test(workers): prove clock and restart safety

JobTrackerApi/Services/DailyExportHostedService.cs

@@ -10,7 +10,8 @@ public sealed class DailyExportHostedService(
     ILogger<DailyExportHostedService> logger,
     IConfiguration configuration,
     AppPaths paths,
-    IStartupReadiness startupReadiness) : BackgroundService
+    IStartupReadiness startupReadiness,
+    TimeProvider timeProvider) : BackgroundService
 {
     protected override async Task ExecuteAsync(CancellationToken stoppingToken)
     {
@@ -25,11 +26,11 @@ public sealed class DailyExportHostedService(
         if (hour is < 0 or > 23) hour = 2;
         while (!stoppingToken.IsCancellationRequested)
         {
-            var now = DateTime.Now;
+            var now = timeProvider.GetLocalNow().DateTime;
             var next = new DateTime(now.Year, now.Month, now.Day, hour, 0, 0);
             if (next <= now) next = next.AddDays(1);
             logger.LogInformation("Next daily export scheduled at {Next}.", next);
-            await Task.Delay(next - now, stoppingToken);
+            await Task.Delay(next - now, timeProvider, stoppingToken);
             await RunOnceAsync(stoppingToken);
         }
     }
@@ -48,12 +49,13 @@ public sealed class DailyExportHostedService(
     {
         var db = services.GetRequiredService<JobTrackerContext>();
         var owner = db.CurrentUserId ?? throw new InvalidOperationException("Daily export requires an explicit owner scope.");
+        var now = timeProvider.GetLocalNow().DateTime;
         var jobs = await db.JobApplications.AsNoTracking().OrderByDescending(job => job.DateApplied).ToListAsync(cancellationToken);
         var jobIds = jobs.Select(job => job.Id).ToList();
         var export = new
         {
             Version = "dailyexport.v2",
-            CreatedAt = DateTime.Now,
+            CreatedAt = now,
             OwnerUserId = owner,
             Companies = await db.Companies.AsNoTracking().OrderBy(company => company.Name).ToListAsync(cancellationToken),
             JobApplications = jobs,
@@ -96,7 +98,7 @@ public sealed class DailyExportHostedService(
 
         var folder = paths.GetOwnerDailyExportsRoot(configuration["Exports:DailyFolder"], owner);
         Directory.CreateDirectory(folder);
-        var finalPath = Path.Combine(folder, $"daily_export_{DateTime.Now:yyyyMMdd}.json");
+        var finalPath = Path.Combine(folder, $"daily_export_{now:yyyyMMdd}.json");
         var temporaryPath = finalPath + $".{Guid.NewGuid():N}.tmp";
         try
         {