• LLM instruction text for a TTS provider, or undefined when it has no markup dialect.

    Each markup-capable provider gets its own expr instruction block — shared marker syntax, but only the types and label vocabularies that provider actually supports; convertMarkup lowers the markers to native syntax. Expr is the only dialect the LLM is ever taught. When steering disables a non-verbal sound, its labels (and any example demonstrating them) are omitted from the block entirely rather than advertised and then revoked.

    Parameters

    Returns string | undefined