tengu_cobalt_plinth_damson
A Claude Code feature flag, read out of the shipped bundle. It has been in the build since v2.1.257, including the newest one read.
The artifact tool's flat verbs are mapped to a canonical action shape, with a gate deciding which toolset is active.
Not Anthropic's. This is the line from the earliest changelog entry here that named it, v2.1.257.
In the changelogs
5Releases whose published page names tengu_cobalt_plinth_damson.
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v2.1.265
Artifact tool actions being consolidated into list/read with a scope parameter
Artifact tool messages now describe actions as unified list/read calls with a scope, not old per-type names
gate cited by this entry
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v2.1.265
New artifact-type instruction wording toggle tied to the 'artifact toolset' consolidation
Artifact instructions can now say 'action: read' instead of 'action: describe_type' when a newer artifact toolset is active
gate cited by this entry
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v2.1.259
Artifact-toolset tool-name substitution layer (data/comments/check)
A substitution layer can rewrite legacy artifact tool actions into consolidated data, comments and check tools, adding a spelling notice to prompts.
gate cited by this entry
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v2.1.257
Artifact tool restructured into action-based dispatch, behind a gated toolset switch
The artifact tool's flat verbs are mapped to a canonical action shape, with a gate deciding which toolset is active.
found in this entry's text, gate cited by this entry
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v2.1.257
New artifact-tool actions: version, open, and handler invocation
Artifact tool output now renders version, open and handler actions including get_handlers, call_handler and run_script.
gate cited by this entry
Gate readings
3| Release | Resolved | This account | Anonymous | Compiled default |
|---|---|---|---|---|
| v2.1.265 | Not enough to say | no value returned | off | off |
| v2.1.259 read on another version | Off in both readings | off | off | off |
| v2.1.257 read on another version | Off in both readings | off | off | 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.
Flag server, over time
20| Read as | Reading | From | Until | Version installed |
|---|---|---|---|---|
| this account | on | 2026-11-02T13:05:04Z | 2026-11-12T09:10:04Z | v2.1.316 to v2.1.322 |
| anonymous | on | 2026-10-17T05:30:04Z | 2026-11-12T09:10:04Z | v2.1.302 to v2.1.322 |
| this account | off | 2026-11-02T12:55:05Z | 2026-11-02T12:55:05Z | v2.1.316 |
| this account | on | 2026-11-01T20:45:05Z | 2026-11-02T12:40:07Z | v2.1.316 |
| this account | off | 2026-11-01T20:40:05Z | 2026-11-01T20:40:05Z | v2.1.316 |
| this account | on | 2026-11-01T20:25:04Z | 2026-11-01T20:30:06Z | v2.1.316 |
| this account | off | 2026-11-01T20:20:05Z | 2026-11-01T20:20:05Z | v2.1.316 |
| this account | on | 2026-10-07T18:00:12Z | 2026-11-01T19:30:06Z | v2.1.292 to v2.1.316 |
| anonymous | no longer carried | 2026-10-17T05:25:57Z | 2026-10-17T05:25:57Z | v2.1.302 |
| anonymous | on | 2026-09-15T15:50:05Z | 2026-10-17T05:10:04Z | v2.1.272 to v2.1.302 |
| this account | off | 2026-10-07T17:59:34Z | 2026-10-07T17:59:34Z | v2.1.293 |
| this account | on | 2026-09-15T15:55:04Z | 2026-10-07T17:10:05Z | v2.1.272 to v2.1.292 |
| this account | off | 2026-09-10T21:47:12Z | 2026-09-15T15:50:05Z | v2.1.268 to v2.1.272 |
| anonymous | off | 2026-08-31T21:35:04Z | 2026-09-15T15:25:04Z | v2.1.251 to v2.1.272 |
| this account | no longer carried | 2026-09-10T21:46:45Z | 2026-09-10T21:46:45Z | v2.1.268 |
| this account | off | 2026-09-08T20:36:15Z | 2026-09-10T17:40:05Z | v2.1.263 to v2.1.267 |
| this account | no longer carried | 2026-09-08T20:34:58Z | 2026-09-08T20:34:58Z | v2.1.265 |
| this account | off | 2026-09-06T02:40:05Z | 2026-09-08T18:45:05Z | v2.1.261 to v2.1.263 |
| this account | no longer carried | 2026-09-06T02:36:19Z | 2026-09-06T02:36:19Z | v2.1.263 |
| this account | off | 2026-08-31T23:15:05Z | 2026-09-06T01:55:04Z | v2.1.251 to v2.1.261 |
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
1The earliest release whose published evidence quoted tengu_cobalt_plinth_damson was v2.1.257, 1 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
1Build by build
59One 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.