Handle interrupted and declined replies

import json
import os
 
import requests
 
 
def stream_reply(body: dict):
    """Yields text pieces; returns a status of 'complete', 'length', 'tool_calls' or 'incomplete'."""
    status = "incomplete"
    with requests.post(
        "https://app.syntic.ai/v1/chat/completions",
        headers={"Authorization": f"Bearer {os.environ['SYNTIC_API_KEY']}"},
        json={**body, "stream": True},
        stream=True,
        timeout=(10, 300),
    ) as r:
        r.raise_for_status()
        finish = None
        for line in r.iter_lines(decode_unicode=True):
            if not line or not line.startswith("data: "):
                continue
            if line == "data: [DONE]":
                status = {"stop": "complete", "length": "length", "tool_calls": "tool_calls"}.get(finish, "complete")
                break
            event = json.loads(line[6:])
            if "error" in event:
                break                                   # stream_error: leave status as incomplete
            choice = (event.get("choices") or [{}])[0]
            finish = choice.get("finish_reason") or finish
            piece = choice.get("delta", {}).get("content")
            if piece:
                yield piece
    return status

export async function* streamReply(body) {
  const res = await fetch('https://app.syntic.ai/v1/chat/completions', {
    method: 'POST',
    headers: { Authorization: `Bearer ${process.env.SYNTIC_API_KEY}`, 'Content-Type': 'application/json' },
    body: JSON.stringify({ ...body, stream: true }),
  })
  if (!res.ok) throw new Error(`${res.status} ${await res.text()}`)
  const decoder = new TextDecoder()
  let buffer = ''
  let finish = null
  for await (const bytes of res.body) {
    buffer += decoder.decode(bytes, { stream: true })
    const lines = buffer.split('\n')
    buffer = lines.pop()
    for (const line of lines) {
      if (!line.startsWith('data: ')) continue
      if (line === 'data: [DONE]') return finish === 'length' ? 'length' : finish === 'tool_calls' ? 'tool_calls' : 'complete'
      const event = JSON.parse(line.slice(6))
      if (event.error) return 'incomplete'
      const choice = event.choices?.[0]
      finish = choice?.finish_reason ?? finish
      if (choice?.delta?.content) yield choice.delta.content
    }
  }
  return 'incomplete' // ended without [DONE]
}