feat: add optional baseUrl and userAgent to Resend constructor

[xiaoyu2er]

Summary

Add optional options to the Resend constructor so callers can override baseUrl and userAgent while keeping the existing default/env behavior.

Changes

• ResendOptions: New optional interface with baseUrl?: string and userAgent?: string.
• Constructor: new Resend(key?, options?) — when options.baseUrl / options.userAgent are provided, they override env and defaults.
• Instance properties: resend.baseUrl and resend.userAgent (readonly) used for requests and headers.
• Defaults: Existing logic preserved via getDefaultBaseUrl() and getDefaultUserAgent() (env RESEND_BASE_URL / RESEND_USER_AGENT then fallbacks).
• Exports: ResendOptions exported from the package entry.

Usage

// Default (env or https://api.resend.com)
const resend = new Resend('re_xxx');

// Custom baseUrl and/or userAgent
const resend = new Resend('re_xxx', {
  baseUrl: 'https://eu.api.resend.com',
  userAgent: 'my-app/1.0',
});

Tests

• src/resend.spec.ts: 10 tests for default values, options override, env override, and that requests use custom baseUrl and User-Agent.

---

Summary by cubic

Adds optional options to the Resend constructor to set baseUrl and User-Agent per instance. Keeps env/default fallback and uses these values in request URLs and headers.

• New Features
  • Constructor: new Resend(key?, { baseUrl?, userAgent? })
  • Options override RESEND_BASE_URL and RESEND_USER_AGENT; otherwise falls back to env/defaults
  • Exposes resend.baseUrl and resend.userAgent (readonly)
  • Exports ResendOptions from the package entry

^{Written for commit dd83549. Summary will update on new commits.}

[cubic-dev-ai]

No issues found across 3 files

Confidence score: 5/5

• Automated review surfaced no issues in the provided summaries.
• No files require special attention.

[xiaoyu2er]

could you take a look @cassiozen @gabrielmfern 🙏

[pkg-pr-new]

Open in StackBlitz

npm i https://pkg.pr.new/resend/resend-node/resend@839

commit: dd83549