# Frontend Development

> Create beautiful, polished, and highly usable Next.js/React/TypeScript interfaces for Clarin CRM. Use when creating or modifying dashboard pages, components, API calls, WebSocket listeners, or UI styling. Enforces visual excellence, micro-interactions, accessibility, and the emerald/slate design system.

- Skill: `diegosouzapw/frontend-development-4` (Agent Skill, multi-file: 2 files)
- Install (CLI): `npx skillmds@latest add diegosouzapw/frontend-development-4`
- Raw SKILL.md: https://api.skillmd.com/api/skills/diegosouzapw/frontend-development-4/raw
- Safety review: pending (external: skill-scanner PASS, skillspector PASS)
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Design & Media
- Author: diegosouzapw (https://skillmd.com/u/diegosouzapw)
- Updated: 2026-09-09
- Page: https://skillmd.com/skills/diegosouzapw/frontend-development-4

---


# Frontend Development — Clarin CRM

## Philosophy: Beauty + Usability

Every UI must feel **premium, polished, and alive**. Think Notion, Linear, Vercel Dashboard — dark themes done right. Never ship something that looks "functional but ugly." Every pixel matters.

## Stack
- Next.js 14.2 (App Router), React 18.3, TypeScript 5.4 (strict mode)
- Tailwind CSS 3.4, lucide-react icons, date-fns, zustand (global state), xlsx
- Build via `docker compose build frontend`

## Project Layout

```
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
```

---

## Design System — emerald/slate (MANDATORY)

**NEVER use green, gray, or any other color palette. Only emerald and slate.**

### Core Palette

| Element | Classes |
|---------|---------|
| Primary buttons | `bg-emerald-600 hover:bg-emerald-700 text-white font-medium shadow-lg shadow-emerald-600/20` |
| Secondary buttons | `bg-slate-700 hover:bg-slate-600 text-slate-200 border border-slate-600` |
| Danger buttons | `bg-red-600/90 hover:bg-red-600 text-white` |
| Page background | `bg-slate-900` |
| Cards/panels | `bg-slate-800/80 backdrop-blur-sm border border-slate-700/50 rounded-xl shadow-xl` |
| Elevated cards | `bg-slate-800 border border-slate-700/50 rounded-xl shadow-2xl shadow-black/20` |
| Text primary | `text-white` or `text-slate-100` |
| Text secondary | `text-slate-400` |
| Text muted | `text-slate-500` |
| Inputs | `bg-slate-800/50 border border-slate-600/50 text-white placeholder-slate-500 rounded-lg` |
| Input focus | `focus:ring-2 focus:ring-emerald-500/40 focus:border-emerald-500 outline-none` |
| Hover rows | `hover:bg-slate-700/40 transition-colors` |
| Dividers | `border-slate-700/50` |
| Badges/pills | `bg-emerald-500/10 text-emerald-400 text-xs font-medium px-2.5 py-0.5 rounded-full` |
| Status green | `bg-emerald-500/10 text-emerald-400` |
| Status yellow | `bg-amber-500/10 text-amber-400` |
| Status red | `bg-red-500/10 text-red-400` |

### Visual Depth & Layers

```
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
```

---

## Visual Excellence Rules

### 1. Transitions & Micro-interactions — ALWAYS
```tsx
// 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'}`}>
```

### 2. Loading States — NEVER leave blank screens
```tsx
// 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" />}
```

### 3. Empty States — ALWAYS beautiful and helpful
```tsx
// 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>
```

### 4. Spacing & Typography Hierarchy
```
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
```

### 5. Icons — ALWAYS use lucide-react
```tsx
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" />
```

### 6. Responsive & Overflow
```tsx
// 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">
```

### 7. Modals — Polished with backdrop
```tsx
// 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>
```

### 8. Tables — Clean and scannable
```tsx
<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>
```

### 9. Form Inputs — Consistent and accessible
```tsx
<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>
```

### 10. Notifications & Toasts
```tsx
// 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>
```

---

## Usability Rules (UX)

1. **Click targets**: Minimum 40px height for buttons and interactive elements. 44px on mobile.
2. **Keyboard navigation**: All interactive elements must be focusable. Use `tabIndex`, `onKeyDown` for custom widgets.
3. **Feedback immediato**: Every click must produce visible feedback within 100ms (hover state, loading indicator, optimistic update).
4. **No dead-ends**: Every empty state has a CTA. Every error has a retry option.
5. **Confirmación destructiva**: Delete actions always show a confirmation dialog with clear consequences.
6. **Search/filter first**: Lists with >10 items must have search. Lists with categories must have filters.
7. **Truncation**: Long text truncates with `...` and shows full text on hover (title attribute or tooltip).
8. **Consistent actions**: Primary action always on the right. Cancel always on the left.
9. **Mobile-ready**: All layouts must work on tablet/mobile. Use responsive grid and flex.
10. **Disable during save**: Buttons disable and show spinner while async operations are in progress.

---

## Code Conventions

### Component Structure
```tsx
"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>
  )
}
```

### API & WebSocket — use @/lib/api.ts
```tsx
import { apiGet, apiPost, apiPut, apiDelete, createWebSocket } from "@/lib/api"
```

### Rules
- All components are functional with hooks. No class components.
- Use `@/` alias for all imports from `src/`.
- Define TypeScript interfaces for all props and API responses.
- Tailwind only — no CSS modules, no styled-components.
- API routes proxy through Next.js rewrites: `/api/:path*` → backend:8080.
- `useCallback` for functions passed as deps or to children.
- Skeleton loaders for content areas. Spinners for actions only.
- Every list has search if >10 items.

## Adding a New Dashboard Page

1. Create `src/app/dashboard/new-page/page.tsx`
2. Add navigation link in `src/app/dashboard/layout.tsx` sidebar
3. Follow the component structure above with `"use client"`, emerald/slate palette
4. Include: page header, search bar, loading skeletons, empty state, content
5. Build and verify: `docker compose build frontend && docker compose up -d`