[Bug]: `customUserVars` not replaced in `env`

[gorootde]

What happened?

When using a custom user var as template in an env, the value is not being replaced properly.

Example:

mcpServers:
    karakeep:
      type: stdio
      command: npx
      args:
        - "-y"
        - "@karakeep/mcp"
      env:
        KARAKEEP_API_ADDR: https://karakeep
        KARAKEEP_API_KEY: "{{API_KEY}}"
      customUserVars:
        API_KEY:
          title: "Karakeep API Key"
          description: "Enter your personal API key for the service."

When placing the API key directly in the env, everything works as expected.

I've tried to configure the API key in the MCP server's settings in an agent, as well as directly in the mcp category. Both variants lead to the issue.

Version Information

registry.librechat.ai/danny-avila/librechat-dev                latest              9cd59b495db6   4 hours ago     2.06GB
registry.librechat.ai/danny-avila/librechat-dev                <none>              d8e7752a417f   2 days ago      2.06GB
registry.librechat.ai/danny-avila/librechat-rag-api-dev-lite   latest              a05a6506b318   12 days ago     1.59GB

3ddf62c8e5511a2c30672dbe3e6e07bedff374e6

Steps to Reproduce

See description

What browsers are you seeing the problem on?

No response

Relevant log output

-

Screenshots

No response

Code of Conduct

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