In chat today, multiple users send a message consisting of the @ symbol followed by the first three letters of a user's username. This happened for me after typing @, typing the first three letters, seeing only one user left and therefore highlighted, and pressing Enter expecting the username to be inserted into the message but instead sending a four-character messaging tagging a three-letter username.
To be clear, I'm not suggesting that Tab no longer do what it does. I'm suggested that Enter select the sole matching username when there is one match and then return the user to typing rather than send the message.
It seems that the use case where the existing functionality -- opening the username suggestions by typing partial username but then abandoning the lookup and sending the message immediately with the partial username -- is rather niche if it exists at all.
I recognize that existing habits may including using tab to select the desired username after starting a partial match, thereby completing the message, followed by immediately pressing Enter to send the message, but this also seems niche if less so. I'd be curious to know what portion of chat messages that @-tag someone also end in that tag.
There is an existing question Is there a way to autocomplete @username without typing the whole thing? that seems similar but I think is asking something different. That asker seems to be asking a "how-do-I?" type question, whereas I am suggesting a change.
