A bot's reply becomes a message when the status is 200 and the type is text,
and an attachment otherwise, but the attachment branch never looked at the
status. Whenever a bot's endpoint failed, its error page landed in the room as
a file: a proxy's 502 page as attachment.html, a 404 as attachment.text.
Apply the text branch's 200 check to attachments too. The error reply test
answered without a content type, which skipped the attachment branch, so it
now answers with an HTML error page.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01JVFo3Lt9T8M5NR7KxVvsZ2
Marcello Costagliola
Kevin McConnell