Hi there, we are currently also looking at this issue.
@Craig - Are there more details available on truncation limits? I have not been able to find any documentation on this nor has our partner.
We currently only have insights based on our previous experience. Here’s what we’ve been able to piece together so far from observing how the preview behaves:
The preview allows a maximum of 140 characters including spaces and can only display them across two lines. If the 140 characters are not fully used within the first two lines of the post, the following characters from the third line are also included. However, the line break is then shown as \n\n.
If adding the next word would exceed the 140-character limit, that word will not be displayed in the preview.
Formatting such as bold or italics is not applied in the preview.
Heading formatting is carried over into the preview. The heading we used most recently had 83 characters including spaces. It seems likely that only around 60–80 characters (including spaces) can be displayed as a heading on the first line. If the heading is longer, the remainder appears in the next line of the preview, but without formatting.
Thanks!