[BUG] Custom endpoint settings.json regression

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?

We're just launching our GitButler integration, and we've had one user who is using a custom backend for CC via the https://github.com/ericc-ch/copilot-api project.

The project encourages you to configure CC in the .claude/settings.json as follows:

{
  "env": {
    "ANTHROPIC_BASE_URL": "http://localhost:4141",
    "ANTHROPIC_AUTH_TOKEN": "dummy",
    "ANTHROPIC_MODEL": "gpt-4.1",
    "ANTHROPIC_SMALL_FAST_MODEL": "gpt-4.1"
  }
}

Since Claude 1.0.111, if you run claude -p "hello" you get an error like the following:

API Error: 401 {"type":"error","error":{"type":"authentication_error","message":"Invalid bearer token"},"request_id":"req_011CT2e7G3LRMFXiwGdQrLLc"} · Please run /login

In the TUI this configuration still works as expected.

In version 1.0.110 this configuration works as expected with -p, so it's a very recent regression.

Of course, using a tool like copilot-api is not going to be a supported use case, but I imagine that this is going to be affecting enterprise users who might be using Amazon Bedrock or Google Vertex AI.

What Should Happen?

Claude should interpret the same as what it does in the TUI.

Error Messages/Logs

Steps to Reproduce

Using https://github.com/ericc-ch/copilot-api:

1. Run npx copilot-api@latest auth to authenticate copilot-api with GitHub
2. Run npx copilot-api@latest start to start the proxy server
3. Add the following to your .claude/settings.json

  "env": {
    "ANTHROPIC_BASE_URL": "http://localhost:4141",
    "ANTHROPIC_AUTH_TOKEN": "dummy",
    "ANTHROPIC_MODEL": "gpt-4.1",
    "ANTHROPIC_SMALL_FAST_MODEL": "gpt-4.1"
  }

1. Run claude -p "hello"

Claude Model

None

Is this a regression?

Yes, this worked in a previous version

Last Working Version

1.0.110

Claude Code Version

1.0.111

Platform

Other

Operating System

macOS

Terminal/Shell

Terminal.app (macOS)

Additional Information

_No response_