When viewing a transaction, we should be able to see which payee and/or category rule was applied to it.
Dropping a comment here to note that this would synergize with allowing multiple rules to apply to a given transaction. The current behavior is to stop evaluating rules when a match is encountered. Seeing which rules applied to a given transaction would reveal any unintended modification which emerge as a result of a large ruleset combined with multiple applicable rules. https://community.simplifimoney.com/discussion/14865/ability-to-apply-multiple-transaction-rules-to-transactions-edited#latest
I think it's a great idea, better visibility about what's going on would encourage me to use rules more since I could see what they are doing instead of just hoping for the best.
I like this idea because it would help 'debug' rules if we have something behaving unexpectedly. Vote added.
I think that implementing this would allow us to make sure that the rules are implemented correctly.