"How I Route claude-sonnet-4-6 to GPT-5 Codex — Without Claude Code Knowing the Difference"

Claude Code always sends claude-sonnet-4-6 in the request body. That string goes to whatever base URL you've configured. Here's what most people don't realize: that string doesn't have to end up at Anthropic. It doesn't even have to end up at a Claude model. The Model Name Is a Routing Hint, Not a Destination When Claude Code makes a request, it sends something like this: { "model": "claude-sonnet-4-6", "messages": [...], "stream": true } If your ANTHROPIC_BASE_URL p...