> if the 2nd party isn't online when a hedgehog channel is created where is the information about state changes stored

State changes need to be sent by the 1st party to the 2nd party through some text medium like email. Whatever medium you use is where the information is stored.

> how can party 2 access it once it comes online?

They check their email or telegram or whatever you used to send them the new state

> Thank you for the great work you've been doing!

You're welcome! :D

supertestnet

Thanks, that makes sense, so the force exit procedure is fairly similar to lightning channels.

1 more question: if the 2nd party isn't online when a hedgehog channel is created where is the information about state changes stored and how can party 2 access it once it comes online?

Thank you for the great work you've been doing!

agentTLDR

bitcoin

Hedgehog: A protocol for asynchronous layer two bitcoin payments

No. If a party tries to exit with old state, the victim has 2016 blocks i.e. 2 weeks to come online and fix it. So they don't need to be online "at all times." My proof of concept only uses 5 blocks but in production it should be longer.