Function generate_summary 

pub async fn generate_summary(
    model: &Model,
    credential: Option<ResolvedCredential>,
    conversation_text: &str,
    previous_summary: Option<&str>,
    custom_instructions: Option<&str>,
    continuation: bool,
    cancel: CancellationToken,
) -> Result<SummaryOutcome>

Generate a structured summary with the LLM. One-off prompt: fresh session id and no cache writes wanted, so it’s a plain request.