Fix chart zero lines, collection log server name, and overview status (#85, #91, #93)

Dashboard/Services/DatabaseService.NocHealth.cs

@@ -8,6 +8,7 @@
 
 using System;
 using System.Collections.Generic;
+using System.Data;
 using System.Threading.Tasks;
 using Microsoft.Data.SqlClient;
 using PerformanceMonitorDashboard.Helpers;
@@ -631,7 +632,7 @@ ORDER BY r.total_elapsed_time DESC
             {
                 using var cmd = new SqlCommand(query, connection);
                 cmd.CommandTimeout = 10;
-                cmd.Parameters.AddWithValue("@thresholdMs", (long)thresholdMinutes * 60 * 1000);
+                cmd.Parameters.Add(new SqlParameter("@thresholdMs", SqlDbType.BigInt) { Value = (long)thresholdMinutes * 60 * 1000 });
                 using var reader = await cmd.ExecuteReaderAsync();
 
                 while (await reader.ReadAsync())
@@ -685,7 +686,7 @@ ORDER BY percent_of_average DESC
             {
                 using var cmd = new SqlCommand(query, connection);
                 cmd.CommandTimeout = 10;
-                cmd.Parameters.AddWithValue("@thresholdPercent", thresholdPercent);
+                cmd.Parameters.Add(new SqlParameter("@thresholdPercent", SqlDbType.Int) { Value = thresholdPercent });
                 using var reader = await cmd.ExecuteReaderAsync();
 
                 while (await reader.ReadAsync())

Dashboard/Services/DatabaseService.cs

@@ -8,6 +8,7 @@
 
 using System;
 using System.Collections.Generic;
+using System.Data;
 using System.Globalization;
 using System.Threading;
 using System.Threading.Tasks;
@@ -302,10 +303,10 @@ public async Task UpdateCollectorScheduleAsync(int scheduleId, bool enabled, int
 
             using var command = new SqlCommand(query, connection);
             command.CommandTimeout = 120;
-            command.Parameters.AddWithValue("@schedule_id", scheduleId);
-            command.Parameters.AddWithValue("@enabled", enabled);
-            command.Parameters.AddWithValue("@frequency_minutes", frequencyMinutes);
-            command.Parameters.AddWithValue("@retention_days", retentionDays);
+            command.Parameters.Add(new SqlParameter("@schedule_id", SqlDbType.Int) { Value = scheduleId });
+            command.Parameters.Add(new SqlParameter("@enabled", SqlDbType.Bit) { Value = enabled });
+            command.Parameters.Add(new SqlParameter("@frequency_minutes", SqlDbType.Int) { Value = frequencyMinutes });
+            command.Parameters.Add(new SqlParameter("@retention_days", SqlDbType.Int) { Value = retentionDays });
 
             await command.ExecuteNonQueryAsync();
         }

Installer/Program.cs

@@ -8,6 +8,7 @@
 
 using System;
 using System.Collections.Generic;
+using System.Data;
 using System.IO;
 using System.Linq;
 using System.Net.Http;
@@ -1341,16 +1342,16 @@ INSERT INTO PerformanceMonitor.config.installation_history
 
                     using (var insertCmd = new SqlCommand(insertSql, connection))
                     {
-                        insertCmd.Parameters.AddWithValue("@installer_version", assemblyVersion);
-                        insertCmd.Parameters.AddWithValue("@installer_info_version", (object?)infoVersion ?? DBNull.Value);
-                        insertCmd.Parameters.AddWithValue("@sql_server_version", sqlVersion);
-                        insertCmd.Parameters.AddWithValue("@sql_server_edition", sqlEdition);
-                        insertCmd.Parameters.AddWithValue("@installation_type", installationType);
-                        insertCmd.Parameters.AddWithValue("@previous_version", (object?)previousVersion ?? DBNull.Value);
-                        insertCmd.Parameters.AddWithValue("@installation_status", status);
-                        insertCmd.Parameters.AddWithValue("@files_executed", filesExecuted);
-                        insertCmd.Parameters.AddWithValue("@files_failed", filesFailed);
-                        insertCmd.Parameters.AddWithValue("@installation_duration_ms", durationMs);
+                        insertCmd.Parameters.Add(new SqlParameter("@installer_version", SqlDbType.NVarChar, 50) { Value = assemblyVersion });
+                        insertCmd.Parameters.Add(new SqlParameter("@installer_info_version", SqlDbType.NVarChar, 100) { Value = (object?)infoVersion ?? DBNull.Value });
+                        insertCmd.Parameters.Add(new SqlParameter("@sql_server_version", SqlDbType.NVarChar, 500) { Value = sqlVersion });
+                        insertCmd.Parameters.Add(new SqlParameter("@sql_server_edition", SqlDbType.NVarChar, 128) { Value = sqlEdition });
+                        insertCmd.Parameters.Add(new SqlParameter("@installation_type", SqlDbType.VarChar, 20) { Value = installationType });
+                        insertCmd.Parameters.Add(new SqlParameter("@previous_version", SqlDbType.NVarChar, 50) { Value = (object?)previousVersion ?? DBNull.Value });
+                        insertCmd.Parameters.Add(new SqlParameter("@installation_status", SqlDbType.VarChar, 20) { Value = status });
+                        insertCmd.Parameters.Add(new SqlParameter("@files_executed", SqlDbType.Int) { Value = filesExecuted });
+                        insertCmd.Parameters.Add(new SqlParameter("@files_failed", SqlDbType.Int) { Value = filesFailed });
+                        insertCmd.Parameters.Add(new SqlParameter("@installation_duration_ms", SqlDbType.BigInt) { Value = durationMs });
 
                         await insertCmd.ExecuteNonQueryAsync().ConfigureAwait(false);
                     }

Lite/Controls/ServerTab.xaml.cs

@@ -536,8 +536,8 @@ Include the latest event timestamp so acknowledgement is only
             DateTime? latestEventTime = null;
             if (blockingCount > 0 || deadlockCount > 0)
             {
-                var latestBlocking = blockedProcessTask.Result.Max(r => (DateTime?)r.CollectionTime);
-                var latestDeadlock = deadlockTask.Result.Max(r => (DateTime?)r.CollectionTime);
+                var latestBlocking = blockedProcessTask.Result.Max(r => (DateTime?)r.EventTime);
+                var latestDeadlock = deadlockTask.Result.Max(r => (DateTime?)r.DeadlockTime);
                 latestEventTime = latestBlocking > latestDeadlock ? latestBlocking : latestDeadlock;
             }
             AlertCountsChanged?.Invoke(blockingCount, deadlockCount, latestEventTime);
@@ -849,12 +849,19 @@ private void UpdateBlockingTrendChart(List<TrendPoint> data, int hoursBack, Date
 
         if (data.Count == 0)
         {
-            /* Show empty chart with correct time range */
+            /* No blocking events — show a flat line at zero so the chart looks active */
+            var zeroLine = BlockingTrendChart.Plot.Add.Scatter(
+                new[] { rangeStart.ToOADate(), rangeEnd.ToOADate() },
+                new[] { 0.0, 0.0 });
+            zeroLine.LegendText = "Blocking Incidents";
+            zeroLine.Color = ScottPlot.Color.FromHex("#E57373");
+            zeroLine.MarkerSize = 0;
             BlockingTrendChart.Plot.Axes.DateTimeTicksBottom();
             BlockingTrendChart.Plot.Axes.SetLimitsX(rangeStart.ToOADate(), rangeEnd.ToOADate());
-            BlockingTrendChart.Plot.Axes.SetLimitsY(0, 1);
             ReapplyAxisColors(BlockingTrendChart);
             BlockingTrendChart.Plot.YLabel("Blocking Incidents");
+            SetChartYLimitsWithLegendPadding(BlockingTrendChart, 0, 1);
+            ShowChartLegend(BlockingTrendChart);
             BlockingTrendChart.Refresh();
             return;
         }
@@ -919,12 +926,19 @@ private void UpdateDeadlockTrendChart(List<TrendPoint> data, int hoursBack, Date
 
         if (data.Count == 0)
         {
-            /* Show empty chart with correct time range */
+            /* No deadlocks — show a flat line at zero so the chart looks active */
+            var zeroLine = DeadlockTrendChart.Plot.Add.Scatter(
+                new[] { rangeStart.ToOADate(), rangeEnd.ToOADate() },
+                new[] { 0.0, 0.0 });
+            zeroLine.LegendText = "Deadlocks";
+            zeroLine.Color = ScottPlot.Color.FromHex("#FFB74D");
+            zeroLine.MarkerSize = 0;
             DeadlockTrendChart.Plot.Axes.DateTimeTicksBottom();
             DeadlockTrendChart.Plot.Axes.SetLimitsX(rangeStart.ToOADate(), rangeEnd.ToOADate());
-            DeadlockTrendChart.Plot.Axes.SetLimitsY(0, 1);
             ReapplyAxisColors(DeadlockTrendChart);
             DeadlockTrendChart.Plot.YLabel("Deadlocks");
+            SetChartYLimitsWithLegendPadding(DeadlockTrendChart, 0, 1);
+            ShowChartLegend(DeadlockTrendChart);
             DeadlockTrendChart.Refresh();
             return;
         }
@@ -1495,13 +1509,13 @@ private static void SetChartYLimitsWithLegendPadding(ScottPlot.WPF.WpfPlot chart
             dataYMin = limits.Bottom;
             dataYMax = limits.Top;
         }
-        if (dataYMax <= dataYMin) dataYMax = dataYMin + 100;
+        if (dataYMax <= dataYMin) dataYMax = dataYMin + 1;
 
         double range = dataYMax - dataYMin;
         double topPadding = range * 0.05;
 
-        /* Only add bottom padding if dataYMin is above zero - don't go negative */
-        double yMin = dataYMin >= 0 ? 0 : dataYMin - (range * 0.10);
+        /* Add small bottom margin when dataYMin is zero so flat lines at Y=0 are visible above the axis */
+        double yMin = dataYMin > 0 ? 0 : dataYMin == 0 ? -(range * 0.05) : dataYMin - (range * 0.10);
         double yMax = dataYMax + topPadding;
 
         chart.Plot.Axes.SetLimitsY(yMin, yMax);

Lite/Database/DuckDbInitializer.cs

@@ -19,7 +19,7 @@ public class DuckDbInitializer
     /// <summary>
     /// Current schema version. Increment this when schema changes require table rebuilds.
     /// </summary>
-    private const int CurrentSchemaVersion = 9;
+    private const int CurrentSchemaVersion = 10;
 
     public DuckDbInitializer(string databasePath, ILogger<DuckDbInitializer>? logger = null)
     {
@@ -328,6 +328,21 @@ Safe to ALTER because this table uses INSERT (not appender). */
                 /* Table doesn't exist yet — will be created with correct schema below */
             }
         }
+
+        if (fromVersion < 10)
+        {
+            /* v10: Added server_name column to collection_log so log entries
+                    can be identified by server without needing a lookup table. */
+            _logger?.LogInformation("Running migration to v10: adding server_name column to collection_log");
+            try
+            {
+                await ExecuteNonQueryAsync(connection, "ALTER TABLE collection_log ADD COLUMN IF NOT EXISTS server_name VARCHAR");
+            }
+            catch
+            {
+                /* Table doesn't exist yet — will be created with correct schema below */
+            }
+        }
     }
 
     /// <summary>

Lite/Database/Schema.cs

@@ -38,6 +38,7 @@ modified_date TIMESTAMP DEFAULT CURRENT_TIMESTAMP
 CREATE TABLE IF NOT EXISTS collection_log (
     log_id BIGINT PRIMARY KEY,
     server_id INTEGER NOT NULL,
+    server_name VARCHAR,
     collector_name VARCHAR NOT NULL,
     collection_time TIMESTAMP NOT NULL,
     duration_ms INTEGER,

Lite/MainWindow.xaml

@@ -97,10 +97,10 @@
                                             <Style TargetType="Ellipse">
                                                 <Setter Property="Fill" Value="{DynamicResource ForegroundMutedBrush}"/>
                                                 <Style.Triggers>
-                                                    <DataTrigger Binding="{Binding IsEnabled}" Value="True">
+                                                    <DataTrigger Binding="{Binding IsOnline}" Value="True">
                                                         <Setter Property="Fill" Value="{DynamicResource SuccessBrush}"/>
                                                     </DataTrigger>
-                                                    <DataTrigger Binding="{Binding IsEnabled}" Value="False">
+                                                    <DataTrigger Binding="{Binding IsOnline}" Value="False">
                                                         <Setter Property="Fill" Value="{DynamicResource ErrorBrush}"/>
                                                     </DataTrigger>
                                                 </Style.Triggers>

Lite/MainWindow.xaml.cs

@@ -249,6 +249,10 @@ private void ServerTabControl_SelectionChanged(object sender, SelectionChangedEv
     private void RefreshServerList()
     {
         var servers = _serverManager.GetAllServers();
+        foreach (var server in servers)
+        {
+            server.IsOnline = _serverManager.GetConnectionStatus(server.Id).IsOnline;
+        }
         ServerListView.ItemsSource = servers;
 
         // Update UI based on server count
@@ -883,9 +887,11 @@ private void CheckConnectionsAndNotify()
         try
         {
             var servers = _serverManager.GetAllServers();
+            bool needsRefresh = false;
             foreach (var server in servers)
             {
                 var status = _serverManager.GetConnectionStatus(server.Id);
+                server.IsOnline = status?.IsOnline;
                 if (status?.IsOnline == null) continue;
 
                 bool isOnline = status.IsOnline == true;
@@ -912,12 +918,22 @@ private void CheckConnectionsAndNotify()
 
                     if (wasOnline != isOnline)
                     {
-                        RefreshServerList();
+                        needsRefresh = true;
                     }
                 }
+                else
+                {
+                    /* First time seeing this server's status — need to refresh */
+                    needsRefresh = true;
+                }
 
                 _previousConnectionStates[server.Id] = isOnline;
             }
+
+            if (needsRefresh)
+            {
+                RefreshServerList();
+            }
         }
         catch (Exception ex)
         {

Lite/Models/ServerConnection.cs

@@ -81,6 +81,13 @@ public bool UseWindowsAuth
         _ => "Windows"
     };
 
+    /// <summary>
+    /// Actual connection status from the most recent connection check.
+    /// null = not checked yet, true = online, false = offline.
+    /// </summary>
+    [JsonIgnore]
+    public bool? IsOnline { get; set; }
+
     /// <summary>
     /// Display-only property for showing status in UI.
     /// </summary>

Lite/Services/LocalDataService.CollectionHealth.cs

@@ -79,7 +79,8 @@ public async Task<List<CollectionLogRow>> GetRecentCollectionLogAsync(int server
     duckdb_duration_ms,
     rows_collected,
     status,
-    error_message
+    error_message,
+    server_name
 FROM collection_log
 WHERE server_id = $1
 AND   collection_time >= $2
@@ -103,7 +104,8 @@ ORDER BY collection_time DESC
                 DuckDbDurationMs = reader.IsDBNull(4) ? null : (int?)Convert.ToInt32(reader.GetValue(4)),
                 RowsCollected = reader.IsDBNull(5) ? null : (int?)Convert.ToInt32(reader.GetValue(5)),
                 Status = reader.GetString(6),
-                ErrorMessage = reader.IsDBNull(7) ? null : reader.GetString(7)
+                ErrorMessage = reader.IsDBNull(7) ? null : reader.GetString(7),
+                ServerName = reader.IsDBNull(8) ? null : reader.GetString(8)
             });
         }
 
@@ -114,6 +116,7 @@ ORDER BY collection_time DESC
 public class CollectionLogRow
 {
     public string CollectorName { get; set; } = "";
+    public string? ServerName { get; set; }
     public DateTime CollectionTime { get; set; }
     public int? DurationMs { get; set; }
     public int? SqlDurationMs { get; set; }

Lite/Services/LocalDataService.Overview.cs

@@ -85,7 +85,7 @@ FROM blocked_process_reports
 SELECT COUNT(*)
 FROM deadlocks
 WHERE server_id = $1
-AND   collection_time >= $2";
+AND   deadlock_time >= $2";
             cmd.Parameters.Add(new DuckDBParameter { Value = serverId });
             cmd.Parameters.Add(new DuckDBParameter { Value = DateTime.UtcNow.AddHours(-1) });
             var result = await cmd.ExecuteScalarAsync();

Lite/Services/LocalDataService.QueryStats.cs

@@ -8,6 +8,7 @@
 
 using System;
 using System.Collections.Generic;
+using System.Data;
 using System.Threading.Tasks;
 using DuckDB.NET.Data;
 using Microsoft.Data.SqlClient;
@@ -27,7 +28,7 @@ public partial class LocalDataService
     quoted_name = QUOTENAME(d.name)
 FROM sys.databases AS d
 WHERE d.name = @database_name;", connection);
-        command.Parameters.AddWithValue("@database_name", databaseName);
+        command.Parameters.Add(new SqlParameter("@database_name", SqlDbType.NVarChar, 128) { Value = databaseName });
         var result = await command.ExecuteScalarAsync();
         return result as string;
     }
@@ -247,7 +248,7 @@ qs.total_elapsed_time DESC
         using var connection = new SqlConnection(connectionString);
         await connection.OpenAsync();
         using var command = new SqlCommand(query, connection) { CommandTimeout = 30 };
-        command.Parameters.AddWithValue("@query_hash", queryHash);
+        command.Parameters.Add(new SqlParameter("@query_hash", SqlDbType.VarChar, 64) { Value = queryHash });
         var result = await command.ExecuteScalarAsync();
         return result as string;
     }
@@ -294,8 +295,8 @@ ps.total_elapsed_time DESC
     @schema_name;";
 
         using var command = new SqlCommand(query, connection) { CommandTimeout = 30 };
-        command.Parameters.AddWithValue("@object_name", objectName);
-        command.Parameters.AddWithValue("@schema_name", schemaName);
+        command.Parameters.Add(new SqlParameter("@object_name", SqlDbType.NVarChar, 128) { Value = objectName });
+        command.Parameters.Add(new SqlParameter("@schema_name", SqlDbType.NVarChar, 128) { Value = schemaName });
         var result = await command.ExecuteScalarAsync();
         return result as string;
     }

Lite/Services/LocalDataService.QueryStore.cs

@@ -8,6 +8,7 @@
 
 using System;
 using System.Collections.Generic;
+using System.Data;
 using System.Threading.Tasks;
 using DuckDB.NET.Data;
 using Microsoft.Data.SqlClient;
@@ -198,7 +199,7 @@ AND   qsp.query_plan IS NOT NULL
     @plan_id;";
 
         using var command = new SqlCommand(query, connection) { CommandTimeout = 30 };
-        command.Parameters.AddWithValue("@plan_id", planId);
+        command.Parameters.Add(new SqlParameter("@plan_id", SqlDbType.BigInt) { Value = planId });
         var result = await command.ExecuteScalarAsync();
         return result as string;
     }

Lite/Services/RemoteCollectorService.BlockedProcessReport.cs

@@ -7,6 +7,7 @@
  */
 
 using System;
+using System.Data;
 using System.Diagnostics;
 using System.Threading;
 using System.Threading.Tasks;
@@ -126,7 +127,7 @@ LEFT JOIN sys.dm_xe_sessions AS dxs
 WHERE ses.name = @session_name;", connection))
         {
             cmd.CommandTimeout = CommandTimeoutSeconds;
-            cmd.Parameters.AddWithValue("@session_name", BlockedProcessXeSessionName);
+            cmd.Parameters.Add(new SqlParameter("@session_name", SqlDbType.NVarChar, 128) { Value = BlockedProcessXeSessionName });
             var result = await cmd.ExecuteScalarAsync(cancellationToken);
 
             if (result != null)
@@ -205,7 +206,7 @@ FROM sys.database_event_sessions AS des
 WHERE des.name = @session_name;", connection))
         {
             cmd.CommandTimeout = CommandTimeoutSeconds;
-            cmd.Parameters.AddWithValue("@session_name", BlockedProcessXeSessionName);
+            cmd.Parameters.Add(new SqlParameter("@session_name", SqlDbType.NVarChar, 128) { Value = BlockedProcessXeSessionName });
             var result = await cmd.ExecuteScalarAsync(cancellationToken);
 
             if (result != null)
@@ -380,8 +381,7 @@ as it lingers in the ring buffer across collection cycles. */
         command.CommandTimeout = CommandTimeoutSeconds;
 
         /* Use the most recent timestamp from DuckDB as the cutoff, or fall back to 10-minute window */
-        command.Parameters.AddWithValue("@cutoff_time",
-            lastCollectedTime ?? DateTime.UtcNow.AddMinutes(-10));
+        command.Parameters.Add(new SqlParameter("@cutoff_time", SqlDbType.DateTime2) { Value = lastCollectedTime ?? DateTime.UtcNow.AddMinutes(-10) });
 
         try
         {