[BUG] `AWS_BEARER_TOKEN_BEDROCK` auth broken in 2.1.92+ (regression from 2.1.91)

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?

Bedrock bearer token authentication stopped working in 2.1.92. Every request returns "403 {"Message":"Authorization header is missing"}" from AWS Bedrock. Downgrading to 2.1.91 fixes the issue immediately without any config changes.

What Should Happen?

Requests should authenticate via AWS_BEARER_TOKEN_BEDROCK set in ~/.claude/settings.json, as they did in 2.1.91.

Error Messages/Logs

Failed to authenticate. API Error: 403 {"Message":"Authorization header is missing"}
Retrying in 4 seconds… (attempt 5/10)

Steps to Reproduce

1. Configure ~/.claude/settings.json with CLAUDE_CODE_USE_BEDROCK=1 and a valid AWS_BEARER_TOKEN_BEDROCK
2. Run claude or claude -p "test"
3. Observe 403 {"Message":"Authorization header is missing"}

Notes:

• The token is valid — aws bedrock list-foundation-models --region us-west-2 succeeds with the same token
• Setting env vars explicitly before launching (CLAUDE_CODE_USE_BEDROCK=1 AWS_BEARER_TOKEN_BEDROCK=... claude -p "test") also fails
• Downgrading to 2.1.91 fixes it: ln -sf ~/.local/share/claude/versions/2.1.91 ~/.local/bin/claude
• Versions 2.1.92 and 2.1.94 both fail
• macOS Darwin 25.2.0, native install

Claude Model

Sonnet (default)

Is this a regression?

Yes, this worked in a previous version

Last Working Version

2.1.91

Claude Code Version

2.1.94

Platform

AWS Bedrock

Operating System

macOS

Terminal/Shell

Warp

Additional Information

Auth is configured entirely via ~/.claude/settings.json env block — no oauthAccount or primaryApiKey in ~/.claude.json. The settings.json env injection appears to work, but the Bedrock client constructor reads process.env before the injection runs, so the token is missing at request time.

Relevant settings.json structure:

{
  "env": {
    "CLAUDE_CODE_USE_BEDROCK": "1",
    "AWS_BEARER_TOKEN_BEDROCK": "<token>",
    "ANTHROPIC_BEDROCK_BASE_URL": "https://bedrock-runtime.us-west-2.amazonaws.com/",
    "ANTHROPIC_MODEL": "us.anthropic.claude-sonnet-4-6",
    "ANTHROPIC_DEFAULT_SONNET_MODEL": "us.anthropic.claude-sonnet-4-6"
  }
}