### Check for existing issues

- [x] I have searched the existing issues and checked that my issue is not a duplicate.

### The Feature

Bedrock Mantle provides application-level isolation mechanisms as described in the following documentation. In our organization, we create projects for cost isolation (CUR), and we require the ability to associate inference requests with a project at request time.

[https://docs.aws.amazon.com/bedrock/latest/userguide/projects.html](vscode-file://vscode-app/Applications/Visual%20Studio%20Code.app/Contents/Resources/app/out/vs/code/electron-browser/workbench/workbench.html)

``` curl -X POST $OPENAI_BASE_URL/responses \ -H "Authorization: Bearer $OPENAI_API_KEY" \ -H "Content-Type: application/json" \ -H "OpenAI-Project: proj_5d5ykleja6cwpirysbb7" \ -d '{ "model": "openai.gpt-oss-120b", "input": "Explain the benefits of using projects in Amazon Bedrock" }' ```

This is the value that is currently set: (Model Row json) ``` { "model_name": "gemma-4-31b-digital-worker-sandbox", "litellm_params": { "aws_region_name": "us-east-1", "custom_llm_provider": "bedrock_mantle", "use_in_pass_through": false, "use_litellm_pr…