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 v2.1.30 Home All releases olderv2.1.29 v2.1.31newer
Claude Code v2.1.30

System Prompt Variants [In Development]

What

Infrastructure for A/B testing different system prompt variants fetched from the server.

Status

Feature-flagged via tengu_vinteuil_phrase

Details
  • New /api/oauth/claude_cli/client_data endpoint for fetching system prompt configuration
  • system_prompt_variant field parsed from client data
  • When the flag is enabled, a simplified "proactive" system prompt path is used
  • Logging added: [SystemPrompt] client_data system_prompt_variant= and [SystemPrompt] path=simple proactive=
Evidence

System prompt variant system (gated by tengu_vinteuil_phrase, search for "system_prompt_variant" and "/api/oauth/claude_cli/client_data")

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

See this entry in the whole of v2.1.30 →