Source Intelligence
Follow Discord

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

Model-specific extra reminders remain driven by two client-data keys

Under the hood
Useful2 Signal4
System Prompt Notable not in their notes

Two client-data keys can still inject model-specific extra instructions once per conversation.

CLAUDE_CODE_TOASTY_THIMBLECLAUDE_CODE_GENTLE_PARASOL
What

Two mechanisms can inject extra instruction text chosen by matching the model name, one for batching behaviour and one as a secondary reminder, each sourced from CLAUDE_CODE_TOASTY_THIMBLE or CLAUDE_CODE_GENTLE_PARASOL or from a server-supplied map. Each applies once per conversation per model. Both existed before this release; the wiring around them has moved.

Details
  • Telemetry records when each is applied.
  • With neither the environment variable nor a server-supplied value set, nothing is injected.
Evidence

CLAUDE_CODE_TOASTY_THIMBLE

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 v2.1.251 →