[BUG] Claude Code in VSCode expects model deployments from Azure Foundry in lowercase

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?

I am using the latest version of Claude Code available for VSCode (2.0.55) and the following configuration with Azure Foundry:

"claudeCode.environmentVariables": [
{
"name": "CLAUDE_CODE_ENABLE_TELEMETRY",
"value": "0"
},
{
"name": "CLAUDE_CODE_SKIP_AUTH_LOGIN",
"value": "1"
},
{
"name": "CLAUDE_CODE_USE_FOUNDRY",
"value": "1"
},
{
"name": "ANTHROPIC_FOUNDRY_RESOURCE",
"value": "<resource_name>"
},
{
"name": "ANTHROPIC_FOUNDRY_API_KEY",
"value": "<api_key>"
},
{
"name": "ANTHROPIC_DEFAULT_SONNET_MODEL",
"value": "<deployment_name>"
},
{
"name": "ANTHROPIC_DEFAULT_HAIKU_MODEL",
"value": "<deployment_name>"
},
{
"name": "ANTHROPIC_DEFAULT_OPUS_MODEL",
"value": "<deployment_name>"
},
{
"name": "CLAUDE_CODE_SUBAGENT-MODEL",
"value": "<deployment_name>"
}
],
"claudeCode.allowDangerouslySkipPermissions": true,
"claudeCode.selectedModel": "sonnet"


In Azure Foundry I have deployed a claude model and some letters are capital like "CLAUDE45-GS", when I use this setting:

{
"name": "ANTHROPIC_DEFAULT_SONNET_MODEL",
"value": "<deployment_name>"
}


Then I get the following error in Chat window:

API Error: 404 {"error":{"code":"DeploymentNotFound","message":"The API deployment claude45-gs does not exist. If you created the deployment within the last 5 minutes, please wait a moment and try again.","details":"The API deployment claudesonnet45-gs does not exist. If you created the deployment within the last 5 minutes, please wait a moment and try again."}}


If I deploy a model with lower case then it works.

What Should Happen?

The extension should not make the configured deployment name to lowercase as deployments into Azure Foundry are case sensitive.

Error Messages/Logs

The deployment name (with lower case) is not found while the deployment name is configured with upper case.

Steps to Reproduce

1. Deploy a model in Azure Foundry including a capital letter.
2. Configure this deployment name into Claude Code settings.
3. Try use the chat window

Claude Model

None

Is this a regression?

Yes, this worked in a previous version

Last Working Version

_No response_

Claude Code Version

2.0.55

Platform

Other

Operating System

Windows

Terminal/Shell

VS Code integrated terminal

Additional Information

_No response_