Server-Sent Events

ingenium.sse (the sse helper) turns a normal handler into a Server-Sent Events stream. Multi-line data is split per spec; object data is JSON-stringified.

Usage

import { ingenium, sse, startKeepAlive } from 'ingenium'

app.get('/events', (ctx) => {
  const stream = sse(ctx)
  startKeepAlive(stream, 15_000)

  let n = 0
  const timer = setInterval(() => {
    stream.send({ event: 'tick', id: String(n), data: { n: n++ } })
    if (n >= 10) {
      clearInterval(timer)
      stream.close()
    }
  }, 1000)
})

API

SseStream exposes:

• send(event | string) - write an event. Pass a string to send a data:-only event, or an object with event, id, and data for full control.
• comment(text) - write a comment line (: keepalive). Useful for keep-alive pings.
• close() - end the stream.
• closed: boolean - whether the underlying response has finished.

startKeepAlive(stream, intervalMs) starts a periodic comment so intermediaries don't drop the idle connection.

Where to next?

• Middleware - middleware that wraps SSE handlers.
• WebSocket - the bidirectional alternative.
• Transports - how the response body is written.
• Graceful shutdown - closing in-flight streams cleanly.