第七章：依赖注入 —— 窗口背后的部门协作机制

窗口人员不自己去“创建审批处、档案处、短信处”，
而是由总控系统按规则把这些部门能力分配给窗口。

builder.Services.AddScoped<ICitizenService, CitizenService>();
builder.Services.AddScoped<IPermitService, PermitService>();
builder.Services.AddSingleton<ISystemClock, SystemClock>();

public class PermitService : IPermitService
{
    private readonly ICitizenService _citizenService;

    public PermitService(ICitizenService citizenService)
    {
        _citizenService = citizenService;
    }

    public Task<PermitDto> CreateAsync(CreatePermitRequest request)
    {
        // 这里可以调用 _citizenService 做核验
        throw new NotImplementedException();
    }
}