openai API `max_completion_tokens` argument is ignored

Look at the server code handling the OpenAI-compatible chat completions endpoint, likely in llama_cpp/server/app.py or similar. Find where the request parameters are parsed and where max_tokens is used. Compare to how max_completion_tokens should be handled. Check the OpenAI API specification for the parameter name. The fix is to ensure max_completion_tokens is read and passed to the generation logic. Test by running the server and using the provided client script to verify the token limit is respected.

Prerequisites

Please answer the following questions for yourself before submitting an issue.

• I am running the latest code. Development is very rapid so there are no tagged versions as of now.
• I carefully followed the README.md.
• I searched using keywords relevant to my issue to make sure that I am creating a new issue that is not already open (or closed).
• I reviewed the Discussions, and have a new bug or useful enhancement to share.

Current Behavior

I'm running llama-server with following command:

python3 -m llama_cpp.server --model models/mys/ggml_llava-v1.5-13b/ggml-model-q4_k.gguf --clip_model_path models/mys/ggml_llava-v1.5-13b/mmproj-model-f16.gguf --model_alias llava-v1.5-13b-q4_k --chat_format llava-1-5 --port 10322

(models downloaded from https://huggingface.co/mys/ggml_llava-v1.5-13b/tree/main)

When I call the server using openai python package:

from openai import OpenAI

client = OpenAI(
    base_url="http://localhost:10322/v1", # "http://<Your api-server IP>:port"
    api_key = "sk-no-key-required"
)

chat_completion = client.chat.completions.create(
    model="models/mys/ggml_llava-v1.5-13b/ggml-model-q4_k.gguf",
    messages=[
        {"role": "user", "content": "Write a limerick about python exceptions"}
    ],
    max_tokens=3,
)
print(chat_completion.usage.completion_tokens)  # returns 3, ok.
print(chat_completion.choices[0].finish_reason)  # returns "length", ok.

chat_completion = client.chat.completions.create(
    model="models/mys/ggml_llava-v1.5-13b/ggml-model-q4_k.gguf",
    messages=[
        {"role": "user", "content": "Write a limerick about python exceptions"}
    ],
    max_completion_tokens=3,
)
print(chat_completion.usage.completion_tokens)  # returns much more than 3 (complete answer).
print(chat_completion.choices[0].finish_reason)   # returns "stop".

According to OpenAI API, max_completion_tokens argument is replacing the deprecated max_tokens argument.
It's seems that only max_tokens is not ignored by the server.

Environment and Context

llama_cpp installed with pip install llama-cpp-python[server]
print(llama_cpp.__version__): 0.3.6
print(openai.__version__): 1.59.7