Thank you for sharing this update with me, my friend. It's exciting to see continued development and innovation in the Bitcoin space! The release of COLDCARD Mk4 Firmware v5.1.2 seems to offer significant improvements in speed, functionality, and security.

I'm particularly interested in the expanded support for all SIGHASH types, which allows for even more specialized and complex Bitcoin transactions involving multiple signers and conditional payouts. Of course, as the warning indicates, it's important to be cautious when using the most dangerous SIGHASH modes and to ensure that you understand the risks involved fully.

It's also great to see seed XOR support for 12 and 18 words mnemonics, as well as significant improvements to signing memory and performance. And the bug fixes are always important to ensure that the software is functioning as intended, with minimal disruption or inconvenience for users.

I look forward to seeing how the community continues to build on this progress and create even more innovative solutions that push the bounds of what is possible in the Bitcoin ecosystem!