feat(cli): add --primary-config, --backup-config, --failover-retry-count to data connection commands

Thread backup data connection fields through management command messages,
ManagementActor handlers, SiteService, site-side SQLite storage, and
deployment/replication actors. The old --configuration CLI flag is kept
as a hidden alias for backwards compatibility.

src/ScadaLink.CLI/Commands/DataConnectionCommands.cs

@@ -38,22 +38,28 @@ public static class DataConnectionCommands
         var idOption = new Option<int>("--id") { Description = "Data connection ID", Required = true };
         var nameOption = new Option<string>("--name") { Description = "Connection name", Required = true };
         var protocolOption = new Option<string>("--protocol") { Description = "Protocol", Required = true };
-        var configOption = new Option<string?>("--configuration") { Description = "Primary configuration JSON" };
+        var configOption = new Option<string?>("--primary-config", "--configuration") { Description = "Primary configuration JSON" };
+        var backupConfigOption = new Option<string?>("--backup-config") { Description = "Backup configuration JSON" };
+        var failoverRetryOption = new Option<int>("--failover-retry-count") { Description = "Number of retries before failover to backup", DefaultValueFactory = _ => 3 };
 
         var cmd = new Command("update") { Description = "Update a data connection" };
         cmd.Add(idOption);
         cmd.Add(nameOption);
         cmd.Add(protocolOption);
         cmd.Add(configOption);
+        cmd.Add(backupConfigOption);
+        cmd.Add(failoverRetryOption);
         cmd.SetAction(async (ParseResult result) =>
         {
             var id = result.GetValue(idOption);
             var name = result.GetValue(nameOption)!;
             var protocol = result.GetValue(protocolOption)!;
             var config = result.GetValue(configOption);
+            var backupConfig = result.GetValue(backupConfigOption);
+            var failoverRetryCount = result.GetValue(failoverRetryOption);
             return await CommandHelpers.ExecuteCommandAsync(
                 result, urlOption, formatOption, usernameOption, passwordOption,
-                new UpdateDataConnectionCommand(id, name, protocol, config));
+                new UpdateDataConnectionCommand(id, name, protocol, config, backupConfig, failoverRetryCount));
         });
         return cmd;
     }
@@ -77,22 +83,28 @@ public static class DataConnectionCommands
         var siteIdOption = new Option<int>("--site-id") { Description = "Site ID", Required = true };
         var nameOption = new Option<string>("--name") { Description = "Connection name", Required = true };
         var protocolOption = new Option<string>("--protocol") { Description = "Protocol (e.g. OpcUa)", Required = true };
-        var configOption = new Option<string?>("--configuration") { Description = "Primary configuration JSON" };
+        var configOption = new Option<string?>("--primary-config", "--configuration") { Description = "Primary configuration JSON" };
+        var backupConfigOption = new Option<string?>("--backup-config") { Description = "Backup configuration JSON" };
+        var failoverRetryOption = new Option<int>("--failover-retry-count") { Description = "Number of retries before failover to backup", DefaultValueFactory = _ => 3 };
 
         var cmd = new Command("create") { Description = "Create a new data connection" };
         cmd.Add(siteIdOption);
         cmd.Add(nameOption);
         cmd.Add(protocolOption);
         cmd.Add(configOption);
+        cmd.Add(backupConfigOption);
+        cmd.Add(failoverRetryOption);
         cmd.SetAction(async (ParseResult result) =>
         {
             var siteId = result.GetValue(siteIdOption);
             var name = result.GetValue(nameOption)!;
             var protocol = result.GetValue(protocolOption)!;
             var config = result.GetValue(configOption);
+            var backupConfig = result.GetValue(backupConfigOption);
+            var failoverRetryCount = result.GetValue(failoverRetryOption);
             return await CommandHelpers.ExecuteCommandAsync(
                 result, urlOption, formatOption, usernameOption, passwordOption,
-                new CreateDataConnectionCommand(siteId, name, protocol, config));
+                new CreateDataConnectionCommand(siteId, name, protocol, config, backupConfig, failoverRetryCount));
         });
         return cmd;
     }

src/ScadaLink.Commons/Messages/Management/DataConnectionCommands.cs

@@ -2,6 +2,6 @@ namespace ScadaLink.Commons.Messages.Management;
 
 public record ListDataConnectionsCommand(int? SiteId = null);
 public record GetDataConnectionCommand(int DataConnectionId);
-public record CreateDataConnectionCommand(int SiteId, string Name, string Protocol, string? PrimaryConfiguration);
+public record CreateDataConnectionCommand(int SiteId, string Name, string Protocol, string? PrimaryConfiguration, string? BackupConfiguration = null, int FailoverRetryCount = 3);
-public record UpdateDataConnectionCommand(int DataConnectionId, string Name, string Protocol, string? PrimaryConfiguration);
+public record UpdateDataConnectionCommand(int DataConnectionId, string Name, string Protocol, string? PrimaryConfiguration, string? BackupConfiguration = null, int FailoverRetryCount = 3);
 public record DeleteDataConnectionCommand(int DataConnectionId);

src/ScadaLink.ManagementService/ManagementActor.cs

@@ -689,7 +689,12 @@ public class ManagementActor : ReceiveActor
     private static async Task<object?> HandleCreateDataConnection(IServiceProvider sp, CreateDataConnectionCommand cmd, string user)
     {
         var repo = sp.GetRequiredService<ISiteRepository>();
-        var conn = new DataConnection(cmd.Name, cmd.Protocol, cmd.SiteId) { PrimaryConfiguration = cmd.PrimaryConfiguration };
+        var conn = new DataConnection(cmd.Name, cmd.Protocol, cmd.SiteId)
+        {
+            PrimaryConfiguration = cmd.PrimaryConfiguration,
+            BackupConfiguration = cmd.BackupConfiguration,
+            FailoverRetryCount = cmd.FailoverRetryCount
+        };
         await repo.AddDataConnectionAsync(conn);
         await repo.SaveChangesAsync();
         await AuditAsync(sp, user, "Create", "DataConnection", conn.Id.ToString(), conn.Name, conn);
@@ -704,6 +709,8 @@ public class ManagementActor : ReceiveActor
         conn.Name = cmd.Name;
         conn.Protocol = cmd.Protocol;
         conn.PrimaryConfiguration = cmd.PrimaryConfiguration;
+        conn.BackupConfiguration = cmd.BackupConfiguration;
+        conn.FailoverRetryCount = cmd.FailoverRetryCount;
         await repo.UpdateDataConnectionAsync(conn);
         await repo.SaveChangesAsync();
         await AuditAsync(sp, user, "Update", "DataConnection", conn.Id.ToString(), conn.Name, conn);

src/ScadaLink.SiteRuntime/Actors/DeploymentManagerActor.cs

@@ -630,7 +630,8 @@ public class DeploymentManagerActor : ReceiveActor, IWithTimers
                     foreach (var dc in command.DataConnections)
                     {
                         await _storage.StoreDataConnectionDefinitionAsync(
-                            dc.Name, dc.Protocol, dc.PrimaryConfigurationJson);
+                            dc.Name, dc.Protocol, dc.PrimaryConfigurationJson,
+                            dc.BackupConfigurationJson, dc.FailoverRetryCount);
                     }
                 }
 

src/ScadaLink.SiteRuntime/Actors/SiteReplicationActor.cs

@@ -185,7 +185,7 @@ public class SiteReplicationActor : ReceiveActor
 
                 if (command.DataConnections != null)
                     foreach (var dc in command.DataConnections)
-                        await _storage.StoreDataConnectionDefinitionAsync(dc.Name, dc.Protocol, dc.PrimaryConfigurationJson);
+                        await _storage.StoreDataConnectionDefinitionAsync(dc.Name, dc.Protocol, dc.PrimaryConfigurationJson, dc.BackupConfigurationJson, dc.FailoverRetryCount);
 
                 if (command.SmtpConfigurations != null)
                     foreach (var smtp in command.SmtpConfigurations)

src/ScadaLink.SiteRuntime/Persistence/SiteStorageService.cs

@@ -79,10 +79,12 @@ public class SiteStorageService
             );
 
             CREATE TABLE IF NOT EXISTS data_connection_definitions (
-                name             TEXT PRIMARY KEY,
+                name                    TEXT PRIMARY KEY,
-                protocol         TEXT NOT NULL,
+                protocol                TEXT NOT NULL,
-                configuration    TEXT,
+                configuration           TEXT,
-                updated_at       TEXT NOT NULL
+                backup_configuration    TEXT,
+                failover_retry_count    INTEGER NOT NULL DEFAULT 3,
+                updated_at              TEXT NOT NULL
             );
 
             CREATE TABLE IF NOT EXISTS smtp_configurations (
@@ -480,23 +482,28 @@ public class SiteStorageService
     /// <summary>
     /// Stores or updates a data connection definition (OPC UA endpoint, etc.).
     /// </summary>
-    public async Task StoreDataConnectionDefinitionAsync(string name, string protocol, string? configJson)
+    public async Task StoreDataConnectionDefinitionAsync(
+        string name, string protocol, string? configJson, string? backupConfigJson = null, int failoverRetryCount = 3)
     {
         await using var connection = new SqliteConnection(_connectionString);
         await connection.OpenAsync();
 
         await using var command = connection.CreateCommand();
         command.CommandText = @"
-            INSERT INTO data_connection_definitions (name, protocol, configuration, updated_at)
+            INSERT INTO data_connection_definitions (name, protocol, configuration, backup_configuration, failover_retry_count, updated_at)
-            VALUES (@name, @protocol, @config, @updatedAt)
+            VALUES (@name, @protocol, @config, @backupConfig, @failoverRetryCount, @updatedAt)
             ON CONFLICT(name) DO UPDATE SET
                 protocol = excluded.protocol,
                 configuration = excluded.configuration,
+                backup_configuration = excluded.backup_configuration,
+                failover_retry_count = excluded.failover_retry_count,
                 updated_at = excluded.updated_at";
 
         command.Parameters.AddWithValue("@name", name);
         command.Parameters.AddWithValue("@protocol", protocol);
         command.Parameters.AddWithValue("@config", (object?)configJson ?? DBNull.Value);
+        command.Parameters.AddWithValue("@backupConfig", (object?)backupConfigJson ?? DBNull.Value);
+        command.Parameters.AddWithValue("@failoverRetryCount", failoverRetryCount);
         command.Parameters.AddWithValue("@updatedAt", DateTimeOffset.UtcNow.ToString("O"));
 
         await command.ExecuteNonQueryAsync();
@@ -512,7 +519,7 @@ public class SiteStorageService
         await connection.OpenAsync();
 
         await using var command = connection.CreateCommand();
-        command.CommandText = "SELECT name, protocol, configuration FROM data_connection_definitions";
+        command.CommandText = "SELECT name, protocol, configuration, backup_configuration, failover_retry_count FROM data_connection_definitions";
 
         var results = new List<StoredDataConnectionDefinition>();
         await using var reader = await command.ExecuteReaderAsync();
@@ -522,7 +529,9 @@ public class SiteStorageService
             {
                 Name = reader.GetString(0),
                 Protocol = reader.GetString(1),
-                ConfigurationJson = reader.IsDBNull(2) ? null : reader.GetString(2)
+                ConfigurationJson = reader.IsDBNull(2) ? null : reader.GetString(2),
+                BackupConfigurationJson = reader.IsDBNull(3) ? null : reader.GetString(3),
+                FailoverRetryCount = reader.GetInt32(4)
             });
         }
 
@@ -562,4 +571,6 @@ public class StoredDataConnectionDefinition
     public string Name { get; init; } = string.Empty;
     public string Protocol { get; init; } = string.Empty;
     public string? ConfigurationJson { get; init; }
+    public string? BackupConfigurationJson { get; init; }
+    public int FailoverRetryCount { get; init; } = 3;
 }

src/ScadaLink.TemplateEngine/Services/SiteService.cs

@@ -96,7 +96,8 @@ public class SiteService
     // --- Data Connection CRUD ---
 
     public async Task<Result<DataConnection>> CreateDataConnectionAsync(
-        int siteId, string name, string protocol, string? configuration, string user,
+        int siteId, string name, string protocol, string? primaryConfiguration,
+        string? backupConfiguration, int failoverRetryCount, string user,
         CancellationToken cancellationToken = default)
     {
         if (string.IsNullOrWhiteSpace(name))
@@ -104,7 +105,12 @@ public class SiteService
         if (string.IsNullOrWhiteSpace(protocol))
             return Result<DataConnection>.Failure("Protocol is required.");
 
-        var connection = new DataConnection(name, protocol, siteId) { PrimaryConfiguration = configuration };
+        var connection = new DataConnection(name, protocol, siteId)
+        {
+            PrimaryConfiguration = primaryConfiguration,
+            BackupConfiguration = backupConfiguration,
+            FailoverRetryCount = failoverRetryCount
+        };
         await _repository.AddDataConnectionAsync(connection, cancellationToken);
         await _repository.SaveChangesAsync(cancellationToken);
 
@@ -115,7 +121,8 @@ public class SiteService
     }
 
     public async Task<Result<DataConnection>> UpdateDataConnectionAsync(
-        int connectionId, string name, string protocol, string? configuration, string user,
+        int connectionId, string name, string protocol, string? primaryConfiguration,
+        string? backupConfiguration, int failoverRetryCount, string user,
         CancellationToken cancellationToken = default)
     {
         var connection = await _repository.GetDataConnectionByIdAsync(connectionId, cancellationToken);
@@ -124,7 +131,9 @@ public class SiteService
 
         connection.Name = name;
         connection.Protocol = protocol;
-        connection.PrimaryConfiguration = configuration;
+        connection.PrimaryConfiguration = primaryConfiguration;
+        connection.BackupConfiguration = backupConfiguration;
+        connection.FailoverRetryCount = failoverRetryCount;
         await _repository.UpdateDataConnectionAsync(connection, cancellationToken);
         await _repository.SaveChangesAsync(cancellationToken);
 

tests/ScadaLink.TemplateEngine.Tests/Services/SiteServiceTests.cs

@@ -93,7 +93,7 @@ public class SiteServiceTests
         _repoMock.Setup(r => r.SaveChangesAsync(It.IsAny<CancellationToken>()))
             .ReturnsAsync(1);
 
-        var result = await _sut.CreateDataConnectionAsync(1, "OPC-Server1", "OpcUa", "{\"url\":\"opc.tcp://localhost\"}", "admin");
+        var result = await _sut.CreateDataConnectionAsync(1, "OPC-Server1", "OpcUa", "{\"url\":\"opc.tcp://localhost\"}", null, 3, "admin");
 
         Assert.True(result.IsSuccess);
         Assert.Equal("OPC-Server1", result.Value.Name);