* fix(llm): filter unexpected config keys to prevent LangChain warnings (#411)
Add allowlist validation for LLM configuration keys to prevent unexpected
parameters like SEARCH_ENGINE from being passed to LLM constructors.
Changes:
- Add ALLOWED_LLM_CONFIG_KEYS set with valid LLM configuration parameters
- Filter out unexpected keys before creating LLM instances
- Log clear warning messages when unexpected keys are removed
- Add unit test for configuration key filtering
This fixes the confusing LangChain warning "WARNING! SEARCH_ENGINE is not
default parameter. SEARCH_ENGINE was transferred to model_kwargs" that
occurred when users accidentally placed configuration keys in wrong sections
of conf.yaml.
* Apply suggestions from code review
Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>
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Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>
