# @dgb-wallet/psbt

DigiByte transaction construction and signing via PSBT (BIP174).

- `buildPsbt({ inputs, outputs })` — construct an unsigned PSBT from UTXOs and outputs, BIP69 sorted by default
- `signAllInputs(psbt, keyPair)` — sign every input with an ECPair; fails loudly if any input can't be signed
- `finalizeAndExtract(psbt)` — after signing, produce broadcast-ready `{ hex, txid }`
- `feeSats(psbt)` / `feeRateSatsPerByte(psbt)` — inspect fee before broadcasting

Supports BIP44 (P2PKH), BIP49 (P2SH-P2WPKH), BIP84 (P2WPKH), BIP86 (P2TR) inputs. Depends on `@dgb-wallet/core` for network params.

## Demo

```bash
cd "D:\Dev\SilentCode\Digibyte"
npm install    # first time only, sets up the workspace
npm run demo -w @dgb-wallet/psbt
```

Derives a key from the public BIP39 test seed, constructs a PSBT spending a synthetic UTXO to two outputs, signs it, and prints the raw transaction hex. The UTXO is fake so this cannot be broadcast — but every other step (derivation, PSBT construction, signature, finalization) is real and identical to what a broadcastable transaction would use. Feed a real UTXO from `scantxoutset` / Blockbook / Electrum-DGB and the same code produces a live transaction.

## Layout

```
src/
  types.ts   — Utxo, Output, BuildParams shapes
  build.ts   — buildPsbt with BIP69 sorting
  sign.ts    — signAllInputs, finalizeAndExtract, fee inspection
  index.ts   — re-exports

scripts/
  build-tx-demo.ts — end-to-end seed → signed-tx demo
```