[Bug]: mentions should not show up as attached links from Mastodon

[wakest]

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Summary

when mentioning a user in a reply, the mention shows up as an attached link from the Mastodon side

link to the comment shown in the screenshot

Steps to Reproduce

1. mention a fediverse account in a lemmy reply
2. load the post into a mastodon account

Technical Details

n/a

Version

BE: 0.19.9

Lemmy Instance URL

lemmy.ml

[Nutomic]

Dont know why this is happening, the Activitypub JSON looks just like the one sent from a Mastodon instance.

curl -H 'accept: application/activity+json' https://lemmy.ml/comment/16895096 | jq:

{
    "content":"<p>hat tip to <a href=\"https://aus.social/users/shlee\" rel=\"nofollow\">@[email protected]</a></p>\n",
    "tag":[
        {
            "href":"https://lemmy.ml/u/wakest",
            "name":"@[email protected]",
            "type":"Mention"
        },
        {
            "href":"https://aus.social/users/shlee",
            "name":"@[email protected]",
            "type":"Mention"
        }
    ],
    ...
}

curl -H 'accept: application/activity+json' https://mastodon.archive.org/@textfiles/113958335475068302 | jq:

{
    "content":"<p><span class=\"h-card\" translate=\"no\"><a href=\"https://mastodon.libre-entreprise.com/@lutindiscret\" class=\"u-url mention\">@<span>lutindiscret</span></a></span> <span class=\"h-card\" translate=\"no\"><a href=\"https://mastodon.social/@LemmyDev\" class=\"u-url mention\">@<span>LemmyDev</span></a></span> This is the absolute first time I&#39;ve ever heard of Lemmy, and the 16th year I&#39;ve heard of Reddit.</p>",
    "tag":[
        {
            "type":"Mention",
            "href":"https://mastodon.libre-entreprise.com/users/lutindiscret",
            "name":"@[email protected]"
        },
        {
            "type":"Mention",
            "href":"https://mastodon.social/users/LemmyDev",
            "name":"@[email protected]"
        }
    ],
    ...
}

So the only difference seems to be that Mastodon includes some additional HTML tags in content, but there is nothing wrong being sent by Lemmy. As this is a problem with the Mastodon UI you should report it to the Mastodon repo.

[flamingo-cant-draw]

The u-url class does seem to be what Mastodon uses to avoid link previews for mentions. It would also be pretty easy for us to add those tags, something like this in link_rule.rs:

let content = node.collect_text();
if MENTIONS_REGEX.is_match(&content) {
  attrs.push("class", "u-url".to_string());
  attrs.push("class", "mention".to_string()
}