Plumb

Signer-side security for Solana multisigs.

Plumb is a browser extension that sits on the Squads V4 approval modal and shows what you are about to sign in plain English. It decodes durable-nonce replay windows, flags owner-mismatched nonce accounts, diffs account and authority changes via Surfpool simulation, and diffs BPF bytecode for program upgrades. Read-only at the signer interface, it never signs or modifies the transaction.