Follow Discord
Sweep 22 Sep 2026 · 17:19Z Build v2.1.280 501 read Stable v2.1.267 Latest v2.1.280 Next v2.1.280 Feeds RSS JSON llms.txt Unofficial
Claude Code v2.1.265 ·

Sessions gain a control-only connection mode

← All of v2.1.265 Home All releases

Sessions can now connect in a controlOnly mode that subscribes to control messages without the full event stream

TierUnder the hoodhow much it should matter to you
Useful1my rating, 1 to 5
Signal1worth watching, 1 to 5
AreaCloud Sessionswhat it touches
KindInternal Changesin v2.1.265,
Group of 4 Under the hood No documentation found

Sessions can now connect in a controlOnly mode that subscribes to control messages without the full event stream

What

  • 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).
  • 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.
  • When a session is opened via attach, the emitted "opened" payload conditionally includes controlOnly: true.

Why

This 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.

Read from
Names in the bundlecontrolOnly
How sure we are
Something disagreesSomething we can check disagrees with this entry, or the writer said they could not settle it.
The writer flagged doubtWhat effect `controlOnly: true` has on an opened session, or when it is set, is not described in the finding.

See this entry in the whole of v2.1.265 →

Feedback