feat(net): server registry, bootstrap servers, peer discovery

src/Core/Chain/ChainProfiles.cs

@@ -34,8 +34,15 @@ public static class ChainProfiles
             [ScriptKind.NativeSegwit] = new(0x04b2430c, 0x04b24746),          // zprv / zpub
             [ScriptKind.NativeSegwitMultisig] = new(0x02aa7a99, 0x02aa7ed3),  // Zprv / Zpub
         },
-        // TODO: popolare con i server reali prima della release (host:tcp:ssl).
-        BootstrapServers = [],
+        // Server di indicizzazione noti per il primo contatto (§3/§9); altri
+        // peer vengono scoperti via server.peers.subscribe.
+        BootstrapServers =
+        [
+            new ServerEndpoint("173.212.224.67", 50001, 50002),
+            new ServerEndpoint("144.91.120.225", 50001, 50002),
+            new ServerEndpoint("66.94.115.80", 50001, 50002),
+            new ServerEndpoint("89.117.149.130", 50001, 50002),
+        ],
         // TODO: popolare con [hash, bits] reali della catena (§7.3) prima della release.
         Checkpoints = [],
     };

src/Core/Net/ElectrumApi.cs

@@ -14,6 +14,9 @@ public sealed record MerkleProofResponse(int BlockHeight, int Pos, IReadOnlyList
 /// <summary>Tip della catena notificato da blockchain.headers.subscribe.</summary>
 public readonly record struct ChainTip(int Height, string HeaderHex);
 
+/// <summary>Peer annunciato da server.peers.subscribe (porte null = non offerte).</summary>
+public sealed record PeerInfo(string Host, int? TcpPort, int? SslPort, string? Version);
+
 /// <summary>
 /// Helper tipizzati sui metodi del protocollo (blueprint §10), sopra il
 /// trasporto JSON-RPC generico di <see cref="ElectrumClient"/>.
@@ -108,4 +111,50 @@ public static class ElectrumApi
 
     public static Task PingAsync(this ElectrumClient c, CancellationToken ct = default) =>
         c.RequestAsync("server.ping", ct);
+
+    /// <summary>Peer annunciati dal server (scoperta di altri server, §9).</summary>
+    public static async Task<IReadOnlyList<PeerInfo>> GetPeersAsync(this ElectrumClient c,
+        CancellationToken ct = default)
+    {
+        var r = await c.RequestAsync("server.peers.subscribe", ct);
+        return ParsePeers(r);
+    }
+
+    /// <summary>
+    /// Parsa la risposta di server.peers.subscribe: lista di
+    /// [ip, hostname, ["v1.4.2", "pN", "tPORTA", "sPORTA", ...]];
+    /// "t"/"s" senza numero = porta di default della rete (risolta dal chiamante).
+    /// </summary>
+    public static IReadOnlyList<PeerInfo> ParsePeers(JsonElement response)
+    {
+        var peers = new List<PeerInfo>();
+        foreach (var entry in response.EnumerateArray())
+        {
+            if (entry.ValueKind != JsonValueKind.Array || entry.GetArrayLength() < 3)
+                continue;
+            var host = entry[1].GetString();
+            if (string.IsNullOrWhiteSpace(host))
+                host = entry[0].GetString();
+            if (string.IsNullOrWhiteSpace(host))
+                continue;
+
+            int? tcp = null, ssl = null;
+            string? version = null;
+            foreach (var feature in entry[2].EnumerateArray())
+            {
+                var f = feature.GetString();
+                if (string.IsNullOrEmpty(f))
+                    continue;
+                switch (f[0])
+                {
+                    case 'v': version = f[1..]; break;
+                    case 't': tcp = int.TryParse(f[1..], out var t) ? t : 0; break;
+                    case 's': ssl = int.TryParse(f[1..], out var s) ? s : 0; break;
+                }
+            }
+            if (tcp is not null || ssl is not null)
+                peers.Add(new PeerInfo(host!, tcp, ssl, version));
+        }
+        return peers;
+    }
 }

src/Core/Net/ServerRegistry.cs

@@ -0,0 +1,106 @@
+using System.Text.Json;
+using PalladiumWallet.Core.Chain;
+
+namespace PalladiumWallet.Core.Net;
+
+/// <summary>Server di indicizzazione noto (bootstrap o scoperto dai peer).</summary>
+public sealed record KnownServer(string Host, int TcpPort, int SslPort, string? Version = null)
+{
+    public int PortFor(bool useSsl) => useSsl ? SslPort : TcpPort;
+
+    public override string ToString() =>
+        $"{Host}  ·  tcp {TcpPort} / ssl {SslPort}" + (Version is null ? "" : $"  ·  v{Version}");
+}
+
+/// <summary>
+/// Registro dei server (blueprint §9): parte dai bootstrap del profilo (§3),
+/// si arricchisce con i peer annunciati via server.peers.subscribe e persiste
+/// le scoperte su file per le sessioni successive.
+/// </summary>
+public sealed class ServerRegistry
+{
+    private readonly ChainProfile _profile;
+    private readonly string _filePath;
+    private readonly List<KnownServer> _servers = [];
+    private readonly object _lock = new();
+
+    public ServerRegistry(ChainProfile profile, string filePath)
+    {
+        _profile = profile;
+        _filePath = filePath;
+
+        foreach (var s in profile.BootstrapServers)
+            _servers.Add(new KnownServer(s.Host, s.TcpPort, s.SslPort));
+
+        if (File.Exists(filePath))
+        {
+            try
+            {
+                var saved = JsonSerializer.Deserialize<List<KnownServer>>(File.ReadAllText(filePath)) ?? [];
+                foreach (var s in saved)
+                    AddIfNew(s);
+            }
+            catch (JsonException)
+            {
+                // File corrotto: si riparte dai soli bootstrap.
+            }
+        }
+    }
+
+    public IReadOnlyList<KnownServer> All
+    {
+        get { lock (_lock) return [.. _servers]; }
+    }
+
+    /// <summary>Primo server noto: default quando l'utente non ne indica uno.</summary>
+    public KnownServer? Default
+    {
+        get { lock (_lock) return _servers.FirstOrDefault(); }
+    }
+
+    /// <summary>
+    /// Chiede al server connesso i peer che annuncia e integra i nuovi nel
+    /// registro (porte mancanti → default del profilo). Ritorna quanti sono nuovi.
+    /// </summary>
+    public async Task<int> DiscoverAsync(ElectrumClient client, CancellationToken ct = default)
+    {
+        var peers = await client.GetPeersAsync(ct);
+        var added = 0;
+        lock (_lock)
+        {
+            foreach (var peer in peers)
+            {
+                var server = new KnownServer(
+                    peer.Host,
+                    peer.TcpPort is > 0 ? peer.TcpPort.Value : _profile.DefaultTcpPort,
+                    peer.SslPort is > 0 ? peer.SslPort.Value : _profile.DefaultSslPort,
+                    peer.Version);
+                if (AddIfNew(server))
+                    added++;
+            }
+            if (added > 0)
+                Save();
+        }
+        return added;
+    }
+
+    private bool AddIfNew(KnownServer server)
+    {
+        if (_servers.Any(s => string.Equals(s.Host, server.Host, StringComparison.OrdinalIgnoreCase)))
+            return false;
+        _servers.Add(server);
+        return true;
+    }
+
+    private void Save()
+    {
+        Directory.CreateDirectory(Path.GetDirectoryName(_filePath)!);
+        // Si salvano solo gli scoperti: i bootstrap vengono dal profilo.
+        var discovered = _servers
+            .Where(s => !_profile.BootstrapServers.Any(b =>
+                string.Equals(b.Host, s.Host, StringComparison.OrdinalIgnoreCase)))
+            .ToList();
+        File.WriteAllText(_filePath, JsonSerializer.Serialize(discovered,
+            new JsonSerializerOptions { WriteIndented = true }));
+    }
+}

src/Core/Storage/AppPaths.cs

@@ -44,6 +44,9 @@ public static class AppPaths
     public static string CertificatePinsPath(NetKind net) =>
         Path.Combine(ForNetwork(net), "server-certs.json");
 
+    public static string ServersPath(NetKind net) =>
+        Path.Combine(ForNetwork(net), "servers.json");
+
     public static string ConfigPath() =>
         Path.Combine(DataRoot(), "config.json");
 }