feat(wallet): decode OP_RETURN payloads and coinbase pool tags in tx details

Transaction detail view silently dropped OP_RETURN messages and coinbase
scriptSig text (e.g. pool tags), since TransactionInspector discarded
scriptPubKey/scriptSig bytes once no destination address could be derived.
Each output/input is decoded independently, so multiple OP_RETURN outputs
in one tx are all shown.

src/App/ViewModels/TransactionDetailsViewModel.cs

@@ -64,13 +64,17 @@ public sealed class TransactionDetailsViewModel
         RbfText = loc[d.RbfSignaled ? "tx.yes" : "tx.no"];
         Inputs = new ObservableCollection<TxIoRow>(d.Inputs.Select((i, n) => new TxIoRow(
             i.IsCoinbase ? loc["tx.coinbase"] : $"{i.PrevTxid}:{i.PrevIndex}",
-            i.IsCoinbase ? loc["tx.coinbase.newcoins"] : i.Address ?? "—",
+            i.IsCoinbase
+                ? i.CoinbaseTag is { Length: > 0 } tag
+                    ? $"{loc["tx.coinbase.newcoins"]} — {tag}"
+                    : loc["tx.coinbase.newcoins"]
+                : i.Address ?? "—",
             i.AmountSats is { } a ? CoinAmount.FormatIn(a, unit) : "—",
             i.IsMine)));
 
         Outputs = new ObservableCollection<TxIoRow>(d.Outputs.Select(o => new TxIoRow(
             $"#{o.Index}",
-            o.Address ?? $"({o.ScriptType})",
+            o.Address ?? (o.OpReturnText is { Length: > 0 } msg ? $"OP_RETURN: {msg}" : $"({o.ScriptType})"),
             CoinAmount.FormatIn(o.AmountSats, unit),
             o.IsMine)));
     }

src/Core/Wallet/TransactionInspector.cs

@@ -5,12 +5,18 @@ using PalladiumWallet.Core.Spv;
 namespace PalladiumWallet.Core.Wallet;
 
 /// <summary>An input of a transaction, with the spent output resolved from the server.</summary>
+/// <param name="CoinbaseTag">
+/// Printable ASCII runs (e.g. pool tags like "/slush/") extracted from the coinbase
+/// scriptSig; null for non-coinbase inputs or if no printable text was found.
+/// </param>
 public sealed record TxInputInfo(
-    string PrevTxid, uint PrevIndex, long? AmountSats, string? Address, bool IsMine, bool IsCoinbase);
+    string PrevTxid, uint PrevIndex, long? AmountSats, string? Address, bool IsMine, bool IsCoinbase,
+    string? CoinbaseTag = null);
 
 /// <summary>An output of a transaction.</summary>
+/// <param name="OpReturnText">Decoded OP_RETURN payload (UTF-8, or hex if not valid text); null otherwise.</param>
 public sealed record TxOutputInfo(
-    uint Index, long AmountSats, string? Address, string ScriptType, bool IsMine);
+    uint Index, long AmountSats, string? Address, string ScriptType, string? OpReturnText, bool IsMine);
 
 /// <summary>
 /// Complete transaction data assembled by querying the server: the raw transaction
@@ -105,8 +111,9 @@ public static class TransactionInspector
         {
             var o = tx.Outputs[i];
             var addr = AddrOf(o.ScriptPubKey);
+            var opReturn = addr is null ? OpReturnTextOf(o.ScriptPubKey) : null;
             outputs.Add(new TxOutputInfo(
-                (uint)i, o.Value.Satoshi, addr, ScriptType(o.ScriptPubKey),
+                (uint)i, o.Value.Satoshi, addr, ScriptType(o.ScriptPubKey), opReturn,
                 addr is not null && ownedAddresses.Contains(addr)));
         }
 
@@ -134,7 +141,7 @@ public static class TransactionInspector
         {
             if (tx.IsCoinBase)
             {
-                inputs.Add(new TxInputInfo("", inp.PrevOut.N, null, null, false, true));
+                inputs.Add(new TxInputInfo("", inp.PrevOut.N, null, null, false, true, CoinbaseTagOf(inp.ScriptSig.ToBytes())));
                 continue;
             }
 
@@ -189,4 +196,48 @@ public static class TransactionInspector
         }
         catch { return "—"; }
     }
+
+    /// <summary>Decodes an OP_RETURN output's pushed data as UTF-8 text, falling back to hex if it isn't valid text.</summary>
+    private static string? OpReturnTextOf(Script script)
+    {
+        if (!script.IsUnspendable) return null;
+        try
+        {
+            var data = script.ToOps().Skip(1)
+                .Where(op => op.PushData is { Length: > 0 })
+                .SelectMany(op => op.PushData)
+                .ToArray();
+            return data.Length == 0 ? null : DecodeUtf8OrHex(data);
+        }
+        catch { return null; }
+    }
+
+    private static string DecodeUtf8OrHex(byte[] data)
+    {
+        var text = System.Text.Encoding.UTF8.GetString(data);
+        var looksLikeText = !text.Contains('�') && text.All(c => !char.IsControl(c) || c is '\n' or '\r' or '\t');
+        return looksLikeText ? text : "0x" + Convert.ToHexString(data);
+    }
+
+    /// <summary>
+    /// Extracts printable-ASCII runs (≥4 chars) from a coinbase scriptSig, e.g. pool
+    /// tags like "/slush/" embedded among the binary BIP34 height and extranonce.
+    /// </summary>
+    private static string? CoinbaseTagOf(byte[] scriptSig)
+    {
+        var runs = new List<string>();
+        var run = new System.Text.StringBuilder();
+        void Flush()
+        {
+            if (run.Length >= 4) runs.Add(run.ToString());
+            run.Clear();
+        }
+        foreach (var b in scriptSig)
+        {
+            if (b is >= 0x20 and <= 0x7E) run.Append((char)b);
+            else Flush();
+        }
+        Flush();
+        return runs.Count == 0 ? null : string.Join(" ", runs);
+    }
 }

tests/PalladiumWallet.Tests/Wallet/TransactionInspectorTests.cs

@@ -195,6 +195,139 @@ public class TransactionInspectorTests
         Assert.Equal(0, server.CallCount("blockchain.block.header"));
     }
 
+    [Fact]
+    public async Task Un_output_OP_RETURN_con_testo_UTF8_viene_decodificato()
+    {
+        var account = Account();
+        var tx = Net.CreateTransaction();
+        tx.Inputs.Add(new TxIn(new OutPoint(uint256.One, 0)));
+        tx.Outputs.Add(Money.Satoshis(1_000_000), account.GetReceiveAddress(0));
+        tx.Outputs.Add(Money.Zero, TxNullDataTemplate.Instance.GenerateScriptPubKey("hello palladium"u8.ToArray()));
+
+        var (server, client) = await StartAsync(tx);
+        await using var _ = server; await using var __ = client;
+
+        var details = await TransactionInspector.FetchAsync(
+            client, Net, tx.GetHash().ToString(), tipHeight: 200, height: 101,
+            Owned(account), netSats: 1_000_000, verified: true);
+
+        var opReturn = Assert.Single(details.Outputs, o => o.Index == 1);
+        Assert.Null(opReturn.Address);
+        Assert.Equal("hello palladium", opReturn.OpReturnText);
+    }
+
+    [Fact]
+    public async Task Un_output_OP_RETURN_con_dati_binari_ricade_su_hex()
+    {
+        var account = Account();
+        byte[] data = [0x00, 0x01, 0xFF, 0xFE, 0x02];
+        var tx = Net.CreateTransaction();
+        tx.Inputs.Add(new TxIn(new OutPoint(uint256.One, 0)));
+        tx.Outputs.Add(Money.Satoshis(1_000_000), account.GetReceiveAddress(0));
+        tx.Outputs.Add(Money.Zero, TxNullDataTemplate.Instance.GenerateScriptPubKey(data));
+
+        var (server, client) = await StartAsync(tx);
+        await using var _ = server; await using var __ = client;
+
+        var details = await TransactionInspector.FetchAsync(
+            client, Net, tx.GetHash().ToString(), tipHeight: 200, height: 101,
+            Owned(account), netSats: 1_000_000, verified: true);
+
+        var opReturn = Assert.Single(details.Outputs, o => o.Index == 1);
+        Assert.Equal("0x" + Convert.ToHexString(data), opReturn.OpReturnText);
+    }
+
+    [Fact]
+    public async Task Piu_output_OP_RETURN_nella_stessa_tx_sono_decodificati_singolarmente()
+    {
+        var account = Account();
+        var tx = Net.CreateTransaction();
+        tx.Inputs.Add(new TxIn(new OutPoint(uint256.One, 0)));
+        tx.Outputs.Add(Money.Satoshis(1_000_000), account.GetReceiveAddress(0));
+        tx.Outputs.Add(Money.Zero, TxNullDataTemplate.Instance.GenerateScriptPubKey("first"u8.ToArray()));
+        tx.Outputs.Add(Money.Zero, TxNullDataTemplate.Instance.GenerateScriptPubKey("second"u8.ToArray()));
+
+        var (server, client) = await StartAsync(tx);
+        await using var _ = server; await using var __ = client;
+
+        var details = await TransactionInspector.FetchAsync(
+            client, Net, tx.GetHash().ToString(), tipHeight: 200, height: 101,
+            Owned(account), netSats: 1_000_000, verified: true);
+
+        Assert.Equal("first", details.Outputs.Single(o => o.Index == 1).OpReturnText);
+        Assert.Equal("second", details.Outputs.Single(o => o.Index == 2).OpReturnText);
+    }
+
+    [Fact]
+    public async Task Un_output_normale_non_ha_testo_OP_RETURN()
+    {
+        var (funding, spend, _, account) = SpendPair();
+        var (server, client) = await StartAsync(funding, spend);
+        await using var _ = server; await using var __ = client;
+
+        var details = await TransactionInspector.FetchAsync(
+            client, Net, spend.GetHash().ToString(), tipHeight: 200, height: 101,
+            Owned(account), netSats: -610_000, verified: true);
+
+        Assert.All(details.Outputs, o => Assert.Null(o.OpReturnText));
+    }
+
+    [Fact]
+    public async Task Il_tag_pool_nello_scriptSig_della_coinbase_viene_estratto()
+    {
+        var account = Account();
+        var coinbase = Net.CreateTransaction();
+        // BIP34 height push (binary) followed by a pool tag (printable ASCII).
+        var scriptSig = new Script(Op.GetPushOp(190), Op.GetPushOp("/slush/"u8.ToArray()));
+        coinbase.Inputs.Add(new TxIn(new OutPoint(uint256.Zero, 0xffffffff), scriptSig));
+        coinbase.Outputs.Add(Money.Satoshis(5_000_000_000), account.GetReceiveAddress(0));
+
+        var (server, client) = await StartAsync(coinbase);
+        await using var _ = server; await using var __ = client;
+
+        var details = await TransactionInspector.FetchAsync(
+            client, Net, coinbase.GetHash().ToString(), tipHeight: 200, height: 190,
+            Owned(account), netSats: 5_000_000_000, verified: true);
+
+        var input = Assert.Single(details.Inputs);
+        Assert.True(input.IsCoinbase);
+        Assert.Contains("/slush/", input.CoinbaseTag);
+    }
+
+    [Fact]
+    public async Task Uno_scriptSig_coinbase_senza_testo_stampabile_non_produce_tag()
+    {
+        var account = Account();
+        var coinbase = Net.CreateTransaction();
+        var scriptSig = new Script(Op.GetPushOp([0x00, 0x01, 0x02]));
+        coinbase.Inputs.Add(new TxIn(new OutPoint(uint256.Zero, 0xffffffff), scriptSig));
+        coinbase.Outputs.Add(Money.Satoshis(5_000_000_000), account.GetReceiveAddress(0));
+
+        var (server, client) = await StartAsync(coinbase);
+        await using var _ = server; await using var __ = client;
+
+        var details = await TransactionInspector.FetchAsync(
+            client, Net, coinbase.GetHash().ToString(), tipHeight: 200, height: 190,
+            Owned(account), netSats: 5_000_000_000, verified: true);
+
+        var input = Assert.Single(details.Inputs);
+        Assert.Null(input.CoinbaseTag);
+    }
+
+    [Fact]
+    public async Task Un_input_normale_non_ha_tag_coinbase()
+    {
+        var (funding, spend, _, account) = SpendPair();
+        var (server, client) = await StartAsync(funding, spend);
+        await using var _ = server; await using var __ = client;
+
+        var details = await TransactionInspector.FetchAsync(
+            client, Net, spend.GetHash().ToString(), tipHeight: 200, height: 101,
+            Owned(account), netSats: -610_000, verified: true);
+
+        Assert.All(details.Inputs, i => Assert.Null(i.CoinbaseTag));
+    }
+
     [Fact]
     public async Task La_cache_delle_tx_evita_le_richieste_al_server()
     {