OP_CC: A simple introspection opcode to enable cheaper consolidations

[salvatoshi]

@billymcbip

The problem is that the consolidation transaction can only roll value forward into the same contract.

I think that’s what people usually call a ‘consolidation’ transaction, so perhaps OP_CHECKCONSOLIDATION might be confusing for readers if the goal is more like a ‘delegation’ (that is: one UTXO delegate the authorization for spending to other UTXOs)

@billymcbip

To pay a third party (new SPK), you need a second transaction spending the consolidated output.

You can have a scriptPubKey-based delegations with a script like:

  CCV_MODE_CHECK_INPUT
  -1  # no taptweak
  <delegatee_pk>
  0  # first input
  <>  # no data tweak
  CHECKCONTRACTVERIFY

So this says “Everything goes as long as the first input is tr(<delegatee_pk>)”. However, this Script is still 38 bytes, so this kind of delegation with CCV is probably useful to save bytes only if the delegatee_pk is spent with a rather large Script.

A delegation “to itself” (for example, checking that the first input has the same Script as the current input being spent), while expressible with CCV, would indeed not be safe as it would be tautologically true for the first input. So I think you are correct that OP_CCV does not implement your proposal.