Method OnModelCreating

backend/Data/AppDbContext.cs:30–268

(ModelBuilder modelBuilder)

    public DbSet<BoardAutomation> BoardAutomations { get; set; }

    protected override void OnModelCreating(ModelBuilder modelBuilder)
    {
        base.OnModelCreating(modelBuilder);

        // User
        modelBuilder.Entity<User>(entity =>
        {
            entity.HasIndex(u => u.Username).IsUnique();
            entity.HasIndex(u => u.Email).IsUnique();
        });

        // Board -> User
        modelBuilder.Entity<Board>(entity =>
        {
            entity.HasOne(b => b.Owner)
                  .WithMany(u => u.Boards)
                  .HasForeignKey(b => b.OwnerId)
                  .OnDelete(DeleteBehavior.Cascade);
        });

        // Column -> Board
        modelBuilder.Entity<Column>(entity =>
        {
            entity.HasOne(c => c.Board)
                  .WithMany(b => b.Columns)
                  .HasForeignKey(c => c.BoardId)
                  .OnDelete(DeleteBehavior.Cascade);
        });

        // TaskCard -> Column
        modelBuilder.Entity<TaskCard>(entity =>
        {
            entity.HasOne(t => t.Column)
                  .WithMany(c => c.TaskCards)
                  .HasForeignKey(t => t.ColumnId)
                  .OnDelete(DeleteBehavior.Cascade);
        });

        // TaskActivity -> TaskCard
        modelBuilder.Entity<TaskActivity>(entity =>
        {
            entity.HasIndex(a => a.TaskCardId); // Optimization

            entity.HasOne(a => a.TaskCard)
                  .WithMany() // TaskCard doesn't need explicit list of activities for now, can query by ID
                  .HasForeignKey(a => a.TaskCardId)
                  .OnDelete(DeleteBehavior.Cascade);

            entity.HasOne(a => a.User)
                  .WithMany()
                  .HasForeignKey(a => a.UserId)
                  .OnDelete(DeleteBehavior.Cascade);
        });

        // BoardMember (User <-> Board many-to-many)
        modelBuilder.Entity<BoardMember>(entity =>
        {
            entity.HasOne(bm => bm.User)