Codex with GPT-5.6-Sol through Azure fails every turn with X-OpenAI-Internal-Codex-Responses-Lite #31870

What version of Codex CLI is running?

v0.144.0

What subscription do you have?

Azure Foundry

Which model were you using?

gpt-5.6-sol

What platform is your computer?

Darwin 24.6.0 arm64 arm

What terminal emulator and version are you using (if applicable)?

cmux

Codex doctor report

What issue are you seeing?

I am attempting to use GPT-5.6-Sol through Azure Foundry. Previous versions like gpt-5.5 work fine, but when I select gpt-5.6-sol, I get the following error for any message I send:

──────────────────────────────────────────────────╮
│ >_ OpenAI Codex (v0.144.0)                       │
│                                                  │
│ model:     gpt-5.6-sol medium   /model to change │
│ directory: ~/stratulus/vibechk                   │
╰──────────────────────────────────────────────────╯

  Tip: New Build faster with the Codex App. Run 'codex app' or visit https://chatgpt.com/codex?app-landing-page=true


› Testing


■ {
  "error": {
    "message": "X-OpenAI-Internal-Codex-Responses-Lite only supports function tools, custom tools, and client-executed tool search.",
    "type": "invalid_request_error",
    "param": "tools",
    "code": "unsupported_value"
  }
}

What steps can reproduce the bug?

1. Connect Codex to Azure using the instructions here:
   https://learn.chatgpt.com/docs/config-file/config-advanced#azure-provider-and-per-provider-tuning

2. Launch codex

3. Switch models to gpt-5.6-sol

4. Type any text, like "testing"

5. See the error

What is the expected behavior?

No response

Additional information

No response