Transaction is duplicated on the wire to signer

[devrandom]

Issue

Several hsmd protocol messages use bitcoin_tx which includes a wally_tx and a wally_psbt. However, wally_psbt already includes a wally_tx, resulting in duplication of the transaction on the wire.

We (VLS project) tried ignoring the top level wally_tx, but discovered that the two transactions differ in the amounts - possibly a different feerate is sometimes used.

In addition to not being DRY, the dupilcation results in additional memory usage in low-resource environments.

[rustyrussell]

Hmm... We've been stuck for a while in the internal transition from txs to psbts. This might well provide motivation to finish it (PSBT everywhere!).

Or at least make sure they match!!

[devrandom]

any plans for moving forward with this?