OpenAI-compat: gateway /v1 plus origin-only Helicone-Target-URL, not oai.helicone.ai #5795

Working config (gateway.helicone.ai/v1 + Helicone-Target-URL origin)

oai.helicone.ai proxies OpenAI. ai-gateway.helicone.ai uses Helicone-managed keys. Helicone-OpenAI-Api-Base is the oai.helicone.ai header. Putting /v1 in Helicone-Target-URL duplicates the path the gateway already appends.

A Chat Completions host whose public catalog is GET https://api.pzero.studio/v1/models (no key) fits the generic gateway if base_url is https://gateway.helicone.ai/v1, Helicone-Target-URL is the origin only, api_key is that host's Bearer, and Helicone-Auth is the Helicone key.

import os
from openai import OpenAI

client = OpenAI(
    api_key="<Bearer key for that host>",
    base_url="https://gateway.helicone.ai/v1",
    default_headers={
        "Helicone-Auth": f"Bearer {os.environ['HELICONE_API_KEY']}",
        "Helicone-Target-URL": "https://api.pzero.studio",
    },
)

r = client.chat.completions.create(
    model="deepseek-v4-flash",
    messages=[{"role": "user", "content": "Say hello"}],
)

Keep embeddings and multimodal off this host.