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alright here it is, my hit-piece on CARs in atproto, with a big ecosystem survey

I think this is legit to call out! STAR-lite is cool and solves a couple other paper cuts. but I think churning on low-level formats in the protocol spec itself probably isn't worth it? I do think the ecosystem can+should migrate away from older flexible IPLD libs to stricter DASL/atproto libs

pretty similar to the relay comparison that @iame.li did a couple months ago. with a bit of attention/coordination I don't think it will be that big of a lift to nail these down. getting the details nailed down in the IETF text first feels like the right sequencing.

yeah, if the reached-for libraries trend toward DASL (with actually-checked CID behaviour, which isn't technically required from the library itself in DASL) then hopefully the safety story gets better. i don't think the footgun will ever go away but maybe a kind of herd immunity works out

for public atproto this was really part 1 -- i think the streaming story is still bad, and that we need changes to DASL. (it doesn't actually say you're allowed to require a specific block order! it also vaguely hints that duplicate blocks could become disallowed! i worry about "happens to work")

(plus we still need to figure out how stream-ordered cars are even signalled, they still don't work by current draft. (i'm overdue for making the wg mailing list follow-up!)) for both spaces and public atproto it's a little disappointing to land at ~2x size/bandwidth overhead. but,

end of the day CARs are mostly fine, probably. documenting the warts for me is as much about documenting what we accept as it is about pushing for it to change. (and about answering "why" for STAR-lite and justifying its slight network-fracturing effect)

so is this also how you export and import spaces? because that circles back around to "are permissioned repos nominally stored as a merkle tree or nah" question

export for sync ya and no, afaik just a set of key/values and a 2kb lthash digest over it. you could keep it as an mst for key-value representation if convenient (but i’d argue that for public repos, storing the mst at all is just a convenience too hehe)

maybe I missed a beat, but I assume nobody is using MST for space data in any form? I have an iteration of the space CAR layout I need to publish...

I do, but only as an internal implementation detail (to be able to reuse the low level stuff ), nothing exposed

that’s me except i also want to expose it 🤷‍♂️ bsky.app/profile/iame...

oh cool. i think stratos does an mst for private data too for yet another reason (hybrid spaces/non-spaces private system).