UX mejorada

backend/server-prod.js

@@ -20,6 +20,29 @@ const client = new MongoClient(uri);
 
 let db;
 let amigosCollection;
+const clients = new Set();
+
+function sseHeaders(res) {
+  res.setHeader('Content-Type', 'text/event-stream');
+  res.setHeader('Cache-Control', 'no-cache');
+  res.setHeader('Connection', 'keep-alive');
+  res.flushHeaders && res.flushHeaders();
+}
+
+function sendEvent(res, event, data) {
+  if (event) res.write(`event: ${event}\n`);
+  res.write(`data: ${JSON.stringify(data)}\n\n`);
+}
+
+function broadcast(event, data) {
+  for (const res of clients) {
+    try {
+      sendEvent(res, event, data);
+    } catch (_) {
+      // ignore write errors; client will be removed on close
+    }
+  }
+}
 
 // Connect to MongoDB
 async function connectDB() {
@@ -67,11 +90,37 @@ app.post('/api/amigos', async (req, res) => {
       id: result.insertedId,
       nombre 
     });
+
+    // Notify SSE clients about the new friend
+    broadcast('amigoAdded', { id: result.insertedId, nombre });
   } catch (error) {
     res.status(500).json({ error: error.message });
   }
 });
 
+// Server-Sent Events for realtime updates
+app.get('/api/events', async (req, res) => {
+  sseHeaders(res);
+  clients.add(res);
+
+  // Send initial snapshot
+  try {
+    if (amigosCollection) {
+      const amigos = await amigosCollection.find({}).toArray();
+      sendEvent(res, 'init', { amigos });
+    } else {
+      sendEvent(res, 'init', { amigos: [] });
+    }
+  } catch (_) {
+    sendEvent(res, 'init', { amigos: [] });
+  }
+
+  req.on('close', () => {
+    clients.delete(res);
+    try { res.end(); } catch (_) {}
+  });
+});
+
 // Health check endpoint
 app.get('/health', (req, res) => {
   res.json({ 

backend/server.js

@@ -15,6 +15,29 @@ const client = new MongoClient(uri);
 
 let db;
 let amigosCollection;
+const clients = new Set();
+
+function sseHeaders(res) {
+  res.setHeader('Content-Type', 'text/event-stream');
+  res.setHeader('Cache-Control', 'no-cache');
+  res.setHeader('Connection', 'keep-alive');
+  res.flushHeaders && res.flushHeaders();
+}
+
+function sendEvent(res, event, data) {
+  if (event) res.write(`event: ${event}\n`);
+  res.write(`data: ${JSON.stringify(data)}\n\n`);
+}
+
+function broadcast(event, data) {
+  for (const res of clients) {
+    try {
+      sendEvent(res, event, data);
+    } catch (_) {
+      // client may be closed
+    }
+  }
+}
 
 // Connect to MongoDB
 async function connectDB() {
@@ -62,11 +85,32 @@ app.post('/api/amigos', async (req, res) => {
       id: result.insertedId,
       nombre 
     });
+
+    // SSE notify
+    broadcast('amigoAdded', { id: result.insertedId, nombre });
   } catch (error) {
     res.status(500).json({ error: error.message });
   }
 });
 
+// SSE endpoint
+app.get('/api/events', async (req, res) => {
+  sseHeaders(res);
+  clients.add(res);
+
+  try {
+    const amigos = await amigosCollection.find({}).toArray();
+    sendEvent(res, 'init', { amigos });
+  } catch (_) {
+    sendEvent(res, 'init', { amigos: [] });
+  }
+
+  req.on('close', () => {
+    clients.delete(res);
+    try { res.end(); } catch (_) {}
+  });
+});
+
 // Start server
 connectDB().then(() => {
   app.listen(PORT, () => {

src/App.jsx

@@ -1,4 +1,4 @@
-import { useState, useEffect } from 'react'
+import { useEffect, useRef, useState } from 'react'
 import './App.css'
 
 // Configure API base URL via Vite env, default to same-origin
@@ -9,11 +9,47 @@ function App() {
   const [amigos, setAmigos] = useState([])
   const [loading, setLoading] = useState(false)
   const [message, setMessage] = useState('')
+  const inputRef = useRef(null)
 
   useEffect(() => {
     fetchAmigos()
   }, [])
 
+  useEffect(() => {
+    // Subscribe to SSE for realtime updates
+    const url = `${API_BASE}/api/events`
+    const es = new EventSource(url)
+
+    const onInit = (e) => {
+      try {
+        const payload = JSON.parse(e.data)
+        if (Array.isArray(payload.amigos)) setAmigos(payload.amigos)
+      } catch (_) {}
+    }
+
+    const onAdded = (e) => {
+      try {
+        const payload = JSON.parse(e.data)
+        setAmigos((prev) => [
+          ...prev,
+          { _id: payload.id || payload._id, nombre: payload.nombre }
+        ])
+      } catch (_) {}
+    }
+
+    es.addEventListener('init', onInit)
+    es.addEventListener('amigoAdded', onAdded)
+    es.onerror = () => {
+      // Let browser auto-reconnect; optionally show a message
+    }
+
+    return () => {
+      es.removeEventListener('init', onInit)
+      es.removeEventListener('amigoAdded', onAdded)
+      es.close()
+    }
+  }, [])
+
   const fetchAmigos = async () => {
     try {
       const response = await fetch(`${API_BASE}/api/amigos`)
@@ -49,7 +85,7 @@ function App() {
       if (response.ok) {
         setMessage(`¡${data.nombre} agregado exitosamente!`)
         setNombre('')
-        fetchAmigos()
+        // No refetch here; SSE will push the update
       } else {
         setMessage(data.error || 'Error al agregar amigo')
       }
@@ -58,6 +94,8 @@ function App() {
       console.error('Error:', error)
     } finally {
       setLoading(false)
+      // Keep focus on the input for rapid entry
+      inputRef.current?.focus()
     }
   }
 
@@ -74,6 +112,8 @@ function App() {
             value={nombre}
             onChange={(e) => setNombre(e.target.value)}
             placeholder="Ingresa el nombre"
+            ref={inputRef}
+            autoFocus
             disabled={loading}
           />
         </div>