Vercel SDK Patterns

Overview

Build a typed, production-ready wrapper around the Vercel REST API (api.vercel.com). Covers authentication, pagination, error handling, retry logic, and common endpoint patterns for deployments, projects, and environment variables.

Prerequisites

• Completed vercel-install-auth setup
• TypeScript project with strict mode enabled
• Vercel access token with appropriate scope

Instructions

Step 1: Create Typed API Client

// lib/vercel-client.ts
interface VercelClientConfig {
  token: string;
  teamId?: string;
  baseUrl?: string;
}

interface VercelError {
  error: { code: string; message: string };
}

class VercelClient {
  private token: string;
  private teamId?: string;
  private baseUrl: string;

  constructor(config: VercelClientConfig) {
    this.token = config.token;
    this.teamId = config.teamId;
    this.baseUrl = config.baseUrl ?? 'https://api.vercel.com';
  }

  private async request<T>(
    method: string,
    path: string,
    body?: unknown
  ): Promise<T> {
    const url = new URL(path, this.baseUrl);
    if (this.teamId) url.searchParams.set('teamId', this.teamId);

    const res = await fetch(url.toString(), {
      method,
      headers: {
        Authorization: `Bearer ${this.token}`,
        'Content-Type': 'application/json',
      },
      body: body ? JSON.stringify(body) : undefined,
    });

    if (!res.ok) {
      const err: VercelError = await res.json();
      throw new VercelApiError(res.status, err.error.code, err.error.message);
    }

    // 204 No Content
    if (res.status === 204) return undefined as T;
    return res.json() as Promise<T>;
  }

  // --- Projects ---
  async listProjects(limit = 20) {
    return this.request<{ projects: VercelProject[] }>(
      'GET', `/v9/projects?limit=${limit}`
    );
  }

  async getProject(idOrName: string) {
    return this.request<VercelProject>('GET', `/v9/projects/${idOrName}`);
  }

  // --- Deployments ---
  async listDeployments(projectId?: string, limit = 20) {
    const params = new URLSearchParams({ limit: String(limit) });
    if (projectId) params.set('projectId', projectId);
    return this.request<{ deployments: VercelDeployment[] }>(
      'GET', `/v6/deployments?${params}`
    );
  }

  async getDeployment(idOrUrl: string) {
    return this.request<VercelDeployment>(
      'GET', `/v13/deployments/${idOrUrl}`
    );
  }

  // --- Environment Variables ---
  async listEnvVars(projectId: string) {
    return this.request<{ envs: VercelEnvVar[] }>(
      'GET', `/v9/projects/${projectId}/env`
    );
  }

  async createEnvVar(projectId: string, envVar: CreateEnvVarInput) {
    return this.request<VercelEnvVar>(
      'POST', `/v9/projects/${projectId}/env`, envVar
    );
  }

  // --- Domains ---
  async listDomains(projectId: string) {
    return this.request<{ domains: VercelDomain[] }>(
      'GET', `/v9/projects/${projectId}/domains`
    );
  }

  async addDomain(projectId: string, domain: string) {
    return this.request<VercelDomain>(
      'POST', `/v9/projects/${projectId}/domains`, { name: domain }
    );
  }
}

Step 2: Define Types

// lib/vercel-types.ts
interface VercelProject {
  id: string;
  name: string;
  framework: string | null;
  latestDeployments: VercelDeployment[];
  targets: Record<string, VercelDeployment>;
  createdAt: number;
  updatedAt: number;
}

interface VercelDeployment {
  uid: string;
  name: string;
  url: string;
  state: 'BUILDING' | 'ERROR' | 'INITIALIZING' | 'QUEUED' | 'READY' | 'CANCELED';
  target: 'production' | 'preview' | null;
  createdAt: number;
  buildingAt: number;
  ready: number;
  meta: Record<string, string>;
}

interface VercelEnvVar {
  id: string;
  key: string;
  value: string;
  type: 'system' | 'encrypted' | 'plain' | 'sensitive';
  target: ('production' | 'preview' | 'development')[];
  createdAt: number;
  updatedAt: number;
}

interface CreateEnvVarInput {
  key: string;
  value: string;
  type: 'encrypted' | 'plain' | 'sensitive';
  target: ('production' | 'preview' | 'development')[];
}

interface VercelDomain {
  name: string;
  verified: boolean;
  redirect: string | null;
  gitBranch: string | null;
  createdAt: number;
  updatedAt: number;
}

Step 3: Custom Error Class

// lib/vercel-errors.ts
class VercelApiError extends Error {
  constructor(
    public status: number,
    public code: string,
    message: string
  ) {
    super(`Vercel API ${status}: [${code}] ${message}`);
    this.name = 'VercelApiError';
  }

  get isRateLimit(): boolean { return this.status === 429; }
  get isNotFound(): boolean { return this.status === 404; }
  get isUnauthorized(): boolean { return this.status === 401 || this.status === 403; }
}

Step 4: Retry with Exponential Backoff

// lib/vercel-retry.ts
async function withRetry<T>(
  fn: () => Promise<T>,
  maxRetries = 3,
  baseDelayMs = 1000
): Promise<T> {
  for (let attempt = 0; attempt <= maxRetries; attempt++) {
    try {
      return await fn();
    } catch (err) {
      if (err instanceof VercelApiError && err.isRateLimit && attempt < maxRetries) {
        const delay = baseDelayMs * Math.pow(2, attempt) + Math.random() * 500;
        console.warn(`Rate limited. Retrying in ${Math.round(delay)}ms...`);
        await new Promise(r => setTimeout(r, delay));
        continue;
      }
      throw err;
    }
  }
  throw new Error('Unreachable');
}

// Usage:
// const projects = await withRetry(() => client.listProjects());

Step 5: Paginated Fetching

// lib/vercel-pagination.ts
async function* paginateDeployments(
  client: VercelClient,
  projectId: string,
  pageSize = 100
): AsyncGenerator<VercelDeployment[]> {
  let until: number | undefined;

  while (true) {
    const params = new URLSearchParams({ limit: String(pageSize) });
    if (until) params.set('until', String(until));
    if (projectId) params.set('projectId', projectId);

    const { deployments } = await client.listDeployments(projectId, pageSize);
    if (deployments.length === 0) break;

    yield deployments;
    until = deployments[deployments.length - 1].createdAt;
    if (deployments.length < pageSize) break;
  }
}

API Endpoint Quick Reference

Output

• Type-safe Vercel API client with full TypeScript coverage
• Custom error class with semantic helpers (isRateLimit, isNotFound)
• Automatic retry with exponential backoff for 429 responses
• Paginated data fetching for large result sets

Error Handling

Examples

Use a scoped API token for a read-only deployment audit

Create a token limited to the required team and read operations, store it only in the approved CI secret store, and call the deployment listing endpoint with an explicit team ID. Paginate results, redact IDs from public logs when they are not needed, and stop retries on 403 or malformed requests rather than masking a permission error. Revoke the token after the short audit window or rotate it according to the organization’s policy.

Resources

• Vercel REST API Reference
• Vercel REST API Endpoints
• Authentication

Next Steps

Proceed to vercel-deploy-preview for preview deployment workflows.