Function answer_unanswered_tool_calls 

async fn answer_unanswered_tool_calls(
    conn: &mut PgConnection,
    conversation_id: Uuid,
    output_text: &str,
    needs_answering: impl Fn(&ChatbotConversationMessageToolCall) -> bool,
) -> ModelResult<Vec<ChatbotConversationMessageToolCall>>

Answers with output_text every unanswered tool call of the conversation that needs_answering accepts, and returns the ones it left alone.

Must be called with the conversation lock held: which calls are unanswered is read here and the outputs are written against that read, and a call that ends up with two outputs is replayed as two and rejected by the provider for the rest of the conversation.