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@cthos @mcc @aeva

Thanks! Yes, it looks like the 2 GB / day estimate was from early January, and they didn't implement the ability to cache images until February, so that's *just* for posts, replies, likes, etc, not a full mirror of the network.

(And in fact the image caching ability is on-demand, they don't get fetched from the PDS until someone using the AppView actually tries to view them. The software can also use the PBC's CDN.)

@mcc @aeva @cthos

That's a great point, and I'm guessing that what @cthos meant by "lightweight" AppView was precisely that it doesn't indefinitely store media - it either has a LRU cache or relies on the Bluesky PBC network's CDN.

@erincandescent @ikuturso @mcc @trwnh @jrose

It's vulnerable to collisions, but I don't think those get you much with PLC? (Only the author of a DID creation request could create the collision.)

For pre-image, it inherits the security properties of SHA-256, which is probably fine, unless you're willing to brute-force the full 120 bits, which is well out of range of foreseeable technology I think - the whole Bitcoin network does like 2^96 hashes of SHA-256 per *year*.

@mcc @aeva @cthos

This is just me thinking out loud without much direct knowledge, but isn't live Atmosphere content supposed to remain available on its home PDS indefinitely? So couldn't an AppView implement an LRU cache rather than a full mirror of all content? Or does this storage cost come from something else that can't be trivially re-fetched later?