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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_ethereal_nova

A Claude Code feature flag, read out of the shipped bundle. It has been in the build since v2.1.229, including the newest one read.

What it is

A /design skill drafting multi-artboard canvases as editable Artifacts is bundled but switched off.

Not Anthropic's. This is the line from the earliest changelog entry here that named it, v2.1.229.

Presence across releases

ReleasesReadingDeclared typeDefault
2.1.245 – 2.1.250 5 releases never mined — —
2.1.238 – 2.1.243 6 releases in the build — bool:true
2.1.229 – 2.1.237 8 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

ReleaseResolvedThis accountAnonymousCompiled default
v2.1.238 Off by default, switched on for this account on on off
v2.1.234 Off in both readings off off on
v2.1.229 read on another version On for this account, and not off by default on on on

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.

Changelog entries naming it

  1. v2.1.238A /design command that drafts a design on a canvas artifact

    A /design command that drafts a design on a canvas artifact now registers by default, if your account allows it.

    gate cited by this entry

  2. v2.1.238The /design skill prompt was rewritten and its page seeder gained warnings

    The /design skill got stricter rules and now demands a path, a description and a favicon emoji.

    gate cited by this entry

  3. v2.1.238The tengu_ethereal_nova gate's built-in default is now on

    A feature switch that used to default off now defaults on when the server says nothing.

    gate cited by this entry

  4. v2.1.234Design canvas skill pins a runtime version and gains explicit failure paths

    The design canvas skill pins a fixed runtime version and adds refusal paths, behind an off-by-default flag.

    named in this entry, gate cited by this entry

  5. v2.1.229New /design skill drafts multi-artboard canvases as an Artifact, gated off

    A /design skill drafting multi-artboard canvases as editable Artifacts is bundled but switched off.

    gate cited by this entry

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_ethereal, up to twelve of them.

tengu_ethereal_mistA 403 injected by your corporate proxy is retried as an outage instead of a hard refusal. 2.1.238

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.