Claude Code is steganographically marking requests
Inspecting the Claude Code binary (v2.1.196), a developer found a function that silently swaps the apostrophe in “Today’s” and the date separator in the system prompt for look-alike Unicode characters — a steganographic marker triggered when ANTHROPIC_BASE_URL is set and the timezone or hostname matches a base64-encoded list of (largely Chinese proxy/reseller and rival-lab) domains, letting the backend flag requests routed through third-party gateways.