Source Intelligence

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.

All of v2.1.251 Home All releases olderv2.1.250
Claude Code v2.1.251

Thumbnail checks in the artifact publish preflight

Not switched on
Useful1 Signal3
Artifacts

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

Thumbnail preflight warnings exist behind an experiment defaulting off.

Feature flag
tengu_cobalt_plinth_campion Not enough to say

Nothing here resolved what this flag was doing on this version, so nothing here should be read as on or off.

This account: no value returned · anonymous baseline: no value returned · compiled default in v2.1.251: on

Read once, for one account on one subscription tier, against v2.1.251. It isn't a statement about your account. What a flag value here can and cannot tell you

What

Publish validation for HTML pages can inspect thumbnails and report problems as preflight warnings, but the experiment controlling it defaults to off, so no publish runs the check in this build.

Details
  • Gate: tengu_cobalt_plinth_campion, default false.
Evidence

kind: "thumbnail"

Strings lifted out of the shipped bundle, so the claim above can be checked against them.

See this entry in the whole of v2.1.251 →