A comment here distinguishes between the ‘plain text’ that’s allowed by the spec, and MarkDown as a markup language (it’s confusingly named, I guess, but that’s what Wikipedia categorises it as too)

Lemmy mostly federates with Lemmy, but everything else out there (PeerTube, PixelFed, etc) has been developed to work well with Mastodon (sometimes to the Fediverse’s detriment), so your Mastodon account should be all you need.

Another commenter (who’s contributed code to Lemmy) pointed to a link that provides the specification for that field: “A simple, human-readable, plain-text name for the object. HTML markup MUST NOT be included.”

So in this case, it’s more that the JSON looks a bit ambiguous: ‘mediaType’ is only referring to the format of the text in a post’s body, but - unlike me - you’d also need to be aware of the spec to know that it doesn’t apply to the title.

Oh, wow. Thanks.

For clarity, I wasn’t intending to say that PieFed treats that field as HTML (it treats it as text), I just meant that if you were looking at that JSON, and being a bit lazy like me and not looking at specs, then it wouldn’t be unreasonable to assume that the ‘mediaType’ field also refers to ‘name’ (rather than a ‘content’ field which this post doesn’t happen to have).

Anyway, this seems to be even more reason why MD shouldn’t be put in titles, and front-ends shouldn’t be encouraging the practise by rendering it.

Yes - it’s easy to do from a command line. For this post, it would be:

curl --header 'accept: application/activity+json' --location https://lemmy.world/post/24241974 | jq .

{  
  "@context": [  
    "https://join-lemmy.org/context.json",  
    "https://www.w3.org/ns/activitystreams"  
  ],  
  "type": "Page",  
  "id": "https://lemmy.world/post/24241974",  
  "attributedTo": "https://lemmy.world/u/amon",  
  "to": [  
    "https://lemmy.world/c/fediverse",  
    "https://www.w3.org/ns/activitystreams#Public"  
  ],  
  "name": "By the way, you can have `Markdown` in Lemmy post titles",  
  "cc": [],  
  "mediaType": "text/html",  
  "attachment": [],  
  "commentsEnabled": true,  
  "sensitive": false,  
  "published": "2025-01-13T20:48:50.824942Z",  
  "language": {  
    "identifier": "en",  
    "name": "English"  
  },  
  "audience": "https://lemmy.world/c/fediverse"  
}   

You can, but maybe you shouldn’t. Given that this post is in the fediverse community, I don’t feel too bad about mentioning that Lemmy is part of a federated network with PieFed and MBIN (I try not to bollock on too much about the platform I happen to be using).

In the ActivityPub JSON for this post, there is no indication that this field contains MarkDown. If anything, it says the opposite, it says it contains HTML. It’s therefore not unreasonable for other platforms to render it as such.

Given this, and the poor support for mobile clients indicated in the comments, and the fact that it’s only a subset of MarkDown tags, but include ones that aren’t part of CommonMark standard, I’d argue that it’s not necessarily a good idea.

OP won’t see your image unfortunately, because of a difference in how embeds are handled (Mastodon’s use of image attachments to Lemmy’s use of MarkDown has been fixed in one direction, but not the other).

For anyone wondering what the image was, it’s here: https://lemmy.dbzer0.com/pictrs/image/5854765e-4707-4b21-b93f-00f3d781ad71.webp

Also, since I’m not replying directly to OP, I think I also have to do this: @mho@social.heise.de

More abuse of this post for testing PieFed user mentions (sorry if you seeing this)

@freamon@lemmy.world

It uses postgres for the DB - I think that and redis are designed to operate at very large scales, so it wouldn’t be them.

My guess would be that it’s something in the interpreted nature of Python - this seems to be why a familiar dismissal of PieFed is a concern about how it will scale.

That said, this site shows that Python is the most popular language for Fediverse apps (just), the likes of Mastodon are written in another interpreted language (Ruby), and I think there are more big websites running Python (with Django or Flask) than people realise. So I don’t know, really, I’m just following other people’s lead on this. I don’t imagine that any problems would be insurmountable though: an admin could restrict the amount of signups, or if new users mean a few more donations, they could just throw money at the problem (more cycles for one server, or splitting up tasks across multiple servers).

In terms of incoming federation, PieFed sites are dealing with as much activity as any general Lemmy instance. It’s not happened yet, but I suppose it’s possible that problems will become apparent if the amount of local users gets over a certain size. A limit on the amount of users per instance isn’t necessarily a bad thing though (it’s cheap, and hopefully easy enough, for someone to spin up another one).

This is all quite old drama, and the issue itself is fixed now, but at one point someone kicked off about how if you uploaded a picture to Lemmy, there was no easy way to delete it (you could delete your post, but the image would still be there at whatever URL was created for it, and it wasn’t even that easy for admins to find and remove it) - so I’m guessing that it stems from that.

Oh yeah, sorry. I didn’t mention that the API isn’t available on production sites like piefed.social. I’ve been messing around with a build of Thunder on my dev instance, and - among other things - the app doesn’t uses the same V3 endpoint that Lemmy does, so it’d always need to be a different version than the one that’s currently available for Lemmy.

No, it’s not geared up for that. There’s a platform called sublinks where the intention is to be initially compatible enough with Lemmy that it can be a drop-in replacement, but they haven’t released anything yet.

It’s not so much that we expect the developers of Lemmy apps to retool. The hope is that, if we can provide a sensible, well-documented API, then it will appeal to front-end developers looking for a project. Also, if there are any devs of Lemmy mobile apps who are unhappy with Lemmy’s API for any reason, then getting involved with PieFed’s whilst it’s still in development, offers them a chance to shape one to their desires.

Speaking of Thunder though - I’ve been able to compile it for desktop, and get it working with PieFed’s API in the state it’s in now. I’ve no experience with Flutter / Dart or front-end development, so it suggests that - for open source Lemmy apps, at least - it doesn’t need to be the original author who ports it, and that the actual details a particular API are only a relatively small part of creating a good mobile app.

As Admiral Pat mentions, embeds are easy enough. I don’t know how Tesseract does it, but a low-tech solution is to just replace ‘watch’ in the URL with ‘embed’ and stick it in a iframe. From Lemmy’s GitHub, it looks like there’s been work on this, but I’m not familiar enough with it to know whether it’s for future versions that haven’t been released yet.

New videos used to come in to Lemmy as expected. There’s been some regression that stopped it. It’s possible to bring them in manually though (by searching for the URL), and - like with embeds - it’s possible that it’s been fixed but not yet released.

PT’s videos channels are ActivityPub Group types like Lemmy’s communities, but it doesn’t handle federation the same way. It does it in a way that’s more compatible with Mastodon. Lemmy’s communities Announce everything they receive (posts, comments, votes, etc) and so if you receive that Announce, then as long as you trust the community, you can trust that the contents haven’t been changed and process it. PT’s video channels only Announce new posts (so on Mastodon, it appears as if the channel has Boosted content by the channel owner), but for everything else, it’s a combination of sending out a ‘post update’ (which is essentially an invitation to query the outboxes it provides for votes and comments), and just flinging out the comment as is, without the HTTP signature. If you get that comment, then you can either use the LD signature that Mastodon includes to verify, or you can look at the ID, and fetch it from it’s source. As such, Lemmy’s federation model is mostly Push-based, whereas PeerTube’s is a bit of Push, and a lot more Pull.

It depends on what youtube is willing to provide. It seems more likely to provide a thumbnail if you use a youtu.be link than a youtube.com link.

Instances running Lemmy from 0.19.4 onwards (I think) provide the option of providing a separate thumbnail manually, which is useful, but your instance is on 0.19.3.

It’s doesn’t seem like feddit.online is aware of the other community (forumlibre@jlai.lu), so it doesn’t have a copy of both posts, so it doesn’t know that they are cross-posts.

If you bring that community into feddit.online, then create a post with the same URL as a recent post (e.g. https://files.catbox.moe/pebvir.jpeg), then they’ll show up.

The picture (or whatever external resource a post is pointing to, like https://bbc.com/news/article.html)

The post you mentioned (‘melting is tough’) isn’t picked up as a cross-post on PieFed instances because the dates are too far apart. A restriction that Rimu wanted was that they should only be detected if they were within 7 days of one another.

However, if you take that URL (https://lemmy.world/pictrs/image/91f96cc8-a194-4cb8-abc6-505261e65420.jpeg), and make a new post with it, then the post you mentioned now shows that it has a cross-post.

A cross-post is just a post that links to the same URL as another post. The codeberg Issue that Blaze linked to mentions an exception, but other than that, there’s not a convenient button that copy-pastes a post’s title, body, and URL into a new ‘Create Post’ form. You can do it manually though, and everything that receives it will detect it as a cross-post, because everything is just looking for matching URLs.