frontend/src/
  app/
    layout.tsx                    → Root layout
    page.tsx                      → Login page
    globals.css                   → Global styles + custom scrollbar classes
    dashboard/
      layout.tsx                  → Dashboard layout with sidebar navigation
      page.tsx                    → Dashboard home
      chats/page.tsx              → Chat management (WhatsApp)
      devices/page.tsx            → WhatsApp device management
      leads/page.tsx              → Leads kanban board
      settings/page.tsx           → Account settings
  components/
    CreateCampaignModal.tsx       → Campaign creation modal
    ImportCSVModal.tsx            → CSV import modal
    NotificationProvider.tsx      → Toast notifications
    TagInput.tsx                  → Tag input component
    WhatsAppTextInput.tsx         → WhatsApp text formatting input
    chat/                         → Chat-related components
  lib/
    api.ts                        → API client + WebSocket factory
    utils.ts                      → Shared utilities

Layer 0 (page):     bg-slate-900
Layer 1 (sidebar):  bg-slate-800/95 backdrop-blur-md
Layer 2 (cards):    bg-slate-800/80 border-slate-700/50
Layer 3 (modals):   bg-slate-800 border-slate-700/50 shadow-2xl
Layer 4 (dropdowns): bg-slate-750 border-slate-600/50 shadow-xl
Overlay:           bg-black/60 backdrop-blur-sm

// EVERY interactive element needs transitions
<button className="... transition-all duration-200 hover:scale-[1.02] active:scale-[0.98]">

// Smooth hover on cards
<div className="... transition-all duration-200 hover:border-slate-600 hover:shadow-lg">

// Fade-in loading states
<div className={`transition-opacity duration-300 ${loading ? 'opacity-50' : 'opacity-100'}`}>

// Skeleton loading — not spinners for content areas
{loading ? (
  <div className="space-y-3">
    {[...Array(5)].map((_, i) => (
      <div key={i} className="h-16 bg-slate-700/50 rounded-lg animate-pulse" />
    ))}
  </div>
) : (
  <ActualContent />
)}

// Use spinners only for actions (saving, submitting)
{saving && <Loader2 className="w-4 h-4 animate-spin" />}

// Never show just "No data" — make it inviting
<div className="flex flex-col items-center justify-center py-16 text-center">
  <div className="w-16 h-16 bg-slate-800 rounded-2xl flex items-center justify-center mb-4">
    <Users className="w-8 h-8 text-slate-500" />
  </div>
  <h3 className="text-lg font-semibold text-slate-300 mb-1">No hay leads todavía</h3>
  <p className="text-sm text-slate-500 mb-6 max-w-sm">
    Los leads aparecerán aquí cuando se sincronicen desde Kommo o se creen manualmente.
  </p>
  <button className="bg-emerald-600 hover:bg-emerald-700 text-white px-4 py-2 rounded-lg text-sm font-medium transition-all duration-200 shadow-lg shadow-emerald-600/20">
    <Plus className="w-4 h-4 mr-2 inline" />
    Crear lead
  </button>
</div>

Page title:      text-2xl font-bold text-white tracking-tight
Section title:   text-lg font-semibold text-slate-100
Card title:      text-base font-medium text-white
Body text:       text-sm text-slate-300
Caption/label:   text-xs font-medium text-slate-400 uppercase tracking-wider
Numbers/stats:   text-3xl font-bold tracking-tight tabular-nums

Page padding:    p-6 (desktop), p-4 (mobile)
Card padding:    p-5 or p-6
Section gaps:    space-y-6
Element gaps:    space-y-3 or gap-3

import { Search, Plus, X, ChevronDown, MoreHorizontal, Settings, Loader2 } from "lucide-react"

// Icons in buttons: w-4 h-4
<button><Plus className="w-4 h-4 mr-2" /> Crear</button>

// Icons standalone: w-5 h-5
<Search className="w-5 h-5 text-slate-400" />

// Icons in empty states: w-8 h-8
<Users className="w-8 h-8 text-slate-500" />

// Tables and lists: ALWAYS handle overflow text
<span className="truncate max-w-[200px]">{name}</span>

// Long content: scroll containers
<div className="overflow-y-auto max-h-[calc(100vh-200px)] scrollbar-thin scrollbar-thumb-slate-700">

// Grid layouts: responsive
<div className="grid grid-cols-1 md:grid-cols-2 lg:grid-cols-3 gap-4">

// Overlay
<div className="fixed inset-0 bg-black/60 backdrop-blur-sm z-50 flex items-center justify-center p-4">
  // Modal
  <div className="bg-slate-800 border border-slate-700/50 rounded-2xl shadow-2xl w-full max-w-lg max-h-[90vh] overflow-y-auto">
    // Header
    <div className="flex items-center justify-between p-6 border-b border-slate-700/50">
      <h2 className="text-lg font-semibold text-white">Título</h2>
      <button className="text-slate-400 hover:text-white transition-colors p-1 rounded-lg hover:bg-slate-700">
        <X className="w-5 h-5" />
      </button>
    </div>
    // Body
    <div className="p-6">...</div>
    // Footer
    <div className="flex justify-end gap-3 p-6 border-t border-slate-700/50">
      <button className="px-4 py-2 text-sm text-slate-300 hover:text-white transition-colors">Cancelar</button>
      <button className="px-4 py-2 text-sm bg-emerald-600 hover:bg-emerald-700 text-white rounded-lg font-medium transition-all shadow-lg shadow-emerald-600/20">Guardar</button>
    </div>
  </div>
</div>

<table className="w-full">
  <thead>
    <tr className="border-b border-slate-700/50">
      <th className="text-left text-xs font-medium text-slate-400 uppercase tracking-wider py-3 px-4">Nombre</th>
    </tr>
  </thead>
  <tbody className="divide-y divide-slate-700/30">
    <tr className="hover:bg-slate-700/30 transition-colors cursor-pointer">
      <td className="py-3 px-4 text-sm text-slate-200">...</td>
    </tr>
  </tbody>
</table>

<label className="block text-xs font-medium text-slate-400 uppercase tracking-wider mb-1.5">
  Nombre
</label>
<input
  type="text"
  className="w-full bg-slate-800/50 border border-slate-600/50 text-white rounded-lg px-3 py-2.5 text-sm placeholder-slate-500 focus:ring-2 focus:ring-emerald-500/40 focus:border-emerald-500 outline-none transition-all"
  placeholder="Ingresa el nombre..."
/>
// Error state
<p className="text-xs text-red-400 mt-1">Este campo es requerido</p>

// Success: emerald accent
<div className="bg-emerald-500/10 border border-emerald-500/20 text-emerald-300 px-4 py-3 rounded-lg text-sm">
  <CheckCircle className="w-4 h-4 inline mr-2" /> Guardado correctamente
</div>

// Error: red accent
<div className="bg-red-500/10 border border-red-500/20 text-red-300 px-4 py-3 rounded-lg text-sm">
  <AlertCircle className="w-4 h-4 inline mr-2" /> Error al guardar
</div>

"use client"

import { useState, useEffect, useCallback } from "react"
import { Search, Plus, Loader2 } from "lucide-react"
import { apiGet, createWebSocket } from "@/lib/api"

interface Lead {
  id: number
  name: string
  phone: string
}

export default function LeadsPage() {
  const [leads, setLeads] = useState<Lead[]>([])
  const [loading, setLoading] = useState(true)
  const [search, setSearch] = useState("")

  const fetchLeads = useCallback(async () => {
    try {
      const data = await apiGet("/api/leads")
      setLeads(data)
    } catch (err) {
      console.error("Error fetching leads:", err)
    } finally {
      setLoading(false)
    }
  }, [])

  useEffect(() => { fetchLeads() }, [fetchLeads])

  // WebSocket for real-time
  useEffect(() => {
    const ws = createWebSocket((msg) => {
      const data = JSON.parse(msg.data)
      if (data.type === "lead_update") fetchLeads()
    })
    return () => ws?.close()
  }, [fetchLeads])

  const filtered = leads.filter(l =>
    l.name.toLowerCase().includes(search.toLowerCase())
  )

  return (
    <div className="p-6 bg-slate-900 min-h-screen">
      {/* Header */}
      <div className="flex items-center justify-between mb-6">
        <div>
          <h1 className="text-2xl font-bold text-white tracking-tight">Leads</h1>
          <p className="text-sm text-slate-400 mt-1">{leads.length} leads en total</p>
        </div>
        <button className="bg-emerald-600 hover:bg-emerald-700 text-white px-4 py-2.5 rounded-lg text-sm font-medium transition-all duration-200 shadow-lg shadow-emerald-600/20 flex items-center gap-2">
          <Plus className="w-4 h-4" /> Nuevo lead
        </button>
      </div>

      {/* Search */}
      <div className="relative mb-4">
        <Search className="absolute left-3 top-1/2 -translate-y-1/2 w-4 h-4 text-slate-500" />
        <input
          value={search}
          onChange={e => setSearch(e.target.value)}
          className="w-full bg-slate-800/50 border border-slate-700/50 text-white rounded-lg pl-10 pr-4 py-2.5 text-sm placeholder-slate-500 focus:ring-2 focus:ring-emerald-500/40 focus:border-emerald-500 outline-none transition-all"
          placeholder="Buscar leads..."
        />
      </div>

      {/* Content with loading/empty states */}
      {loading ? (
        <div className="space-y-3">
          {[...Array(5)].map((_, i) => (
            <div key={i} className="h-16 bg-slate-800/50 rounded-lg animate-pulse" />
          ))}
        </div>
      ) : filtered.length === 0 ? (
        <EmptyState />
      ) : (
        <LeadsList leads={filtered} />
      )}
    </div>
  )
}

import { apiGet, apiPost, apiPut, apiDelete, createWebSocket } from "@/lib/api"