James, cosigners,

I am sympathetic to the idea of a CTV+CSFS soft fork, mainly for its flagship use case: LN-Symmetry.

However i think it is premature to call for a "final review and activation" of these opcodes when there is still:

• disagreement between Bitcoin protocol developers/researchers that it is the way to go for enabling more expressive scripting capabilities in Bitcoin¹;
• disagreement between Bitcoin developers on how the functionality of at least one of the proposed opcodes should be achieved²;
• no review after three months, from any of the champions or signers of this letter, on the PR for integrating one of the two proposed opcodes to the test network³.

The flagship use case of the proposal has also not been properly demonstrated. As a point of comparison Greg Sanders provided motivation for ANYPREVOUT, a soft fork that no one even called to be "finally reviewed and activated", by publishing a detailed proof of concept of LN-Symmetry (with full specification as a BOLT draft + an implementation in one of the major Lightning clients).

A comprehensive exploration gives confidence a use case is actually realistic in practice. Of course it's not necessary to go to such lengths just to demonstrate it to be possible, but it is reasonable to expect a champion to have something to show if they are calling for changing Bitcoin. Fortunately i hear some have taken upon themselves to further explore LN-Symmetry and multiparty channels using CTV+CSFS, which could provide tangible motivation for the soft fork. Let's see what they come up with.

Finally, it seems the post contains a built-in assumption that Bitcoin Core contributors are detached from the research in more expressive scripting capabilities. It is incorrect. A number of individuals have been involved both with Bitcoin Core development and Bitcoin protocol research, with substantial contributions in both areas.

Therefore it seems the stalling state of the CTV+CSFS proposal is not due to apathy as this open letter would lead to believe, but controversy on the content of the proposal among Bitcoin protocol developers as well as a lack of involvement from the part of champions in reaching consensus.

In these conditions calling for an impending change to Bitcoin's consensus rules seems unadvisable, and the urgency with a six months deadline is nothing short of reckless.

I remain confident we can make progress toward enabling more expressive scripting capabilities in Bitcoin. The path forward is by building consensus on the basis of strong technical arguments, and the politics of pushing for the premature activation of a consensus change are working against it.

Best, Antoine Poinsot