[FEATURE] Compatability with non "default" AWS Bedrock Mantle Projects

Preflight Checklist

• [x] I have searched existing requests and this feature hasn't been requested yet
• [x] This is a single feature request (not multiple features)

Problem Statement

Based on the API docs for AWS Bedrock-Mantle, the way to set the Bedrock-Mantle Project on inference requests is via the anthropic-workspace-id or OpenAI-Project headers.

Configuring ClaudeCode with CLAUDE_CODE_USE_MANTLE=1 to use Bedrock-Mantle appears to not pick up either ANTHROPIC_WORKSPACE_ID or ANTHROPIC_AWS_WORKSPACE_ID to be used as a header in the request.

Proposed Solution

Impletment support for an environment variable and claude code setting like:

MANTLE_PROJECT=<MANTLE_PROJECT_ID>

that sets the anthropic-workspace-id header in inference requests to the value of the env var.

This would enable an intuitive and seamless mechanism to enable multi-project support for Bedrock-Mantle users

Alternative Solutions

My current workaround is setting ANTHROPIC_CUSTOM_HEADERS: "anthropic-workspace-id: <MANTLE_PROJECT_ID>

Priority

High - Significant impact on productivity

Feature Category

CLI commands and flags

Use Case Example

I need to utilize different Bedrock-Mantle projects within a single AWS account.

Additional Context

_No response_