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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 v2.1.223 Home All releases ←olderv2.1.222 v2.1.224newer→
Claude Code v2.1.223

Thrifty-sonic narrowed to one model; plan artifacts moved to its own gate

Not switched on
Useful3 Signal4
Plan Mode Notable not in their notes

Plan artifacts now have their own switch instead of riding along with an unrelated experiment.

Plan artifacts read CLAUDE_CODE_PLAN_ARTIFACTS and a gate that falls back to false, so it is off by default.

Feature flag
tengu_thrifty_sonic On for this account, and not off by default

The flag server returned on for the one account this site reads, and nothing in this release compiles it off by default. The compiled default is shown below, and says which it is when we cannot read one: a fifth of gates compile in a string or a number rather than on or off, and most published releases have no gate table behind them at all. No client can see what the server returns for your account.

This account: on · anonymous baseline: on · compiled default in v2.1.223: on

These values were read against a different version of Claude Code, so treat them as the nearest reading available instead of one taken on this release.

tengu_basalt_loom 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 v2.1.223: on

These values were read against a different version of Claude Code, so treat them as the nearest reading available instead of one taken on this release.

Read once, for one account on one subscription tier, against v2.1.223. It isn't a statement about your account. What a flag value here can and cannot tell you

CLAUDE_CODE_PLAN_ARTIFACTS
What

The thrifty-sonic experiment now only applies to a single model, and the plan-artifacts toggle no longer shares its gate.

Details
  • The thrifty-sonic check short-circuits unless the model resolves to claude-opus-5, before tengu_thrifty_sonic is consulted; its environment variable is unchanged.
  • Plan artifacts now read the environment variable CLAUDE_CODE_PLAN_ARTIFACTS and the gate tengu_basalt_loom, which falls back to false, replacing the tengu_thrifty_sonic read that was there.
Evidence

CLAUDE_CODE_PLAN_ARTIFACTS

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

Related

Other releases about the same thing. Found by shared names or similar wording; neither means one caused the other.

See this entry in the whole of v2.1.223 →