Provide a way for multisig participant to determine if they need to sign a multisig message

[lenkan]

Currently, it is difficult for a participant of a multisig group to know if they need to sign a multisig message or not. The participant receives notifications, but there is no easy way to determine if they have already signed it or not. Consider the following scenario:

1. Member 1 creates multisig inception event.
2. Member 2 creates /multisig/icp message and sends to Member 2
3. Member 2 receives notification with the /multisig/icp message
4. Member 2 creates multisig inception event from data in message
5. Member 2 creates identical /multisig/icp message and sends to Member 1
6. Member 1 receives notification with the /multisig/icp message from Member 2

Here, Member 1 does not need to act on the notification because it already signed this message in step 2. During the dev call today it seems like this type of functionality is available in the codebase, but it is currently not exposed in the API.

Some possible solutions:

• Skip creation of the notification if a participant does not need to act.
• Add a flag to the notification to indicate if the user needs to act or not.
• .... discuss