Combined CTV/APO into minimal TXHASH+CSFS

The discussion emphasizes the complexity and potential risks associated with implementing upgrade hooks versus introducing new opcodes in the context of blockchain and Bitcoin development. The argument posits that from a practical standpoint, both strategies necessitate client updates and deployment of forks, making them similarly demanding in terms of implementation efforts. Moreover, it is highlighted that the benefits of conserving code on the Core side might be marginal at best.

The conversation shifts towards a critique of a proposed method for assembling sighash messages through the manipulation of transaction components using CAT and SHA opcodes. This approach is viewed with skepticism due to doubts about the necessity of creating fundamentally different combinations of transaction component hashes. Furthermore, it is argued that performing such operations on the stack leans more towards computation rather than verification, which is deemed inefficient for layer 1 (L1) processes. This critique underscores a preference for "Complex Instruction Set Computer" (CISC) over "Reduced Instruction Set Computer" (RISC)-style opcodes within Bitcoin, based on the efficiency of anticipating user needs despite acknowledging that a balance between the two approaches could be beneficial.

Additionally, the discussion touches upon the potential applications of CSFS (Client-Side Filtering System), like key delegation and possibly federations, though it concedes a lack of depth in explaining these uses. The argument suggests that if the primary application for CSFS is to facilitate the unification of BIP 118 and 119, it might be more straightforward to activate both proposals simultaneously as they are currently written. The contributor (@reardencode) receives commendation for their innovative approach and useful contributions, particularly highlighting the inclusion of a "what is hashed?" table in their document, which adds value to the discourse on this topic.