We scan this tool’s changelog a few times a day and keep the changes that would alter your agent’s next action: 28 since January 2026, each linked to its source.
k6When an asynchronous test flow needs requests and checks to remain in one group across `await`, run it with the experimental `async-metric-context` feature and use an async `group()` callback. `group_duration` then measures until the callback’s returned promise settles.
k6 run --features async-metric-context <script.js>When preparing binary test data or checking response fields, use the documented `Uint8Array` conversions and `Set` operations. To serialize an exact numeric JSON value, pass its decimal text to `JSON.rawJSON()` before `JSON.stringify()`; k6 v2.3.0 release notes document these examples.
const bytes = Uint8Array.fromHex('6b36');
console.log(bytes.toBase64()); // azY=When debugging a script with at most one configured scenario, run `k6 run --once script.js` to execute its function once with one VU and one iteration while preserving scenario settings, including browser settings.
k6 run --once <script.js>When multiple k6 processes send metrics to the same Prometheus endpoint, set `K6_PROMETHEUS_RW_LABELS` to comma-separated `key=value` labels and run with `--out experimental-prometheus-rw` so each process's time series can be distinguished.
K6_PROMETHEUS_RW_LABELS="environment=production,server=srv1" k6 run --out experimental-prometheus-rw <script.js>When debugging a script with multiple configured scenarios, run `k6 run --scenario <name> <script.js>` to run only the named workload. Separate multiple scenario names with commas.
k6 run --scenario homepage script.jsIf an HTTPS test fails because the server omits an intermediate certificate, set `tlsAIAFetch: true` in the k6 options to fetch it while verifying the TLS chain.
export const options = {
tlsAIAFetch: true,
};When reviewing WebSocket message handling, check the socket state before sending. Send only when `socket.readyState === WebSocket.OPEN`; `OPEN` means the connection is ready to communicate.
if (socket.readyState === WebSocket.OPEN) {
socket.send('hello');
}When a test needs to attach to an existing Chromium-based browser, pass its CDP WebSocket endpoint to `chromium.connectOverCDP()` inside the iteration and use the returned browser. k6 closes the connection at iteration end; call `browser.close()` to close it earlier.
import { chromium } from 'k6/browser';
export default async function () {
const browser = await chromium.connectOverCDP('ws://localhost:9222/devtools/browser/<BROWSER_ID>');
const page = await browser.newPage();
try {
await page.goto('https://quickpizza.grafana.com/');
} finally {
await page.close();
await browser.close();
}
}When inspecting load zones in a configured Grafana Cloud k6 stack, run `k6 cloud load-zone list`; add `--json` for a JSON array instead of the default table.
k6 cloud load-zone listWhen implementing a writable stream in k6 v2.2.0, import `WritableStream` from `k6/experimental/streams`. Create it with a `write` handler, then call `getWriter()`, `write()`, and `close()` as shown.
import { WritableStream } from 'k6/experimental/streams';
export default async function () {
const stream = new WritableStream({
write(chunk) {
console.log(`wrote ${chunk}`);
},
});
const writer = stream.getWriter();
await writer.write('hello');
await writer.close();
}