Planner should support lack of a source account

[turbocrime]

Specifically for delegator voting, it's important to be able to construct transactions that do not have a restricted source.

The RPC documentation also indicates that omitting a source is valid in order to indicate this preference.

#1499 recently prevented an absent source 35ed14c

what was the specific motivation for issue #1433 requesting this? it seems to refer to #1412 (edit: perhaps #1421) however the only mention of source in that PR is where it looks for native tokens to pay gas

it does not seem strictly necessary to require source for that. if source is absent, it should be permissible to pay gas from any account, right? so the requirement could be reversed

[Valentine1898]

Delegate voting is directly related to staking and delegating.

The design of staking in minifront assumes that user accounts are isolated, and that they can manage their stakes on each account separately. However, the user cannot delegate from all accounts with a single transaction.

It seems to me that it would be a good idea to port this design for delegate voting as well. I.e. I think that instead of voting with all accounts in one transaction there should be an interface where the user can switch between accounts and vote for each account separately.

[TalDerei]

If we remove the strict enforcement of the source in both the TPR and planner, funds could theoretically be spent from any account. Currently, we enforce account isolation and limit the ability to spend funds from different accounts.

However, I agree with @Valentine1898's approach. Although the source field isn't a strict requirement at the RPC level and can be omitted, I don't think it's a desirable feature. Transactions should ideally be strictly linked to a source account in my opinion.

[plaidfinch]

On further consideration, this makes sense to me. Interfaces for delegator voting can present an account switcher.