server/utils/ExpandQuery.py

from langchain_core.messages import HumanMessage, SystemMessage

def expand_query(query,llm,factor=3):
    system_instruction= f"""
    You are an expert academic search optimization assistant for a college RAG database.
    Your job is to rewrite the user's input query into {factor} different, keyword-rich search variations.

    CRITICAL INSTRUCTIONS:
    1. Maintain the exact semantic meaning but change casual or ambiguous phrasing into formal university terminology (e.g., convert 'faculties' to 'professors, lecturers, teaching staff', or 'syllabus' to 'curriculum scheme').
    2. Do NOT add any introductory text, pleasantries, or explanations.
    3. Do NOT include numbers, bullet points, hyphens, or numbering prefixes (like '1.', '2.').
    4. Output ONLY the raw alternative queries, separating each distinct query with a single newline character (\n).
    """

    messages= [SystemMessage(system_instruction),HumanMessage(query)]

    response= llm.invoke(messages)
    final_queries= response.content.split("\n\n")
    final_queries.append(query)

    return final_queries