tengu_cobalt_plinth_sloe
A Claude Code feature flag, read out of the shipped bundle. It was in the build from v2.1.281 and was gone by v2.1.296.
The Artifact tool's instructions now come in versions v0, v1 and v2, picked once per session by an env var, the session origin or a flag
Not Anthropic's. This is the line from the earliest changelog entry here that named it, v2.1.281.
In the changelogs
3Releases whose published page names tengu_cobalt_plinth_sloe.
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v2.1.281
Artifact tool text variants v0/v1/v2 selected by env var or flag
The Artifact tool's instructions now come in versions v0, v1 and v2, picked once per session by an env var, the session origin or a flag
gate cited by this entry, found in this entry's text
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v2.1.281
Artifacts tool: prompt text variants behind tengu_cobalt_plinth_sloe
The Artifacts tool's instructions to the model now come in three text variants, v0, v1 and v2, chosen once per session
gate cited by this entry, found in this entry's text
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v2.1.281
New gate tengu_swirling_squid for Artifact capabilities inherited from a type
Behind
tengu_swirling_squid, publishing an Artifact made from a published type notes that its capabilities come from that typegate cited by this entry, found in this entry's text
Gate readings
1| Release | Resolved | This account | Anonymous | Compiled default |
|---|---|---|---|---|
| v2.1.281 read on another version | Not enough to say | no value returned | no value returned | not a boolean we can read |
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.
Flag server, over time
4| Read as | Reading | From | Until | Version installed |
|---|---|---|---|---|
| this account | no longer carried | 2026-10-10T22:00:07Z | 2026-10-10T22:00:07Z | v2.1.296 |
| anonymous | no longer carried | 2026-10-10T21:25:04Z | 2026-10-10T21:25:04Z | v2.1.296 |
| this account | "v0" | 2026-09-23T20:10:05Z | 2026-10-10T21:25:04Z | v2.1.281 to v2.1.296 |
| anonymous | "v0" | 2026-09-23T20:05:05Z | 2026-10-10T18:30:07Z | v2.1.281 to v2.1.296 |
One row per unbroken stretch of one reading, newest first, from snapshots taken every twenty-five minutes or so. No longer carried is not off: it means the flag server stopped returning the gate at all, which is what a retired experiment looks like. The version column is what was installed when the reading was taken, not what caused it.
First cited
2The earliest release whose published evidence quoted tengu_cobalt_plinth_sloe was v2.1.281, 23 Sep 2026. That is the oldest release this project wrote about it, so it is a floor on the name's age and not the release that introduced it. It is not a presence reading: which builds carried the name is the table below.
Presence across releases
2Build by build
38One 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.
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.