api-integration

What this skill does

# API Integration (Apidog + MCP)

Integrate OpenAPI specifications with your frontend using Apidog MCP for single source of truth.

## Goal

The AI agent always uses the latest API specification to generate types and implement features correctly.

## Architecture

```
Apidog (or Backend)
  → OpenAPI 3.0/3.1 Spec
    → MCP Server (apidog-mcp-server)
      → AI Agent reads spec
        → Generate TypeScript types
          → TanStack Query hooks
            → React Components
```

## Process

### 1. Expose OpenAPI from Apidog

**Option A: Remote URL**
- Export OpenAPI spec from Apidog
- Host at a URL (e.g., `https://api.example.com/openapi.json`)

**Option B: Local File**
- Export OpenAPI spec to file
- Place in project (e.g., `./api-spec/openapi.json`)

### 2. Wire MCP Server

```json
// .claude/mcp.json or settings
{
  "mcpServers": {
    "API specification": {
      "command": "npx",
      "args": [
        "-y",
        "apidog-mcp-server@latest",
        "--oas=https://api.example.com/openapi.json"
      ]
    }
  }
}
```

**With Local File:**
```json
{
  "mcpServers": {
    "API specification": {
      "command": "npx",
      "args": [
        "-y",
        "apidog-mcp-server@latest",
        "--oas=./api-spec/openapi.json"
      ]
    }
  }
}
```

**Multiple APIs:**
```json
{
  "mcpServers": {
    "Main API": {
      "command": "npx",
      "args": ["-y", "apidog-mcp-server@latest", "--oas=https://api.main.com/openapi.json"]
    },
    "Auth API": {
      "command": "npx",
      "args": ["-y", "apidog-mcp-server@latest", "--oas=https://api.auth.com/openapi.json"]
    }
  }
}
```

### 3. Generate Types & Client

Create `/src/api` directory for all API-related code:

```
/src/api/
  ├── types.ts          # Generated from OpenAPI
  ├── client.ts         # HTTP client (axios/fetch)
  ├── queries/          # TanStack Query hooks
  │   ├── users.ts
  │   ├── posts.ts
  │   └── ...
  └── mutations/        # TanStack Mutation hooks
      ├── users.ts
      ├── posts.ts
      └── ...
```

**Option A: Hand-Written Types (Lightweight)**
```typescript
// src/api/types.ts
import { z } from 'zod'

// Define schemas from OpenAPI
export const UserSchema = z.object({
  id: z.string(),
  name: z.string(),
  email: z.string().email(),
  createdAt: z.string().datetime(),
})

export type User = z.infer<typeof UserSchema>

export const CreateUserSchema = UserSchema.omit({ id: true, createdAt: true })
export type CreateUserDTO = z.infer<typeof CreateUserSchema>
```

**Option B: Code Generation (Recommended for large APIs)**
```bash
# Using openapi-typescript
pnpm add -D openapi-typescript
npx openapi-typescript https://api.example.com/openapi.json -o src/api/types.ts

# Using orval
pnpm add -D orval
npx orval --input https://api.example.com/openapi.json --output src/api
```

### 4. Create HTTP Client

```typescript
// src/api/client.ts
import axios from 'axios'
import createAuthRefreshInterceptor from 'axios-auth-refresh'

export const apiClient = axios.create({
  baseURL: import.meta.env.VITE_API_URL,
  headers: {
    'Content-Type': 'application/json',
  },
})

// Request interceptor - add auth token
apiClient.interceptors.request.use((config) => {
  const token = localStorage.getItem('accessToken')
  if (token) {
    config.headers.Authorization = `Bearer ${token}`
  }
  return config
})

// Response interceptor - handle token refresh
const refreshAuth = async (failedRequest: any) => {
  try {
    const refreshToken = localStorage.getItem('refreshToken')
    const response = await axios.post('/auth/refresh', { refreshToken })

    const { accessToken } = response.data
    localStorage.setItem('accessToken', accessToken)

    failedRequest.response.config.headers.Authorization = `Bearer ${accessToken}`
    return Promise.resolve()
  } catch (error) {
    localStorage.removeItem('accessToken')
    localStorage.removeItem('refreshToken')
    window.location.href = '/login'
    return Promise.reject(error)
  }
}

createAuthRefreshInterceptor(apiClient, refreshAuth, {
  statusCodes: [401],
  pauseInstanceWhileRefreshing: true,
})
```

### 5. Build Query Layer

**Feature-based query organization:**

```typescript
// src/api/queries/users.ts
import { queryOptions } from '@tanstack/react-query'
import { apiClient } from '../client'
import { User, UserSchema } from '../types'

// Query key factory
export const usersKeys = {
  all: ['users'] as const,
  lists: () => [...usersKeys.all, 'list'] as const,
  list: (filters: string) => [...usersKeys.lists(), { filters }] as const,
  details: () => [...usersKeys.all, 'detail'] as const,
  detail: (id: string) => [...usersKeys.details(), id] as const,
}

// API functions
async function fetchUsers(): Promise<User[]> {
  const response = await apiClient.get('/users')
  return z.array(UserSchema).parse(response.data)
}

async function fetchUser(id: string): Promise<User> {
  const response = await apiClient.get(`/users/${id}`)
  return UserSchema.parse(response.data)
}

// Query options
export function usersListQueryOptions() {
  return queryOptions({
    queryKey: usersKeys.lists(),
    queryFn: fetchUsers,
    staleTime: 30_000,
  })
}

export function userQueryOptions(id: string) {
  return queryOptions({
    queryKey: usersKeys.detail(id),
    queryFn: () => fetchUser(id),
    staleTime: 60_000,
  })
}

// Hooks
export function useUsers() {
  return useQuery(usersListQueryOptions())
}

export function useUser(id: string) {
  return useQuery(userQueryOptions(id))
}
```

**Mutations:**

```typescript
// src/api/mutations/users.ts
import { useMutation, useQueryClient } from '@tanstack/react-query'
import { apiClient } from '../client'
import { CreateUserDTO, User, UserSchema } from '../types'
import { usersKeys } from '../queries/users'

async function createUser(data: CreateUserDTO): Promise<User> {
  const response = await apiClient.post('/users', data)
  return UserSchema.parse(response.data)
}

export function useCreateUser() {
  const queryClient = useQueryClient()

  return useMutation({
    mutationFn: createUser,
    onSuccess: (newUser) => {
      // Add to cache
      queryClient.setQueryData(usersKeys.detail(newUser.id), newUser)

      // Invalidate list
      queryClient.invalidateQueries({ queryKey: usersKeys.lists() })
    },
  })
}
```

## Validation Strategy

**Always validate API responses:**

```typescript
import { z } from 'zod'

// Runtime validation
async function fetchUser(id: string): Promise<User> {
  const response = await apiClient.get(`/users/${id}`)

  try {
    return UserSchema.parse(response.data)
  } catch (error) {
    console.error('API response validation failed:', error)
    throw new Error('Invalid API response format')
  }
}
```

**Or use safe parse:**
```typescript
const result = UserSchema.safeParse(response.data)

if (!result.success) {
  console.error('Validation errors:', result.error.errors)
  throw new Error('Invalid user data')
}

return result.data
```

## Error Handling

**Global error handling:**
```typescript
import { QueryCache } from '@tanstack/react-query'

const queryCache = new QueryCache({
  onError: (error, query) => {
    if (axios.isAxiosError(error)) {
      if (error.response?.status === 404) {
        toast.error('Resource not found')
      } else if (error.response?.status === 500) {
        toast.error('Server error. Please try again.')
      }
    }
  },
})
```

## Best Practices

1. **Single Source of Truth** - OpenAPI spec via MCP is authoritative
2. **Validate Responses** - Use Zod schemas for runtime validation
3. **Encapsulation** - Keep all API details in `/src/api`
4. **Type Safety** - Export types from generated/hand-written schemas
5. **Error Handling** - Handle auth errors, network errors, validation errors
6. **Query Key Factories** - Hierarchical keys for flexible invalidation
7. **Feature-Based Organization** - Group queries/mutations by feature

## Workflow with AI Agent

1. **Agent reads latest OpenAPI spec** via Apidog MCP
2. **Agent generates or upd