This was what I was suggesting all along, sorry if I wasn't clear.
That's great. So, basically the multi-level refund problem is solved by this?
Yes. So to be clear, I think there are 2 desirable end-goal proposals (ignoring difficulty of changing things for a minute):
* Transactions and blocks keep referring to other transactions by full txid, but signature hashes are computed off normalized txids (which are recursively defined to use normalized txids all the way back to coinbases). Is this what you are suggesting now as well?
* Blocks commit to full transaction data, but transactions and signature hashes use normalized txids.
The benefit of the latter solution is that it doesn't need "fixing up" transactions whose inputs have been malleated, but comes at the cost of doing a very invasive hard fork.