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Sweep 22 Oct 2026 · 04:32Z Build v2.1.308 527 read Stable v2.1.308 Latest v2.1.308 Next v2.1.308 Feeds RSS JSON llms.txt llms-full.txt Unofficial
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Claude Code v2.1.223 ·

New prompt-variant experiment for two tools

An alternate prompt wording for two tools exists but stays off unless you set an environment variable.

Nothing to try yet Notable No documentation found In Development
JSON All of v2.1.223
Nothing to try yetTier: how much it should matter to you
2Useful: my rating, 1 to 5
3Signal: worth watching, 1 to 5
AgentsArea: what it touches
In DevelopmentKind: in v2.1.223,
What probably matters to youSection of the release

Alternate tool prompt variants sit behind CLAUDE_CODE_PARCHMENT_FERN and a gate defaulting to false.

What

Two model-scoped predicates were added that swap in an alternate prompt variant for their tools. Off by default in this build.

Details
  • Enabled by the environment variable CLAUDE_CODE_PARCHMENT_FERN, a per-model opus_5_prompt_bundle capability, a settings key, or the gate tengu_parchment_fern, which falls back to false.
  • One of the two predicates is additionally conditioned on the existing per-model tengu_velvet_mallet gate.
  • When active, the variants appear as marker prefixes in the prompt-cache key.
Evidence

tengu_parchment_fern

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

Read from
Names in the bundleCLAUDE_CODE_PARCHMENT_FERN
Feature flag
tengu_parchment_fern Off in both readings

The flag server returned off for the account this site reads and for the anonymous baseline. A reading of off cannot rule out a rollout these two readings sit outside of.

This account: off · anonymous baseline: off · compiled default in v2.1.223: not a boolean we can read

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_velvet_mallet Off in both readings

The flag server returned off for the account this site reads and for the anonymous baseline. A reading of off cannot rule out a rollout these two readings sit outside of.

This account: off · anonymous baseline: off · compiled default in v2.1.223: not a boolean we can read

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

What has happened since
Flag reading moved The flag server now returns off for tengu_parchment_fern, read as this account. A reading is one sample. Claude Code evaluates its flags remotely, so no client sees the targeting rule behind a value and this says nothing about your account.
Flag reading moved The flag server now returns nothing at all, having stopped carrying it for tengu_parchment_fern, read as this account. A reading is one sample. Claude Code evaluates its flags remotely, so no client sees the targeting rule behind a value and this says nothing about your account.

See this across every release →

How sure we are
One source agreesOne thing we can check says the same as this entry.
The name it cites is new in this buildNew in this build: CLAUDE_CODE_PARCHMENT_FERN

See this entry in the whole of v2.1.223 →

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