[BUG] v2.1.81: VS Code extension fails with 503 error on Bedrock (CLI works fine)

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?

After updating the VS Code extension to v2.1.81, Claude Code fails to connect to AWS Bedrock with error 503. The CLI version 2.1.81 works fine with the same credentials.

## Error Message (VS Code only)
API Error: 503 Bedrock is unable to process your request.

## Environment

• VS Code Extension Version: 2.1.81 (broken) → 2.1.79 (working)
• CLI Version: 2.1.81 (works fine)
• VS Code Version: 1.112.0
• OS: Windows 10 Enterprise LTSC 2019
• Model: Claude Sonnet 4.5 via AWS Bedrock
• Provider: AWS Bedrock

## Configuration
```json
{
"terminal.integrated.env.windows": {
"CLAUDE_CODE_USE_BEDROCK": "1",
"AWS_PROFILE": "<profile-name>",
"CLAUDE_CODE_GIT_BASH_PATH": "C:\\Program Files\\Git\\bin\\bash.exe"
},
"claudeCode.disableLoginPrompt": true
}

What Should Happen?

VS Code extension should connect to Bedrock successfully (as CLI v2.1.81 does, and as VS Code extension v2.1.79 did)

Workaround

Rolling back to v2.1.79 resolves the issue.

Notes

• Claude Code CLI works fine with same credentials
• No authentication errors (401/403), specifically a 503 service error

Error Messages/Logs

Steps to Reproduce

1. Configure AWS Bedrock credentials
2. Update VS Code extension to v2.1.81 (CLI can stay at 2.1.81)
3. Try to send a message in Claude Code sidebar/panel
4. Receive 503 error

Claude Model

Sonnet (default)

Is this a regression?

Yes, this worked in a previous version

Last Working Version

2.1.79

Claude Code Version

2.1.81

Platform

AWS Bedrock

Operating System

Windows

Terminal/Shell

PowerShell

Additional Information

• CLI v2.1.81 works perfectly with same credentials and configuration
• Issue is specific to the VS Code extension
• No authentication errors (401/403), specifically a 503 service error