{"version":"2.1.265","anchor":"session-event-stream-can-connect-in-control-only-mode","canonical_anchor":"session-event-stream-can-connect-in-control-only-mode","heading":"Sessions gain a control-only connection mode","tier":"internal","area":"Sessions","scope":null,"heads_up":null,"url":"https:\/\/changelogs.core-directive.com\/v\/2.1.265\/e\/session-event-stream-can-connect-in-control-only-mode","release_url":"https:\/\/changelogs.core-directive.com\/v\/2.1.265","markdown":"### Sessions gain a control-only connection mode\n\nSessions can now connect in a controlOnly mode that subscribes to control messages without the full event stream\n\n**What**\n\n- Sessions and their control\/event channel gained a `controlOnly` mode, threaded through from session-open callers down to the low-level session-open call (defaulting to unset\/false).\n\n- `SessionsV2Client` appends `control_only=1` to the session events stream URL when configured with `controlOnly`, letting a connection subscribe to control messages only, without the full event stream.\n\n- When a session is opened via attach, the emitted \"opened\" payload conditionally includes `controlOnly: true`.\n\n**Why**\n\nThis lets a client connect to a session just to receive control messages, without also receiving the full event stream, which is more efficient when only control signaling is needed.\n\n- Area: Sessions\n- Names: `control_only=1`\n- Tier: Under the hood\n- Useful: 2\/5\n- Signal: 2\/5"}