OpenCode

Recommended: use cc-switch for setup: https://github.com/farion1231/cc-switch/releases

If you do not use cc-switch, configure a custom provider with the Responses API:

{
  "$schema": "https://opencode.ai/config.json",
  "provider": {
    "codex_proxy": {
      "npm": "@ai-sdk/openai",
      "name": "Codex Proxy",
      "options": {
        "baseURL": "https://codex.miaomiaocode.com/v1",
        "apiKey": "{env:OPENAI_API_KEY}"
      },
      "models": {
        "gpt-5-codex-mini": {
          "name": "gpt-5-codex-mini"
        }
      }
    }
  },
  "model": "codex_proxy/gpt-5-codex-mini"
}

You can also use opencode auth login or /connect instead of inventing a project-specific environment variable.