Signer HealthCheck

[matthiasdebernardini]

Describe the enhancement
It would be great for a wallet that has separate signers to be able to ask and show that they still have signing capability (in case of a bad update, lost or stolen keys).

I think it should be at the wallet level, because you'd have to know how many signers there are and which address type they have and the specific api that the signer has (ledger, coldcard, sparrow).

Use case
A wallet that uses hardware signers would want to know if they can still sign without spending any money.

Additional context
The API for ths would be very tricky, the wallet would need to introspect into the descriptor and understand all the combinations for how to satisfy it (say a complex miniscript) but also it would want to know that each key in the descriptor can sign as well.

This would be a great feature for bdk v2, once they figure out what they want to do about the signing capability of BDK