Use opencodex models in T3 Code through Claude Code

A developer documented how to use opencodex models in T3 Code through Claude Code, resolving a misleading model-access error. The fix involves setting ANTHROPIC_BASE_URL and CLAUDE_CODE_ENABLE_GATEWAY_MODEL_DISCOVERY in T3's Claude provider settings, then restarting T3 Code. The developer verified the setup on macOS with T3 Code 0.0.33, Claude Code 2.1.229, and opencodex 2.14.1.

T3 Code can list custom models under its Claude provider and still fail when you use one: There's an issue with the selected model gpt-5.6-sol . It may not exist or you may not have access to it. The model may be fine. T3 Code launches Claude Code through the Claude Agent SDK, so running ocx claude in a terminal does not configure the Claude process that T3 starts. You need to pass the opencodex proxy settings through T3's Claude provider. I verified this setup on macOS with T3 Code 0.0.33, Claude Code 2.1.229, and opencodex 2.14.1. Claude Code, T3 Code, and opencodex should already be installed. Configure at least one model in opencodex, then check that the proxy is healthy: ocx status ocx health --json Test your model outside T3 Code: ocx claude \ -p \ --model gpt-5.6-sol \ --output-format text \ 'Reply with exactly: OK' Replace gpt-5.6-sol with the route you configured. Fix opencodex first if this command fails. Open Settings → Providers → Claude , expand the Claude provider, and add these environment variables: | Variable | Value | Sensitive | |---|---|---| ANTHROPIC BASE URL | http://127.0.0.1:10100 | No | CLAUDE CODE ENABLE GATEWAY MODEL DISCOVERY | 1 | No | If your opencodex proxy uses another port, change 10100 to match it. Keep Binary path set to the real Claude executable, usually claude . Do not set it to ocx : T3's Claude Agent SDK expects a Claude Code executable, while ocx claude is a launcher that prepares the environment and then starts Claude. In the same Claude provider settings, add the exact opencodex route to the custom model list if T3 does not already show it. For example: gpt-5.6-sol Quit T3 Code completely with Cmd+Q , then reopen it. T3 does not add changed provider variables to a Claude process that is already running. Create a new thread, select the custom model under the Claude provider, and send a small test prompt: Reply with exactly: OK ocx claude normally launches Claude Code with ANTHROPIC BASE URL pointed at the local proxy and enables gateway model discovery. T3 Code starts Claude itself, but its provider settings let you pass the same variables to the Claude child process. Without ANTHROPIC BASE URL , Claude sends the request to Anthropic. Anthropic does not know an opencodex route such as gpt-5.6-sol , so T3 shows the misleading model-access error. With the proxy URL set, Claude sends the request to opencodex, which resolves the route and calls the configured provider. Quit T3 Code with Cmd+Q and reopen it. Starting a new thread is not enough if T3 is reusing the old Claude provider process. Then confirm the proxy is still running: ocx status ocx health --json Check the Claude provider's environment-variable names and the proxy port. Keep the binary path set to claude . 127.0.0.1 means the device running the Claude process. Run opencodex on that device and configure the Claude provider for that T3 environment. A proxy running only on your Mac is not available at 127.0.0.1 from another machine. Do not copy an API key into T3 unless your opencodex configuration requires one. Follow opencodex's current authentication guidance for ANTHROPIC AUTH TOKEN ; setting it unnecessarily can disable the existing Claude subscription login and connectors.