Using Codex

Compatibility: doesn't work today. Current Codex (CLI release 0.159.2, published 2026-09-29) talks to custom providers only through the OpenAI Responses API at /v1/responses. Codex no longer accepts wire_api = "chat". luv13 serves only /v1/chat/completions, and https://api.luv13.ai/v1/responses returns 404. So Codex can't use luv13 directly.

Before you start

• A luv13 API key comes from the Quickstart. The model used in luv13 examples is GLM-5.3 Flash (luv13/glm-5.3-flash).
• You don't need either for Codex yet, but the tests below show your key works with luv13 itself.

Facts about luv13 that affect this setup:

• luv13 serves one generation endpoint, POST /v1/chat/completions, plus GET /v1/models. /v1/responses, /v1/messages, /v1/completions and /v1/embeddings return 404 (checked 2026-09-30). See Endpoints.
• Every model costs a flat $0.33 per 1M tokens, input the same as output. See Pricing.
• The model list at https://api.luv13.ai/v1/models doesn't report context length, so luv13 publishes no per-model limits. See the model list.

Test your key and model first

Run these two checks in a terminal before you touch the tool. They take a few seconds and rule out key and model problems.

1. The model id exists. This call needs no key:

curl -s https://api.luv13.ai/v1/models

The list should include "id":"luv13/glm-5.3-flash".

2. Your key works for chat. Set the key in your shell first (export LUV13_API_KEY="your luv13 key"), then run:

curl -s https://api.luv13.ai/v1/chat/completions \
  -H "Authorization: Bearer $LUV13_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "luv13/glm-5.3-flash",
    "messages": [{"role": "user", "content": "Reply with the word ready."}],
    "max_tokens": 20
  }'

With a valid key you should get back a JSON chat completion whose choices[0].message.content holds the reply, plus a usage block. If you see {"error":{"code":401,"message":"unauthorized","type":"invalid_auth"}} instead, the key is missing or wrong, and no tool setting will fix that.

To see why Codex fails, send a request to the Responses path Codex would use:

curl -s -o /dev/null -w "%{http_code}\n" -X POST https://api.luv13.ai/v1/responses \
  -H "Authorization: Bearer $LUV13_API_KEY" -H "Content-Type: application/json" \
  -d '{"model":"luv13/glm-5.3-flash","input":"hi"}'

This prints 404 (checked 2026-09-30).

What Codex's docs say

Codex's advanced config docs (read 2026-09-30) define custom providers in ~/.codex/config.toml under [model_providers.<id>]. Every example uses wire_api = "responses", for example:

[model_providers.proxy]
name = "OpenAI using LLM proxy"
base_url = "https://proxy.example.com/v1"
wire_api = "responses"

The config reference entry for model_providers.<id>.wire_api says: "Protocol used by the provider. responses is the only supported value, and it is the default when omitted."

What happens if you try luv13 anyway

This is the config you'd write. It won't work. It's shown only so you can recognize the errors.

# ~/.codex/config.toml. Does NOT work with luv13 today.
model_provider = "luv13"
model = "luv13/glm-5.3-flash"

[model_providers.luv13]
name = "luv13"
base_url = "https://api.luv13.ai/v1"
env_key = "LUV13_API_KEY"
wire_api = "responses"

• With wire_api = "responses" (or the line left out), Codex sends requests to https://api.luv13.ai/v1/responses, which returns 404.
• With wire_api = "chat", Codex refuses the config. Its source at rust-v0.159.2 (codex-rs/model-provider-info/src/lib.rs) defines this error:

  `wire_api = "chat"` is no longer supported.
  How to fix: set `wire_api = "responses"` in your provider config.
  More info: https://github.com/openai/codex/discussions/7782

What works and what doesn't

Common errors

General tip: a proxy that converts Responses API requests to Chat Completions could in theory sit between Codex and luv13. That hasn't been tested with luv13, and it isn't covered by luv13's docs.

Sources

• Codex docs, "Advanced configuration" (read 2026-09-30)
• Codex docs, "Configuration reference", model_providers.<id>.wire_api entry (read 2026-09-30)
• Codex source at tag rust-v0.159.2, codex-rs/model-provider-info/src/lib.rs (read 2026-09-30)
• Codex releases on GitHub (latest rust-v0.159.2, published 2026-09-29)
• luv13 /v1/responses returning 404, checked live with curl on 2026-09-30

Related: Using Claude Code, Using Cline, Endpoints, Compatible Tools.