The tray polls this with its cloud_token to learn which cloud AI clients (ChatGPT, Claude.ai, …) actually have an ACTIVE connector for THIS machine — i.e. a non-expired OAuth refresh token issued to that client for this token. Lets the menu bar show real connection status ('Connected' only when a grant exists) instead of inferring it from 'the app is installed' or 'the relay is up' (both false-positives). Authenticated by the cloud_token itself — the same credential the relay uses. Cached per token for a few seconds (see _CONNECTED_CLIENTS_TTL) — the poll rate would otherwise saturate the API.

Response (no published contract; shipped trays ignore unknown fields): clients[] each carry stale_token (bool), and the top level carries it too. True = the machine's live tunnel is on ANOTHER token (reinstall), so these grants cannot work: the tray may offer "Reconnect this AI".