feat: Phase 2 — Delegated State, Auth, Review-Gate, Notifications, Zombie-Reset

backend/Services/NotificationService.cs

@@ -0,0 +1,61 @@
+using Microsoft.EntityFrameworkCore;
+using Nexus.Api.Data;
+using Nexus.Api.Models;
+
+namespace Nexus.Api.Services;
+
+public sealed class NotificationService(NexusDbContext db) : INotificationService
+{
+    public async Task<Notification> CreateAsync(string type, string title, string? message, string forUser, Guid? taskId = null, CancellationToken ct = default)
+    {
+        var notification = new Notification
+        {
+            Type = type,
+            Title = title,
+            Message = message,
+            ForUser = forUser.ToLowerInvariant(),
+            TaskId = taskId
+        };
+        db.Notifications.Add(notification);
+        await db.SaveChangesAsync(ct);
+        return notification;
+    }
+
+    public async Task<IReadOnlyList<Notification>> GetForUserAsync(string forUser, int limit = 50, bool unreadOnly = false, CancellationToken ct = default)
+    {
+        var query = db.Notifications
+            .Where(n => n.ForUser == forUser.ToLowerInvariant());
+
+        if (unreadOnly)
+            query = query.Where(n => !n.IsRead);
+
+        return await query
+            .OrderByDescending(n => n.CreatedAt)
+            .Take(limit)
+            .ToListAsync(ct);
+    }
+
+    public async Task<bool> MarkAsReadAsync(Guid id, CancellationToken ct = default)
+    {
+        var notification = await db.Notifications.FindAsync([id], ct);
+        if (notification is null) return false;
+
+        notification.IsRead = true;
+        await db.SaveChangesAsync(ct);
+        return true;
+    }
+
+    public async Task<int> MarkAllAsReadAsync(string forUser, CancellationToken ct = default)
+    {
+        var count = await db.Notifications
+            .Where(n => n.ForUser == forUser.ToLowerInvariant() && !n.IsRead)
+            .ExecuteUpdateAsync(s => s.SetProperty(n => n.IsRead, true), ct);
+        return count;
+    }
+
+    public async Task<int> GetUnreadCountAsync(string forUser, CancellationToken ct = default)
+    {
+        return await db.Notifications
+            .CountAsync(n => n.ForUser == forUser.ToLowerInvariant() && !n.IsRead, ct);
+    }
+}