[BUG] Despite thinking being enabled, I can not run claude-code properly due to clear_thinking_20251015 strategy

Preflight Checklist

• [x] I have searched existing issues and this hasn't been reported yet
• [x] This is a single bug report (please file separate reports for different bugs)
• [x] I am using the latest version of Claude Code

What's Wrong?

When I try to input any prompt inside the claude, the error 'clear_thinking_20251015' strategy requires 'thinking' to be enabled pops out when I have already set "alwaysThinkingEnabled": true in my ~/.claude/settings.json.

What Should Happen?

Should works in general.

Error Messages/Logs

API Error: 400 {"error":{"message":"litellm.BadRequestError: OpenAIException - litellm.BadRequestError: Vertex_aiException BadRequestError - b'{\"type\":\"error\",\"error\":{\"type\":\"invalid_request_error\",\"message\":\"`clear_thinking_20251015` strategy requires
     `thinking` to be enabled\"},\"request_id\":\"req_vrtx_011CXatYWV561km9ggyjdufj\"}'. Received Model Group=claude-4.5-sonnet\nAvailable Model Group Fallbacks=None. Received Model Group=openai/claude-4.5-sonnet\nAvailable Model Group
     Fallbacks=None","type":null,"param":null,"code":"400"}}

Steps to Reproduce

1. Open Claude
2. Type something randomly

Claude Model

Sonnet (default)

Is this a regression?

Yes, this worked in a previous version

Last Working Version

_No response_

Claude Code Version

2.1.23

Platform

Anthropic API

Operating System

macOS

Terminal/Shell

iTerm2

Additional Information

Should be related to the following issues:

1. https://github.com/anthropics/claude-code/issues/11690
2. https://github.com/anthropics/claude-code/issues/11773
3. https://github.com/anthropics/claude-code/issues/11533

But sadly I didn't find any useful information from these issues...