ({ x: Number(node[0]), y: Number(node[1]) }));
+        coreVal = Array.isArray(item.core) ? Number(item.core[0]) : 0;
+      }
+
+      return { ...item, term: termName, isType2, lineData, color, coreVal };
     });
+
+    return processed.sort((a, b) => a.coreVal - b.coreVal);
   }, [data]);
 
-  if (!data || !data.results) {
+  if (!data || (!data.levels && !data.results)) {
     return <p className="text-center mt-10 text-slate-500">Cargando gráfico final...</p>;
   }
 
   return (
     <div className="w-full h-[550px] mt-2 bg-white p-6 rounded-2xl shadow-sm border border-slate-200 flex flex-col">
-      <h3 className="text-2xl font-bold mb-4 text-center text-slate-800">Espectro Difuso Final</h3>
+
+      {/* Título */}
+      <h3 className="text-2xl font-bold mb-4 text-center text-slate-800">
+        {criterionName ? `Criterio: ${criterionName}` : 'Espectro Difuso Final'}
+      </h3>
       
       {/* Gráfica */}
       <div className="flex-1 w-full min-h-[400px]">
         <ResponsiveContainer width="100%" height="100%">
-          <LineChart margin={{ top: 10, right: 30, left: 10, bottom: 10 }}>
+          <ComposedChart margin={{ top: 10, right: 30, left: 10, bottom: 10 }}>
             <CartesianGrid strokeDasharray="3 3" opacity={0.5} vertical={false} />
             <XAxis 
-              dataKey="x" 
-              type="number" 
-              domain={[0, 1]}
-              tickCount={11}
-              tick={{ fill: '#475569', fontWeight: 600, fontSize: 14 }}
-              allowDuplicatedCategory={false}
-            />
-            <YAxis 
-              domain={[0, 1]} 
-              tickCount={6} 
-              tick={{ fill: '#475569', fontSize: 14 }}
+              dataKey="x" type="number" domain={[0, 1]} tickCount={11}
+              tick={{ fill: '#475569', fontWeight: 600, fontSize: 14 }} allowDuplicatedCategory={false}
             />
+            <YAxis domain={[0, 1]} tickCount={6} tick={{ fill: '#475569', fontSize: 14 }} />
             <Tooltip 
-              formatter={(value, name) => [Number(value).toFixed(3), name]}
+              formatter={(value, name) => Array.isArray(value) ? [`[${Number(value[0]).toFixed(3)}, ${Number(value[1]).toFixed(3)}]`, name] : [Number(value).toFixed(3), name]}
               labelFormatter={(label) => `X: ${Number(label).toFixed(3)}`}
               contentStyle={{ borderRadius: '12px', border: 'none', boxShadow: '0 10px 15px -3px rgb(0 0 0 / 0.1)' }}
             />
 
             {sortedResults.map((item) => {
-              const lineData = [...(item.left_nodes || []), ...(item.right_nodes || [])].map(node => ({
-                x: Number(node[0]),
-                y: Number(node[1])
-              }));
-
-              return (
-                <Line
-                  key={item.term}
-                  data={lineData}
-                  type="linear"
-                  dataKey="y"
-                  name={item.term.toUpperCase()}
-                  stroke={item.color} 
-                  strokeWidth={4}
-                  dot={{ r: 5, strokeWidth: 2, fill: '#fff' }}
-                  activeDot={{ r: 8 }}
-                  isAnimationActive={true}
-                  animationDuration={1500}
-                />
-              );
+              if (item.isType2) {
+                return (
+                  <React.Fragment key={item.term}>
+                    <Area data={item.lineData} type="linear" dataKey="range" name={`${item.term.toUpperCase()} (Incertidumbre)`} fill={item.color} fillOpacity={0.25} stroke="none" isAnimationActive={true} animationDuration={1500} />
+                    <Line data={item.lineData} type="linear" dataKey="upperY" name={`${item.term.toUpperCase()} (Máx)`} stroke={item.color} strokeWidth={2} strokeDasharray="5 5" dot={false} activeDot={{ r: 6 }} isAnimationActive={true} animationDuration={1500} />
+                    <Line data={item.lineData} type="linear" dataKey="lowerY" name={`${item.term.toUpperCase()} (Mín)`} stroke={item.color} strokeWidth={3} dot={{ r: 4, strokeWidth: 2, fill: '#fff' }} activeDot={{ r: 8 }} isAnimationActive={true} animationDuration={1500} />
+                  </React.Fragment>
+                );
+              } else {
+                return <Line key={item.term} data={item.lineData} type="linear" dataKey="y" name={item.term.toUpperCase()} stroke={item.color} strokeWidth={4} dot={{ r: 5, strokeWidth: 2, fill: '#fff' }} activeDot={{ r: 8 }} isAnimationActive={true} animationDuration={1500} />;
+              }
             })}
-          </LineChart>
+          </ComposedChart>
         </ResponsiveContainer>
       </div>
 
@@ -80,22 +86,11 @@ const Step3FinalGraph = ({ data }) => {
       <div className="flex flex-wrap justify-center gap-x-8 gap-y-3 mt-6 pb-2">
         {sortedResults.map((item) => (
             <div key={`legend-${item.term}`} className="flex items-center gap-2">
-                
-                <span 
-                    className="w-3.5 h-3.5 rounded-full shadow-sm"
-                    style={{ backgroundColor: item.color }} 
-                />
-
-                <span 
-                    className="text-sm font-medium uppercase tracking-wide" 
-                    style={{ color: item.color }}
-                    >
-                    {item.term}
-                </span>
+                <span className="w-3.5 h-3.5 rounded-full shadow-sm" style={{ backgroundColor: item.color }} />
+                <span className="text-sm font-medium uppercase tracking-wide" style={{ color: item.color }}>{item.term}</span>
             </div>
         ))}
       </div>
-
     </div>
   );
 };
diff --git a/frontend/src/components/membershipFunction/Controls.jsx b/frontend/src/components/membershipFunction/Controls.jsx
index f879c4a..565cc84 100644
--- a/frontend/src/components/membershipFunction/Controls.jsx
+++ b/frontend/src/components/membershipFunction/Controls.jsx
@@ -22,7 +22,6 @@ export default function Controls({
       </h3>
       
       <div className="grid grid-cols-1 md:grid-cols-2 gap-8">
-        {/* Lado izquierdo (Pendiente ascendente) */}
         <div className="space-y-4 bg-slate-50 p-4 rounded-xl border border-slate-100">
           <div>
             <label className="flex justify-between text-xs font-bold text-slate-600 mb-1">
@@ -37,7 +36,6 @@ export default function Controls({
             <input type="range" min={absoluteMin} max={absoluteMax} step="0.001" value={currentMf.coreStart} onChange={(e) => updateCurrentMf('coreStart', e.target.value)} className="w-full cursor-pointer h-1.5" style={{ accentColor: selectedColor }} />
           </div>
           
-          {/* Botón subescala izquierda */}
           <div className="pt-2 border-t border-slate-200 flex justify-end">
             <button 
               onClick={() => onOpenSubscale(selectedTerm, 'left', leftSubscale)}
@@ -48,22 +46,20 @@ export default function Controls({
           </div>
         </div>
 
-        {/* Lado derecho (Pendiente descendente) */}
         <div className="space-y-4 bg-slate-50 p-4 rounded-xl border border-slate-100">
-          <div>
-            <label className="flex justify-between text-xs font-bold text-slate-600 mb-1">
-              <span>Fin del Núcleo (Punto superior)</span><span style={{ color: selectedColor }}>{currentMf.coreEnd.toFixed(3)}</span>
-            </label>
-            <input type="range" min={absoluteMin} max={absoluteMax} step="0.001" value={currentMf.coreEnd} onChange={(e) => updateCurrentMf('coreEnd', e.target.value)} className="w-full cursor-pointer h-1.5" style={{ accentColor: selectedColor }} />
-          </div>
           <div>
             <label className="flex justify-between text-xs font-bold text-slate-600 mb-1">
               <span>Fin del Soporte (Punto inferior)</span><span style={{ color: selectedColor }}>{currentMf.supportEnd.toFixed(3)}</span>
             </label>
             <input type="range" min={absoluteMin} max={absoluteMax} step="0.001" value={currentMf.supportEnd} onChange={(e) => updateCurrentMf('supportEnd', e.target.value)} className="w-full cursor-pointer h-1.5" style={{ accentColor: selectedColor, opacity: 0.7 }} />
           </div>
+          <div>
+            <label className="flex justify-between text-xs font-bold text-slate-600 mb-1">
+              <span>Fin del Núcleo (Punto superior)</span><span style={{ color: selectedColor }}>{currentMf.coreEnd.toFixed(3)}</span>
+            </label>
+            <input type="range" min={absoluteMin} max={absoluteMax} step="0.001" value={currentMf.coreEnd} onChange={(e) => updateCurrentMf('coreEnd', e.target.value)} className="w-full cursor-pointer h-1.5" style={{ accentColor: selectedColor }} />
+          </div>
 
-          {/* Botón subescala derecha */}
           <div className="pt-2 border-t border-slate-200 flex justify-end">
             <button 
               onClick={() => onOpenSubscale(selectedTerm, 'right', rightSubscale)}
diff --git a/frontend/src/pages/DocEditor.jsx b/frontend/src/pages/DocEditor.jsx
index 4cdc508..1ebf5f9 100644
--- a/frontend/src/pages/DocEditor.jsx
+++ b/frontend/src/pages/DocEditor.jsx
@@ -24,6 +24,7 @@ export default function DocEditor() {
 
   // ESTADO: FASE 3
   const [finalResult, setFinalResult] = useState(null);
+  const [submitError, setSubmitError] = useState(null);
 
   // MANEJADORES: FASE 1
   const handleCriterionChange = (val) => { setCriterionName(val); if (errors.criterion) setErrors({ ...errors, criterion: false }); };
@@ -119,6 +120,7 @@ export default function DocEditor() {
 
   // Petición para el endpoint "build"
   const handleFinalSubmit = async () => {
+    setSubmitError(null);
     const scaleKeys = Object.keys(baseScale);
     
     const payload = {
@@ -157,14 +159,35 @@ export default function DocEditor() {
     setIsLoading(true);
     try {
       const result = await buildFuzzyGraph(payload);
-      console.log("RESPUESTA DEL BACKEND:", result);
-      
       setFinalResult(result);
       setStep(3);
-
     } catch (error) {
-      console.error(error);
-      alert("Error del servidor: \n" + JSON.stringify(error, null, 2));
+      console.error("Error capturado:", error);
+      let friendlyMessage = "Ocurrió un error de validación.";
+      
+      if (Array.isArray(error)) {
+        friendlyMessage = error.map(err => {
+          let msg = err.msg.replace("Value error, ", ""); 
+          
+          // Traducción de mensajes del backend
+          msg = msg.replace("a < b", "el 'Inicio del Soporte' no puede ser mayor que el 'Inicio del Núcleo'");
+          msg = msg.replace("b <= c", "el 'Inicio del Núcleo' no puede ser mayor que el 'Fin del Núcleo'");
+          msg = msg.replace("c < d", "el 'Fin del Núcleo' no puede ser mayor que el 'Fin del Soporte'");
+          msg = msg.replace("El soporte debe cumplir", "Revisa los valores:");
+          msg = msg.replace("El núcleo debe cumplir", "Revisa los valores:");
+
+          if (err.loc && err.loc.includes("levels")) {
+            const levelIndex = err.loc[err.loc.indexOf("levels") + 1];
+            const termName = scaleKeys[levelIndex] || `Nivel ${Number(levelIndex) + 1}`;
+            return `• En la etiqueta "${termName}": ${msg}`;
+          }
+          return `• ${msg}`;
+        }).join("\n");
+      } else if (typeof error === 'string') {
+        friendlyMessage = error;
+      }
+      
+      setSubmitError(friendlyMessage);
     } finally {
       setIsLoading(false);
     }
@@ -191,12 +214,13 @@ export default function DocEditor() {
           onBack={() => setStep(1)}
           subscales={subscales}
           onOpenSubscale={handleOpenSubscale}
+          submitError={submitError}
         />
       )}
 
       {step === 3 && finalResult && (
         <div className="flex flex-col gap-6 w-full">
-          <Step3FinalGraph data={finalResult} />
+          <Step3FinalGraph data={finalResult} criterionName={criterionName} />
 
           <button 
             onClick={() => console.log("Lógica para guardar")}
diff --git a/frontend/src/services/docService.js b/frontend/src/services/docService.js
index 53c3cc8..16ea154 100644
--- a/frontend/src/services/docService.js
+++ b/frontend/src/services/docService.js
@@ -12,12 +12,10 @@ export const calculateValueFunction = async (payload) => {
 
 export const buildFuzzyGraph = async (payload) => {
   try {
-    const response = await api.post('/criteria/doc-mf/build', payload);
+    const response = await api.post('/criteria/doc-it2mf/build', payload);
     return response.data;
   } catch (error) {
     console.error('Error building fuzzy graph:', error);
     throw error.response?.data?.detail || error.message;
   }
-
-
 };
\ No newline at end of file