# router.py
# =================================
# Core-first routing
# Let Core reasoning dominate
# Skill is attached only on strong signals
# =================================

def route_skill(prompt: str):
    """
    Returns:
    - skill name (str) if high confidence
    - None if Core/Base should handle it
    """

    if not prompt:
        return None

    text = prompt.lower()

    # ---------- STRONG SIGNALS (explicit tasks) ----------

    # Excel / spreadsheet specific actions
    excel_signals = [
        "excel file", "spreadsheet", "xlsx", "csv",
        "sheet", "pivot table", "cell", "column", "row"
    ]
    if any(k in text for k in excel_signals):
        return "excel"

    # VAT / Invoice calculations
    vat_signals = [
        "vat calculation", "invoice total",
        "tax amount", "vat %", "bill amount"
    ]
    if any(k in text for k in vat_signals):
        return "vat"

    # Document processing (analysis, extraction)
    doc_signals = [
        "analyze document", "extract from pdf",
        "document review", "read this pdf",
        "contract analysis"
    ]
    if any(k in text for k in doc_signals):
        return "docs"

    # ---------- WEAK / AMBIGUOUS INPUT ----------
    # Let Base + Core reasoning decide
    return None