[BUG] `alwaysThinkingEnabled: true` in settings.json does not enable thinking mode by default on Bedrock

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?

alwaysThinkingEnabled: true in ~/.claude/settings.json does not enable
thinking mode by default when starting a new session on Bedrock. The setting is
ignored silently.

Additionally, enabling thinking mode via /config only takes effect for the
current session and does not persist across sessions.

Alt+T toggle works correctly within a session.

### Steps to reproduce

1. Add "alwaysThinkingEnabled": true to ~/.claude/settings.json
2. Start a new Claude Code session
3. Thinking mode is OFF
4. Enable thinking mode via /config
5. Exit session and start a new session
6. Thinking mode is OFF again

### Environment

• Claude Code version: 2.1.42
• Provider: Amazon Bedrock
• Model: Application Inference Profile (Opus 4.6)
• OS: Ubuntu 22.04 (Linux 6.8.0-1044-aws)
• Node.js: v22.19.0

### settings.json

``json
{
"env": {
"CLAUDE_CODE_USE_BEDROCK": "1",
"AWS_REGION": "ap-northeast-1",
"ANTHROPIC_MODEL":
"arn:aws:bedrock:ap-northeast-1:...:application-inference-profile/..."
},
"language": "japanese",
"alwaysThinkingEnabled": true
}
``

### Notes

• Changelog v2.0.67: "Thinking mode configuration has moved to /config"
• Changelog v2.0.72: "Fix thinking mode toggle in /config not persisting

correctly"

• Despite these fixes, the issue still persists in v2.1.42 on Bedrock

What Should Happen?

• alwaysThinkingEnabled: true in settings.json should enable thinking mode by

default on session start

• /config thinking mode toggle should persist across sessions
• Both methods should work consistently on Bedrock, same as on direct Anthropic

API

Error Messages/Logs

Steps to Reproduce

### Steps to reproduce

1. Add "alwaysThinkingEnabled": true to ~/.claude/settings.json
2. Start a new Claude Code session
3. Thinking mode is OFF
4. Enable thinking mode via /config
5. Exit session and start a new session
6. Thinking mode is OFF again

### Environment

• Claude Code version: 2.1.42
• Provider: Amazon Bedrock
• Model: Application Inference Profile (Opus 4.6)
• OS: Ubuntu 22.04 (Linux 6.8.0-1044-aws)
• Node.js: v22.19.0

### settings.json

``json
{
"env": {
"CLAUDE_CODE_USE_BEDROCK": "1",
"AWS_REGION": "ap-northeast-1",
"ANTHROPIC_MODEL":
"arn:aws:bedrock:ap-northeast-1:...:application-inference-profile/..."
},
"language": "japanese",
"alwaysThinkingEnabled": true
}
``

Claude Model

Opus

Is this a regression?

I don't know

Last Working Version

_No response_

Claude Code Version

2.1.42 (Claude Code)

Platform

AWS Bedrock

Operating System

Ubuntu/Debian Linux

Terminal/Shell

Other

Additional Information

_No response_