I’m developing a Bitcoin application (“Bitcoin Monitor”) whose goal is not to replace wallets, but to orchestrate standard PSBT signing flows in a robust and long-term-resilient way.
My current setup is:
Bitcoin multisig 2-of-2 (A + B)
P2WSH
Two Ledger devices (Ledger A and Ledger B)
PSBT signing via HWI
Watch-only wallet / UTXO scanning handled by my application
I’ve validated this setup using Sparrow, but I want to remove Sparrow from the trust and dependency model.
The core concern I’m trying to address is:
If Sparrow disappears, I don’t want to be locked into a third-party UI to spend my funds.
Where I am today
My application can build a PSBT from known UTXOs.
I can call hwi signtx and obtain partial signatures.
Ledger requires a “first confirmation / review step” before signing, which I understand is normal behavior.
I want to reliably sign with Ledger A first, then Ledger B, and then finalize and broadcast the transaction.
What I’m trying to achieve (target architecture)
Use only Bitcoin standards (PSBT, descriptors, BIP32/48 derivation paths).
Make my application a PSBT orchestrator, not a wallet.
Let the Ledger devices perform all signing, with no private keys ever exposed.
Ensure the setup remains usable even if Sparrow, Specter, or any other UI disappears.
My questions
- What is the minimum PSBT information required for Ledger to:
recognize inputs as belonging to the device
avoid alarming warnings
allow clean multi-step signing (Ledger A then Ledger B)
Is storing and using descriptors (receive + change) considered the recommended long-term approach for this use case?
In a 2-of-2 P2WSH multisig, is the following flow considered correct and robust?
build PSBT
sign with Ledger A (via HWI)
sign with Ledger B (via HWI)
finalize and broadcast (Bitcoin Core)
- Are there any pitfalls to avoid when designing this without Sparrow (e.g. derivation paths, witness_utxo vs non_witness_utxo, Ledger-specific UX constraints)?
I’m explicitly trying to avoid proprietary formats and UI lock-in, and would appreciate feedback from people who have designed similar multisig, institutional, or long-term custody setups.
Thanks in advance
Victor
