Source Intelligence

DisclaimerUnofficial, and not affiliated with Anthropic. Nearly all of this is read straight out of what ships: npm bundles, captured prompts, published docs. Anthropic's own notes go in verbatim, marked as theirs. The rest is my reading, and every entry carries the strings behind it. If one looks wrong, vote it down and say why.

All of v2.1.251 Home All releases olderv2.1.250
Claude Code v2.1.251

Cloud sessions report why they failed to start

You'll notice
Useful3 Signal2
Cloud Sessions

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

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: off

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

--print
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.

Related

Other releases about the same thing. Found by shared names or similar wording; neither means one caused the other.

See this entry in the whole of v2.1.251 →