\documentclass{article}
\usepackage[margin=2cm]{geometry}
\usepackage[style=web]{chatui}

\begin{document}

\section*{chatui: image and file attachments}

\begin{chatconversation}[chat.example.com]

\begin{chatuser}
Here's a screenshot of the error I'm seeing.
\chatimage[0.55\linewidth]{sample.png}
\end{chatuser}

\begin{chatthinking}
\tstep{User attached a screenshot; also see the log file below.}
\end{chatthinking}

\begin{chatassistant}
Got it, I can see the issue in the screenshot. I also generated a
full report for you:
\chatfile{crash-report.pdf}{212 KB}
\chatfile{stack-trace.log}{18 KB}
\end{chatassistant}

\end{chatconversation}

\end{document}