fix(sdk): allow higher value utxos and return change (#45)

* refactor: allow higher (wrong) value utxos

* fix: consolidate out amount instead of parsing to int

* feat: return sell price, postage for buyers clarity

packages/sdk/src/inscription/instant-buy.ts

@@ -121,6 +121,8 @@ export async function generateBuyerPsbt({
   // seller psbt merge
 
   const decodedSellerPsbt = bitcoin.Psbt.fromHex(sellerPsbt, { network: networkObj })
+  const sellPrice = (decodedSellerPsbt.data.globalMap.unsignedTx as any).tx.outs[0].value - postage
+
   // inputs
   ;(psbt.data.globalMap.unsignedTx as any).tx.ins[2] = (decodedSellerPsbt.data.globalMap.unsignedTx as any).tx.ins[0]
   psbt.data.inputs[2] = decodedSellerPsbt.data.inputs[0]
@@ -166,7 +168,9 @@ export async function generateBuyerPsbt({
   return {
     hex: psbt.toHex(),
     base64: psbt.toBase64(),
-    fee
+    fee,
+    postage,
+    sellPrice
   }
 }
 

packages/sdk/src/transactions/OrdTransaction.ts

@@ -303,7 +303,7 @@ export class OrdTransaction {
       throw new Error("No commit address found. Please generate a commit address.")
     }
 
-    const outAmount = this.#outs.reduce((acc, cur) => (acc = +cur.value), 0)
+    const outAmount = this.#outs.reduce((acc, cur) => (acc += cur.value), 0)
     const amount = this.postage + this.#feeForWitnessData! + outAmount
 
     const utxos = await OrditApi.fetchSpendables({
@@ -313,7 +313,7 @@ export class OrdTransaction {
       type: this.#safeMode === "on" ? "spendable" : "all"
     })
 
-    const suitableUTXO = utxos.find((utxo) => utxo.value === amount)
+    const suitableUTXO = utxos.find((utxo) => utxo.value >= amount)
     if (!suitableUTXO) {
       throw new Error("No suitable unspent found for reveal.")
     }