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

A stripped-down system prompt mode, off in this build

Not switched on
Useful3 Signal5
System Prompt Notable not in their notes

A mode keeps the system prompt static and moves environment details into conversation reminders, off by default.

The static-prompt mode is off unless an env var is set, with the remote flag defaulting false.

CLAUDE_CODE_CARVED_SLATE
What

A mode that keeps the system prompt static and instead injects the environment snapshot, output-style guidance and language instructions as reminder blocks in the conversation. It is off unless CLAUDE_CODE_CARVED_SLATE is set; otherwise a remote flag decides, and that flag defaults to false.

Details
  • The reminder injection is further suppressed when the CLAUDE_CODE_SIMPLE env var indicates simple mode, or when the session is a bare fork.
  • Only main agents and teammates get the reminders; a subagent gets them only when it is the main session.
Evidence

a.CLAUDE_CODE_CARVED_SLATE ?? x(HXt, !1)

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 →