PSBT Signing Flow Patterns A summary of how PSBTs flow through different hardware wallet transports. Flow types USB direct (online signer) Wallets: Trezor, Ledger, BitBox02, Coldcard via USB, Jade USB, Keystone (charging only). Pro: fastest. Con: USB connectivity = potentially compromised host. microSD airgap (true offline) Wallets: Coldcard, Passport, Jade (with SD), Keystone. Pro: no USB connection; truly airgapped. Con: SD card handling overhead. QR airgap (animated QR / BCUR) Wallets: Passport, Coldcard Q, Jade, Keystone, SeedSigner, Krux. Pro: no physical connection. Con: scan time for b…