QR-based signing flow payloads in Miniscript context

Sean Carlin is currently developing Signingroom.io, a platform designed to facilitate the coordination of multisig transactions without acting as a full software wallet. The primary aim is to streamline the process where signers can easily gather, communicate, and merge their signatures, emphasizing ease and efficiency particularly through the use of fountain QRs. This method improves the air-gapped multisig experience by minimizing friction.

Carlin has expressed a preference for a specific method of handling data payloads in multisig transactions, specifically endorsing Option B, which involves transmitting only the signatures rather than the entire Partially Signed Bitcoin Transaction (PSBT). He supports this due to its efficiency in reducing the amount of data transmitted, which avoids the need for complex QR codes and speeds up the process. Carlin suggests enhancing this option by including a simple identifier with each signature payload, such as an unsigned transaction ID or a session ID, to help verify and manage multiple sessions effectively.

Furthermore, Carlin agrees on the need for a more scalable approach to device compatibility checks within the system. Instead of relying on a comprehensive list of model and version strings, he advocates for a device-agnostic feature array that could include supported features like "taproot" and "miniscript." This approach would likely reduce the need for constant updates and maintenance of a centralized device database.

Lastly, Carlin touches upon the improvement of error handling mechanisms by proposing the adoption of standardized integer error codes similar to those used in JSON-RPC. This would potentially allow for more precise user guidance and troubleshooting, enhancing the overall user experience. He concludes with openness to further collaboration, especially regarding the transport and QR aspects of the system once traditional PSBT fountain QR codes are implemented.