### Check for existing issues

- [x] I have searched the existing issues and checked that my issue is not a duplicate.

### What happened?

**Summary**

`vectorStores.retrieve()` and `vectorStores.delete()` fail on the LiteLLM proxy with: `Invalid model name passed in model=None`

While other vector store operations work correctly:

- `vectorStores.create` - `vectorStores.files.create` - `vectorStores.files.poll` - `vectorStores.files.list`

**Environment**

- LiteLLM Docker latest - OpenAI provider - OpenAI Node SDK - LiteLLM used as an OpenAI-compatible proxy - LiteLLM Configuration ```yaml model_list: - model_name: gpt-5.2 litellm_params: model: openai/gpt-5.2 api_key: os.environ/OPENAI_API_KEY

general_settings: master_key: os.environ/LITELLM_MASTER_KEY ```

- OpenAI Client Configuration ```ts const client = new OpenAI({ apiKey: 'xxxxxxx', baseURL: 'http://localhost:4000/v1', defaultHeaders: { 'x-litellm-model': 'gpt-5.2' }, defaultQuery: { model: 'gpt-5.2' }, }); ```

**Investigation**

From investigating the LiteLLM codebase, it looks like the retrieve/delete routes directly call: ```python return await processor.base_process_llm_request( ... …