Hello,
This is primarily aimed at developers of SPV wallets.
The recently reported decrease in number of full nodes could have several reasons, one of them that less people are running Bitcoin Core for the wallet because the other wallets are getting ahead in both features and useability.
It's great to see innovation in wallets, but it's worrying that the number of full nodes decreases.
It may be that lots of people would support the network by running a full node, but don't want to go through the trouble of installing bitcoin core separately (and get confused because it's a wallet, too).
Hence I'd like to explore the idea of adding an option to popular SPV wallets, to spin a bitcoind process in the background. This could be pretty much transparent to the user - it would sync in the background, the wallet could show statistics about the node, but is not dependent on it.
In exchange the user would get increased (full node level) security, as the SPV wallet would have a local trusted node.
Is there any way that Bitcoin Core can help to accomedate this 'embedded' usage? Specific Interfaces, special builds - maybe add a walletless bitcoind build to gitian - bindings, dlls, etc?