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Sweep 22 Oct 2026 · 04:32Z Build v2.1.308 527 read Stable v2.1.308 Latest v2.1.308 Next v2.1.308 Feeds RSS JSON llms.txt llms-full.txt Unofficial
HomeReleasesv2.1.251entry #158

Claude Code v2.1.251 ·

Cloud sessions report why they failed to start

A cloud session that failed to start now shows the actual reason instead of a generic error.

You'll notice New Features
JSON All of v2.1.251
You'll noticeTier: how much it should matter to you
3Useful: my rating, 1 to 5
2Signal: worth watching, 1 to 5
Cloud SessionsArea: what it touches
New FeaturesKind: in v2.1.251,
New FeaturesSection of the release
What

When a cloud session is polled, for example under --print, a recorded startup failure is now raised as that specific error instead of the generic archived-or-errored response, so you see the actual reason the session never came up.

Details
  • gated on tengu_linear_brook, which defaults to on in this build
  • with the flag off, polling falls back to the previous generic result
Evidence

if (n.startupFailure && FNt()) throw T(n.startupFailure);

Strings lifted out of the shipped bundle, so the claim above can be checked against them.

Read from
Names in the bundle--print
Feature flag
tengu_linear_brook Not enough to say

Nothing here resolved what this flag was doing on this version, so nothing here should be read as on or off.

This account: no value returned · anonymous baseline: no value returned · compiled default in v2.1.251: on

Read once, for one account on one subscription tier, against v2.1.251. It isn't a statement about your account. What a flag value here can and cannot tell you

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.

Added since A small documentation edit on CLI reference touched a line naming --print after this was published. | `--bg`, `--background` | Start the session as a [background agent](/docs/en/agent-view) and return immediately. Prints the session ID and management commands. Combine with `--exec` to run a shell command as a background job instead of a … cli-reference see the edit
Confirmed since Anthropic's documentation has since written up --print, on Claude Code changelog. * Fixed PermissionRequest hooks not firing in `--print` mode changelog see the edit
How sure we are
Two sources agreeTwo things we can check say the same as this entry.
Anthropic's documentation agreesAnthropic's documentation has since written up --print, on Claude Code changelog.
The name it cites is new in this buildNew in this build: tengu_linear_brook

See this entry in the whole of v2.1.251 →

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