Thanks for the feedback!
Exactly! That’s a motivation behind this post: there should be an RPC that any wallet could implement to show a user useful signing info for user ops and allow that user to engage in 4337 transactions. Some users may like their existing wallet for whatever reason and not want to migrate key materials. We’ve already heard from ThirdWeb and others that their SDKs would probably support the big consumer wallets as signers if such an RPC existed. I see no downside in specifying this.
Regarding filling in fields:
A paymaster is something that can either be set by the dApp, or by the wallet.
If the application fills it in, the wallet is expected to use it.
If the dApp didn’t fill in the paymaster (which means, the application doesn’t care about actual payment model), the wallet may use its own configuration and fill in a paymaster.
In any case, when displaying the UserOp to the user, the user may select to change the paymaster - but this is up to the wallet UX to decide.
OK, so to be clear, you’re saying here that the AA wallet is receiving an eth_sendUserOperation call, right? If so I think the 4337 EIP could better specify that the eth_sendUserOperation does not have to have a valid signature.