Anthropic Claude Code secretly checks if you're in China, sparking developer backlash

User LegitMichel777 found that Claude Code 2.1.196 has a hidden feature that checks if your system timezone is set to China (Asia/Shanghai or Asia/Urumqi) and if your URL matches a list of 147 Chinese tech and AI lab domains, including Baidu, Alibaba, ByteDance, Moonshot AI, and others. This has been in the tool since April.

The detection results are hidden in system prompts, not sent separately. For example, the date format changes from "2026-06-30" to "2026/06/30", and apostrophes are replaced with special Unicode characters to mark different statuses. Anthropic team member Thariq Shihipar said this was an "experimental" measure from March 2026 to stop unauthorized reselling and model distillation. They've already added better fixes and plan to remove this code in the next update on July 2, 2026.