Send email from Hono with SNDR.

Hono's small surface — c.req for the request, c.json/c.text for the response, typed bindings for env vars on Workers — is a clean fit for transactional email. The SDK requires Node-compatible crypto and Buffer in addition to fetch. Enable nodejs_compat on Workers; use the HTTP API for targets without Node compatibility. The recipes below cover the four patterns: a typed POST endpoint, a webhook receiver, an OTP flow, and a Cloudflare Workers configuration with typed env bindings.

1. Send from a typed POST handler

   Hono validates JSON bodies via @hono/zod-validator when you add it; without it, c.req.json() returns unknown — narrow with your own type guards or Zod.

   // src/index.ts (Node or Bun)
   import { Hono } from 'hono';
   import { Sndr, SndrError } from '@rkiza/sndr';
   
   const sndr = new Sndr(process.env.SNDR_API_KEY!);
   const app = new Hono();
   
   app.post('/api/welcome', async (c) => {
     const { email, name } = (await c.req.json()) as { email: string; name: string };
     try {
       const { id } = await sndr.emails.send({
         from: 'hello@yourdomain.com',
         to: email,
         subject: `Welcome, ${name}`,
         html: `<p>Thanks for joining us, ${name}.</p>`,
       });
       return c.json({ id });
     } catch (err) {
       if (err instanceof SndrError) {
         return c.json(
           { error: { code: err.code, message: err.message } },
           err.status as 400 | 401 | 403 | 404 | 422 | 429 | 500,
         );
       }
       throw err;
     }
   });
   
   export default app; // Node/Bun adapters pick this up

2. Verify an incoming webhook

   Hono's c.req.raw exposes the underlying Web Request — call .arrayBuffer() to read the raw bytes before any JSON parse step consumes the stream.

   import { Hono } from 'hono';
   import { verifyWebhookSignature } from '@rkiza/sndr';
   import type { WebhookEventPayload } from '@rkiza/sndr';
   
   const app = new Hono();
   
   app.post('/webhooks/sndr', async (c) => {
     const raw = Buffer.from(await c.req.raw.arrayBuffer());
     const ok = verifyWebhookSignature(
       raw,
       c.req.header('x-sndr-signature') ?? '',
       process.env.SNDR_WEBHOOK_SECRET!,
     );
     if (!ok) return c.text('bad signature', 400);
   
     const event = JSON.parse(raw.toString('utf8')) as WebhookEventPayload;
     switch (event.type) {
       case 'email.delivered':
         // event.data.email_id, event.data.to: string[]
         break;
       case 'email.bounced':
         // event.data.email_id, event.data.error
         break;
       case 'email.unsubscribed':
         // event.data.addresses: string[]
         break;
     }
   
     return c.text('ok');
   });
   
   export default app;

3. Cloudflare Workers — typed env bindings

   On Workers, env vars and secrets live on the Bindings type. Instantiate Sndr per-request because each request gets its own env. The SDK is small (~6 KB gzipped) so the per-request cost is negligible.

   import { Hono } from 'hono';
   import { Sndr } from '@rkiza/sndr';
   
   type Bindings = {
     SNDR_API_KEY: string;
     SNDR_WEBHOOK_SECRET: string;
   };
   
   const app = new Hono<{ Bindings: Bindings }>();
   
   app.post('/api/welcome', async (c) => {
     const sndr = new Sndr(c.env.SNDR_API_KEY);
     const { email, name } = (await c.req.json()) as { email: string; name: string };
     const { id } = await sndr.emails.send({
       from: 'hello@yourdomain.com',
       to: email,
       subject: `Welcome, ${name}`,
       html: `<p>Thanks for joining us, ${name}.</p>`,
     });
     return c.json({ id });
   });
   
   export default app;

4. OTP flow with KV-backed storage

   On Workers, store the (email → code) pair in KV with a short TTL. On Node, swap KV for Redis. The handler shape is identical because Hono abstracts the runtime.

   import { Hono } from 'hono';
   import { Sndr } from '@rkiza/sndr';
   
   type Bindings = {
     SNDR_API_KEY: string;
     OTP: KVNamespace;
   };
   
   const app = new Hono<{ Bindings: Bindings }>();
   
   app.post('/api/otp/send', async (c) => {
     const sndr = new Sndr(c.env.SNDR_API_KEY);
     const { email } = (await c.req.json()) as { email: string };
     const code = String(Math.floor(100000 + Math.random() * 900000));
     // KV value TTL is in seconds. 10-min lifetime.
     await c.env.OTP.put(`otp:${email}`, code, { expirationTtl: 600 });
   
     await sndr.emails.send({
       from: 'auth@yourdomain.com',
       to: email,
       subject: `Your sign-in code: ${code}`,
       text: `Your code is ${code}. It expires in 10 minutes.`,
     });
   
     return c.json({ ok: true });
   });

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