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archipelagoandClaude Opus 5 5faf1a3c5f docs(quick-260731-upz): PSBT-first signing architecture spec
Watch-only descriptor wallets, external signers, multisig, air-gap transport
and honest LND limits — a spec a future /gsd-plan-phase can consume.

- Names the current gap: bitcoin.rs:203 passes disable_private_keys=false and
  bitcoin.rs:229-231 imports wpkh(xprv/...), so Core holds the BIP-84 account
  PRIVATE key today. Closing that is Phase 1 and unblocks everything else
- Full Core RPC loop with wallet- vs node-scoped RPCs; analyzepsbt drives UI
- Tier 1 single-sig with mandatory [fingerprint/derivation] key origin; Tier 2
  wsh(sortedmulti) on BIP-48; taproot/MuSig2 deferred as UNVERIFIED
- BC-UR v2 primary (fountain-coded, degrades gracefully), BBQr for Coldcard,
  file fallback always; animated multi-frame is mandatory, not optional
- LND: channel/revocation/HTLC keys CANNOT be air-gapped; funding tx must
  NEVER be self-broadcast (type-level refusal, not a boolean)
- On-chain (PSBT-protectable) vs lightning (necessarily hot) split, with the
  exact user-facing sentence the UI must use
- Hot wallet kept as explicitly-secondary with server-enforced limits; safe
  path is the DEFAULT, per T1's survivors
- Migration section refuses to over-alarm: the audit found no entropy defect,
  so no Archipelago user needs to rotate a seed
- 7 phases with dependencies, candidate requirements, and hardware gating
- Answers two open items in docs/hardware-signer-design.md
- Flags bitcoin-knots:latest as an unpinned tag vs ADR-009

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
2026-07-31 23:09:17 -04:00
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