From 9671aa08c2a7eb0af75ad3016585872c5b781f75 Mon Sep 17 00:00:00 2001
From: Ava Chow <github@achow101.com>
Date: Mon, 16 Mar 2026 14:05:39 -0700
Subject: [PATCH] psbt: add tx input and output fields in PSBTInput and
 PSBTOutput

PSBTInput should be aware of the previous txid, output index, and
sequence numbers for inputs, extracting them from the global
unsigned tx.

PSBTOutput should be aware of the output amount and script, extracting
them from the global unsigned tx.

This prepares for PSBTv2 where these fields are serialized.
---
 src/psbt.cpp                  | 10 ++++++++--
 src/psbt.h                    | 24 ++++++++++++++++++------
 src/rpc/rawtransaction.cpp    | 18 ++----------------
 src/test/fuzz/deserialize.cpp |  4 ++--
 4 files changed, 30 insertions(+), 26 deletions(-)

diff --git a/src/psbt.cpp b/src/psbt.cpp
index 416eae11d1f..29f16e73c87 100644
--- a/src/psbt.cpp
+++ b/src/psbt.cpp
@@ -15,8 +15,14 @@ using common::PSBTError;
 
 PartiallySignedTransaction::PartiallySignedTransaction(const CMutableTransaction& tx) : tx(tx)
 {
-    inputs.resize(tx.vin.size(), PSBTInput(GetVersion()));
-    outputs.resize(tx.vout.size(), PSBTOutput(GetVersion()));
+    inputs.reserve(tx.vin.size());
+    for (const CTxIn& input : tx.vin) {
+        inputs.emplace_back(GetVersion(), input.prevout.hash, input.prevout.n, input.nSequence);
+    }
+    outputs.reserve(tx.vout.size());
+    for (const CTxOut& output : tx.vout) {
+        outputs.emplace_back(GetVersion(), output.nValue, output.scriptPubKey);
+    }
 }
 
 bool PartiallySignedTransaction::IsNull() const
diff --git a/src/psbt.h b/src/psbt.h
index 4272cd3a807..dcf0d6bd1a5 100644
--- a/src/psbt.h
+++ b/src/psbt.h
@@ -280,6 +280,10 @@ public:
     std::map<uint160, std::vector<unsigned char>> hash160_preimages;
     std::map<uint256, std::vector<unsigned char>> hash256_preimages;
 
+    Txid prev_txid;
+    uint32_t prev_out;
+    std::optional<uint32_t> sequence;
+
     // Taproot fields
     std::vector<unsigned char> m_tap_key_sig;
     std::map<std::pair<XOnlyPubKey, uint256>, std::vector<unsigned char>> m_tap_script_sigs;
@@ -304,8 +308,11 @@ public:
     void FromSignatureData(const SignatureData& sigdata);
     void Merge(const PSBTInput& input);
     uint32_t GetVersion() const { return m_psbt_version; }
-    explicit PSBTInput(uint32_t psbt_version)
-        : m_psbt_version(psbt_version)
+    explicit PSBTInput(uint32_t psbt_version, const Txid& prev_txid, uint32_t prev_out, std::optional<uint32_t> sequence = std::nullopt)
+        : m_psbt_version(psbt_version),
+        prev_txid(prev_txid),
+        prev_out(prev_out),
+        sequence(sequence)
     {
         assert(m_psbt_version == 0);
     }
@@ -816,13 +823,18 @@ public:
     std::map<std::vector<unsigned char>, std::vector<unsigned char>> unknown;
     std::set<PSBTProprietary> m_proprietary;
 
+    CAmount amount;
+    CScript script;
+
     bool IsNull() const;
     void FillSignatureData(SignatureData& sigdata) const;
     void FromSignatureData(const SignatureData& sigdata);
     void Merge(const PSBTOutput& output);
     uint32_t GetVersion() const { return m_psbt_version; }
-    explicit PSBTOutput(uint32_t psbt_version)
-        : m_psbt_version(psbt_version)
+    explicit PSBTOutput(uint32_t psbt_version, CAmount amount, const CScript& script)
+        : m_psbt_version(psbt_version),
+        amount(amount),
+        script(script)
     {
         assert(m_psbt_version == 0);
     }
@@ -1264,7 +1276,7 @@ public:
         // Read input data
         unsigned int i = 0;
         while (!s.empty() && i < tx->vin.size()) {
-            PSBTInput input(psbt_ver);
+            PSBTInput input(psbt_ver, tx->vin[i].prevout.hash, tx->vin[i].prevout.n, tx->vin[i].nSequence);
             s >> input;
             inputs.push_back(input);
 
@@ -1287,7 +1299,7 @@ public:
         // Read output data
         i = 0;
         while (!s.empty() && i < tx->vout.size()) {
-            PSBTOutput output(psbt_ver);
+            PSBTOutput output(psbt_ver, tx->vout[i].nValue, tx->vout[i].scriptPubKey);
             s >> output;
             outputs.push_back(output);
             ++i;
diff --git a/src/rpc/rawtransaction.cpp b/src/rpc/rawtransaction.cpp
index 67067110648..517a02bf39d 100644
--- a/src/rpc/rawtransaction.cpp
+++ b/src/rpc/rawtransaction.cpp
@@ -1649,14 +1649,7 @@ static RPCMethod createpsbt()
     CMutableTransaction rawTx = ConstructTransaction(request.params[0], request.params[1], request.params[2], rbf, self.Arg<uint32_t>("version"));
 
     // Make a blank psbt
-    PartiallySignedTransaction psbtx;
-    psbtx.tx = rawTx;
-    for (unsigned int i = 0; i < rawTx.vin.size(); ++i) {
-        psbtx.inputs.emplace_back(0);
-    }
-    for (unsigned int i = 0; i < rawTx.vout.size(); ++i) {
-        psbtx.outputs.emplace_back(0);
-    }
+    PartiallySignedTransaction psbtx(rawTx);
 
     // Serialize the PSBT
     DataStream ssTx{};
@@ -1717,14 +1710,7 @@ static RPCMethod converttopsbt()
     }
 
     // Make a blank psbt
-    PartiallySignedTransaction psbtx;
-    psbtx.tx = tx;
-    for (unsigned int i = 0; i < tx.vin.size(); ++i) {
-        psbtx.inputs.emplace_back(0);
-    }
-    for (unsigned int i = 0; i < tx.vout.size(); ++i) {
-        psbtx.outputs.emplace_back(0);
-    }
+    PartiallySignedTransaction psbtx(tx);
 
     // Serialize the PSBT
     DataStream ssTx{};
diff --git a/src/test/fuzz/deserialize.cpp b/src/test/fuzz/deserialize.cpp
index b3f35baa0fc..15150c4a444 100644
--- a/src/test/fuzz/deserialize.cpp
+++ b/src/test/fuzz/deserialize.cpp
@@ -192,11 +192,11 @@ FUZZ_TARGET_DESERIALIZE(prefilled_transaction_deserialize, {
     DeserializeFromFuzzingInput(buffer, prefilled_transaction);
 })
 FUZZ_TARGET_DESERIALIZE(psbt_input_deserialize, {
-    PSBTInput psbt_input(0);
+    PSBTInput psbt_input(0, Txid{}, 0);
     DeserializeFromFuzzingInput(buffer, psbt_input);
 })
 FUZZ_TARGET_DESERIALIZE(psbt_output_deserialize, {
-    PSBTOutput psbt_output(0);
+    PSBTOutput psbt_output(0, 0, CScript());
     DeserializeFromFuzzingInput(buffer, psbt_output);
 })
 FUZZ_TARGET_DESERIALIZE(block_deserialize, {