I would like to give an update on "federation" on Bluesky.
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@jdp23 @mcc not adversary (directly), just forced to be less cooperative by being a US entity under meddling FCC and congress! I would also note that how bsky.app shows content to bsky users NOT applying their own blocklist/mod service is uncharted and unspecified territory. they never promised they even would and reserve the right to just not. its a hard problem! I refer to it as "federated moderation" and its totally fair they never even promised to try doing it
@jdp23 @mcc also note: there is a weird migration corner-case where the "blob store" of high-activity/high-attachment-volume accounts seems to glitch out when people move between PDS implementations. fascinating from the POV of someone who's been studying migration corner-cases in both protocols for years 🤯
https://bsky.app/profile/matthewcort.land/post/3m2nvkpx5tc2d -
So. The thread above. An update.
We finally got a live test of the "Gertrude scenario", when a popular Blacksky user got permbanned by Bluesky. I, using my own PDS and blacksky's website, can't see him or his posts ( https://blacksky.community/profile/did:plc:2aebn3xk5t63net43eeepire/post/3m2iokicegs2b ). What gives?
A lot of people claim this is because Blacksky really is using Bluesky's appview, and gave me a way to verify this looking at headers. This seems to contradict Rudy's previous claims. I've asked Rudy for clarification: https://bsky.app/profile/did:plc:2aebn3xk5t63net43eeepire/post/3m2jve23cf22m
Follow up, 2025-12-27: Rudy here confirms the Blacksky appview is still being worked on (eg: blacksky uses bluesky's appview still)
The sticking point, as he describes it, is "backfill". This alludes to the issue that makes me compare ATProto to blockchain: to get the features users expect, every node on the network must mirror the network's entire history. This is impractical, which is why bluesky is as of this moment a federated network with effectively only one node.
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Follow up, 2025-12-27: Rudy here confirms the Blacksky appview is still being worked on (eg: blacksky uses bluesky's appview still)
The sticking point, as he describes it, is "backfill". This alludes to the issue that makes me compare ATProto to blockchain: to get the features users expect, every node on the network must mirror the network's entire history. This is impractical, which is why bluesky is as of this moment a federated network with effectively only one node.
@mcc its really weird for it to be controversial to compare ATProto to blockchain when it was an explicit selling point of the protocol before blockchains became embarrassing to develop for!!
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Follow up, 2025-12-27: Rudy here confirms the Blacksky appview is still being worked on (eg: blacksky uses bluesky's appview still)
The sticking point, as he describes it, is "backfill". This alludes to the issue that makes me compare ATProto to blockchain: to get the features users expect, every node on the network must mirror the network's entire history. This is impractical, which is why bluesky is as of this moment a federated network with effectively only one node.
@mcc it's such a confusing aspect of the protocol. why does everything need the firehose? how do they expect it to scale??
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@mcc it's such a confusing aspect of the protocol. why does everything need the firehose? how do they expect it to scale??
@whitequark If hypothetically, just hypothetically, we imagine that a core design requirement of the protocol was "regardless of what happens in future, it must continue to be necessary that the company Bluesky LLC exists"… the decision becomes a lot less confusing.
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@whitequark If hypothetically, just hypothetically, we imagine that a core design requirement of the protocol was "regardless of what happens in future, it must continue to be necessary that the company Bluesky LLC exists"… the decision becomes a lot less confusing.
@whitequark (More charitably: If one considered fast, full-text search to be a highest priority feature, and it was merely *unimportant* to the designer whether a second full-service node could ever function… then one might make the decisions bluesky made here.
As for scaling, I assume when the day comes they need it to actually scale they'll either discontinue or break the externally-published linear event stream?)
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@whitequark (More charitably: If one considered fast, full-text search to be a highest priority feature, and it was merely *unimportant* to the designer whether a second full-service node could ever function… then one might make the decisions bluesky made here.
As for scaling, I assume when the day comes they need it to actually scale they'll either discontinue or break the externally-published linear event stream?)
@mcc @whitequark reminds me of the good(*) old days when the Twitter firehose was open... Surely history would never repeat...
(*) in hindsight probably not actually.
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@mcc it's such a confusing aspect of the protocol. why does everything need the firehose? how do they expect it to scale??
@whitequark @mcc given the history of the whole thing, I find it exceedingly likely that this is a feature rather than a bug, i.e. the entire premise of it was to capture an emerging market and user-base by riding the decentralisation buzz and tying it into blockchain/web3 (and NFTs to a lesser extent). it's also on brand - solutions that purport to empower users while really just maintaining plausible deniability for control and financial gain are the lifeblood of that class of technologist.
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Follow up, 2025-12-27: Rudy here confirms the Blacksky appview is still being worked on (eg: blacksky uses bluesky's appview still)
The sticking point, as he describes it, is "backfill". This alludes to the issue that makes me compare ATProto to blockchain: to get the features users expect, every node on the network must mirror the network's entire history. This is impractical, which is why bluesky is as of this moment a federated network with effectively only one node.
:frogsiren: BLUESKY HAS OFFICIALLY NETSPLIT :frogsiren:
There has always been more than one Fediverse. Different instances make different moderation decisions so some instances can't see posts by some users.
There has only ever been one Bluesky because every ATProto frontend uses the same Appview.
It is January 2026 and that's no longer true; Blacksky's Appview is available for beta use and there is at least 1 user banned on Bluesky but not Blacksky. And vice versa.
Rudy wants revolution. (@rude1.blacksky.team)
Bluesky runs an appview. Blacksky runs an appview. A complete appview is a several terabytes sized database of the >18 billion follows, likes and posts of all bsky users, ever and forever. To run a different appview is to make a fork in bsky’s timeline. One has new posts from Łink. One doesn’t.
Bluesky Social (bsky.app)
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:frogsiren: BLUESKY HAS OFFICIALLY NETSPLIT :frogsiren:
There has always been more than one Fediverse. Different instances make different moderation decisions so some instances can't see posts by some users.
There has only ever been one Bluesky because every ATProto frontend uses the same Appview.
It is January 2026 and that's no longer true; Blacksky's Appview is available for beta use and there is at least 1 user banned on Bluesky but not Blacksky. And vice versa.
Rudy wants revolution. (@rude1.blacksky.team)
Bluesky runs an appview. Blacksky runs an appview. A complete appview is a several terabytes sized database of the >18 billion follows, likes and posts of all bsky users, ever and forever. To run a different appview is to make a fork in bsky’s timeline. One has new posts from Łink. One doesn’t.
Bluesky Social (bsky.app)
@mcc I haven't thought about the term 'netsplit' in AGES.
Also: Huh. Makes one wonder what Blewski's response will be.
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:frogsiren: BLUESKY HAS OFFICIALLY NETSPLIT :frogsiren:
There has always been more than one Fediverse. Different instances make different moderation decisions so some instances can't see posts by some users.
There has only ever been one Bluesky because every ATProto frontend uses the same Appview.
It is January 2026 and that's no longer true; Blacksky's Appview is available for beta use and there is at least 1 user banned on Bluesky but not Blacksky. And vice versa.
Rudy wants revolution. (@rude1.blacksky.team)
Bluesky runs an appview. Blacksky runs an appview. A complete appview is a several terabytes sized database of the >18 billion follows, likes and posts of all bsky users, ever and forever. To run a different appview is to make a fork in bsky’s timeline. One has new posts from Łink. One doesn’t.
Bluesky Social (bsky.app)
@mcc Would this mean that there'd be a new bridgy specifically to Blacksky?
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@mcc Would this mean that there'd be a new bridgy specifically to Blacksky?
@mayintoronto No - Bridgy Fed supports any ATProto PDS, including the ones run by Blacksky
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:frogsiren: BLUESKY HAS OFFICIALLY NETSPLIT :frogsiren:
There has always been more than one Fediverse. Different instances make different moderation decisions so some instances can't see posts by some users.
There has only ever been one Bluesky because every ATProto frontend uses the same Appview.
It is January 2026 and that's no longer true; Blacksky's Appview is available for beta use and there is at least 1 user banned on Bluesky but not Blacksky. And vice versa.
Rudy wants revolution. (@rude1.blacksky.team)
Bluesky runs an appview. Blacksky runs an appview. A complete appview is a several terabytes sized database of the >18 billion follows, likes and posts of all bsky users, ever and forever. To run a different appview is to make a fork in bsky’s timeline. One has new posts from Łink. One doesn’t.
Bluesky Social (bsky.app)
@mcc for us tech noobies in the audience, could you explain what does this mean?
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:frogsiren: BLUESKY HAS OFFICIALLY NETSPLIT :frogsiren:
There has always been more than one Fediverse. Different instances make different moderation decisions so some instances can't see posts by some users.
There has only ever been one Bluesky because every ATProto frontend uses the same Appview.
It is January 2026 and that's no longer true; Blacksky's Appview is available for beta use and there is at least 1 user banned on Bluesky but not Blacksky. And vice versa.
Rudy wants revolution. (@rude1.blacksky.team)
Bluesky runs an appview. Blacksky runs an appview. A complete appview is a several terabytes sized database of the >18 billion follows, likes and posts of all bsky users, ever and forever. To run a different appview is to make a fork in bsky’s timeline. One has new posts from Łink. One doesn’t.
Bluesky Social (bsky.app)
The "portable identity" elements of Bluesky/ATProto make the netsplit just a tad odd. My account is hosted on a PDS server I run, so I'm beholden to no frontend. If I log in through the main Blacksky frontend (Bluesky appview) one user I'm following shows only an error message. Via the Staging Blacksky frontend (atproto.africa), I can see I'm following him and see his posts. I'm SO curious about the edge cases. I assume if I boost him it's hidden from the Bluesky appview. What if I reply to him?
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The "portable identity" elements of Bluesky/ATProto make the netsplit just a tad odd. My account is hosted on a PDS server I run, so I'm beholden to no frontend. If I log in through the main Blacksky frontend (Bluesky appview) one user I'm following shows only an error message. Via the Staging Blacksky frontend (atproto.africa), I can see I'm following him and see his posts. I'm SO curious about the edge cases. I assume if I boost him it's hidden from the Bluesky appview. What if I reply to him?
@mcc When you are suspended by bluesky corp, is the ban at the app view or PDS level?
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@mayintoronto No - Bridgy Fed supports any ATProto PDS, including the ones run by Blacksky
@quillmatiq @mayintoronto @mcc But what if I want to cancel the bridge, but only to the Nazi one? Can I do that, and advise my correspondents to migrate to BlackSky? How hard would that be?
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@quillmatiq @mayintoronto @mcc But what if I want to cancel the bridge, but only to the Nazi one? Can I do that, and advise my correspondents to migrate to BlackSky? How hard would that be?
@martinvermeer Not today, but stay tuned for next week
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The "portable identity" elements of Bluesky/ATProto make the netsplit just a tad odd. My account is hosted on a PDS server I run, so I'm beholden to no frontend. If I log in through the main Blacksky frontend (Bluesky appview) one user I'm following shows only an error message. Via the Staging Blacksky frontend (atproto.africa), I can see I'm following him and see his posts. I'm SO curious about the edge cases. I assume if I boost him it's hidden from the Bluesky appview. What if I reply to him?
Oh and I can't get staging.blacksky on my phone app. So imagine if you were using Mastodon, but you saw a slightly different list of posters, *and potentially a different set of your own posts*, depending on whether you were using your PC or your phone. This is great if there's a banned user you want to follow— you get an *option* to follow them. Mastodon.social can deny me the *option* to follow someone, on Fediverse. But except in that edge case this *might* not be a fantastic user experience!
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@mcc for us tech noobies in the audience, could you explain what does this mean?
@coracinho Does this help? https://mastodon.social/@mcc/115918101156654032
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@mcc When you are suspended by bluesky corp, is the ban at the app view or PDS level?
@fabrice This is a VERY interesting question, as the answer appears to be "all of them". And when Link got banned, *that answer appeared to be surprising even to Bluesky employees*. The original messaging from Bluesky suggested you'd get banned only by the "labeler"— a third thing altogether. But there's obvious problems with that answer, and it's never what Bluesky implemented. After Link got banned Bluesky said they were reviewing this, but I don't think *changed* anything.
