Missing Required Header in Documentation

[ivan-velikanov]

Issue: The API documentation is incomplete - it's missing a critical required header.

Current Documentation:

• Only shows anthropic-version: 2023-06-01 as required header
• Examples suggest this is sufficient for API calls

Actual Behavior:

• Requests fail with "OAuth authentication is currently not supported"
• Both headers are required:
  anthropic-version: 2023-06-01
  anthropic-beta:
  claude-code-20250219,oauth-2025-04-20,interleaved-thinking-2025-05-14,fine-grained-tool-streaming-2025-05-14

Test Case:

Fails (per docs)

curl -X POST http://localhost:8080/v1/messages
-H "Content-Type: application/json"
-H "anthropic-version: 2023-06-01"
-d '{"model": "claude-3-5-haiku-20241022", "max_tokens": 10, "messages": [{"role": "user", "content": "test"}]}'

Works (actual requirement)

curl -X POST http://localhost:8080/v1/messages
-H "Content-Type: application/json"
-H "anthropic-version: 2023-06-01"
-H "anthropic-beta:
claude-code-20250219,oauth-2025-04-20,interleaved-thinking-2025-05-14,fine-grained-tool-streaming-2025-05-14"
-d '{"model": "claude-3-5-haiku-20241022", "max_tokens": 10, "messages": [{"role": "user", "content": "test"}]}'

Fix: Update docs/api-http.md examples to include the required anthropic-beta header.

[dangerzone]

@ivan-velikanov Did your additional headers also work with Sonnet? I tried the fix you suggested and it works with haiku, but sonnet. I'm not sure if I did something wrong. I'm using claude-sonnet-4-20250514 as the model name.

[ivan-velikanov]

You can see the full back and forth api calls and responses in the ccflare web interface (Requests tab, and then click one of the request and click more details). From that see how the requests that come from claude-code actually look, then replicate it. That will work.
What I additionally did was one-by-one removed headers (this experiment can be done using claude code itself) to see which is absolutely essential