Stream task events (SSE)

GET /api/v1/r/tasks/{taskId}/events opens a Server-Sent Events stream that emits one event per status change or progress tick. The connection stays open until the task reaches a terminal state (completed, failed, cancelled), then closes. Prefer this over polling GET /r/tasks/{taskId} — lower latency, fewer requests.

Connect

Use a Bearer token (JWT, sk-, or dk-):

curl -N \
  -H "Authorization: Bearer sk-..." \
  https://core.cyberun.cloud/api/v1/r/tasks/{taskId}/events

The browser’s built-in EventSource does not support custom headers, which means it can’t carry an Authorization header. Server-side runtimes (Node fetch, Python requests, httpx), React Native, or libraries like eventsource work fine. In a browser, proxy through your own backend.

Event types

Event	Meaning
`status`	Task status changed (e.g. `pending` → `waiting` → `queued` → `running`).
`progress`	Execution tick with `progress`, `step_current`, `step_total`, and the active node.
`completed`	Task finished. Includes the output object.
`failed`	Task failed. Includes the error string.
`cancelled`	Task was cancelled before reaching a terminal state.
`error`	Server-side error fetching status. The stream may still continue.

`status`

event: status
data: {"task_id":"...","status":"running","timestamp":"2026-02-01T14:30:05Z"}

`progress`

event: progress
data: {
  "task_id":"...",
  "progress":0.35,
  "current_node":"3",
  "step_current":7,
  "step_total":20,
  "timestamp":"2026-02-01T14:30:10Z"
}

Nerfstudio tasks add stage (download, process_data, train, export, upload) and a human-readable message to the payload.

Field	Type	Meaning
`progress`	number	`0.0`–`1.0` overall progress.
`step_current`	integer	Steps completed so far (when the runtime reports steps).
`step_total`	integer	Total steps for this run.
`current_node`	string	The runtime’s active node identifier (ComfyUI node ID for ComfyUI workflows).
`stage`	string	Nerfstudio-only. Coarse phase name.
`message`	string	Nerfstudio-only. Free-form status text.

Terminal events

event: completed
data: {"task_id":"...","status":"completed","completed_at":"...","output":{...}}

event: failed
data: {"task_id":"...","status":"failed","error":"ComfyUI execution error: ..."}

event: cancelled
data: {"task_id":"...","status":"cancelled"}

After any of these three the server closes the connection.

`error`

event: error
data: {"message":"failed to fetch task status"}

A transient server-side problem reading task state. Treat it as recoverable — the task itself may still be running. If the stream also closes, fall back to polling (see below).

Example stream

A typical ComfyUI task end-to-end:

event: status
data: {"task_id":"...","status":"waiting","timestamp":"..."}

event: status
data: {"task_id":"...","status":"queued","timestamp":"..."}

event: status
data: {"task_id":"...","status":"running","timestamp":"..."}

event: progress
data: {"task_id":"...","progress":0.15,"step_current":3,"step_total":20,"current_node":"3"}

event: progress
data: {"task_id":"...","progress":0.5,"step_current":10,"step_total":20,"current_node":"3"}

event: progress
data: {"task_id":"...","progress":1.0,"step_current":20,"step_total":20,"current_node":"3"}

event: completed
data: {"task_id":"...","status":"completed","output":{...}}

Polling fallback

If your network drops SSE, or you’d rather not hold a connection open, poll GET /r/tasks/{taskId} until task_status is one of completed, failed, cancelled. Three seconds between polls is a reasonable default.

curl -s \
  -H "Authorization: Bearer sk-..." \
  https://core.cyberun.cloud/api/v1/r/tasks/{taskId}

When the task is completed, fetch the artifact links via GET /r/tasks/{taskId}/result.

Consume the stream

import json, requests

API_KEY = "sk-..."
BASE = "https://core.cyberun.cloud/api/v1/r"

with requests.get(
    f"{BASE}/tasks/{task_id}/events",
    headers={"Authorization": f"Bearer {API_KEY}"},
    stream=True,
) as stream:
    event_type = None
    for line in stream.iter_lines(decode_unicode=True):
        if not line:
            continue
        if line.startswith("event:"):
            event_type = line[6:].strip()
        elif line.startswith("data:"):
            data = json.loads(line[5:].strip())
            if event_type == "progress":
                pct = int(data["progress"] * 100)
                print(f"{pct}% ({data['step_current']}/{data['step_total']})")
            elif event_type in ("completed", "failed", "cancelled"):
                print(event_type, data)
                break

const API_KEY = process.env.CYBERUN_KEY!;
const BASE = 'https://core.cyberun.cloud/api/v1/r';

const resp = await fetch(`${BASE}/tasks/${taskId}/events`, {
	headers: { Authorization: `Bearer ${API_KEY}` }
});

const reader = resp.body!.getReader();
const decoder = new TextDecoder();
let buffer = '';
let eventType = '';

while (true) {
	const { done, value } = await reader.read();
	if (done) break;
	buffer += decoder.decode(value, { stream: true });
	const lines = buffer.split('\n');
	buffer = lines.pop() ?? '';

	for (const line of lines) {
		if (line.startsWith('event:')) {
			eventType = line.slice(6).trim();
		} else if (line.startsWith('data:')) {
			const data = JSON.parse(line.slice(5).trim());
			if (eventType === 'progress') {
				console.log(`${Math.round(data.progress * 100)}%`);
			} else if (eventType === 'completed' || eventType === 'failed' || eventType === 'cancelled') {
				console.log(eventType, data);
				return;
			}
		}
	}
}

Generate an API key — issue an sk- credential.
API reference — the full endpoint catalog.
Webhooks — push delivery of terminal events instead of streaming.

Overview

Guides

Endpoints

Stream task events (SSE)

Connect

Event types

`status`

`progress`

Terminal events

`error`

Example stream

Polling fallback

Consume the stream

​Connect

​Event types

​status

​progress

​Terminal events

​error

​Example stream

​Polling fallback

​Consume the stream

​Related

Connect

Event types

`status`

`progress`

Terminal events

`error`

Example stream

Polling fallback

Consume the stream

Related