mocha-4 genesis file does not define an app version

[rootulp]

Context

https://celestia-team.slack.com/archives/C02PFFCGMNW/p1725353291554399?thread_ts=1725273825.398589&cid=C02PFFCGMNW

Problem

Attempt to sync a v2.1.2 node from genesis with the genesis.json file defined at https://github.com/celestiaorg/networks/blob/master/mocha-4/genesis.json

Proposal

Option 1: modify Mocha genesis.json

• Identify if there are any issues with updating the existing genesis.json file.
• Update the mocha-4 genesis file (I checked both celestia and arabica-11 and they have the correct app version in the genesis)

"version": {
   "app_version": "1"
}

• Update https://github.com/celestiaorg/networks/blob/master/mocha-4/genesis_hash.txt
• Update the checksum for the download-genesis command so it works with the modified genesis.

Option 2: modify celestia-app to accomodate mocha-4's lack of app version in genesis.json

[evan-forbes]

is it possible to modify the genesis and sync an existing network from scratch? if so, is that a bug? my understanding of the genesis is that its the first block.

edit:
It appears that this is possible! however, the change involved changing the genesis state to something the app was expecting (app version v1). Committing to the hash of a json file is likely not a good idea and everything important has to be committed to elsewhere, but still seems slightly weird to not commit to the entire thing.

[rootulp]

As an alternative to modifying the genesis file: can celestia-app interpret an InitGenesis invocation on a genesis file with an unpopulated app version as 1?

Did this only surface for DevOps maintained Mocha nodes because it was a regression in v2.x.x?