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Sweep 22 Oct 2026 · 21:04Z Build v2.1.309 528 read Stable v2.1.308 Latest v2.1.309 Next v2.1.309 Feeds RSS JSON llms.txt llms-full.txt Unofficial
HomeReleasesv2.1.251entry #308

Claude Code v2.1.251 ·

Thumbnail checks in the artifact publish preflight

Publish checks could warn about page thumbnails, but the experiment is off.

Nothing to try yet In Development
JSON All of v2.1.251
Nothing to try yetTier: how much it should matter to you
1Useful: my rating, 1 to 5
3Signal: worth watching, 1 to 5
ArtifactsArea: what it touches
In DevelopmentKind: in v2.1.251,
In DevelopmentSection of the release

Thumbnail preflight warnings exist behind an experiment defaulting off.

What

Publish validation for HTML pages can inspect thumbnails and report problems as preflight warnings, but the experiment controlling it defaults to off, so no publish runs the check in this build.

Details
Evidence

kind: "thumbnail"

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

Read from
Feature flag
tengu_cobalt_plinth_campion 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

How sure we are
One source agreesOne thing we can check says the same as this entry.
The name it cites is new in this buildNew in this build: tengu_cobalt_plinth_campion

See this entry in the whole of v2.1.251 →

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