# `reporters/herdr-probe` Source: [`src/reporters/herdr-probe.ts`](https://github.com/AI-for-dev/combo/blob/main/src/reporters/herdr-probe.ts) Asking herdr whether it would open a pane, without opening one. `/herdr on` used to answer one question - are we inside herdr - and that was the wrong one. A herdr that is there and refuses every request looks exactly like a herdr that is there and works: the reporter drops a pane it cannot open, silently, because display is an observer and an observer that warns is a participant. `agent.start` changed shape between protocols and nothing said a word for two releases. So the command asks, and the trick is the pane it names. Sent with a `target_pane_id` that cannot exist, `pane.split` separates the two answers herdr gives: `invalid_request` when the request itself is wrong, and `pane_not_found` when the request was understood and only that pane was missing. The second is the one we are fishing for, and neither opens anything. It probes `pane.split` alone, because nothing else runs without the pane id it returns. `scripts/check-herdr.ts` is what covers the other five, against the schema rather than against a live server. ## `probeHerdr` *function* ```typescript export async function probeHerdr(send: HerdrSend): Promise { /* … */ } ``` Why a pane would not open, or `undefined` when one would. Never throws: a broken probe must not be worse than no probe.