Stream Output

// 1. Create a thread first (or reuse an existing one).
const threadRes = await fetch("http://127.0.0.1:3001/threads", {
  method: "POST",
  headers: { "content-type": "application/json" },
  body: JSON.stringify({}),
})
const { thread_id } = (await threadRes.json()) as { thread_id: string }
 
// 2. Start a streaming run on that thread.
const res = await fetch(`http://127.0.0.1:3001/threads/${thread_id}/runs/stream`, {
  method: "POST",
  headers: { "content-type": "application/json" },
  body: JSON.stringify({
    route: "/navlog#agent",
    input: { messages: [{ role: "user", content: "latest LLM benchmarks" }] },
  }),
})
 
if (!res.ok || !res.body) {
  throw new Error(`stream failed: ${res.status}`)
}
 
const reader = res.body.pipeThrough(new TextDecoderStream()).getReader()
let buffer = ""
 
while (true) {
  const { value, done } = await reader.read()
  if (done) break
  buffer += value
  // SSE frames are delimited by a blank line.
  const frames = buffer.split("\n\n")
  buffer = frames.pop() ?? ""
  for (const frame of frames) {
    // Ignore SSE comments (for example, the `: ping` heartbeat) first.
    const lines = frame.split("\n").filter((line) => !line.startsWith(":"))
    // Event frames have an "event:" line and a "data:" line.
    const eventLine = lines.find((l) => l.startsWith("event: "))
    const dataLine = lines.find((l) => l.startsWith("data: "))
    if (!eventLine || !dataLine) continue
    const eventType = eventLine.slice("event: ".length)
    const payload = JSON.parse(dataLine.slice("data: ".length))
 
    switch (eventType) {
      case "chunk":
        // Streamed text fragment: append it to the display.
        if (typeof payload === "string") process.stdout.write(payload)
        break
      case "tool_call":
        console.log(`\n[tool_call] ${payload.name}`, payload.input)
        break
      case "tool_result":
        console.log(`[tool_result] ${payload.name}`, payload.output)
        break
      case "plan_update":
        console.log("[plan_update]", payload)
        break
      case "interrupt":
        console.log("[interrupt]", payload)
        break
      case "done":
        console.log("\n[done]", payload.output)
        break
      default:
        // subagent.start, subagent.token, subagent.tool_call,
        // subagent.tool_result, subagent.end, etc.
        console.log(`[${eventType}]`, payload)
    }
  }
}