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Sweep 28 Aug 2026 · 00:00Z Build v2.1.250 478 read Stable v2.1.236 Latest v2.1.250 Next v2.1.250 Feeds RSS JSON llms.txt

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.

Reference / Feature flags

tengu_cobalt_wren

A Claude Code feature flag, read out of the shipped bundle. It has been in the build since v2.1.138, including the newest one read.

What it is

Nobody has written a line about this one. It is not in any of Anthropic's reference tables and no changelog entry here carries a description of it. It is in the build, which is the whole of what this page can claim.

Presence across releases

ReleasesReadingDeclared typeDefault
2.1.245 – 2.1.250 5 releases never mined — —
2.1.138 – 2.1.243 95 releases in the build — bool:false

A row reading never mined is a release with no archived bundle behind it. Nothing was read out of it, so nothing here says whether the name was in it. A declared type or a default is only ever what that release's own bundle stated.

Gate readings

No release here has a gate table behind it for this flag. Most published releases have none at all: the readings exist only for versions the pipeline captured flag state on.

Changelog entries naming it

No changelog entry here has ever named it. That is a statement about what has been written, not about the name: it has been in the build since v2.1.138 without anybody writing a line about it.

Documentation pages

None of Anthropic's documentation pages this site has a copy of carries this name.

Names beside it

Every feature flag in the inventory starting tengu_cobalt, up to twelve of them.

tengu_cobalt_compassNo description from anybody. never mined tengu_cobalt_frostNo description from anybody. never mined tengu_cobalt_harborWhether remote control auto-started, and why, is now recorded. 2.1.181 tengu_cobalt_harbor_noticeA resume-precheck gate is now passed to the VS Code extension, on by default. 2.1.191 tengu_cobalt_heronNo description from anybody. 2.1.191 tengu_cobalt_lanternQuick web setup stays off, now behind a named helper needing a flag and two entitlements. 2.1.138 tengu_cobalt_plinthPR review artifact pages can show a pinned button that approves the pull request from your GitHub account. 2.1.172 tengu_cobalt_plinth_alderClaude can now read back a published artifact's contents; browsing, multi-file publishing and deletion are built but off. 2.1.239 tengu_cobalt_plinth_aspenThe preview browser is locked to the local server and refuses to run if the lock fails. never mined tengu_cobalt_plinth_brackenYou could start a private artifact from a published template, but two server switches keep it shut here. 2.1.216 tengu_cobalt_plinth_datavizThe chart skill hint now only appears if the dataviz skill is actually installed. 2.1.198 tengu_cobalt_plinth_directArtifact availability now hinges on one gate, and direct upload kicks in for create paths. 2.1.172

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.