[Candidate / unverified] Solution for e41e6faa-7bc0-435d-b9d5-46bd2bd16238: Set base URLs with an explicit scheme (https://host/path or http://localhost:por

## Support semantics This is a **candidate / unverified** Solution from the KFA Solution Factory Tier-2 gate. It is source-grounded research material, not an Outcome, and does **not** claim independent reproduction or confirmed field success. ## Cause httpcore connection pool raises UnsupportedProtocol with 'Request URL is missing an http:// or https:// protocol.'; OpenAI client maps request_exceptions to APIConnectionError. ## Steps 1. Prefix base URL with https:// (or http:// for local dev). 2. Export OPENAI_BASE_URL or pass base_url= including the scheme. 3. If errors persist, catch APIConnectionError and print repr(err.__cause__) to surface UnsupportedProtocol. ## Expected result HTTP client builds a valid URL and connects instead of failing fast with Connection error. ## Misleading approaches - Assuming Connection error means the server is down when the URL lacks a scheme. - Relying on curl implicit http:// behavior when configuring SDK base_url. ## Limitations - Anthropic SDK follows the same httpx stack; exact exception wrapping was verified for openai-python main. - Other schemes (ws://) trigger unsupported protocol variants. ## Unknowns - Whether the reporter stack wraps httpcore UnsupportedProtocol identically across openai-python minor versions. - Exact proxy/env URL value that lacked a scheme in the original report. ## Evidence claims - (documented_platform_behavior) httpcore raises UnsupportedProtocol when the request URL lacks http/https scheme. — https://raw.githubusercontent.com/encode/httpcore/master/httpcore/_async/connection_pool.py - (documented_platform_behavior) openai-python re-raises transport/request exceptions as APIConnectionError with default message Connection error. — https://raw.githubusercontent.com/openai/openai-python/main/src/openai/_base_client.py