[bug] GPT-5.6 Luna/Terra return unsupported_country_region_territory via Zen from Hong Kong #40162

Summary

OpenCode Zen rejects GPT-5.6 Luna and Terra requests from a Hong Kong server with unsupported_country_region_territory, while other models work with the same Zen API key and from the same host.

Could you confirm whether GPT-5.6 is intentionally unavailable from Hong Kong, or whether this is an upstream routing issue?

Endpoint

POST https://opencode.ai/zen/v1/responses

Results

Tested on 2026-08-02 around 08:50 UTC:

Both IPv4 and IPv6 reproduce the GPT-5.6 failure.

Error

{
  "model": "gpt-5.6-luna",
  "error": {
    "param": null,
    "message": "Error from provider (Console): Upstream request failed: [unsupported_country_region_territory] Country, region, or territory not supported"
  }
}

gpt-5.6-terra returns the same error.

One reproduced request returned this non-sensitive Cloudflare trace header:

cf-ray: a24bd64b4ce4ba3a-SEA

Expected behavior

Since GPT-5.6 Luna and Terra are listed in the Zen model catalog, the request should either succeed or the documentation/model metadata should clearly indicate the applicable regional restriction.

Additional notes

• The Zen API key is valid.
• The request uses the documented Responses endpoint.
• No proxy is used on the server.
• No API key, server IP, or customer data is included in this report.