Use `editMessageMedia` to keep daily announcements updated

[nmlorg]

https://core.telegram.org/bots/api#october-31-2024:

• Introduced the ability to add media to existing text messages using the method editMessageMedia.

• Can you remove media?
• What happens if the length of the text is greater than the caption limit?
• Can you still use editMessageText to change the text, or do you have to use editMessageCaption after adding an image?
• If you sendMessage(text='a' * 2000), then editMessageMedia to add a picture, does it fail, does it change to a message with caption='a' * 2000, does it change to a message with caption='a' * 1024, or what?
• If it changes to caption='a' * 2000, can you editMessageCaption(caption='b' * 2000)? Can you edit it at all, or is it stuck? Can you remove the image, edit the text, then readd the image?

Depending on how this turns out, I'd like to start sending all announcements as text messages, immediately editing them to add media (if appropriate), and also keeping media updated (including removing it) as event titles/etc. change.

[nmlorg]

(After a power outage just for fun…)

Calling editMessageMedia on a sendMessaged message converts it to a media message altogether, and its existing text is simply discarded. If you want it to have text, you have to supply a caption= to editMessageMedia (as part of the media= argument).

• Setting media.media=None, ='', or sending a media= without an internal media= all emit a 400 from TBA.
• The initial text is discarded, so its length is irrelevant.
• editMessageText on a converted message throws a 400 ("there is no text in the message to edit").
• The initial text is discarded.
• The caption appears to follow all existing rules.

So this would be a one-way process:  If the record for a message that didn't include any image when sent is changed so that the message would have included an image if it were sent now, we can go ahead and add the image. That's it :slightly_frowning_face:.