fix(ui): AuditLogQueryService uses scope-per-query to avoid DbContext race (#23 M7)

tests/ScadaLink.CentralUI.Tests/Services/AuditLogQueryServiceTests.cs

@@ -1,3 +1,6 @@
+using Microsoft.EntityFrameworkCore;
+using Microsoft.EntityFrameworkCore.Diagnostics;
+using Microsoft.Extensions.DependencyInjection;
 using NSubstitute;
 using ScadaLink.CentralUI.Services;
 using ScadaLink.Commons.Entities.Audit;
@@ -6,6 +9,8 @@ using ScadaLink.Commons.Messages.Health;
 using ScadaLink.Commons.Types;
 using ScadaLink.Commons.Types.Audit;
 using ScadaLink.Commons.Types.Enums;
+using ScadaLink.ConfigurationDatabase;
+using ScadaLink.ConfigurationDatabase.Repositories;
 using ScadaLink.HealthMonitoring;
 
 namespace ScadaLink.CentralUI.Tests.Services;
@@ -134,6 +139,89 @@ public class AuditLogQueryServiceTests
         Assert.Equal(4, snapshot.BacklogTotal);
     }
 
+    // ─────────────────────────────────────────────────────────────────────────
+    // #23 M7 — DbContext concurrency race regression (Bundle H follow-up)
+    //
+    // The drill-in deep link (/audit/log?correlationId=…) triggers an OnInitialized
+    // auto-load query that races AuditFilterBar.GetAllSitesAsync() on the SAME
+    // scoped Blazor-circuit ScadaLinkDbContext. EF Core then throws
+    // "A second operation was started on this context instance before a previous
+    // operation completed." AuditLogQueryService now opens its OWN DI scope per
+    // QueryAsync call (scope-per-query) so it never shares the page's scoped
+    // context — these tests pin that contract.
+    // ─────────────────────────────────────────────────────────────────────────
+
+    [Fact]
+    public async Task AuditLogQueryService_ConcurrentQueries_DoNotRace()
+    {
+        // A real ScadaLinkDbContext (SQLite in-memory) registered as SCOPED with
+        // the real AuditLogRepository — exactly the shared-scoped-context shape
+        // that produces the EF race when one context services two operations.
+        using var connection = new Microsoft.Data.Sqlite.SqliteConnection("DataSource=:memory:");
+        connection.Open();
+
+        var services = new ServiceCollection();
+        services.AddLogging();
+        services.AddDbContext<ScadaLinkDbContext>(options =>
+            options.UseSqlite(connection)
+                   .ConfigureWarnings(w => w.Ignore(RelationalEventId.PendingModelChangesWarning)));
+        services.AddScoped<IAuditLogRepository, AuditLogRepository>();
+
+        await using var provider = services.BuildServiceProvider();
+
+        // Create the schema once on a throwaway scope.
+        using (var seedScope = provider.CreateScope())
+        {
+            var ctx = seedScope.ServiceProvider.GetRequiredService<ScadaLinkDbContext>();
+            await ctx.Database.EnsureCreatedAsync();
+        }
+
+        var scopeFactory = provider.GetRequiredService<IServiceScopeFactory>();
+        var sut = new AuditLogQueryService(scopeFactory, EmptyAggregator());
+
+        var filter = new AuditLogQueryFilter(Channel: AuditChannel.ApiOutbound);
+
+        // Fire two QueryAsync calls in parallel. With scope-per-query each gets a
+        // fresh DbContext, so this completes cleanly; with a shared scoped context
+        // EF throws "A second operation was started on this context instance".
+        var t1 = sut.QueryAsync(filter);
+        var t2 = sut.QueryAsync(filter);
+
+        var results = await Task.WhenAll(t1, t2);
+
+        Assert.All(results, Assert.NotNull);
+    }
+
+    [Fact]
+    public async Task QueryAsync_OpensFreshScopePerCall_NotSharedAcrossCalls()
+    {
+        // Two sequential calls must each resolve the repository from a distinct
+        // scope — the service must never cache a single repository instance.
+        var resolvedRepos = new List<IAuditLogRepository>();
+
+        var services = new ServiceCollection();
+        services.AddScoped<IAuditLogRepository>(_ =>
+        {
+            var repo = Substitute.For<IAuditLogRepository>();
+            repo.QueryAsync(Arg.Any<AuditLogQueryFilter>(), Arg.Any<AuditLogPaging>(), Arg.Any<CancellationToken>())
+                .Returns(Task.FromResult<IReadOnlyList<AuditEvent>>(Array.Empty<AuditEvent>()));
+            resolvedRepos.Add(repo);
+            return repo;
+        });
+
+        await using var provider = services.BuildServiceProvider();
+        var sut = new AuditLogQueryService(
+            provider.GetRequiredService<IServiceScopeFactory>(),
+            EmptyAggregator());
+
+        await sut.QueryAsync(new AuditLogQueryFilter());
+        await sut.QueryAsync(new AuditLogQueryFilter());
+
+        // Each QueryAsync opened its own scope → two distinct repo instances.
+        Assert.Equal(2, resolvedRepos.Count);
+        Assert.NotSame(resolvedRepos[0], resolvedRepos[1]);
+    }
+
     private static SiteHealthState StateWithBacklog(string siteId, int? pending)
     {
         SiteAuditBacklogSnapshot? backlog = pending.HasValue