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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 v2.1.257 ·

New CLI messaging when resuming a session that's already running

Resuming a session that is already running elsewhere starts a copy and points you to claude attach to join the live one.

TierYou'll noticehow much it should matter to you
Useful3my rating, 1 to 5
Signal3worth watching, 1 to 5
AreaSessionswhat it touches
KindImprovementsin v2.1.257,
You'll notice

Resuming a session that is already running elsewhere starts a copy and points you to claude attach to join the live one.

Trying to continue or resume a session id that's already running elsewhere (a background job, another process, or a handle conflict) now starts a copy of it instead of attaching, and prints a note explaining why, pointing to claude attach as the way to join the live session.

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Names in the bundleclaude attach
Since it was published

The entry above is what we published on the day. These lines were added later, as Anthropic's own pages caught up, and they sit beside the original rather than replacing it.

Confirmed since Anthropic's documentation has since written up claude attach, on Manage multiple agents with agent view. | `claude attach <id>` | Attach to a session in this terminal | agent-view see the edit
How sure we are
One source agreesOne thing we can check says the same as this entry.
Anthropic's documentation agreesAnthropic's documentation has since written up claude attach, on Manage multiple agents with agent view.

See this entry in the whole of v2.1.257 →

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