- Add base_url field to OpenAIConfig with default "https://api.openai.com/v1"
- Update sample_run_config to support OPENAI_BASE_URL environment variable
- Modify get_base_url() to return configured base_url instead of hardcoded value
- Add comprehensive test suite covering:
- Default base URL behavior
- Custom base URL from config
- Environment variable override
- Config precedence over environment variables
- Client initialization with configured URL
- Model availability checks using configured URL
This enables users to configure custom OpenAI-compatible API endpoints
via environment variables or configuration files.
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