off-chain sends are co-signed by the Ark server [...] but it can never spend your coins
That is not how Ark works.
Wait on the website, section how it works:
The server can never take your money [...] a wallet left untouched past expiry can be swept by the server.
A wallet swept means coins can be spend, money can be taken.
No mention of sender/server collusion (the sender can be the server by the way), no mention of the frequency of required user interaction (or delegated signing).
I think the documentation needs some work to not mislead the users.
From the github readme:
That is not how Ark works.
Wait on the website, section how it works:
A wallet swept means coins can be spend, money can be taken.
No mention of sender/server collusion (the sender can be the server by the way), no mention of the frequency of required user interaction (or delegated signing).
I think the documentation needs some work to not mislead the users.