Add --preserve-jobs flag to CLI and GUI installers

Installer/Program.cs

@@ -95,6 +95,7 @@ static async Task<int> Main(string[] args)
                 Console.WriteLine("  -h, --help           Show this help message");
                 Console.WriteLine("  --reinstall          Drop existing database and perform clean install");
                 Console.WriteLine("  --reset-schedule     Reset collection schedule to recommended defaults");
+                Console.WriteLine("  --preserve-jobs      Keep existing SQL Agent jobs (owner, schedule, notifications)");
                 Console.WriteLine("  --encrypt=<level>    Connection encryption: mandatory (default), optional, strict");
                 Console.WriteLine("  --trust-cert         Trust server certificate without validation");
                 Console.WriteLine();
@@ -115,6 +116,7 @@ static async Task<int> Main(string[] args)
             bool automatedMode = args.Length > 0;
             bool reinstallMode = args.Any(a => a.Equals("--reinstall", StringComparison.OrdinalIgnoreCase));
             bool resetSchedule = args.Any(a => a.Equals("--reset-schedule", StringComparison.OrdinalIgnoreCase));
+            bool preserveJobs = args.Any(a => a.Equals("--preserve-jobs", StringComparison.OrdinalIgnoreCase));
             bool trustCert = args.Any(a => a.Equals("--trust-cert", StringComparison.OrdinalIgnoreCase));
 
             /*Parse encryption option (default: Mandatory)*/
@@ -135,6 +137,7 @@ static async Task<int> Main(string[] args)
             var filteredArgs = args
                 .Where(a => !a.Equals("--reinstall", StringComparison.OrdinalIgnoreCase))
                 .Where(a => !a.Equals("--reset-schedule", StringComparison.OrdinalIgnoreCase))
+                .Where(a => !a.Equals("--preserve-jobs", StringComparison.OrdinalIgnoreCase))
                 .Where(a => !a.Equals("--trust-cert", StringComparison.OrdinalIgnoreCase))
                 .Where(a => !a.StartsWith("--encrypt=", StringComparison.OrdinalIgnoreCase))
                 .ToArray();
@@ -653,6 +656,16 @@ INSERT...WHERE NOT EXISTS re-populates with current recommended values
                             Console.Write("(resetting schedule) ");
                         }
 
+                        /*
+                        Preserve existing SQL Agent jobs if requested — flip the T-SQL
+                        variable so existing jobs are left untouched during upgrade
+                        */
+                        if (preserveJobs && fileName.StartsWith("45_", StringComparison.Ordinal))
+                        {
+                            sqlContent = sqlContent.Replace("@preserve_jobs bit = 0", "@preserve_jobs bit = 1");
+                            Console.Write("(preserving existing jobs) ");
+                        }
+
                         /*
                         Remove SQLCMD directives (:r includes) as we're executing files directly
                         */

InstallerGui/MainWindow.xaml

@@ -186,6 +186,12 @@
                           Margin="0,0,0,10"
                           Foreground="{DynamicResource ForegroundBrush}"/>
 
+                <!-- Preserve Jobs Checkbox -->
+                <CheckBox x:Name="PreserveJobsCheckBox"
+                          Content="Keep existing SQL Agent jobs (owner, schedule, notifications)"
+                          Margin="0,0,0,10"
+                          Foreground="{DynamicResource ForegroundBrush}"/>
+
                 <!-- Validation Checkbox -->
                 <CheckBox x:Name="ValidationCheckBox"
                           Content="Run validation after install (recommended)"

InstallerGui/MainWindow.xaml.cs

@@ -401,11 +401,13 @@ Execute installation
                 Community dependencies install automatically before validation (98_validate)
                 */
                 bool resetSchedule = ResetScheduleCheckBox.IsChecked == true;
+                bool preserveJobs = PreserveJobsCheckBox.IsChecked == true;
                 _installationResult = await InstallationService.ExecuteInstallationAsync(
                     _connectionString,
                     _sqlFiles,
                     isCleanInstall,
                     resetSchedule,
+                    preserveJobs,
                     progress,
                     preValidationAction: async () =>
                     {

InstallerGui/Services/InstallationService.cs

@@ -325,6 +325,7 @@ public static async Task<InstallationResult> ExecuteInstallationAsync(
             List<string> sqlFiles,
             bool cleanInstall,
             bool resetSchedule = false,
+            bool preserveJobs = false,
             IProgress<InstallationProgress>? progress = null,
             Func<Task>? preValidationAction = null,
             CancellationToken cancellationToken = default)
@@ -422,6 +423,17 @@ Execute SQL files
                         });
                     }
 
+                    /*Preserve existing SQL Agent jobs if requested*/
+                    if (preserveJobs && fileName.StartsWith("45_", StringComparison.Ordinal))
+                    {
+                        sqlContent = sqlContent.Replace("@preserve_jobs bit = 0", "@preserve_jobs bit = 1");
+                        progress?.Report(new InstallationProgress
+                        {
+                            Message = "Preserving existing SQL Agent jobs...",
+                            Status = "Info"
+                        });
+                    }
+
                     /*Remove SQLCMD directives*/
                     sqlContent = SqlCmdDirectivePattern.Replace(sqlContent, "");
 

README.md

@@ -146,6 +146,7 @@ A GUI installer (`PerformanceMonitorInstallerGui.exe`) is also included in the r
 | `USERNAME PASSWORD` | SQL Authentication credentials (positional, optional) |
 | `--reinstall` | Drop existing database and perform clean install |
 | `--reset-schedule` | Reset collection schedule to recommended defaults during upgrade |
+| `--preserve-jobs` | Keep existing SQL Agent jobs unchanged (owner, schedule, notifications) |
 | `--encrypt=optional\|mandatory\|strict` | Connection encryption level (default: mandatory) |
 | `--trust-cert` | Trust server certificate without validation (default: require valid cert) |