[Bug]: attachments are not parsed on message update

[jerbob92]

Bug Description

Attachments look like this on a new message activity:

attachments=[Attachment(content_type='text/html', content_url=None, content='<p>hey</p>', name=None, thumbnail_url=None)]

But on message update it looks like this:

attachments=[{'contentType': 'text/html', 'content': '<p>hey2</p>'}]

Steps to Reproduce

1. Send message
2. Update message

Expected Behavior

Activities are parsed in the same way for all activity types.

Actual Behavior

Activies are not parsed in the same way for all activity types.

SDK Version

2.0.0a78

Python Version

3.14.2

Additional Context

No response

[corinagum]

Thanks for reporting jerbob92. attachments field is only declared on MessageActivity, not on MessageUpdateActivity. Will need to review with the team how we want to resolve this.

For discussion:

Of the message type activities, only message.py declares attachments.

• messageUpdate - can definitely carry attachments
• messageDelete - conceptually can attachments, but in practice seems impractical. We don't appear to have direct Teams SDK direction either way on schema rules.
• messageReaction - does not carry attachments in practice. Same as above.

The decision here would be to decide how to resolve this in-scope. Practically, I think only messageUpdate needs the fix. However, APX and TS/C# should be reviewed; C# does not have this bug as MessageUpdateActivity inherit from MessageActivity. TS doesn't extend MessageActivity, but at runtime will not be dropped. TS users won't see a crash, but won't receive the benefit of the Attachment type. TS and PY need fixes; PY more urgent than TS.

[jerbob92]

Corina (@corinagum) thanks! Is there currently anything still blocking a fix for this?

[corinagum]

jerbob92 Thanks for the ping. Currently our blocker is just the final decision and funding. Pinging Umang (@umangsehgal) and Ricky Castaneda (@MSFTRickyCastaneda) for visibility.