Index: ChapterX.Infrastructure/Repositories/CollaborationRepository.cs
===================================================================
--- ChapterX.Infrastructure/Repositories/CollaborationRepository.cs	(revision 73b69b22fa1e9888b8530a66db4a150efb8f52bc)
+++ ChapterX.Infrastructure/Repositories/CollaborationRepository.cs	(revision a7550ca4790b7d1a7515a4a688b871e32313d8bf)
@@ -2,9 +2,5 @@
 using ChapterX.Domain.Repositories;
 using ChapterX.Infrastructure.Data.DataContext;
-using System;
-using System.Collections.Generic;
-using System.Linq;
-using System.Text;
-using System.Threading.Tasks;
+using Microsoft.EntityFrameworkCore;
 
 namespace ChapterX.Infrastructure.Repositories
@@ -15,4 +11,18 @@
         {
         }
+
+        public override async Task<IEnumerable<Collaboration>> GetAllAsync(CancellationToken cancellationToken = default)
+            => await _dbSet
+                .Include(c => c.User)
+                .ToListAsync(cancellationToken);
+
+        public async Task<bool> DeleteByUserAndStoryAsync(int userId, int storyId, CancellationToken cancellationToken = default)
+        {
+            var collab = await _dbSet.FirstOrDefaultAsync(c => c.UserId == userId && c.StoryId == storyId, cancellationToken);
+            if (collab == null) return false;
+            _dbSet.Remove(collab);
+            await _context.SaveChangesAsync(cancellationToken);
+            return true;
+        }
     }
 }
Index: ChapterX.Infrastructure/Repositories/UserRepository.cs
===================================================================
--- ChapterX.Infrastructure/Repositories/UserRepository.cs	(revision 73b69b22fa1e9888b8530a66db4a150efb8f52bc)
+++ ChapterX.Infrastructure/Repositories/UserRepository.cs	(revision a7550ca4790b7d1a7515a4a688b871e32313d8bf)
@@ -12,4 +12,10 @@
         }
 
+        public override async Task<IEnumerable<User>> GetAllAsync(CancellationToken cancellationToken = default)
+            => await _dbSet
+                .Include(u => u.Admin)
+                .Include(u => u.Writer)
+                .ToListAsync(cancellationToken);
+
         public async Task<User?> GetByEmailAsync(string email, CancellationToken cancellationToken = default)
             => await _dbSet