[Bug] Claude Code 2.1.153 + DeepSeek V4 → 400 thinking mode error

[leanmore]

Self Checks / 自检

• I have read the FAQ section in README.
  我已阅读 README 中的常见问题。

• I have searched for existing issues, including closed ones.
  我已搜索过已有的 Issue，包括已关闭的。

CC Switch Version / 版本号

3.15.0

Operating System / 操作系统

Windows

Related App / 涉及应用

Claude Code

Steps to Reproduce / 重现步骤

1. Configure CC Switch to proxy Claude Code to DeepSeek V4 via Anthropic-compatible endpoint:
   • Set ANTHROPIC_BASE_URL=https://api.deepseek.com/anthropic
   • Provide a valid DeepSeek API key
2. In VS Code, open Claude Code plugin (version 2.1.153)
3. Start a conversation by asking a question that triggers reasoning_content (e.g., "Explain quantum computing in detail")
4. After receiving the response, ask a follow-up question (e.g., "Can you elaborate on the second point?")
5. Observe the error: HTTP 400 with message "The content[].thinking in the thinking mode must be passed back to the API."

Expected Behavior / 期望行为

Claude Code should continue the conversation normally through CC Switch, without any manual intervention regarding thinking mode. The proxy should handle DeepSeek's reasoning_content requirement transparently.

Actual Behavior / 实际行为

After a few turns, Claude Code fails with HTTP 400 error. DeepSeek API rejects the request because the thinking block (or reasoning_content) is missing or malformed.

Additional Context / 补充信息

• DeepSeek models used: deepseek-v4-pro[1M], deepseek-v4-flash[1M]
• VS Code version: 1.122.0 (user setup)
  • Commit: 6a49527b96e326fe62fbdb56f60e16877c9aa724
  • Electron: 39.8.8 / Chromium: 142.0.7444.265 / Node.js: 22.22.1
• CC Switch local proxy port: 127.0.0.1:15721
• The issue likely stems from protocol incompatibility:
  • DeepSeek V4 enables thinking mode by default, requiring clients to send back reasoning_content in subsequent requests.
  • Claude Code 2.1.153 sends thinking.type="adaptive" (unsupported) and does not preserve/return reasoning_content.
• Workaround: Bypass CC Switch and use a dedicated proxy like dsv4-cc-proxy (https://gitcode.csdn.net) that handles the thinking mode translation.
• This problem started after updating Claude Code plugin to 2.1.153. Older versions worked fine.

[zhengwh]

MacOS has the same error

API Error: 400 The `content[].thinking` in the thinking mode must be passed back to the API

Resolution on Mac

Steps:

1. Remove the claude code ,you can ask the deepseek in web
2. Set the claude.json ,pls do not upgrade automatically
3. install the special version with curl

# 1. 
rm -f ~/.local/bin/claude

# 2. 
rm -rf ~/.local/share/claude

then

vim ~/.claude/settings.json


{
  "env": {
    "DISABLE_AUTOUPDATER": "1"
  }
}

then

curl -fsSL https://claude.ai/install.sh | bash -s 2.1.150

ok, just enjoy it

[HydrangeaPurple]

Just downgrade Claude Code to 2.1.150

claude_bootstrap.zip

---

This is a modified version of the claude installation powershell script, you can specify the version number using the interactive command line

[leonid-mironyx]

was this introduced intentionally :) :) ?

[cgoder]

156版本同样如此

[undefine4080]

奇怪，只有 v4pro 会报这个错误，glm5.1 没这问题。不确定是模型适配的问题，还是 CC 内部的问题

[HydrangeaPurple]

奇怪，只有 v4pro 会报这个错误，glm5.1 没这问题。不确定是模型适配的问题，还是 CC 内部的问题

Deepseek requires the return of the thinking chain after tool calls, but the claude code does not send.

[wanglaohan]

cc 掺屎了吧

[FFengIll]

please try https://github.com/tingly-dev/tingly-box to help
and some deepseek support here tingly-dev/tingly-box#1042

[farion1231]

感谢反馈！

这个问题已经在 CC Switch v3.16.0 / v3.16.1 中修复或实现，相关变更已进入 release notes / changelog。我们先关闭这个 issue。

如果你升级到 v3.16.1 或更新版本后仍然可以稳定复现，请在这里补充以下信息，我们会重新打开继续跟进：

• CC Switch 版本
• 操作系统
• 相关应用版本（Claude Code / Codex / Claude Desktop 等）
• 复现步骤
• 相关日志或截图

再次感谢你的反馈和复现信息。