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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

tengu_cobalt_plinth_campion

flag in the build JSON

A Claude Code feature flag, read out of the shipped bundle. It has been in the build since v2.1.251, including the newest one read.

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

Not Anthropic's. This is the line from the earliest changelog entry here that named it, v2.1.251.

First seen v2.1.251 28 Aug 2026
Last seen v2.1.280 22 Sep 2026
Builds23 / 123on this box, as of v2.1.280
Written about v2.1.251 first named in a changelog, 28 Aug 2026
v2.1.251in the build not in the build never minedv2.1.280

In the changelogs

3

Releases whose published page names tengu_cobalt_plinth_campion.

  1. v2.1.257
    Artifact publish gains a 'live document' thumbnail-skip path

    Publishing a live artifact can skip thumbnail extraction, showing a dedicated note when the page declares one.

    gate cited by this entry

  2. v2.1.251
    Thumbnail checks in the artifact publish preflight

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

    gate cited by this entry, found in this entry's text

  3. v2.1.251
    Artifact publishing can attach page thumbnails, switched off in this build

    Published pages could carry light and dark thumbnails, but the feature is off.

    gate cited by this entry, found in this entry's text

Gate readings

2
ReleaseResolvedThis accountAnonymousCompiled default
v2.1.257 read on another version Not enough to say no value returned no value returned off
v2.1.251 Not enough to say no value returned no value returned off

Two arms, because they disagree: this account is the one account this site reads and anonymous is a baseline with no identity attached. A reading says nothing about your account, and off cannot rule out a rollout both readings sit outside of. What these readings can and cannot show.

First cited

0

No release's published evidence quotes this name. The ledger indexes the Evidence lines of every changelog on this site, so this says nobody here has ever quoted it; it says nothing about how old the name is.

Presence across releases

1
BuildsHow manyDatesReading
v2.1.251 – v2.1.28023 builds28 Aug 2026 → 22 Sep 2026 in the build

Build by build

23

One row per release since the first build this name was read out of. Absent means the build was read and the name was not in it, never mined means no bundle for that release was ever archived, and a declared type or a default is only ever what that release's own bundle stated.

BuildDateStateThe record behind it
v2.1.25128 Aug 2026·addedverdict: added · default bool:false
v2.1.25231 Aug 2026·presentverdict: present · default bool:false
v2.1.2571 Sep 2026·presentverdict: present · default bool:false
v2.1.2581 Sep 2026·presentverdict: present · default bool:false
v2.1.2592 Sep 2026·presentverdict: present · default bool:false
v2.1.2603 Sep 2026·presentverdict: present · default bool:false
v2.1.2614 Sep 2026·presentverdict: present · default bool:false
v2.1.2636 Sep 2026·presentverdict: present · default bool:false
v2.1.2658 Sep 2026·presentverdict: present · default bool:false
v2.1.2668 Sep 2026·presentverdict: present · default bool:false
v2.1.2679 Sep 2026·presentverdict: present · default bool:false
v2.1.26810 Sep 2026·presentverdict: present · default bool:false
v2.1.26911 Sep 2026·presentverdict: present · default bool:false
v2.1.27012 Sep 2026·presentverdict: present · default bool:false
v2.1.27114 Sep 2026·presentverdict: present · default bool:false
v2.1.27214 Sep 2026·presentverdict: present · default bool:false
v2.1.27315 Sep 2026·presentverdict: present · default bool:false
v2.1.27416 Sep 2026·presentverdict: present · default bool:false
v2.1.27517 Sep 2026·presentverdict: present · default bool:false
v2.1.27618 Sep 2026·presentverdict: present · default bool:false
v2.1.27718 Sep 2026·presentverdict: present · default bool:false
v2.1.27819 Sep 2026·presentverdict: present · default bool:false
v2.1.28022 Sep 2026·presentverdict: present · default bool:false

Read out of the published npm bundle release by release, and out of Anthropic's own documentation as this site captured it. Nothing on this page is a description anybody here wrote about what the feature flag does. All feature flags.

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