}
        return content.substring(0, maxChars) + "...";
    }

    /**
     * Builds a smart summary of the assistant message for history.
     * Preserves the beginning (direct answer) and end (conclusion) of long responses,
     * omitting the middle section, and appends source titles.
     *
     * @param msg the assistant chat message
     * @param maxChars the maximum characters for the summary