fix: escape html notification variables

Encode template variables in HTML bodies while preserving text and subjects.

Ref: IT-1115

.gitignore

@@ -480,3 +480,6 @@ $RECYCLE.BIN/
 
 # Vim temporary swap files
 *.swp
+
+# Local Docker Compose secrets and ports
+docker/environments/.env.local

AGENTS.md

@@ -0,0 +1,27 @@
+# HrynCo Notification Service Agent Rules
+
+## Git workflow
+
+- Treat `main` as the only default and integration branch for this repository.
+- Start every task branch from the latest `origin/main`.
+- Before creating a task branch, fetch the remote, switch to `main`, and fast-forward it from `origin/main`.
+- Create the task branch only after confirming that local `main` matches `origin/main`.
+- Open pull requests from the task branch into `main`.
+- Do not use `development` as the base or pull-request target for new work in this repository.
+- Do not commit, push, publish, deploy, or merge unless the repository owner explicitly requests that step.
+
+Recommended branch preparation:
+
+```text
+git fetch origin
+git switch main
+git pull --ff-only origin main
+git switch -c <task-branch>
+```
+
+## Delivery
+
+- Keep changes focused and preserve backward compatibility where practical.
+- Update the matching repository documentation when behavior, contracts, configuration, routing, or workflows change.
+- Run the solution build and relevant tests before handoff.
+- Use Conventional Commit messages with a lowercase subject and finish the commit body with `Ref: <issue-id>` when an issue exists.

Directory.Packages.props

@@ -4,10 +4,12 @@
   </PropertyGroup>
   <ItemGroup>
     <!-- Entity Framework Core -->
-    <PackageVersion Include="Microsoft.EntityFrameworkCore" Version="9.0.5" />
-    <PackageVersion Include="Microsoft.EntityFrameworkCore.Design" Version="9.0.5" />
-    <PackageVersion Include="Microsoft.EntityFrameworkCore.Relational" Version="9.0.5" />
-    <PackageVersion Include="Npgsql.EntityFrameworkCore.PostgreSQL" Version="9.0.4" />
+    <PackageVersion Include="HrynCo.DAL.Abstract" Version="1.0.11" />
+    <PackageVersion Include="HrynCo.DAL.EF" Version="1.0.11" />
+    <PackageVersion Include="Microsoft.EntityFrameworkCore" Version="10.0.7" />
+    <PackageVersion Include="Microsoft.EntityFrameworkCore.Design" Version="10.0.7" />
+    <PackageVersion Include="Microsoft.EntityFrameworkCore.Relational" Version="10.0.7" />
+    <PackageVersion Include="Npgsql.EntityFrameworkCore.PostgreSQL" Version="10.0.1" />
     <!-- MediatR -->
     <PackageVersion Include="MediatR" Version="12.4.1" />
     <PackageVersion Include="MediatR.Extensions.Microsoft.DependencyInjection" Version="11.1.0" />
@@ -28,7 +30,7 @@
     <PackageVersion Include="Serilog.Sinks.Seq" Version="9.0.0" />
     <!-- HrynCo shared packages -->
     <PackageVersion Include="HrynCo.Common" Version="1.0.11" />
-    <PackageVersion Include="HrynCo.RabbitMq" Version="1.0.15" />
+    <PackageVersion Include="HrynCo.RabbitMq" Version="1.0.17" />
     <PackageVersion Include="Microsoft.NET.Test.Sdk" Version="17.14.1" />
     <PackageVersion Include="coverlet.collector" Version="6.0.4" />
     <PackageVersion Include="xunit" Version="2.9.3" />
@@ -37,4 +39,4 @@
     <PackageVersion Include="Testcontainers.PostgreSql" Version="4.6.0" />
     <PackageVersion Include="Microsoft.AspNetCore.Mvc.Testing" Version="9.0.5" />
   </ItemGroup>
-</Project>
+</Project>

HrynCo.NotificationService.DAL.Abstract/Entities/Entity.cs

@@ -1,17 +0,0 @@
-namespace HrynCo.NotificationService.DAL.Abstract.Entities;
-
-public abstract class Entity<TId> : IEntity<TId> where TId : struct
-{
-    public TId Id { get; set; }
-    public DateTimeOffset Created { get; set; }
-    public DateTimeOffset? Updated { get; set; }
-}
-
-public abstract class Entity : Entity<Guid>
-{
-    protected Entity()
-    {
-        Id = Guid.NewGuid();
-        Created = DateTimeOffset.UtcNow;
-    }
-}

HrynCo.NotificationService.DAL.Abstract/Entities/IEntity.cs

@@ -1,8 +0,0 @@
-namespace HrynCo.NotificationService.DAL.Abstract.Entities;
-
-public interface IEntity<TId> where TId : struct
-{
-    TId Id { get; set; }
-    DateTimeOffset Created { get; set; }
-    DateTimeOffset? Updated { get; set; }
-}

HrynCo.NotificationService.DAL.Abstract/HrynCo.NotificationService.DAL.Abstract.csproj

@@ -6,4 +6,8 @@
     <Nullable>enable</Nullable>
   </PropertyGroup>
 
+  <ItemGroup>
+    <PackageReference Include="HrynCo.DAL.Abstract" />
+  </ItemGroup>
+
 </Project>

HrynCo.NotificationService.DAL.Abstract/ITransaction.cs

@@ -1,7 +0,0 @@
-namespace HrynCo.NotificationService.DAL.Abstract;
-
-public interface ITransaction : IAsyncDisposable
-{
-    Task CommitAsync(CancellationToken cancellationToken = default);
-    Task RollbackAsync(CancellationToken cancellationToken = default);
-}

HrynCo.NotificationService.DAL.Abstract/IUnitOfWork.cs

@@ -1,11 +0,0 @@
-namespace HrynCo.NotificationService.DAL.Abstract;
-
-public interface IUnitOfWork
-{
-    Task SaveChangesAsync(CancellationToken cancellationToken = default);
-    Task<ITransaction> BeginTransactionAsync(CancellationToken cancellationToken = default);
-    ITransaction? GetCurrentTransaction();
-
-    Task ExecuteInTransactionAsync(Func<Task> action);
-    Task<TResult> ExecuteInTransactionAsync<TResult>(Func<Task<TResult>> action);
-}

HrynCo.NotificationService.DAL.Abstract/Providers/EmailChannel.cs

@@ -1,4 +1,4 @@
-using HrynCo.NotificationService.DAL.Abstract.Entities;
+using HrynCo.DAL.Abstract.Entities;
 
 namespace HrynCo.NotificationService.DAL.Abstract.Providers;
 
@@ -12,4 +12,4 @@ public class EmailChannel : Entity
     public int? MonthlyLimit { get; set; }
     public int WarnThresholdPercent { get; set; } = 90;
     public bool IsActive { get; set; } = true;
-}
+}

HrynCo.NotificationService.DAL.Abstract/Providers/EmailChannelUsage.cs

@@ -1,13 +1,14 @@
-using HrynCo.NotificationService.DAL.Abstract.Entities;
-
 namespace HrynCo.NotificationService.DAL.Abstract.Providers;
 
 /// <summary>
 /// Tracks email send counts per EmailChannel per calendar day.
 /// Monthly counts are derived by summing daily records within a month.
 /// </summary>
-public class EmailChannelUsage : Entity
+public class EmailChannelUsage
 {
+    public Guid Id { get; set; }
+    public DateTimeOffset Created { get; set; }
+    public DateTimeOffset? Updated { get; set; }
     public Guid ProviderId { get; set; }
     public DateOnly Date { get; set; }
     public int SentCount { get; set; }

HrynCo.NotificationService.DAL.Abstract/Repositories/IEmailTemplateRepository.cs

@@ -4,10 +4,10 @@ namespace HrynCo.NotificationService.DAL.Abstract.Repositories;
 
 public interface IEmailTemplateRepository
 {
-    Task<IReadOnlyList<EmailTemplate>> GetAllAsync(CancellationToken ct = default);
+    Task<IReadOnlyList<EmailTemplate>> GetAllAsync(string? serviceName = null, string? key = null, CancellationToken ct = default);
     Task<IReadOnlyList<EmailTemplate>> GetByServiceAsync(string serviceName, CancellationToken ct = default);
     Task<EmailTemplate?> GetAsync(string serviceName, string key, string languageCode, CancellationToken ct = default);
     Task AddAsync(EmailTemplate template, CancellationToken ct = default);
     Task UpdateAsync(EmailTemplate template, CancellationToken ct = default);
     Task DeleteAsync(EmailTemplate template, CancellationToken ct = default);
-}
+}

HrynCo.NotificationService.DAL.Abstract/Templates/EmailTemplate.cs

@@ -1,4 +1,4 @@
-using HrynCo.NotificationService.DAL.Abstract.Entities;
+using HrynCo.DAL.Abstract.Entities;
 
 namespace HrynCo.NotificationService.DAL.Abstract.Templates;
 

HrynCo.NotificationService.DAL.EF/Core/EfRepository.cs

@@ -1,45 +0,0 @@
-using System.Linq.Expressions;
-using Microsoft.EntityFrameworkCore;
-
-namespace HrynCo.NotificationService.DAL.EF.Core;
-
-internal abstract class EfRepository<TEntity>
-    where TEntity : class
-{
-    protected NotificationDbContext DbContext { get; }
-    protected DbSet<TEntity> DbSet { get; }
-
-    protected EfRepository(NotificationDbContext dbContext)
-    {
-        DbContext = dbContext;
-        DbSet = dbContext.Set<TEntity>();
-    }
-
-    protected async Task AddAsync(TEntity entity, CancellationToken ct = default)
-    {
-        await DbSet.AddAsync(entity, ct);
-    }
-
-    protected async Task AddRangeAsync(IEnumerable<TEntity> entities, CancellationToken ct = default)
-    {
-        await DbSet.AddRangeAsync(entities, ct);
-    }
-
-    protected void Update(TEntity entity)
-    {
-        DbSet.Update(entity);
-    }
-
-    protected void Delete(TEntity entity)
-    {
-        DbSet.Remove(entity);
-    }
-
-    protected void DeleteRange(IEnumerable<TEntity> entities)
-    {
-        DbSet.RemoveRange(entities);
-    }
-
-    protected Task<bool> ExistsAsync(Expression<Func<TEntity, bool>> predicate, CancellationToken ct = default) =>
-        DbSet.AnyAsync(predicate, ct);
-}

HrynCo.NotificationService.DAL.EF/Core/EfTransactionAdapter.cs

@@ -1,29 +0,0 @@
-using HrynCo.NotificationService.DAL.Abstract;
-using Microsoft.EntityFrameworkCore.Storage;
-
-namespace HrynCo.NotificationService.DAL.EF.Core;
-
-internal sealed class EfTransactionAdapter : ITransaction
-{
-    private readonly IDbContextTransaction _transaction;
-
-    internal EfTransactionAdapter(IDbContextTransaction transaction)
-    {
-        _transaction = transaction;
-    }
-
-    public Task CommitAsync(CancellationToken cancellationToken = default)
-    {
-        return _transaction.CommitAsync(cancellationToken);
-    }
-
-    public Task RollbackAsync(CancellationToken cancellationToken = default)
-    {
-        return _transaction.RollbackAsync(cancellationToken);
-    }
-
-    public ValueTask DisposeAsync()
-    {
-        return _transaction.DisposeAsync();
-    }
-}

HrynCo.NotificationService.DAL.EF/Core/EfUnitOfWork.cs

@@ -1,105 +0,0 @@
-using HrynCo.NotificationService.DAL.Abstract;
-using Microsoft.EntityFrameworkCore;
-using Microsoft.EntityFrameworkCore.Storage;
-
-namespace HrynCo.NotificationService.DAL.EF.Core;
-
-internal abstract class EfUnitOfWork<TDbContext> : IUnitOfWork
-    where TDbContext : DbContext
-{
-    private readonly TDbContext _context;
-    private EfTransactionAdapter? _currentTransaction;
-
-    protected EfUnitOfWork(TDbContext context)
-    {
-        _context = context;
-    }
-
-    public Task SaveChangesAsync(CancellationToken cancellationToken = default)
-    {
-        return _context.SaveChangesAsync(cancellationToken);
-    }
-
-    public async Task<ITransaction> BeginTransactionAsync(CancellationToken cancellationToken = default)
-    {
-        if (_currentTransaction != null)
-        {
-            return _currentTransaction;
-        }
-
-        IDbContextTransaction tx = await _context.Database.BeginTransactionAsync(cancellationToken);
-        _currentTransaction = new EfTransactionAdapter(tx);
-        return _currentTransaction;
-    }
-
-    public ITransaction? GetCurrentTransaction()
-    {
-        return _currentTransaction;
-    }
-
-    public async Task ExecuteInTransactionAsync(Func<Task> action)
-    {
-        ITransaction? existing = GetCurrentTransaction();
-        bool ownsTransaction = existing is null;
-        ITransaction tx = existing ?? await BeginTransactionAsync();
-
-        try
-        {
-            await action();
-            if (ownsTransaction)
-            {
-                await tx.CommitAsync();
-            }
-        }
-        catch
-        {
-            if (ownsTransaction)
-            {
-                await tx.RollbackAsync();
-            }
-
-            throw;
-        }
-        finally
-        {
-            if (ownsTransaction)
-            {
-                await tx.DisposeAsync();
-            }
-        }
-    }
-
-    public async Task<TResult> ExecuteInTransactionAsync<TResult>(Func<Task<TResult>> action)
-    {
-        ITransaction? existing = GetCurrentTransaction();
-        bool ownsTransaction = existing is null;
-        ITransaction tx = existing ?? await BeginTransactionAsync();
-
-        try
-        {
-            TResult result = await action();
-            if (ownsTransaction)
-            {
-                await tx.CommitAsync();
-            }
-
-            return result;
-        }
-        catch
-        {
-            if (ownsTransaction)
-            {
-                await tx.RollbackAsync();
-            }
-
-            throw;
-        }
-        finally
-        {
-            if (ownsTransaction)
-            {
-                await tx.DisposeAsync();
-            }
-        }
-    }
-}

HrynCo.NotificationService.DAL.EF/Core/NotificationBaseRepository.cs

@@ -0,0 +1,20 @@
+namespace HrynCo.NotificationService.DAL.EF.Core;
+
+using HrynCo.DAL.Abstract.Entities;
+using HrynCo.DAL.EF.Core;
+
+public abstract class NotificationBaseRepository<TEntity>
+    : BaseRepository<NotificationEfRepository<TEntity>, NotificationDbContext, TEntity, Guid> where TEntity : Entity
+{
+    protected NotificationBaseRepository(NotificationDbContext dbContext)
+    {
+        DbContext = dbContext;
+    }
+
+    private NotificationDbContext DbContext { get; set; }
+
+    protected override NotificationEfRepository<TEntity> CreateEfRepository()
+    {
+        return new NotificationEfRepository<TEntity>(DbContext);
+    }
+}

HrynCo.NotificationService.DAL.EF/Core/NotificationEfRepository.cs

@@ -0,0 +1,13 @@
+namespace HrynCo.NotificationService.DAL.EF.Core;
+
+using HrynCo.DAL.Abstract.Entities;
+using HrynCo.DAL.EF.Core;
+
+public class NotificationEfRepository<TEntity> : BaseEfRepository<NotificationDbContext, TEntity, Guid>
+    where TEntity : class, IEntity<Guid>
+{
+    public NotificationEfRepository(NotificationDbContext dbContext) :
+        base(dbContext)
+    {
+    }
+}

HrynCo.NotificationService.DAL.EF/Core/UnitOfWork.cs

@@ -1,8 +0,0 @@
-namespace HrynCo.NotificationService.DAL.EF.Core;
-
-internal sealed class UnitOfWork : EfUnitOfWork<NotificationDbContext>
-{
-    public UnitOfWork(NotificationDbContext context) : base(context)
-    {
-    }
-}

HrynCo.NotificationService.DAL.EF/Entities/EmailChannelEntity.cs

@@ -1,4 +1,4 @@
-using HrynCo.NotificationService.DAL.Abstract.Entities;
+using HrynCo.DAL.Abstract.Entities;
 using HrynCo.NotificationService.DAL.Abstract.Providers;
 
 namespace HrynCo.NotificationService.DAL.EF.Entities;

HrynCo.NotificationService.DAL.EF/Entities/EmailChannelUsageEntity.cs

@@ -1,4 +1,4 @@
-using HrynCo.NotificationService.DAL.Abstract.Entities;
+using HrynCo.DAL.Abstract.Entities;
 
 namespace HrynCo.NotificationService.DAL.EF.Entities;
 

HrynCo.NotificationService.DAL.EF/Entities/EmailTemplateEntity.cs

@@ -1,4 +1,4 @@
-using HrynCo.NotificationService.DAL.Abstract.Entities;
+using HrynCo.DAL.Abstract.Entities;
 
 namespace HrynCo.NotificationService.DAL.EF.Entities;
 

HrynCo.NotificationService.DAL.EF/HrynCo.NotificationService.DAL.EF.csproj

@@ -5,7 +5,7 @@
   </ItemGroup>
 
   <ItemGroup>
-    <PackageReference Include="Microsoft.EntityFrameworkCore" />
+    <PackageReference Include="HrynCo.DAL.EF" />
     <PackageReference Include="Microsoft.EntityFrameworkCore.Design">
       <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
       <PrivateAssets>all</PrivateAssets>

HrynCo.NotificationService.DAL.EF/NotificationUnitOfWork.cs

@@ -0,0 +1,10 @@
+namespace HrynCo.NotificationService.DAL.EF;
+
+using HrynCo.DAL.EF.Core;
+
+public class NotificationUnitOfWork : EfUnitOfWork<NotificationDbContext>
+{
+    public NotificationUnitOfWork(NotificationDbContext context) : base(context)
+    {
+    }
+}

HrynCo.NotificationService.DAL.EF/Repositories/EmailChannelRepository.cs

@@ -1,3 +1,5 @@
+namespace HrynCo.NotificationService.DAL.EF.Repositories;
+
 using System.Text.Json;
 using HrynCo.NotificationService.DAL.Abstract.Providers;
 using HrynCo.NotificationService.DAL.Abstract.Repositories;
@@ -5,9 +7,7 @@ using HrynCo.NotificationService.DAL.EF.Core;
 using HrynCo.NotificationService.DAL.EF.Entities;
 using Microsoft.EntityFrameworkCore;
 
-namespace HrynCo.NotificationService.DAL.EF.Repositories;
-
-internal sealed class EmailChannelRepository : EfRepository<EmailChannelEntity>, IEmailChannelRepository
+internal sealed class EmailChannelRepository : NotificationBaseRepository<EmailChannelEntity>, IEmailChannelRepository
 {
     public EmailChannelRepository(NotificationDbContext dbContext) : base(dbContext)
     {
@@ -15,20 +15,14 @@ internal sealed class EmailChannelRepository : EfRepository<EmailChannelEntity>,
 
     public async Task<IReadOnlyList<EmailChannel>> GetAllAsync(CancellationToken ct = default)
     {
-        var entities = await DbSet
-            .AsNoTracking()
-            .OrderBy(x => x.ServiceName)
-            .ThenBy(x => x.Priority)
-            .ToListAsync(ct);
+        var entities = await EfRepository.Get().ToListAsync(ct);
 
         return entities.Select(MapToDomain).ToList();
     }
 
     public async Task<IReadOnlyList<EmailChannel>> GetByServiceAsync(string serviceName, CancellationToken ct = default)
     {
-        var entities = await DbSet
-            .AsNoTracking()
-            .Where(x => x.ServiceName == serviceName)
+        var entities = await EfRepository.Get(x => x.ServiceName == serviceName)
             .OrderBy(x => x.Priority)
             .ToListAsync(ct);
 
@@ -38,8 +32,7 @@ internal sealed class EmailChannelRepository : EfRepository<EmailChannelEntity>,
     public async Task<IReadOnlyList<ChannelWithUsage>> GetAllWithUsageSummaryAsync(
         DateOnly today, CancellationToken ct = default)
     {
-        var rows = await DbSet
-            .AsNoTracking()
+        var rows = await EfRepository.Get()
             .OrderBy(c => c.ServiceName)
             .ThenBy(c => c.Priority)
             .Select(c => new
@@ -61,30 +54,24 @@ internal sealed class EmailChannelRepository : EfRepository<EmailChannelEntity>,
 
     public async Task<EmailChannel?> GetByIdAsync(Guid id, CancellationToken ct = default)
     {
-        EmailChannelEntity? entity = await DbSet.AsNoTracking().FirstOrDefaultAsync(x => x.Id == id, ct);
+        EmailChannelEntity? entity = await EfRepository.GetByIdAsync(id);
         return entity is null ? null : MapToDomain(entity);
     }
 
     public Task AddAsync(EmailChannel channel, CancellationToken ct = default)
     {
-        return base.AddAsync(MapToEntity(channel), ct);
+        return EfRepository.AddAsync(MapToEntity(channel));
     }
 
-    public Task UpdateAsync(EmailChannel channel, CancellationToken ct = default)
+    public async Task UpdateAsync(EmailChannel channel, CancellationToken ct = default)
     {
         EmailChannelEntity entity = MapToEntity(channel);
-        entity.Updated = DateTimeOffset.UtcNow;
-        Update(entity);
-        return Task.CompletedTask;
+        await EfRepository.UpdateAsync(entity);
     }
 
     public async Task DeleteAsync(EmailChannel channel, CancellationToken ct = default)
     {
-        EmailChannelEntity? entity = await DbSet.FindAsync([channel.Id], ct);
-        if (entity is not null)
-        {
-            Delete(entity);
-        }
+        await EfRepository.DeleteAsync(channel.Id);
     }
 
     private static EmailChannel MapToDomain(EmailChannelEntity e)
@@ -128,8 +115,8 @@ internal sealed class EmailChannelRepository : EfRepository<EmailChannelEntity>,
         return type switch
         {
             EmailChannelType.Smtp => JsonSerializer.Deserialize<SmtpChannelSettings>(json)
-                                 ?? throw new InvalidOperationException(
-                                     "Failed to deserialize SMTP EmailChannel settings."),
+                                     ?? throw new InvalidOperationException(
+                                         "Failed to deserialize SMTP EmailChannel settings."),
             _ => throw new InvalidOperationException($"Unknown or undefined email channel type: {type}")
         };
     }

HrynCo.NotificationService.DAL.EF/Repositories/EmailChannelUsageRepository.cs

@@ -5,7 +5,7 @@ using Microsoft.EntityFrameworkCore;
 
 namespace HrynCo.NotificationService.DAL.EF.Repositories;
 
-internal sealed class EmailChannelUsageRepository : EfRepository<EmailChannelUsageEntity>, IEmailChannelUsageRepository
+internal sealed class EmailChannelUsageRepository : NotificationBaseRepository<EmailChannelUsageEntity>, IEmailChannelUsageRepository
 {
     public EmailChannelUsageRepository(NotificationDbContext dbContext) : base(dbContext)
     {
@@ -13,7 +13,8 @@ internal sealed class EmailChannelUsageRepository : EfRepository<EmailChannelUsa
 
     public async Task<int> GetDailyCountAsync(Guid providerId, DateOnly date, CancellationToken ct = default)
     {
-        EmailChannelUsageEntity? entity = await DbSet
+        EmailChannelUsageEntity? entity = await EfRepository.Get()
+            .AsNoTracking()
             .FirstOrDefaultAsync(x => x.ProviderId == providerId && x.Date == date, ct);
 
         return entity?.SentCount ?? 0;
@@ -21,7 +22,7 @@ internal sealed class EmailChannelUsageRepository : EfRepository<EmailChannelUsa
 
     public async Task<int> GetMonthlyCountAsync(Guid providerId, int year, int month, CancellationToken ct = default)
     {
-        return await DbSet
+        return await EfRepository.Get()
             .Where(x => x.ProviderId == providerId
                         && x.Date.Year == year
                         && x.Date.Month == month)
@@ -30,15 +31,16 @@ internal sealed class EmailChannelUsageRepository : EfRepository<EmailChannelUsa
 
     public async Task IncrementUsageAsync(Guid providerId, DateOnly date, CancellationToken ct = default)
     {
-        EmailChannelUsageEntity? entity = await DbSet
+        EmailChannelUsageEntity? entity = await EfRepository.Get()
+            .AsNoTracking()
             .FirstOrDefaultAsync(x => x.ProviderId == providerId && x.Date == date, ct);
 
         if (entity is null)
-            await AddAsync(new EmailChannelUsageEntity { ProviderId = providerId, Date = date, SentCount = 1 }, ct);
+            await EfRepository.AddAsync(new EmailChannelUsageEntity { ProviderId = providerId, Date = date, SentCount = 1 });
         else
         {
             entity.SentCount++;
-            Update(entity);
+            await EfRepository.UpdateAsync(entity);
         }
     }
 }

HrynCo.NotificationService.DAL.EF/Repositories/EmailTemplateRepository.cs

@@ -6,21 +6,38 @@ using Microsoft.EntityFrameworkCore;
 
 namespace HrynCo.NotificationService.DAL.EF.Repositories;
 
-internal sealed class EmailTemplateRepository : EfRepository<EmailTemplateEntity>, IEmailTemplateRepository
+internal sealed class EmailTemplateRepository
+    : NotificationBaseRepository<EmailTemplateEntity>, IEmailTemplateRepository
 {
     public EmailTemplateRepository(NotificationDbContext dbContext) : base(dbContext)
     {
     }
 
-    public async Task<IReadOnlyList<EmailTemplate>> GetAllAsync(CancellationToken ct = default)
+    public async Task<IReadOnlyList<EmailTemplate>> GetAllAsync(string? serviceName = null, string? key = null, CancellationToken ct = default)
     {
-        List<EmailTemplateEntity> entities = await DbSet.ToListAsync(ct);
+        IQueryable<EmailTemplateEntity> query = EfRepository.Get();
+
+        if (!string.IsNullOrWhiteSpace(serviceName))
+        {
+            query = query.Where(x => x.ServiceName == serviceName);
+        }
+
+        if (!string.IsNullOrWhiteSpace(key))
+        {
+            query = query.Where(x => x.Key == key);
+        }
+
+        List<EmailTemplateEntity> entities = await query
+            .OrderBy(x => x.ServiceName).ThenBy(x => x.Key)
+            .AsNoTracking()
+            .ToListAsync(ct);
         return entities.Select(MapToDomain).ToList();
     }
 
     public async Task<IReadOnlyList<EmailTemplate>> GetByServiceAsync(string serviceName, CancellationToken ct = default)
     {
-        List<EmailTemplateEntity> entities = await DbSet
+        List<EmailTemplateEntity> entities = await EfRepository.Get()
+            .AsNoTracking()
             .Where(x => x.ServiceName == serviceName)
             .ToListAsync(ct);
 
@@ -29,28 +46,48 @@ internal sealed class EmailTemplateRepository : EfRepository<EmailTemplateEntity
 
     public async Task<EmailTemplate?> GetAsync(string serviceName, string key, string languageCode, CancellationToken ct = default)
     {
-        EmailTemplateEntity? entity = await DbSet.FirstOrDefaultAsync(
-            x => x.ServiceName == serviceName && x.Key == key && x.LanguageCode == languageCode, ct);
+        EmailTemplateEntity? entity = await EfRepository.Get()
+            .AsNoTracking()
+            .FirstOrDefaultAsync(
+                x => x.ServiceName == serviceName && x.Key == key && x.LanguageCode == languageCode, ct);
 
         return entity is null ? null : MapToDomain(entity);
     }
 
-    public Task AddAsync(EmailTemplate EmailTemplate, CancellationToken ct = default) =>
-        base.AddAsync(MapToEntity(EmailTemplate), ct);
-
-    public Task UpdateAsync(EmailTemplate EmailTemplate, CancellationToken ct = default)
+    public Task AddAsync(EmailTemplate EmailTemplate, CancellationToken ct = default)
     {
-        EmailTemplateEntity entity = MapToEntity(EmailTemplate);
-        entity.Updated = DateTimeOffset.UtcNow;
-        Update(entity);
-        return Task.CompletedTask;
+        return EfRepository.AddAsync(MapToEntity(EmailTemplate));
+    }
+
+    public async Task UpdateAsync(EmailTemplate EmailTemplate, CancellationToken ct = default)
+    {
+        EmailTemplateEntity? entity = await EfRepository.Get()
+            .FirstOrDefaultAsync(x => x.Id == EmailTemplate.Id, ct);
+
+        if (entity is null)
+        {
+            return;
+        }
+
+        entity.ServiceName = EmailTemplate.ServiceName;
+        entity.Key = EmailTemplate.Key;
+        entity.LanguageCode = EmailTemplate.LanguageCode;
+        entity.Subject = EmailTemplate.Subject;
+        entity.HtmlBody = EmailTemplate.HtmlBody;
+        entity.TextBody = EmailTemplate.TextBody;
+        entity.Variables = EmailTemplate.Variables
+            .Select(v => new EmailTemplateVariableData { Name = v.Name, Required = v.Required })
+            .ToList();
+
+        await EfRepository.SaveChangesAsync();
     }
 
     public async Task DeleteAsync(EmailTemplate EmailTemplate, CancellationToken ct = default)
     {
-        EmailTemplateEntity? entity = await DbSet.FindAsync([EmailTemplate.Id], ct);
+        EmailTemplateEntity? entity = await EfRepository.Get()
+            .FirstOrDefaultAsync(x => x.Id == EmailTemplate.Id, ct);
         if (entity is not null)
-            Delete(entity);
+            await EfRepository.DeleteAsync(entity);
     }
 
     private static EmailTemplate MapToDomain(EmailTemplateEntity e) => new()
@@ -80,4 +117,4 @@ internal sealed class EmailTemplateRepository : EfRepository<EmailTemplateEntity
         Created = t.Created,
         Updated = t.Updated
     };
-}
+}

HrynCo.NotificationService.DAL.EF/ServiceCollectionExtensions.cs

@@ -1,4 +1,4 @@
-using HrynCo.NotificationService.DAL.Abstract;
+using HrynCo.DAL.Abstract;
 using HrynCo.NotificationService.DAL.Abstract.Repositories;
 using HrynCo.NotificationService.DAL.EF.Core;
 using HrynCo.NotificationService.DAL.EF.Repositories;
@@ -16,10 +16,10 @@ public static class ServiceCollectionExtensions
         services.AddDbContext<NotificationDbContext>(options =>
             options.UseNpgsql(connectionString));
 
-        services.AddScoped<IUnitOfWork, UnitOfWork>();
         services.AddScoped<IEmailTemplateRepository, EmailTemplateRepository>();
         services.AddScoped<IEmailChannelRepository, EmailChannelRepository>();
         services.AddScoped<IEmailChannelUsageRepository, EmailChannelUsageRepository>();
+        services.AddScoped<IUnitOfWork, NotificationUnitOfWork>();
 
         return services;
     }

HrynCo.NotificationService.Migrator/DevelopmentDataSeeder.cs

@@ -0,0 +1,116 @@
+namespace HrynCo.NotificationService.Migrator;
+
+using HrynCo.NotificationService.DAL.Abstract.Providers;
+using HrynCo.NotificationService.DAL.Abstract.Repositories;
+using HrynCo.NotificationService.DAL.Abstract.Templates;
+using Microsoft.Extensions.Logging;
+
+internal sealed class DevelopmentDataSeeder
+{
+    internal const string DefaultServiceName = "TestService";
+    internal const string DefaultLanguageCode = "en";
+
+    private readonly IEmailChannelRepository _channels;
+    private readonly IEmailTemplateRepository _templates;
+    private readonly ILogger<DevelopmentDataSeeder> _logger;
+
+    public DevelopmentDataSeeder(
+        IEmailChannelRepository channels,
+        IEmailTemplateRepository templates,
+        ILogger<DevelopmentDataSeeder> logger)
+    {
+        _channels = channels;
+        _templates = templates;
+        _logger = logger;
+    }
+
+    public async Task SeedAsync(string serviceName, CancellationToken cancellationToken = default)
+    {
+        if (string.IsNullOrWhiteSpace(serviceName))
+            throw new InvalidOperationException("Development seed service name is not configured.");
+
+        await SeedMailpitChannelAsync(serviceName, cancellationToken);
+
+        foreach (EmailTemplate template in CreateTemplates(serviceName))
+        {
+            EmailTemplate? existing = await _templates.GetAsync(
+                template.ServiceName, template.Key, template.LanguageCode, cancellationToken);
+
+            if (existing is not null)
+            {
+                _logger.LogInformation(
+                    "Development email template already exists; leaving it unchanged [ServiceName={ServiceName}, Key={TemplateKey}, LanguageCode={LanguageCode}]",
+                    template.ServiceName, template.Key, template.LanguageCode);
+                continue;
+            }
+
+            await _templates.AddAsync(template, cancellationToken);
+            _logger.LogInformation(
+                "Created development email template [ServiceName={ServiceName}, Key={TemplateKey}, LanguageCode={LanguageCode}]",
+                template.ServiceName, template.Key, template.LanguageCode);
+        }
+    }
+
+    private async Task SeedMailpitChannelAsync(string serviceName, CancellationToken cancellationToken)
+    {
+        IReadOnlyList<EmailChannel> existingChannels = await _channels.GetByServiceAsync(
+            serviceName, cancellationToken);
+
+        if (existingChannels.Count > 0)
+        {
+            _logger.LogInformation(
+                "Development email channel already exists; leaving all channels unchanged [ServiceName={ServiceName}]",
+                serviceName);
+            return;
+        }
+
+        var channel = new EmailChannel
+        {
+            ServiceName = serviceName,
+            Priority = 1,
+            EmailChannelType = EmailChannelType.Smtp,
+            Settings = new SmtpChannelSettings
+            {
+                Host = "mailpit",
+                Port = 1025,
+                Username = string.Empty,
+                Password = string.Empty,
+                UseSsl = false,
+                FromEmail = "no-reply@local.hrynco.test",
+                FromName = "HrynCo Development"
+            },
+            WarnThresholdPercent = 90,
+            IsActive = true,
+            Created = DateTimeOffset.UtcNow
+        };
+
+        await _channels.AddAsync(channel, cancellationToken);
+        _logger.LogInformation(
+            "Created Mailpit development email channel [ServiceName={ServiceName}]",
+            serviceName);
+    }
+
+    private static IReadOnlyList<EmailTemplate> CreateTemplates(string serviceName)
+    {
+        DateTimeOffset created = DateTimeOffset.UtcNow;
+
+        return
+        [
+            new EmailTemplate
+            {
+                ServiceName = serviceName,
+                Key = "TestEmail",
+                LanguageCode = DefaultLanguageCode,
+                Subject = "Test notification",
+                HtmlBody = "<p>Hello {{RecipientName}},</p><p>{{Message}}</p>",
+                TextBody = "Hello {{RecipientName}}, {{Message}}",
+                Variables =
+                [
+                    new EmailTemplateVariable { Name = "RecipientName", Required = true },
+                    new EmailTemplateVariable { Name = "Message", Required = true }
+                ],
+                Created = created
+            }
+        ];
+    }
+}

HrynCo.NotificationService.Migrator/Program.cs

@@ -1,5 +1,7 @@
-using HrynCo.NotificationService.DAL.EF;
+using HrynCo.NotificationService.DAL.EF;
+using HrynCo.NotificationService.Migrator;
 using Microsoft.EntityFrameworkCore;
+using Microsoft.Extensions.Configuration;
 using Microsoft.Extensions.DependencyInjection;
 using Microsoft.Extensions.Hosting;
 using Serilog;
@@ -21,8 +23,8 @@ try
             var connectionString = ctx.Configuration["App:ConnectionString"]
                 ?? throw new InvalidOperationException("App:ConnectionString is not configured.");
 
-            services.AddDbContext<NotificationDbContext>(options =>
-                options.UseNpgsql(connectionString));
+            services.AddNotificationDataAccess(connectionString);
+            services.AddScoped<DevelopmentDataSeeder>();
         })
         .Build();
 
@@ -32,6 +34,18 @@ try
     Log.Information("Applying migrations...");
     await db.Database.MigrateAsync();
     Log.Information("Migrations applied successfully.");
+
+    var environment = scope.ServiceProvider.GetRequiredService<IHostEnvironment>();
+    if (environment.IsDevelopment())
+    {
+        string serviceName = host.Services.GetRequiredService<IConfiguration>()["DevelopmentSeed:ServiceName"]
+                             ?? DevelopmentDataSeeder.DefaultServiceName;
+
+        Log.Information("Seeding development email configuration...");
+        var seeder = scope.ServiceProvider.GetRequiredService<DevelopmentDataSeeder>();
+        await seeder.SeedAsync(serviceName);
+        Log.Information("Development email configuration is ready.");
+    }
 }
 catch (Exception ex)
 {

HrynCo.NotificationService.Migrator/Properties/AssemblyInfo.cs

@@ -0,0 +1,3 @@
+using System.Runtime.CompilerServices;
+
+[assembly: InternalsVisibleTo("HrynCo.NotificationService.Services.Tests")]

HrynCo.NotificationService.Services.Tests/DevelopmentDataSeederTests.cs

@@ -0,0 +1,83 @@
+namespace HrynCo.NotificationService.Services.Tests;
+
+using HrynCo.NotificationService.DAL.Abstract.Providers;
+using HrynCo.NotificationService.DAL.Abstract.Repositories;
+using HrynCo.NotificationService.DAL.Abstract.Templates;
+using HrynCo.NotificationService.Migrator;
+using Microsoft.Extensions.Logging.Abstractions;
+using NSubstitute;
+
+public sealed class DevelopmentDataSeederTests
+{
+    private readonly IEmailChannelRepository _channels = Substitute.For<IEmailChannelRepository>();
+    private readonly IEmailTemplateRepository _templates = Substitute.For<IEmailTemplateRepository>();
+
+    [Fact]
+    public async Task SeedAsync_WhenConfigurationIsMissing_CreatesMailpitChannelAndTestTemplate()
+    {
+        _channels.GetByServiceAsync("TestService", Arg.Any<CancellationToken>())
+            .Returns(Array.Empty<EmailChannel>());
+        _templates.GetAsync("TestService", "TestEmail", "en", Arg.Any<CancellationToken>())
+            .Returns((EmailTemplate?)null);
+
+        DevelopmentDataSeeder seeder = CreateSeeder();
+
+        await seeder.SeedAsync("TestService", CancellationToken.None);
+
+        await _channels.Received(1).AddAsync(
+            Arg.Is<EmailChannel>(channel => IsMailpitChannel(channel)),
+            Arg.Any<CancellationToken>());
+        await _templates.Received(1).AddAsync(
+            Arg.Is<EmailTemplate>(template =>
+                template.ServiceName == "TestService" &&
+                template.Key == "TestEmail" &&
+                template.Variables.Any(variable => variable.Name == "Message" && variable.Required)),
+            Arg.Any<CancellationToken>());
+    }
+
+    [Fact]
+    public async Task SeedAsync_WhenConfigurationExists_DoesNotDuplicateOrOverwriteIt()
+    {
+        _channels.GetByServiceAsync("TestService", Arg.Any<CancellationToken>())
+            .Returns([new EmailChannel
+            {
+                ServiceName = "TestService",
+                EmailChannelType = EmailChannelType.Smtp,
+                Settings = new SmtpChannelSettings()
+            }]);
+        _templates.GetAsync("TestService", "TestEmail", "en", Arg.Any<CancellationToken>())
+            .Returns(new EmailTemplate
+            {
+                ServiceName = "TestService",
+                Key = "TestEmail",
+                LanguageCode = "en",
+                Subject = "Existing",
+                HtmlBody = "Existing",
+                TextBody = "Existing"
+            });
+
+        DevelopmentDataSeeder seeder = CreateSeeder();
+
+        await seeder.SeedAsync("TestService", CancellationToken.None);
+
+        await _channels.DidNotReceive().AddAsync(Arg.Any<EmailChannel>(), Arg.Any<CancellationToken>());
+        await _templates.DidNotReceive().AddAsync(Arg.Any<EmailTemplate>(), Arg.Any<CancellationToken>());
+        await _channels.DidNotReceive().UpdateAsync(Arg.Any<EmailChannel>(), Arg.Any<CancellationToken>());
+        await _templates.DidNotReceive().UpdateAsync(Arg.Any<EmailTemplate>(), Arg.Any<CancellationToken>());
+    }
+
+    private DevelopmentDataSeeder CreateSeeder() => new(
+        _channels,
+        _templates,
+        NullLogger<DevelopmentDataSeeder>.Instance);
+
+    private static bool IsMailpitChannel(EmailChannel channel)
+    {
+        return channel.ServiceName == "TestService" &&
+               channel.IsActive &&
+               channel.Settings is SmtpChannelSettings smtp &&
+               smtp.Host == "mailpit" &&
+               smtp.Port == 1025 &&
+               !smtp.UseSsl;
+    }
+}

HrynCo.NotificationService.Services.Tests/EmailProcessing/EmailTemplateRenderingServiceTests.cs

@@ -0,0 +1,88 @@
+namespace HrynCo.NotificationService.Services.Tests.EmailProcessing;
+
+using HrynCo.NotificationService.Contracts.Messages;
+using HrynCo.NotificationService.DAL.Abstract.Templates;
+using HrynCo.NotificationService.Worker.Services.EmailProcessing;
+
+public sealed class EmailTemplateRenderingServiceTests
+{
+    private readonly EmailTemplateRenderingService _service = new();
+
+    [Fact]
+    public void Render_InterpolatesItemTrackerVariables()
+    {
+        EmailTemplate template = CreateTemplate();
+        SendEmailMessageData data = CreateData(new Dictionary<string, string>
+        {
+            ["AppName"] = "StoreMate",
+            ["VerificationUrl"] = "https://example.invalid/verify"
+        });
+
+        RenderedEmail result = _service.Render(template, data);
+
+        Assert.Equal("Verify StoreMate", result.Subject);
+        Assert.Equal("<a href=\"https://example.invalid/verify\">Verify</a>", result.HtmlBody);
+        Assert.Equal("Verify at https://example.invalid/verify", result.TextBody);
+    }
+
+    [Fact]
+    public void Render_WhenRequiredVariableIsMissing_ThrowsObservableFailure()
+    {
+        EmailTemplate template = CreateTemplate();
+        SendEmailMessageData data = CreateData(new Dictionary<string, string>
+        {
+            ["AppName"] = "StoreMate"
+        });
+
+        InvalidDataException exception = Assert.Throws<InvalidDataException>(
+            () => _service.Render(template, data));
+
+        Assert.Equal("Required template variables are missing: VerificationUrl.", exception.Message);
+    }
+
+    [Fact]
+    public void Render_HtmlEncodesVariablesWithoutChangingSubjectOrTextBody()
+    {
+        EmailTemplate template = CreateTemplate();
+        SendEmailMessageData data = CreateData(new Dictionary<string, string>
+        {
+            ["AppName"] = "Invemory <script>alert('xss')</script>",
+            ["VerificationUrl"] = "https://example.invalid/verify?next=\" onclick=\"alert('xss')"
+        });
+
+        RenderedEmail result = _service.Render(template, data);
+
+        Assert.Equal("Verify Invemory <script>alert('xss')</script>", result.Subject);
+        Assert.Equal(
+            "<a href=\"https://example.invalid/verify?next=&quot; onclick=&quot;alert(&#39;xss&#39;)\">Verify</a>",
+            result.HtmlBody);
+        Assert.Equal(
+            "Verify at https://example.invalid/verify?next=\" onclick=\"alert('xss')",
+            result.TextBody);
+    }
+
+    private static EmailTemplate CreateTemplate() => new()
+    {
+        ServiceName = "StoreMate-Prod",
+        Key = "EmailVerification",
+        LanguageCode = "uk",
+        Subject = "Verify {{AppName}}",
+        HtmlBody = "<a href=\"{{VerificationUrl}}\">Verify</a>",
+        TextBody = "Verify at {{VerificationUrl}}",
+        Variables =
+        [
+            new EmailTemplateVariable { Name = "AppName", Required = true },
+            new EmailTemplateVariable { Name = "VerificationUrl", Required = true }
+        ]
+    };
+
+    private static SendEmailMessageData CreateData(IReadOnlyDictionary<string, string> variables) => new()
+    {
+        ServiceName = "StoreMate-Prod",
+        TemplateKey = "EmailVerification",
+        RecipientEmail = "owner@example.com",
+        RecipientName = "Owner",
+        LanguageCode = "uk",
+        Variables = variables
+    };
+}

HrynCo.NotificationService.Services.Tests/EmailProcessing/EmailTemplateServiceTests.cs

@@ -0,0 +1,30 @@
+namespace HrynCo.NotificationService.Services.Tests.EmailProcessing;
+
+using HrynCo.NotificationService.DAL.Abstract.Repositories;
+using HrynCo.NotificationService.Worker.Services.EmailProcessing;
+using NSubstitute;
+
+public sealed class EmailTemplateServiceTests
+{
+    [Fact]
+    public async Task GetAsync_WhenRequestedLanguageDoesNotExist_DoesNotSilentlyFallback()
+    {
+        IEmailTemplateRepository repository = Substitute.For<IEmailTemplateRepository>();
+        var service = new EmailTemplateService(repository);
+
+        InvalidOperationException exception = await Assert.ThrowsAsync<InvalidOperationException>(
+            () => service.GetAsync("StoreMate-Prod", "EmailVerification", "UK", CancellationToken.None));
+
+        Assert.Contains("language='uk'", exception.Message);
+        await repository.Received(1).GetAsync(
+            "StoreMate-Prod",
+            "EmailVerification",
+            "uk",
+            CancellationToken.None);
+        await repository.DidNotReceive().GetAsync(
+            "StoreMate-Prod",
+            "EmailVerification",
+            "en",
+            Arg.Any<CancellationToken>());
+    }
+}

HrynCo.NotificationService.Services.Tests/EmailProcessing/NotificationDeliveryErrorFormatterTests.cs

@@ -0,0 +1,58 @@
+namespace HrynCo.NotificationService.Services.Tests.EmailProcessing;
+
+using HrynCo.NotificationService.Worker.Services.EmailProcessing;
+using System.Net.Mail;
+using System.Net.Sockets;
+
+public sealed class NotificationDeliveryErrorFormatterTests
+{
+    [Fact]
+    public void Format_UsesInnermostMessageAndRemovesLineBreaks()
+    {
+        var exception = new InvalidOperationException(
+            "outer",
+            new Exception("provider failed\r\nretry rejected"));
+
+        string result = NotificationDeliveryErrorFormatter.Format(exception);
+
+        Assert.Equal(
+            "Notification delivery failed after all retry attempts (provider failed retry rejected).",
+            result);
+    }
+
+    [Fact]
+    public void Format_UnresolvedSmtpHost_AddsSafeChannelContext()
+    {
+        var socketException = new SocketException((int)SocketError.HostNotFound);
+        var exception = new SmtpException("Failure sending mail.", socketException);
+
+        string result = NotificationDeliveryErrorFormatter.Format(exception);
+
+        Assert.Equal(
+            $"SMTP delivery failed after all retry attempts: the configured SMTP server host could not be resolved ({socketException.Message}).",
+            result);
+    }
+
+    [Fact]
+    public void Format_RefusedSmtpConnection_AddsSafeChannelContext()
+    {
+        var socketException = new SocketException((int)SocketError.ConnectionRefused);
+        var exception = new SmtpException("Failure sending mail.", socketException);
+
+        string result = NotificationDeliveryErrorFormatter.Format(exception);
+
+        Assert.Equal(
+            $"SMTP delivery failed after all retry attempts: the configured SMTP server refused the connection ({socketException.Message}).",
+            result);
+    }
+
+    [Fact]
+    public void Format_LongError_IsBoundedToOutboxColumnLength()
+    {
+        var exception = new Exception(new string('x', 2100));
+
+        string result = NotificationDeliveryErrorFormatter.Format(exception);
+
+        Assert.Equal(2000, result.Length);
+    }
+}

HrynCo.NotificationService.Services.Tests/EmailProcessing/NotificationResultPublisherTests.cs

@@ -0,0 +1,107 @@
+namespace HrynCo.NotificationService.Services.Tests.EmailProcessing;
+
+using HrynCo.NotificationService.Contracts.Messages;
+using HrynCo.NotificationService.Worker.Services.EmailProcessing;
+using Hrynco.RabbitMq;
+using Microsoft.Extensions.Logging.Abstractions;
+using NSubstitute;
+
+public sealed class NotificationResultPublisherTests
+{
+    [Fact]
+    public async Task PublishAsync_TerminalFailure_PublishesNeutralFailureResultToReplyQueue()
+    {
+        IRabbitMqPublisher rabbitMqPublisher = Substitute.For<IRabbitMqPublisher>();
+        var publisher = new NotificationResultPublisher(
+            rabbitMqPublisher,
+            NullLogger<NotificationResultPublisher>.Instance);
+        SendEmailMessage message = CreateMessage();
+        NotificationResultMessage? publishedResult = null;
+        rabbitMqPublisher
+            .When(x => x.PublishAsync(
+                "item-tracker.notifications.result",
+                Arg.Any<NotificationResultMessage>(),
+                Arg.Any<CancellationToken>()))
+            .Do(call => publishedResult = call.ArgAt<NotificationResultMessage>(1));
+
+        await publisher.PublishAsync(
+            message,
+            "Email provider could not deliver the notification.",
+            CancellationToken.None);
+
+        await rabbitMqPublisher.Received(1).PublishAsync(
+            "item-tracker.notifications.result",
+            Arg.Any<NotificationResultMessage>(),
+            CancellationToken.None);
+        Assert.NotNull(publishedResult);
+        Assert.Equal(message.CorrelationContext.CorrelationId, publishedResult.CorrelationContext.CorrelationId);
+        Assert.Null(publishedResult.CorrelationContext.ReplyTo);
+        Assert.Equal(message.Data.ServiceName, publishedResult.Data.ServiceName);
+        Assert.Equal(message.Data.TemplateKey, publishedResult.Data.TemplateKey);
+        Assert.Equal(message.Data.RecipientEmail, publishedResult.Data.RecipientEmail);
+        Assert.Equal("Email provider could not deliver the notification.", publishedResult.Data.ErrorMessage);
+        Assert.False(publishedResult.Data.IsSuccess);
+    }
+
+    [Fact]
+    public async Task PublishAsync_NoReplyQueue_DoesNotPublish()
+    {
+        IRabbitMqPublisher rabbitMqPublisher = Substitute.For<IRabbitMqPublisher>();
+        var publisher = new NotificationResultPublisher(
+            rabbitMqPublisher,
+            NullLogger<NotificationResultPublisher>.Instance);
+        SendEmailMessage message = CreateMessage();
+        message.CorrelationContext = message.CorrelationContext with { ReplyTo = null };
+
+        await publisher.PublishAsync(message, "delivery failed", CancellationToken.None);
+
+        await rabbitMqPublisher.DidNotReceive()
+            .PublishAsync<NotificationResultData>(
+                Arg.Any<string>(),
+                Arg.Any<NotificationResultMessage>(),
+                Arg.Any<CancellationToken>());
+    }
+
+    [Fact]
+    public async Task PublishAsync_ResultBrokerFailure_IsBestEffort()
+    {
+        IRabbitMqPublisher rabbitMqPublisher = Substitute.For<IRabbitMqPublisher>();
+        rabbitMqPublisher
+            .PublishAsync(
+                Arg.Any<string>(),
+                Arg.Any<NotificationResultMessage>(),
+                Arg.Any<CancellationToken>())
+            .Returns<Task>(_ => throw new InvalidOperationException("reply broker unavailable"));
+        var publisher = new NotificationResultPublisher(
+            rabbitMqPublisher,
+            NullLogger<NotificationResultPublisher>.Instance);
+
+        Exception? exception = await Record.ExceptionAsync(() => publisher.PublishAsync(
+            CreateMessage(),
+            "delivery failed",
+            CancellationToken.None));
+
+        Assert.Null(exception);
+    }
+
+    private static SendEmailMessage CreateMessage()
+    {
+        return new SendEmailMessage
+        {
+            CorrelationContext = new CorrelationContext
+            {
+                CorrelationId = "correlation-id",
+                ReplyTo = "item-tracker.notifications.result"
+            },
+            Data = new SendEmailMessageData
+            {
+                ServiceName = "TestService",
+                TemplateKey = "TestEmail",
+                RecipientEmail = "test.user@itemtracker.local",
+                RecipientName = "Test User",
+                LanguageCode = "en",
+                Variables = new Dictionary<string, string>()
+            }
+        };
+    }
+}

HrynCo.NotificationService.Services.Tests/EmailProcessing/RecipientAddressRedactorTests.cs

@@ -0,0 +1,16 @@
+namespace HrynCo.NotificationService.Services.Tests.EmailProcessing;
+
+using HrynCo.NotificationService.Worker.Services.EmailProcessing;
+
+public sealed class RecipientAddressRedactorTests
+{
+    [Theory]
+    [InlineData("owner@example.com", "o***@e***.com")]
+    [InlineData("a@b.test", "a***@b***.test")]
+    [InlineData("invalid", "***")]
+    [InlineData(null, "<missing>")]
+    public void Redact_DoesNotExposeFullAddress(string? address, string expected)
+    {
+        Assert.Equal(expected, RecipientAddressRedactor.Redact(address));
+    }
+}

HrynCo.NotificationService.Services.Tests/EmailProcessing/SendEmailContractTests.cs

@@ -0,0 +1,60 @@
+namespace HrynCo.NotificationService.Services.Tests.EmailProcessing;
+
+using System.Text.Json;
+using HrynCo.NotificationService.Contracts.Messages;
+using HrynCo.NotificationService.Worker.Services.EmailProcessing;
+
+public sealed class SendEmailContractTests
+{
+    private const string ItemTrackerPayload = """
+        {
+          "CorrelationContext": {
+            "CorrelationId": "3ec4ad3f-0a8a-49f3-b31d-cdad5d1b95cc",
+            "ReplyTo": "item-tracker.notifications.result"
+          },
+          "Data": {
+            "ServiceName": "StoreMate-Prod",
+            "TemplateKey": "EmailVerification",
+            "RecipientEmail": "owner@example.com",
+            "RecipientName": "StoreMate Owner",
+            "Variables": {
+              "AppName": "StoreMate",
+              "VerificationUrl": "https://example.invalid/sensitive-token"
+            },
+            "LanguageCode": "uk"
+          }
+        }
+        """;
+
+    [Fact]
+    public void PascalCaseItemTrackerPayload_DeserializesWithoutLosingValues()
+    {
+        SendEmailMessage? message = JsonSerializer.Deserialize<SendEmailMessage>(ItemTrackerPayload);
+
+        Assert.NotNull(message);
+        SendEmailMessageValidator.Validate(message);
+        Assert.Equal("3ec4ad3f-0a8a-49f3-b31d-cdad5d1b95cc", message.CorrelationContext.CorrelationId);
+        Assert.Equal("item-tracker.notifications.result", message.CorrelationContext.ReplyTo);
+        Assert.Equal("StoreMate-Prod", message.Data.ServiceName);
+        Assert.Equal("EmailVerification", message.Data.TemplateKey);
+        Assert.Equal("owner@example.com", message.Data.RecipientEmail);
+        Assert.Equal("StoreMate Owner", message.Data.RecipientName);
+        Assert.Equal("uk", message.Data.LanguageCode);
+        Assert.Equal("StoreMate", message.Data.Variables["AppName"]);
+        Assert.Equal(
+            "https://example.invalid/sensitive-token",
+            message.Data.Variables["VerificationUrl"]);
+    }
+
+    [Fact]
+    public void MissingLanguageCode_IsRejected()
+    {
+        SendEmailMessage? message = JsonSerializer.Deserialize<SendEmailMessage>(
+            ItemTrackerPayload.Replace("\"uk\"", "null", StringComparison.Ordinal));
+
+        InvalidDataException exception = Assert.Throws<InvalidDataException>(
+            () => SendEmailMessageValidator.Validate(message!));
+
+        Assert.Equal("LanguageCode is required.", exception.Message);
+    }
+}

HrynCo.NotificationService.Services.Tests/EmailProcessing/SendEmailDeliveryValidatorTests.cs

@@ -0,0 +1,77 @@
+namespace HrynCo.NotificationService.Services.Tests.EmailProcessing;
+
+using HrynCo.NotificationService.Contracts.Messages;
+using HrynCo.NotificationService.Worker;
+using Hrynco.RabbitMq;
+
+public sealed class SendEmailDeliveryValidatorTests
+{
+    [Fact]
+    public void ValidItemTrackerDelivery_IsAccepted()
+    {
+        string? error = SendEmailDeliveryValidator.GetValidationError(
+            CreateMessage(),
+            CreateContext(),
+            SendEmailConsumer.SupportedMessageType);
+
+        Assert.Null(error);
+    }
+
+    [Fact]
+    public void MissingMessageId_IsRejected()
+    {
+        RabbitMqMessageContext context = CreateContext() with { MessageId = null };
+
+        string? error = SendEmailDeliveryValidator.GetValidationError(
+            CreateMessage(),
+            context,
+            SendEmailConsumer.SupportedMessageType);
+
+        Assert.Equal("AMQP MessageId is required.", error);
+    }
+
+    [Fact]
+    public void UnsupportedContractVersion_IsRejected()
+    {
+        RabbitMqMessageContext context = CreateContext() with
+        {
+            MessageType = "Notification.SendEmail.v2"
+        };
+
+        string? error = SendEmailDeliveryValidator.GetValidationError(
+            CreateMessage(),
+            context,
+            SendEmailConsumer.SupportedMessageType);
+
+        Assert.Equal("Unsupported AMQP message type 'Notification.SendEmail.v2'.", error);
+    }
+
+    private static RabbitMqMessageContext CreateContext() => new()
+    {
+        QueueName = SendEmailConsumer.IncomingQueue,
+        Exchange = string.Empty,
+        RoutingKey = SendEmailConsumer.IncomingQueue,
+        MessageId = Guid.NewGuid().ToString("D"),
+        MessageType = SendEmailConsumer.SupportedMessageType,
+        CorrelationId = "correlation-id",
+        ContentType = "application/json"
+    };
+
+    private static SendEmailMessage CreateMessage() => new()
+    {
+        CorrelationContext = new CorrelationContext
+        {
+            CorrelationId = "correlation-id",
+            ReplyTo = "item-tracker.notifications.result"
+        },
+        Data = new SendEmailMessageData
+        {
+            ServiceName = "StoreMate-Prod",
+            TemplateKey = "EmailVerification",
+            RecipientEmail = "owner@example.com",
+            RecipientName = "Owner",
+            LanguageCode = "uk",
+            Variables = new Dictionary<string, string> { ["AppName"] = "StoreMate" }
+        }
+    };
+}

HrynCo.NotificationService.Services.Tests/EmailProcessing/SendEmailServiceTests.cs

@@ -0,0 +1,123 @@
+namespace HrynCo.NotificationService.Services.Tests.EmailProcessing;
+
+using HrynCo.NotificationService.Contracts.Messages;
+using HrynCo.NotificationService.DAL.Abstract.Providers;
+using HrynCo.NotificationService.DAL.Abstract.Repositories;
+using HrynCo.NotificationService.DAL.Abstract.Templates;
+using HrynCo.NotificationService.Worker.Services.EmailProcessing;
+using Hrynco.RabbitMq;
+using Microsoft.Extensions.Logging.Abstractions;
+using NSubstitute;
+
+public sealed class SendEmailServiceTests
+{
+    [Fact]
+    public async Task ProcessAsync_ValidItemTrackerMessage_SendsOnceAndUpdatesUsage()
+    {
+        Guid channelId = Guid.NewGuid();
+        var settings = new SmtpChannelSettings
+        {
+            Host = "smtp.example.invalid",
+            Port = 587,
+            Username = "smtp-user",
+            Password = "not-a-real-secret",
+            UseSsl = true,
+            FromEmail = "notifications@example.com",
+            FromName = "StoreMate"
+        };
+        var channel = new EmailChannel
+        {
+            Id = channelId,
+            ServiceName = "StoreMate-Prod",
+            Priority = 1,
+            EmailChannelType = EmailChannelType.Smtp,
+            Settings = settings,
+            IsActive = true
+        };
+        var template = new EmailTemplate
+        {
+            ServiceName = "StoreMate-Prod",
+            Key = "EmailVerification",
+            LanguageCode = "uk",
+            Subject = "Verify {{AppName}}",
+            HtmlBody = "<p>{{AppName}}</p>",
+            TextBody = "{{AppName}}",
+            Variables = [new EmailTemplateVariable { Name = "AppName", Required = true }]
+        };
+
+        IEmailChannelRepository channels = Substitute.For<IEmailChannelRepository>();
+        channels.GetByServiceAsync("StoreMate-Prod", Arg.Any<CancellationToken>())
+            .Returns([channel]);
+        IEmailChannelUsageRepository usage = Substitute.For<IEmailChannelUsageRepository>();
+        IEmailTemplateService templates = Substitute.For<IEmailTemplateService>();
+        templates.GetAsync("StoreMate-Prod", "EmailVerification", "uk", Arg.Any<CancellationToken>())
+            .Returns(template);
+        var renderer = new EmailTemplateRenderingService();
+        var smtp = new RecordingSmtpEmailSender();
+        INotificationResultPublisher resultPublisher = Substitute.For<INotificationResultPublisher>();
+        var service = new SendEmailService(
+            channels,
+            usage,
+            templates,
+            renderer,
+            smtp,
+            resultPublisher,
+            NullLogger<SendEmailService>.Instance);
+        var message = new SendEmailMessage
+        {
+            CorrelationContext = new CorrelationContext
+            {
+                CorrelationId = Guid.NewGuid().ToString("D")
+            },
+            Data = new SendEmailMessageData
+            {
+                ServiceName = "StoreMate-Prod",
+                TemplateKey = "EmailVerification",
+                RecipientEmail = "owner@example.com",
+                RecipientName = "Owner",
+                LanguageCode = "uk",
+                Variables = new Dictionary<string, string> { ["AppName"] = "StoreMate" }
+            }
+        };
+
+        await service.ProcessAsync(message, CancellationToken.None);
+
+        Assert.Equal(1, smtp.SendCount);
+        Assert.Same(settings, smtp.Settings);
+        Assert.Equal("Verify StoreMate", smtp.Email?.Subject);
+        Assert.Equal("owner@example.com", smtp.RecipientEmail);
+        Assert.Equal("Owner", smtp.RecipientName);
+        await usage.Received(1).IncrementUsageAsync(
+            channelId,
+            Arg.Any<DateOnly>(),
+            CancellationToken.None);
+        await resultPublisher.Received(1).PublishAsync(
+            message,
+            null,
+            CancellationToken.None);
+    }
+
+    private sealed class RecordingSmtpEmailSender : ISmtpEmailSender
+    {
+        public int SendCount { get; private set; }
+        public SmtpChannelSettings? Settings { get; private set; }
+        public RenderedEmail? Email { get; private set; }
+        public string? RecipientEmail { get; private set; }
+        public string? RecipientName { get; private set; }
+
+        public Task SendAsync(
+            SmtpChannelSettings settings,
+            RenderedEmail email,
+            string recipientEmail,
+            string recipientName,
+            CancellationToken cancellationToken)
+        {
+            SendCount++;
+            Settings = settings;
+            Email = email;
+            RecipientEmail = recipientEmail;
+            RecipientName = recipientName;
+            return Task.CompletedTask;
+        }
+    }
+}

HrynCo.NotificationService.Services.Tests/HrynCo.NotificationService.Services.Tests.csproj

@@ -10,6 +10,7 @@
   <ItemGroup>
     <PackageReference Include="coverlet.collector" />
     <PackageReference Include="Microsoft.NET.Test.Sdk" />
+    <PackageReference Include="NSubstitute" />
     <PackageReference Include="xunit" />
     <PackageReference Include="xunit.runner.visualstudio" />
   </ItemGroup>
@@ -21,6 +22,10 @@
   <ItemGroup>
     <ProjectReference Include="..\HrynCo.NotificationService.Services\HrynCo.NotificationService.Services.csproj" />
     <ProjectReference Include="..\HrynCo.NotificationService.DAL.Abstract\HrynCo.NotificationService.DAL.Abstract.csproj" />
+    <ProjectReference Include="..\HrynCo.NotificationService.Contracts\HrynCo.NotificationService.Contracts.csproj" />
+    <ProjectReference Include="..\HrynCo.NotificationService.Worker.Services\HrynCo.NotificationService.Worker.Services.csproj" />
+    <ProjectReference Include="..\HrynCo.NotificationService.Worker\HrynCo.NotificationService.Worker.csproj" />
+    <ProjectReference Include="..\HrynCo.NotificationService.Migrator\HrynCo.NotificationService.Migrator.csproj" />
   </ItemGroup>
 
-</Project>
+</Project>

HrynCo.NotificationService.Services.Tests/UnitTest1.cs

@@ -1,10 +0,0 @@
-namespace HrynCo.NotificationService.Services.Tests;
-
-public class UnitTest1
-{
-    [Fact]
-    public void Test1()
-    {
-
-    }
-}

HrynCo.NotificationService.Services/Behaviors/TransactionBehavior.cs

@@ -1,5 +1,5 @@
 using HrynCo.Common;
-using HrynCo.NotificationService.DAL.Abstract;
+using HrynCo.DAL.Abstract;
 using MediatR;
 
 namespace HrynCo.NotificationService.Services.Behaviors;
@@ -18,11 +18,15 @@ public class TransactionBehavior<TRequest, TResponse> : IPipelineBehavior<TReque
 
     public Task<TResponse> Handle(TRequest request, RequestHandlerDelegate<TResponse> next, CancellationToken cancellationToken) =>
         _profiler.MeasureExecutionAsync(
-            () => _unitOfWork.ExecuteInTransactionAsync(async () =>
+            async () =>
             {
-                TResponse response = await next();
-                await _unitOfWork.SaveChangesAsync(cancellationToken);
-                return response;
-            }),
+                TResponse? response = default;
+                await _unitOfWork.ExecuteInTransactionAsync(async () =>
+                {
+                    response = await next();
+                });
+
+                return response!;
+            },
             typeof(TRequest).Name);
-}
+}

HrynCo.NotificationService.Services/Core/RequestHandler.cs

@@ -1,4 +1,3 @@
-using HrynCo.NotificationService.DAL.Abstract;
 using HrynCo.NotificationService.Services.Logging;
 using MediatR;
 using Serilog;
@@ -8,14 +7,12 @@ namespace HrynCo.NotificationService.Services.Core;
 public abstract class RequestHandler<TRequest, TResponse> : IRequestHandler<TRequest, TResponse>
     where TRequest : IRequest<TResponse>
 {
-    protected RequestHandler(IContextualSerilogLogger<TRequest> logger, IUnitOfWork unitOfWork)
+    protected RequestHandler(IContextualSerilogLogger<TRequest> logger)
     {
         Logger = logger.Logger;
-        UnitOfWork = unitOfWork;
     }
 
     protected ILogger Logger { get; }
-    protected IUnitOfWork UnitOfWork { get; }
 
     public Task<TResponse> Handle(TRequest request, CancellationToken cancellationToken)
     {
@@ -23,4 +20,4 @@ public abstract class RequestHandler<TRequest, TResponse> : IRequestHandler<TReq
     }
 
     protected abstract Task<TResponse> DoOnHandle(TRequest request, CancellationToken cancellationToken);
-}
+}

HrynCo.NotificationService.Services/EmailChannels/Create/CreateEmailChannelHandler.cs

@@ -1,4 +1,4 @@
-using HrynCo.NotificationService.DAL.Abstract;
+using HrynCo.DAL.Abstract;
 using HrynCo.NotificationService.DAL.Abstract.Providers;
 using HrynCo.NotificationService.DAL.Abstract.Repositories;
 using HrynCo.NotificationService.Services.Core;
@@ -14,9 +14,8 @@ internal sealed class CreateEmailChannelHandler
 
     public CreateEmailChannelHandler(
         IContextualSerilogLogger<CreateEmailChannelCommand> logger,
-        IUnitOfWork unitOfWork,
         IEmailChannelRepository channels)
-        : base(logger, unitOfWork)
+        : base(logger)
     {
         _channels = channels;
     }

HrynCo.NotificationService.Services/EmailChannels/Delete/DeleteEmailChannelHandler.cs

@@ -1,4 +1,4 @@
-using HrynCo.NotificationService.DAL.Abstract;
+using HrynCo.DAL.Abstract;
 using HrynCo.NotificationService.DAL.Abstract.Repositories;
 using HrynCo.NotificationService.Services.Core;
 using HrynCo.NotificationService.Services.Logging;
@@ -13,9 +13,8 @@ internal sealed class DeleteEmailChannelHandler
 
     public DeleteEmailChannelHandler(
         IContextualSerilogLogger<DeleteEmailChannelCommand> logger,
-        IUnitOfWork unitOfWork,
         IEmailChannelRepository channels)
-        : base(logger, unitOfWork)
+        : base(logger)
     {
         _channels = channels;
     }

HrynCo.NotificationService.Services/EmailChannels/Get/GetEmailChannelHandler.cs

@@ -1,4 +1,3 @@
-using HrynCo.NotificationService.DAL.Abstract;
 using HrynCo.NotificationService.DAL.Abstract.Providers;
 using HrynCo.NotificationService.DAL.Abstract.Repositories;
 using HrynCo.NotificationService.Services.Core;
@@ -14,9 +13,8 @@ internal sealed class GetEmailChannelHandler
 
     public GetEmailChannelHandler(
         IContextualSerilogLogger<GetEmailChannelQuery> logger,
-        IUnitOfWork unitOfWork,
         IEmailChannelRepository channels)
-        : base(logger, unitOfWork)
+        : base(logger)
     {
         _channels = channels;
     }

HrynCo.NotificationService.Services/EmailChannels/GetAll/GetAllEmailChannelsHandler.cs

@@ -1,4 +1,3 @@
-using HrynCo.NotificationService.DAL.Abstract;
 using HrynCo.NotificationService.DAL.Abstract.Providers;
 using HrynCo.NotificationService.DAL.Abstract.Repositories;
 using HrynCo.NotificationService.Services.Core;
@@ -14,9 +13,8 @@ internal sealed class GetAllEmailChannelsHandler
 
     public GetAllEmailChannelsHandler(
         IContextualSerilogLogger<GetAllEmailChannelsQuery> logger,
-        IUnitOfWork unitOfWork,
         IEmailChannelRepository channels)
-        : base(logger, unitOfWork)
+        : base(logger)
     {
         _channels = channels;
     }

HrynCo.NotificationService.Services/EmailChannels/GetByService/GetEmailChannelsHandler.cs

@@ -1,4 +1,3 @@
-using HrynCo.NotificationService.DAL.Abstract;
 using HrynCo.NotificationService.DAL.Abstract.Providers;
 using HrynCo.NotificationService.DAL.Abstract.Repositories;
 using HrynCo.NotificationService.Services.Core;
@@ -14,9 +13,8 @@ internal sealed class GetEmailChannelsHandler
 
     public GetEmailChannelsHandler(
         IContextualSerilogLogger<GetEmailChannelsQuery> logger,
-        IUnitOfWork unitOfWork,
         IEmailChannelRepository channels)
-        : base(logger, unitOfWork)
+        : base(logger)
     {
         _channels = channels;
     }

HrynCo.NotificationService.Services/EmailChannels/GetUsageSummary/GetChannelUsageSummaryHandler.cs

@@ -1,4 +1,3 @@
-using HrynCo.NotificationService.DAL.Abstract;
 using HrynCo.NotificationService.DAL.Abstract.Repositories;
 using HrynCo.NotificationService.Services.Core;
 using HrynCo.NotificationService.Services.Logging;
@@ -13,9 +12,8 @@ internal sealed class GetChannelUsageSummaryHandler
 
     public GetChannelUsageSummaryHandler(
         IContextualSerilogLogger<GetChannelUsageSummaryQuery> logger,
-        IUnitOfWork unitOfWork,
         IEmailChannelRepository channelsRepository)
-        : base(logger, unitOfWork)
+        : base(logger)
     {
         _channelsRepository = channelsRepository;
     }

HrynCo.NotificationService.Services/EmailChannels/Send/SendEmailHandler.cs

@@ -1,6 +1,6 @@
 using System.Net;
 using System.Net.Mail;
-using HrynCo.NotificationService.DAL.Abstract;
+using System.Text;
 using HrynCo.NotificationService.DAL.Abstract.Providers;
 using HrynCo.NotificationService.DAL.Abstract.Repositories;
 using HrynCo.NotificationService.Services.Core;
@@ -17,10 +17,9 @@ internal sealed class SendEmailHandler
 
     public SendEmailHandler(
         IContextualSerilogLogger<SendEmailCommand> logger,
-        IUnitOfWork unitOfWork,
         IEmailChannelRepository channels,
         IEmailChannelUsageRepository usage)
-        : base(logger, unitOfWork)
+        : base(logger)
     {
         _channels = channels;
         _usage = usage;
@@ -50,14 +49,16 @@ internal sealed class SendEmailHandler
             {
                 From = new MailAddress(smtp.FromEmail, smtp.FromName),
                 Subject = request.Subject,
-                Body = request.HtmlBody,
-                IsBodyHtml = true
+                Body = request.TextBody ?? string.Empty,
+                IsBodyHtml = false,
+                BodyEncoding = Encoding.UTF8,
+                SubjectEncoding = Encoding.UTF8
             };
 
-            if (!string.IsNullOrWhiteSpace(request.TextBody))
+            if (!string.IsNullOrWhiteSpace(request.HtmlBody))
             {
-                var plain = AlternateView.CreateAlternateViewFromString(request.TextBody, null, "text/plain");
-                mail.AlternateViews.Add(plain);
+                var html = AlternateView.CreateAlternateViewFromString(request.HtmlBody, Encoding.UTF8, "text/html");
+                mail.AlternateViews.Add(html);
             }
 
             mail.To.Add(new MailAddress(request.RecipientEmail, request.RecipientName));

HrynCo.NotificationService.Services/EmailChannels/TestSmtp/TestSmtpHandler.cs

@@ -1,6 +1,5 @@
 using System.Net;
 using System.Net.Mail;
-using HrynCo.NotificationService.DAL.Abstract;
 using HrynCo.NotificationService.Services.Core;
 using HrynCo.NotificationService.Services.Logging;
 using static HrynCo.NotificationService.Services.Core.ServiceResultHelper;
@@ -11,9 +10,8 @@ internal sealed class TestSmtpHandler
     : RequestHandler<TestSmtpCommand, ServiceResult<Unit>>
 {
     public TestSmtpHandler(
-        IContextualSerilogLogger<TestSmtpCommand> logger,
-        IUnitOfWork unitOfWork)
-        : base(logger, unitOfWork)
+        IContextualSerilogLogger<TestSmtpCommand> logger)
+        : base(logger)
     {
     }
 

HrynCo.NotificationService.Services/EmailChannels/Update/UpdateEmailChannelHandler.cs

@@ -1,4 +1,4 @@
-using HrynCo.NotificationService.DAL.Abstract;
+using HrynCo.DAL.Abstract;
 using HrynCo.NotificationService.DAL.Abstract.Repositories;
 using HrynCo.NotificationService.Services.Core;
 using HrynCo.NotificationService.Services.Logging;
@@ -13,9 +13,8 @@ internal sealed class UpdateEmailChannelHandler
 
     public UpdateEmailChannelHandler(
         IContextualSerilogLogger<UpdateEmailChannelCommand> logger,
-        IUnitOfWork unitOfWork,
         IEmailChannelRepository channels)
-        : base(logger, unitOfWork)
+        : base(logger)
     {
         _channels = channels;
     }

HrynCo.NotificationService.Services/EmailTemplates/Create/CreateEmailTemplateHandler.cs

@@ -1,4 +1,3 @@
-using HrynCo.NotificationService.DAL.Abstract;
 using HrynCo.NotificationService.DAL.Abstract.Repositories;
 using HrynCo.NotificationService.DAL.Abstract.Templates;
 using HrynCo.NotificationService.Services.Core;
@@ -14,9 +13,8 @@ internal sealed class CreateEmailTemplateHandler
 
     public CreateEmailTemplateHandler(
         IContextualSerilogLogger<CreateEmailTemplateCommand> logger,
-        IUnitOfWork unitOfWork,
         IEmailTemplateRepository templates)
-        : base(logger, unitOfWork)
+        : base(logger)
     {
         _templates = templates;
     }

HrynCo.NotificationService.Services/EmailTemplates/Delete/DeleteEmailTemplateHandler.cs

@@ -1,4 +1,4 @@
-using HrynCo.NotificationService.DAL.Abstract;
+using HrynCo.DAL.Abstract;
 using HrynCo.NotificationService.DAL.Abstract.Repositories;
 using HrynCo.NotificationService.Services.Core;
 using HrynCo.NotificationService.Services.Logging;
@@ -13,9 +13,8 @@ internal sealed class DeleteEmailTemplateHandler
 
     public DeleteEmailTemplateHandler(
         IContextualSerilogLogger<DeleteEmailTemplateCommand> logger,
-        IUnitOfWork unitOfWork,
         IEmailTemplateRepository templates)
-        : base(logger, unitOfWork)
+        : base(logger)
     {
         _templates = templates;
     }

HrynCo.NotificationService.Services/EmailTemplates/Get/GetEmailTemplateHandler.cs

@@ -1,4 +1,3 @@
-using HrynCo.NotificationService.DAL.Abstract;
 using HrynCo.NotificationService.DAL.Abstract.Repositories;
 using HrynCo.NotificationService.DAL.Abstract.Templates;
 using HrynCo.NotificationService.Services.Core;
@@ -14,9 +13,8 @@ internal sealed class GetEmailTemplateHandler
 
     public GetEmailTemplateHandler(
         IContextualSerilogLogger<GetEmailTemplateQuery> logger,
-        IUnitOfWork unitOfWork,
         IEmailTemplateRepository templates)
-        : base(logger, unitOfWork)
+        : base(logger)
     {
         _templates = templates;
     }

HrynCo.NotificationService.Services/EmailTemplates/GetAll/GetAllEmailTemplatesHandler.cs

@@ -1,4 +1,3 @@
-using HrynCo.NotificationService.DAL.Abstract;
 using HrynCo.NotificationService.DAL.Abstract.Repositories;
 using HrynCo.NotificationService.DAL.Abstract.Templates;
 using HrynCo.NotificationService.Services.Core;
@@ -14,9 +13,8 @@ internal sealed class GetAllEmailTemplatesHandler
 
     public GetAllEmailTemplatesHandler(
         IContextualSerilogLogger<GetAllEmailTemplatesQuery> logger,
-        IUnitOfWork unitOfWork,
         IEmailTemplateRepository templates)
-        : base(logger, unitOfWork)
+        : base(logger)
     {
         _templates = templates;
     }
@@ -24,7 +22,7 @@ internal sealed class GetAllEmailTemplatesHandler
     protected override async Task<ServiceResult<IReadOnlyList<EmailTemplate>>> DoOnHandle(
         GetAllEmailTemplatesQuery request, CancellationToken cancellationToken)
     {
-        var templates = await _templates.GetAllAsync(cancellationToken);
+        var templates = await _templates.GetAllAsync(request.ServiceName, request.Key, cancellationToken);
         return Success(templates);
     }
 }

HrynCo.NotificationService.Services/EmailTemplates/GetAll/GetAllEmailTemplatesQuery.cs

@@ -4,4 +4,5 @@ using HrynCo.NotificationService.Services.Core;
 
 namespace HrynCo.NotificationService.Services.EmailTemplates.GetAll;
 
-public sealed record GetAllEmailTemplatesQuery : IRequest<ServiceResult<IReadOnlyList<EmailTemplate>>>;
+public sealed record GetAllEmailTemplatesQuery(string? ServiceName = null, string? Key = null)
+    : IRequest<ServiceResult<IReadOnlyList<EmailTemplate>>>;

HrynCo.NotificationService.Services/EmailTemplates/GetByService/GetEmailTemplatesHandler.cs

@@ -1,4 +1,3 @@
-using HrynCo.NotificationService.DAL.Abstract;
 using HrynCo.NotificationService.DAL.Abstract.Repositories;
 using HrynCo.NotificationService.DAL.Abstract.Templates;
 using HrynCo.NotificationService.Services.Core;
@@ -14,9 +13,8 @@ internal sealed class GetEmailTemplatesHandler
 
     public GetEmailTemplatesHandler(
         IContextualSerilogLogger<GetEmailTemplatesQuery> logger,
-        IUnitOfWork unitOfWork,
         IEmailTemplateRepository templates)
-        : base(logger, unitOfWork)
+        : base(logger)
     {
         _templates = templates;
     }

HrynCo.NotificationService.Services/EmailTemplates/Update/UpdateEmailTemplateHandler.cs

@@ -1,4 +1,4 @@
-using HrynCo.NotificationService.DAL.Abstract;
+using HrynCo.DAL.Abstract;
 using HrynCo.NotificationService.DAL.Abstract.Repositories;
 using HrynCo.NotificationService.Services.Core;
 using HrynCo.NotificationService.Services.Logging;
@@ -13,9 +13,8 @@ internal sealed class UpdateEmailTemplateHandler
 
     public UpdateEmailTemplateHandler(
         IContextualSerilogLogger<UpdateEmailTemplateCommand> logger,
-        IUnitOfWork unitOfWork,
         IEmailTemplateRepository templates)
-        : base(logger, unitOfWork)
+        : base(logger)
     {
         _templates = templates;
     }

HrynCo.NotificationService.Web.IntegrationTests/AdminTemplatesIndexViewTests.cs

@@ -0,0 +1,32 @@
+namespace HrynCo.NotificationService.Web.IntegrationTests;
+
+public sealed class AdminTemplatesIndexViewTests
+{
+    [Fact]
+    public void CreateAndEditLinks_UseExplicitFilterQueryInterpolation()
+    {
+        string view = File.ReadAllText(FindIndexView());
+
+        Assert.Contains("/admin/templates/create@(filterQuery)", view);
+        Assert.Contains("@t.LanguageCode@(filterQuery)", view);
+        Assert.DoesNotContain("create@filterQuery", view);
+        Assert.DoesNotContain("LanguageCode@filterQuery", view);
+    }
+
+    private static string FindIndexView()
+    {
+        DirectoryInfo? directory = new(AppContext.BaseDirectory);
+        while (directory is not null && !File.Exists(Path.Combine(directory.FullName, "HrynCo.NotificationService.slnx")))
+        {
+            directory = directory.Parent;
+        }
+
+        Assert.NotNull(directory);
+        return Path.Combine(
+            directory.FullName,
+            "HrynCo.NotificationService.Web",
+            "Views",
+            "AdminTemplates",
+            "Index.cshtml");
+    }
+}

HrynCo.NotificationService.Web.IntegrationTests/UnitTest1.cs

@@ -1,10 +0,0 @@
-namespace HrynCo.NotificationService.Web.IntegrationTests;
-
-public class UnitTest1
-{
-    [Fact]
-    public void Test1()
-    {
-
-    }
-}

HrynCo.NotificationService.Web/Controllers/Admin/AdminTemplatesController.cs

@@ -23,9 +23,12 @@ public class AdminTemplatesController : Controller
 
     // GET /admin/templates
     [HttpGet("")]
-    public async Task<IActionResult> Index(CancellationToken ct)
+    public async Task<IActionResult> Index([FromQuery] string? serviceName, [FromQuery] string? key, CancellationToken ct)
     {
-        var result = await _mediator.Send(new GetAllEmailTemplatesQuery(), ct);
+        ViewData["ServiceNameFilter"] = serviceName;
+        ViewData["KeyFilter"] = key;
+
+        var result = await _mediator.Send(new GetAllEmailTemplatesQuery(serviceName, key), ct);
         if (!result.IsSuccess)
         {
             ModelState.AddModelError("", result.Error?.Message ?? "Failed to load templates.");
@@ -37,14 +40,24 @@ public class AdminTemplatesController : Controller
 
     // GET /admin/templates/create
     [HttpGet("create")]
-    public IActionResult Create()
+    public IActionResult Create([FromQuery] string? serviceNameFilter, [FromQuery] string? keyFilter)
     {
-        return View("Edit", new EmailTemplateEditViewModel());
+        return View("Edit", new EmailTemplateEditViewModel
+        {
+            ServiceNameFilter = serviceNameFilter,
+            KeyFilter = keyFilter
+        });
     }
 
     // GET /admin/templates/{serviceName}/{key}/{languageCode}
     [HttpGet("{serviceName}/{key}/{languageCode}")]
-    public async Task<IActionResult> Edit(string serviceName, string key, string languageCode, CancellationToken ct)
+    public async Task<IActionResult> Edit(
+        string serviceName,
+        string key,
+        string languageCode,
+        [FromQuery] string? serviceNameFilter,
+        [FromQuery] string? keyFilter,
+        CancellationToken ct)
     {
         var result = await _mediator.Send(new GetEmailTemplateQuery(serviceName, key, languageCode), ct);
         if (!result.IsSuccess || result.Result is null)
@@ -60,7 +73,9 @@ public class AdminTemplatesController : Controller
             Subject = template.Subject,
             HtmlBody = template.HtmlBody,
             TextBody = template.TextBody,
-            VariablesJson = JsonSerializer.Serialize(template.Variables)
+            VariablesJson = JsonSerializer.Serialize(template.Variables),
+            ServiceNameFilter = serviceNameFilter,
+            KeyFilter = keyFilter
         };
 
         return View(vm);
@@ -124,15 +139,21 @@ public class AdminTemplatesController : Controller
             }
         }
 
-        return RedirectToAction(nameof(Index));
+        return RedirectToAction(nameof(Index), new { serviceName = model.ServiceNameFilter, key = model.KeyFilter });
     }
 
     // POST /admin/templates/{serviceName}/{key}/{languageCode}/delete
     [HttpPost("{serviceName}/{key}/{languageCode}/delete")]
     [ValidateAntiForgeryToken]
-    public async Task<IActionResult> Delete(string serviceName, string key, string languageCode, CancellationToken ct)
+    public async Task<IActionResult> Delete(
+        string serviceName,
+        string key,
+        string languageCode,
+        [FromForm] string? serviceNameFilter,
+        [FromForm] string? keyFilter,
+        CancellationToken ct)
     {
         await _mediator.Send(new DeleteEmailTemplateCommand(serviceName, key, languageCode), ct);
-        return RedirectToAction(nameof(Index));
+        return RedirectToAction(nameof(Index), new { serviceName = serviceNameFilter, key = keyFilter });
     }
 }

HrynCo.NotificationService.Web/Controllers/Admin/ViewModels/EmailTemplateEditViewModel.cs

@@ -25,6 +25,8 @@ public class EmailTemplateEditViewModel
 
     // JSON array: [{"name":"UserName","required":true}, ...]
     public string VariablesJson { get; set; } = "[]";
+    public string? ServiceNameFilter { get; set; }
+    public string? KeyFilter { get; set; }
 
     public bool IsNew => Id == null;
     public string PageTitle => IsNew ? "Create Email Template" : "Edit Email Template";

HrynCo.NotificationService.Web/Controllers/Api/EmailTemplates/EmailTemplatesController.cs

@@ -1,6 +1,7 @@
 using HrynCo.NotificationService.Web.Infrastructure;
 using HrynCo.NotificationService.Services.EmailTemplates.Create;
 using HrynCo.NotificationService.Services.EmailTemplates.Delete;
+using HrynCo.NotificationService.Services.EmailTemplates.GetAll;
 using HrynCo.NotificationService.Services.EmailTemplates.Get;
 using HrynCo.NotificationService.Services.EmailTemplates.GetByService;
 using HrynCo.NotificationService.Services.EmailTemplates.Update;
@@ -15,9 +16,9 @@ public sealed class EmailTemplatesController : ApiControllerBase
     public EmailTemplatesController(IMediator mediator) : base(mediator) { }
 
     [HttpGet]
-    public async Task<IActionResult> GetAll([FromQuery] string serviceName, CancellationToken cancellationToken)
+    public async Task<IActionResult> GetAll([FromQuery] string? serviceName, [FromQuery] string? key, CancellationToken cancellationToken)
     {
-        var result = await Mediator.Send(new GetEmailTemplatesQuery(serviceName), cancellationToken);
+        var result = await Mediator.Send(new GetAllEmailTemplatesQuery(serviceName, key), cancellationToken);
         return FromServiceResult(result);
     }
 

HrynCo.NotificationService.Web/HrynCo.NotificationService.Web.http

@@ -1,6 +1,47 @@
-@HrynCo.NotificationService.Api_HostAddress = http://localhost:5188
+@host = http://localhost:5188
 
-GET {{HrynCo.NotificationService.Api_HostAddress}}/weatherforecast/
-Accept: application/json
+### Create a new email template
+POST {{host}}/api/v1/email-templates
+Content-Type: application/json
 
-###
+{
+  "ServiceName": "StoreMate-Prod",
+  "Key": "ShareInvite",
+  "LanguageCode": "uk",
+  "Subject": "Вас запрошено",
+  "HtmlBody": "<html><body><div style=\"font-family: Arial, sans-serif; color: #1f2937;\"><p>Вітаємо, \u007b\u007bRecipientName\u007d\u007d.</p><h1>Вас запрошено</h1><p>\u007b\u007bInviterName\u007d\u007d запросив вас приєднатися до \u007b\u007bAppName\u007d\u007d, щоб ви могли безпечно співпрацювати.</p><p><a href=\"\u007b\u007bInviteLink\u007d\u007d\">Відкрити запрошення</a></p><p>Запрошення дійсне до <strong>\u007b\u007bValidUntil\u007d\u007d</strong>.</p></div></body></html>",
+  "TextBody": "Вітаємо, \u007b\u007bRecipientName\u007d\u007d.\n\n\u007b\u007bInviterName\u007d\u007d запросив вас приєднатися до \u007b\u007bAppName\u007d\u007d, щоб ви могли безпечно співпрацювати.\n\nВідкрийте запрошення: \u007b\u007bInviteLink\u007d\u007d\nДійсне до: \u007b\u007bValidUntil\u007d\u007d",
+  "Variables": [
+    { "Name": "RecipientName", "Required": false },
+    { "Name": "InviterName", "Required": false },
+    { "Name": "AppName", "Required": false },
+    { "Name": "InviteLink", "Required": false },
+    { "Name": "ValidUntil", "Required": false }
+  ]
+}
+
+### Get the created template
+GET {{host}}/api/v1/email-templates/StoreMate-Prod/ShareInvite/uk
+
+### List all templates for the service
+GET {{host}}/api/v1/email-templates?serviceName=StoreMate-Prod
+
+### Update the template
+PUT {{host}}/api/v1/email-templates/StoreMate-Prod/ShareInvite/uk
+Content-Type: application/json
+
+{
+  "Subject": "Вас запрошено",
+  "HtmlBody": "<html><body><p>Вітаємо, \u007b\u007bRecipientName\u007d\u007d.</p><p>\u007b\u007bInviterName\u007d\u007d запросив вас приєднатися до \u007b\u007bAppName\u007d\u007d.</p><p><a href=\"\u007b\u007bInviteLink\u007d\u007d\">Відкрити запрошення</a></p><p>Дійсне до <strong>\u007b\u007bValidUntil\u007d\u007d</strong>.</p></body></html>",
+  "TextBody": "Вітаємо, \u007b\u007bRecipientName\u007d\u007d.\n\n\u007b\u007bInviterName\u007d\u007d запросив вас приєднатися до \u007b\u007bAppName\u007d\u007d.\n\nВідкрийте запрошення: \u007b\u007bInviteLink\u007d\u007d\nДійсне до: \u007b\u007bValidUntil\u007d\u007d",
+  "Variables": [
+    { "Name": "RecipientName", "Required": false },
+    { "Name": "InviterName", "Required": false },
+    { "Name": "AppName", "Required": false },
+    { "Name": "InviteLink", "Required": false },
+    { "Name": "ValidUntil", "Required": false }
+  ]
+}
+
+### Delete the template
+DELETE {{host}}/api/v1/email-templates/StoreMate-Prod/ShareInvite/uk

HrynCo.NotificationService.Web/Program.cs

@@ -3,11 +3,11 @@ using HrynCo.NotificationService.DAL.EF;
 using HrynCo.NotificationService.Services;
 using Scalar.AspNetCore;
 
-var builder = WebApplication.CreateBuilder(args);
+WebApplicationBuilder builder = WebApplication.CreateBuilder(args);
 
 builder.AddSerilog();
 
-var appSettings = builder.Configuration
+AppSettings appSettings = builder.Configuration
     .GetSection(AppSettings.SectionName)
     .Get<AppSettings>() ?? throw new InvalidOperationException("App settings are not configured.");
 
@@ -18,17 +18,14 @@ builder.Services.AddControllersWithViews()
 builder.Services.AddNotificationDataAccess(appSettings.ConnectionString);
 builder.Services.AddNotificationServices();
 
-var app = builder.Build();
+WebApplication app = builder.Build();
 
-if (app.Environment.IsDevelopment())
+app.MapOpenApi();
+app.MapScalarApiReference(options =>
 {
-    app.MapOpenApi();
-    app.MapScalarApiReference(options =>
-    {
-        options.Title = "HrynCo Notification Service";
-        options.Theme = ScalarTheme.DeepSpace;
-    });
-}
+    options.Title = "HrynCo Notification Service";
+    options.Theme = ScalarTheme.DeepSpace;
+});
 
 app.UseStaticFiles();
 app.UseHttpsRedirection();

HrynCo.NotificationService.Web/Views/AdminTemplates/Edit.cshtml

@@ -10,6 +10,8 @@
     @Html.AntiForgeryToken()
     <input asp-for="Id" type="hidden" />
     <input type="hidden" name="IsNew" value="@Model.IsNew" />
+    <input asp-for="ServiceNameFilter" type="hidden" />
+    <input asp-for="KeyFilter" type="hidden" />
 
     @if (!ViewData.ModelState.IsValid)
     {
@@ -21,55 +23,278 @@
         </div>
     }
 
-    <div class="row g-3 mb-3">
-        <div class="col-md-5">
-            <label asp-for="ServiceName" class="form-label fw-semibold">Service Name</label>
-            <input asp-for="ServiceName" class="form-control" readonly="@(!Model.IsNew)" />
-            <span asp-validation-for="ServiceName" class="text-danger small"></span>
+    <ul class="nav nav-tabs template-editor-tabs mb-3" id="templateEditorTabs" role="tablist">
+        <li class="nav-item" role="presentation">
+            <button class="nav-link active" id="edit-tab" data-bs-toggle="tab" data-bs-target="#edit-pane" type="button" role="tab" aria-controls="edit-pane" aria-selected="true">
+                Edit
+            </button>
+        </li>
+        <li class="nav-item" role="presentation">
+            <button class="nav-link" id="preview-tab" data-bs-toggle="tab" data-bs-target="#preview-pane" type="button" role="tab" aria-controls="preview-pane" aria-selected="false">
+                Preview
+            </button>
+        </li>
+    </ul>
+
+    <div class="tab-content">
+        <div class="tab-pane fade show active" id="edit-pane" role="tabpanel" aria-labelledby="edit-tab" tabindex="0">
+            <div class="row g-3 mb-3">
+                <div class="col-md-5">
+                    <label asp-for="ServiceName" class="form-label fw-semibold">Service Name</label>
+                    <input asp-for="ServiceName" class="form-control" readonly="@(!Model.IsNew)" />
+                    <span asp-validation-for="ServiceName" class="text-danger small"></span>
+                </div>
+                <div class="col-md-5">
+                    <label asp-for="Key" class="form-label fw-semibold">Key</label>
+                    <input asp-for="Key" class="form-control" readonly="@(!Model.IsNew)" />
+                    <span asp-validation-for="Key" class="text-danger small"></span>
+                </div>
+                <div class="col-md-2">
+                    <label asp-for="LanguageCode" class="form-label fw-semibold">Language</label>
+                    <input asp-for="LanguageCode" class="form-control" readonly="@(!Model.IsNew)" />
+                    <span asp-validation-for="LanguageCode" class="text-danger small"></span>
+                </div>
+            </div>
+
+            <div class="mb-3">
+                <label asp-for="Subject" class="form-label fw-semibold">Subject</label>
+                <input asp-for="Subject" class="form-control" />
+                <span asp-validation-for="Subject" class="text-danger small"></span>
+            </div>
+
+            <div class="mb-3">
+                <label asp-for="HtmlBody" class="form-label fw-semibold">HTML Body</label>
+                <textarea asp-for="HtmlBody" class="form-control font-monospace" rows="10"></textarea>
+                <span asp-validation-for="HtmlBody" class="text-danger small"></span>
+            </div>
+
+            <div class="mb-3">
+                <label asp-for="TextBody" class="form-label fw-semibold">Text Body</label>
+                <textarea asp-for="TextBody" class="form-control font-monospace" rows="5"></textarea>
+            </div>
+
+            <div class="mb-3">
+                <label asp-for="VariablesJson" class="form-label fw-semibold">Variables (JSON)</label>
+                <textarea asp-for="VariablesJson" class="form-control font-monospace" rows="4"
+                          placeholder='[{"name":"UserName","required":true}]'></textarea>
+                <span asp-validation-for="VariablesJson" class="text-danger small"></span>
+                <div class="form-text">JSON array of <code>{"name":"...", "required":true|false}</code></div>
+            </div>
         </div>
-        <div class="col-md-5">
-            <label asp-for="Key" class="form-label fw-semibold">Key</label>
-            <input asp-for="Key" class="form-control" readonly="@(!Model.IsNew)" />
-            <span asp-validation-for="Key" class="text-danger small"></span>
+
+        <div class="tab-pane fade" id="preview-pane" role="tabpanel" aria-labelledby="preview-tab" tabindex="0">
+            <div class="template-preview-panel mb-3">
+                <div class="template-preview-panel-header">
+                    <div>
+                        <div class="template-preview-title">Preview</div>
+                        <div class="template-preview-subtitle">Rendered with sample values from the variable list.</div>
+                    </div>
+                    <span id="previewStatus" class="badge text-bg-secondary">Ready</span>
+                </div>
+
+                <div class="template-preview-body">
+                    <div class="template-preview-source template-preview-section-block">
+                        <div class="template-preview-section-title">Sample values</div>
+                        <div id="previewVariables" class="template-preview-variables"></div>
+                        <div class="form-text mt-2">Change these values to see the rendered output update immediately.</div>
+                    </div>
+
+                    <div class="template-preview-output">
+                        <div class="template-preview-section-title">Rendered subject</div>
+                        <div id="previewSubject" class="template-preview-subject"></div>
+
+                        <div class="template-preview-section-title mt-3">Rendered HTML</div>
+                        <iframe id="previewHtmlFrame" class="template-preview-frame" title="Email HTML preview"></iframe>
+
+                        <div class="template-preview-section-title mt-3">Rendered text</div>
+                        <pre id="previewText" class="template-preview-text mb-0"></pre>
+                    </div>
+                </div>
+            </div>
         </div>
-        <div class="col-md-2">
-            <label asp-for="LanguageCode" class="form-label fw-semibold">Language</label>
-            <input asp-for="LanguageCode" class="form-control" readonly="@(!Model.IsNew)" />
-            <span asp-validation-for="LanguageCode" class="text-danger small"></span>
-        </div>
-    </div>
-
-    <div class="mb-3">
-        <label asp-for="Subject" class="form-label fw-semibold">Subject</label>
-        <input asp-for="Subject" class="form-control" />
-        <span asp-validation-for="Subject" class="text-danger small"></span>
-    </div>
-
-    <div class="mb-3">
-        <label asp-for="HtmlBody" class="form-label fw-semibold">HTML Body</label>
-        <textarea asp-for="HtmlBody" class="form-control font-monospace" rows="10"></textarea>
-        <span asp-validation-for="HtmlBody" class="text-danger small"></span>
-    </div>
-
-    <div class="mb-3">
-        <label asp-for="TextBody" class="form-label fw-semibold">Text Body</label>
-        <textarea asp-for="TextBody" class="form-control font-monospace" rows="5"></textarea>
-    </div>
-
-    <div class="mb-3">
-        <label asp-for="VariablesJson" class="form-label fw-semibold">Variables (JSON)</label>
-        <textarea asp-for="VariablesJson" class="form-control font-monospace" rows="4"
-                  placeholder='[{"name":"UserName","required":true}]'></textarea>
-        <span asp-validation-for="VariablesJson" class="text-danger small"></span>
-        <div class="form-text">JSON array of <code>{"name":"...", "required":true|false}</code></div>
     </div>
 
     @section FormActions {
         <button type="submit" form="templateForm" class="btn btn-primary">
             <i class="bi bi-floppy me-1"></i> Save
         </button>
-        <a href="/admin/templates" class="btn btn-secondary">
+        <a href="/admin/templates@(string.IsNullOrWhiteSpace(Model.ServiceNameFilter) && string.IsNullOrWhiteSpace(Model.KeyFilter) ? string.Empty : $"?serviceName={Uri.EscapeDataString(Model.ServiceNameFilter ?? string.Empty)}&key={Uri.EscapeDataString(Model.KeyFilter ?? string.Empty)}")" class="btn btn-secondary">
             <i class="bi bi-x-lg me-1"></i> Cancel
         </a>
     }
+
+    @section Scripts {
+        <script>
+            (function () {
+                const subjectField = document.getElementById('Subject');
+                const htmlField = document.getElementById('HtmlBody');
+                const textField = document.getElementById('TextBody');
+                const variablesField = document.getElementById('VariablesJson');
+                const previewVariablesHost = document.getElementById('previewVariables');
+                const previewSubject = document.getElementById('previewSubject');
+                const previewText = document.getElementById('previewText');
+                const previewFrame = document.getElementById('previewHtmlFrame');
+                const previewStatus = document.getElementById('previewStatus');
+                const previewTab = document.getElementById('preview-tab');
+
+                if (!subjectField || !htmlField || !textField || !variablesField || !previewVariablesHost || !previewSubject || !previewText || !previewFrame || !previewStatus) {
+                    return;
+                }
+
+                function escapeHtml(value) {
+                    return String(value)
+                        .replace(/&/g, '&amp;')
+                        .replace(/</g, '&lt;')
+                        .replace(/>/g, '&gt;')
+                        .replace(/"/g, '&quot;')
+                        .replace(/'/g, '&#39;');
+                }
+
+                function parseVariables() {
+                    const raw = variablesField.value?.trim() || '[]';
+                    const parsed = JSON.parse(raw);
+
+                    if (!Array.isArray(parsed)) {
+                        throw new Error('Variables JSON must be an array.');
+                    }
+
+                    return parsed
+                        .filter(item => item && typeof item.Name === 'string' && item.Name.trim().length > 0)
+                        .map(item => ({
+                            name: item.Name.trim(),
+                            required: !!item.Required
+                        }));
+                }
+
+                function buildSampleValue(name) {
+                    return `Sample ${name}`;
+                }
+
+                function renderVariableInputs() {
+                    let variables = [];
+
+                    try {
+                        variables = parseVariables();
+                        previewStatus.className = 'badge text-bg-secondary';
+                        previewStatus.textContent = 'Ready';
+                    } catch (error) {
+                        previewVariablesHost.innerHTML = `<div class="alert alert-warning mb-0">${escapeHtml(error.message || 'Invalid variables JSON')}</div>`;
+                        previewStatus.className = 'badge text-bg-danger';
+                        previewStatus.textContent = 'Invalid JSON';
+                        updatePreview();
+                        return;
+                    }
+
+                    if (variables.length === 0) {
+                        previewVariablesHost.innerHTML = '<div class="text-muted small">No variables defined.</div>';
+                        updatePreview();
+                        return;
+                    }
+
+                    const currentValues = readVariableValues();
+                    previewVariablesHost.innerHTML = variables.map(variable => {
+                        const value = Object.prototype.hasOwnProperty.call(currentValues, variable.name)
+                            ? currentValues[variable.name]
+                            : buildSampleValue(variable.name);
+                        return `
+                            <div class="mb-2">
+                                <label class="form-label small fw-semibold mb-1">${escapeHtml(variable.name)}${variable.required ? ' *' : ''}</label>
+                                <input type="text" class="form-control form-control-sm preview-variable-input" data-variable-name="${escapeHtml(variable.name)}" value="${escapeHtml(value)}" />
+                            </div>
+                        `;
+                    }).join('');
+
+                    previewVariablesHost.querySelectorAll('.preview-variable-input').forEach(input => {
+                        input.addEventListener('input', updatePreview);
+                    });
+
+                    updatePreview();
+                }
+
+                function readVariableValues() {
+                    const values = {};
+                    previewVariablesHost.querySelectorAll('.preview-variable-input').forEach(input => {
+                        values[input.dataset.variableName] = input.value;
+                    });
+                    return values;
+                }
+
+                function interpolate(text, values) {
+                    let result = text || '';
+
+                    Object.keys(values).forEach(key => {
+                        const token = new RegExp(`\\{\\{${key.replace(/[.*+?^${}()|[\]\\]/g, '\\$&')}\\}\\}`, 'g');
+                        result = result.replace(token, values[key] ?? '');
+                    });
+
+                    return result;
+                }
+
+                function updatePreview() {
+                    let values = {};
+
+                    try {
+                        values = readVariableValues();
+                    } catch (error) {
+                        values = {};
+                    }
+
+                    const renderedSubject = interpolate(subjectField.value, values);
+                    const renderedHtml = interpolate(htmlField.value, values);
+                    const renderedText = interpolate(textField.value, values);
+
+                    previewSubject.textContent = renderedSubject || '(empty subject)';
+                    previewText.textContent = renderedText || '(empty text body)';
+                    previewFrame.srcdoc = `
+                        <!DOCTYPE html>
+                        <html lang="en">
+                        <head>
+                            <meta charset="utf-8" />
+                            <meta name="viewport" content="width=device-width, initial-scale=1" />
+                            <style>
+                                body {
+                                    margin: 0;
+                                    padding: 24px;
+                                    background: #eef2f7;
+                                    color: #1f2937;
+                                    font-family: Arial, Helvetica, sans-serif;
+                                }
+                                .email-shell {
+                                    max-width: 640px;
+                                    margin: 0 auto;
+                                    background: #ffffff;
+                                    border: 1px solid #dbe3ee;
+                                    border-radius: 20px;
+                                    overflow: hidden;
+                                    box-shadow: 0 12px 30px rgba(15, 23, 42, .08);
+                                }
+                                .email-body {
+                                    padding: 28px 36px;
+                                }
+                                img { max-width: 100%; height: auto; }
+                                a { color: #2563eb; }
+                            </style>
+                        </head>
+                        <body>
+                            <div class="email-shell">
+                                <div class="email-body">
+                                    ${renderedHtml || '<div style="color:#6b7280">No HTML body provided.</div>'}
+                                </div>
+                            </div>
+                        </body>
+                        </html>`;
+                }
+
+                variablesField.addEventListener('input', renderVariableInputs);
+                subjectField.addEventListener('input', updatePreview);
+                htmlField.addEventListener('input', updatePreview);
+                textField.addEventListener('input', updatePreview);
+                if (previewTab) {
+                    previewTab.addEventListener('shown.bs.tab', updatePreview);
+                }
+
+                renderVariableInputs();
+            })();
+        </script>
+    }
 </form>

HrynCo.NotificationService.Web/Views/AdminTemplates/Index.cshtml

@@ -2,15 +2,50 @@
 @model IReadOnlyList<EmailTemplate>
 @{
     ViewData["Title"] = "Email Templates";
+    var serviceNameFilter = ViewData["ServiceNameFilter"] as string ?? string.Empty;
+    var keyFilter = ViewData["KeyFilter"] as string ?? string.Empty;
+    var filterQuery = string.IsNullOrWhiteSpace(serviceNameFilter) && string.IsNullOrWhiteSpace(keyFilter)
+        ? string.Empty
+        : $"?serviceNameFilter={Uri.EscapeDataString(serviceNameFilter)}&keyFilter={Uri.EscapeDataString(keyFilter)}";
+    var listQuery = string.IsNullOrWhiteSpace(serviceNameFilter) && string.IsNullOrWhiteSpace(keyFilter)
+        ? string.Empty
+        : $"?serviceName={Uri.EscapeDataString(serviceNameFilter)}&key={Uri.EscapeDataString(keyFilter)}";
 }
 
 <div class="page-header">
     <h2><i class="bi bi-envelope-paper"></i> Email Templates</h2>
-    <a href="/admin/templates/create" class="btn btn-primary btn-sm">
+    <a href="/admin/templates/create@(filterQuery)" class="btn btn-primary btn-sm">
         <i class="bi bi-plus-lg me-1"></i> Create New Template
     </a>
 </div>
 
+<div class="card shadow-sm mb-3">
+    <div class="card-body">
+        <form id="templateFiltersForm" method="get" action="/admin/templates" class="row g-2 align-items-end">
+            <div class="col-12 col-md-5">
+                <label class="form-label fw-semibold" for="serviceName">Service Name</label>
+                <input id="serviceName"
+                       name="serviceName"
+                       value="@serviceNameFilter"
+                       class="form-control"
+                       placeholder="Filter by service name" />
+            </div>
+            <div class="col-12 col-md-5">
+                <label class="form-label fw-semibold" for="key">Key</label>
+                <input id="key"
+                       name="key"
+                       value="@keyFilter"
+                       class="form-control"
+                       placeholder="Filter by key" />
+            </div>
+            <div class="col-12 col-md-2 d-flex gap-2">
+                <button type="submit" class="btn btn-primary w-100">Filter</button>
+                <a id="clearTemplateFilters" href="/admin/templates" class="btn btn-outline-secondary w-100">Clear</a>
+            </div>
+        </form>
+    </div>
+</div>
+
 @if (!ViewData.ModelState.IsValid)
 {
     <div class="alert alert-danger">
@@ -21,6 +56,61 @@
     </div>
 }
 
+<script>
+    (() => {
+        const storageKey = 'hrynco.notificationService.adminTemplates.filters';
+        const form = document.getElementById('templateFiltersForm');
+        const serviceNameInput = document.getElementById('serviceName');
+        const keyInput = document.getElementById('key');
+        const clearLink = document.getElementById('clearTemplateFilters');
+
+        if (!form || !serviceNameInput || !keyInput || !clearLink) {
+            return;
+        }
+
+        const saveState = () => {
+            const state = {
+                serviceName: serviceNameInput.value ?? '',
+                key: keyInput.value ?? ''
+            };
+
+            localStorage.setItem(storageKey, JSON.stringify(state));
+        };
+
+        const restoreState = () => {
+            const raw = localStorage.getItem(storageKey);
+            if (!raw) {
+                return false;
+            }
+
+            try {
+                const state = JSON.parse(raw);
+                const serviceName = typeof state.serviceName === 'string' ? state.serviceName : '';
+                const key = typeof state.key === 'string' ? state.key : '';
+
+                serviceNameInput.value = serviceName;
+                keyInput.value = key;
+
+                return serviceName.length > 0 || key.length > 0;
+            } catch {
+                localStorage.removeItem(storageKey);
+                return false;
+            }
+        };
+
+        form.addEventListener('submit', saveState);
+        clearLink.addEventListener('click', () => localStorage.removeItem(storageKey));
+
+        const hasQueryParams = new URLSearchParams(window.location.search).toString().length > 0;
+        if (!hasQueryParams && restoreState()) {
+            form.requestSubmit();
+            return;
+        }
+
+        saveState();
+    })();
+</script>
+
 @if (Model is null || Model.Count == 0)
 {
     <div class="card shadow-sm table-card">
@@ -56,13 +146,15 @@ else
                             <td>@t.LanguageCode</td>
                             <td>@t.Subject</td>
                             <td class="text-end">
-                                <a href="/admin/templates/@t.ServiceName/@t.Key/@t.LanguageCode"
+                                <a href="/admin/templates/@t.ServiceName/@t.Key/@t.LanguageCode@(filterQuery)"
                                    class="btn btn-sm btn-outline-primary me-1">
                                     <i class="bi bi-pencil"></i> Edit
                                 </a>
                                 <form method="post"
                                       action="/admin/templates/@t.ServiceName/@t.Key/@t.LanguageCode/delete"
                                       class="d-inline">
+                                    <input type="hidden" name="serviceNameFilter" value="@serviceNameFilter" />
+                                    <input type="hidden" name="keyFilter" value="@keyFilter" />
                                     @Html.AntiForgeryToken()
                                     <button type="submit"
                                             class="btn btn-sm btn-outline-danger"

HrynCo.NotificationService.Web/Views/Shared/_EditorLayout.cshtml

@@ -14,3 +14,4 @@
         </div>
     </div>
 </div>
+@RenderSection("Scripts", required: false)

HrynCo.NotificationService.Web/wwwroot/css/admin.css

@@ -118,9 +118,10 @@ body {
 .empty-state .bi { font-size: 2.5rem; opacity: .35; display: block; margin-bottom: .75rem; }
 .empty-state p { font-size: .9rem; margin-bottom: 0; }
 
-/* ── Editor wrapper — constrains width ───────────────── */
+/* ── Editor wrapper ──────────────────────────────────── */
 .editor-wrapper {
-    max-width: 860px;
+    width: 100%;
+    max-width: none;
 }
 
 /* ── Editor card ──────────────────────────────────────── */
@@ -154,6 +155,149 @@ body {
     border-radius: 0 0 .5rem .5rem !important;
 }
 
+/* ── Editor tabs ─────────────────────────────────────── */
+.template-editor-tabs {
+    border-bottom-color: #dce3eb;
+}
+
+.template-editor-tabs .nav-link {
+    color: #526072;
+    font-weight: 600;
+    border-radius: .5rem .5rem 0 0;
+}
+
+.template-editor-tabs .nav-link.active {
+    color: #0d6efd;
+}
+
+/* ── Tab content ──────────────────────────────────────── */
+.tab-content {
+    min-width: 0;
+}
+
+/* ── Email template preview ───────────────────────────── */
+.template-preview-panel {
+    border: 1px solid #dce3eb;
+    border-radius: .75rem;
+    background: #fff;
+    overflow: hidden;
+    box-shadow: 0 10px 24px rgba(15, 23, 42, .06);
+}
+
+.template-preview-panel-header {
+    display: flex;
+    justify-content: space-between;
+    align-items: flex-start;
+    gap: 1rem;
+    padding: 1rem 1.25rem;
+    background: linear-gradient(180deg, #f9fbff 0%, #f3f6fb 100%);
+    border-bottom: 1px solid #e1e7ef;
+}
+
+.template-preview-title {
+    font-size: .9rem;
+    font-weight: 700;
+    color: #1f2937;
+}
+
+.template-preview-subtitle {
+    font-size: .82rem;
+    color: #6b7280;
+    margin-top: .15rem;
+}
+
+.template-preview-body {
+    display: grid;
+    grid-template-columns: minmax(0, 1fr);
+    gap: 1rem;
+    padding: 1rem 1.25rem 1.25rem;
+}
+
+.template-preview-source,
+.template-preview-output {
+    min-width: 0;
+}
+
+.template-preview-section-block {
+    padding: 1rem;
+    border: 1px solid #e5ebf2;
+    border-radius: .65rem;
+    background: #fafcff;
+}
+
+.template-preview-section-title {
+    font-size: .7rem;
+    font-weight: 700;
+    letter-spacing: .08em;
+    text-transform: uppercase;
+    color: #6b7280;
+    margin-bottom: .5rem;
+}
+
+.template-preview-variables {
+    display: grid;
+    grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
+    gap: .75rem 1rem;
+    max-width: none;
+}
+
+.template-preview-variables > div {
+    margin-bottom: 0 !important;
+}
+
+.template-preview-variables .form-label {
+    font-size: .72rem;
+    margin-bottom: .2rem;
+}
+
+.template-preview-variables .form-control-sm {
+    background: #fff;
+    min-height: calc(1.5em + .45rem + 2px);
+    padding: .2rem .45rem;
+    font-size: .82rem;
+}
+
+.template-preview-subject {
+    padding: .75rem 1rem;
+    border: 1px dashed #cfd8e3;
+    border-radius: .5rem;
+    background: #f8fafc;
+    min-height: 3rem;
+    font-weight: 600;
+    color: #111827;
+    white-space: pre-wrap;
+    word-break: break-word;
+}
+
+.template-preview-frame {
+    width: 100%;
+    height: 420px;
+    border: 1px solid #cfd8e3;
+    border-radius: .5rem;
+    background: #eef2f7;
+}
+
+.template-preview-text {
+    padding: .75rem 1rem;
+    border: 1px solid #cfd8e3;
+    border-radius: .5rem;
+    background: #0f172a;
+    color: #e2e8f0;
+    min-height: 120px;
+    white-space: pre-wrap;
+    word-break: break-word;
+}
+
+@media (max-width: 992px) {
+    .template-preview-body {
+        grid-template-columns: 1fr;
+    }
+
+    .template-preview-frame {
+        height: 360px;
+    }
+}
+
 /* ── Form-section divider ─────────────────────────────── */
 .form-section-title {
     font-size: .68rem;

HrynCo.NotificationService.Worker.Services/EmailProcessing/EmailTemplateRenderingService.cs

@@ -0,0 +1,50 @@
+namespace HrynCo.NotificationService.Worker.Services.EmailProcessing;
+
+using System.Net;
+using System.Text;
+using HrynCo.NotificationService.Contracts.Messages;
+using HrynCo.NotificationService.DAL.Abstract.Templates;
+
+internal sealed class EmailTemplateRenderingService : IEmailTemplateRenderingService
+{
+    public RenderedEmail Render(EmailTemplate template, SendEmailMessageData data)
+    {
+        string[] missingVariables = template.Variables
+            .Where(variable => variable.Required)
+            .Select(variable => variable.Name)
+            .Where(name => !data.Variables.TryGetValue(name, out string? value) || string.IsNullOrWhiteSpace(value))
+            .ToArray();
+
+        if (missingVariables.Length > 0)
+        {
+            throw new InvalidDataException(
+                $"Required template variables are missing: {string.Join(", ", missingVariables)}.");
+        }
+
+        return new RenderedEmail(
+            Interpolate(template.Subject, data.Variables),
+            InterpolateHtml(template.HtmlBody, data.Variables),
+            Interpolate(template.TextBody, data.Variables));
+    }
+
+    private static string InterpolateHtml(string text, IReadOnlyDictionary<string, string> variables)
+    {
+        return Interpolate(text, variables, WebUtility.HtmlEncode);
+    }
+
+    private static string Interpolate(string text, IReadOnlyDictionary<string, string> variables)
+    {
+        return Interpolate(text, variables, static value => value);
+    }
+
+    private static string Interpolate(
+        string text,
+        IReadOnlyDictionary<string, string> variables,
+        Func<string, string> encodeValue)
+    {
+        var sb = new StringBuilder(text);
+        foreach (var (key, value) in variables)
+            sb.Replace($"{{{{{key}}}}}", encodeValue(value));
+        return sb.ToString();
+    }
+}

HrynCo.NotificationService.Worker.Services/EmailProcessing/EmailTemplateService.cs

@@ -0,0 +1,35 @@
+namespace HrynCo.NotificationService.Worker.Services.EmailProcessing;
+
+using HrynCo.NotificationService.DAL.Abstract.Repositories;
+using HrynCo.NotificationService.DAL.Abstract.Templates;
+
+internal sealed class EmailTemplateService : IEmailTemplateService
+{
+    private readonly IEmailTemplateRepository _templateRepository;
+
+    public EmailTemplateService(IEmailTemplateRepository templateRepository)
+    {
+        _templateRepository = templateRepository;
+    }
+
+    public async Task<EmailTemplate> GetAsync(
+        string serviceName,
+        string templateKey,
+        string? languageCode,
+        CancellationToken cancellationToken)
+    {
+        if (string.IsNullOrWhiteSpace(languageCode))
+            throw new InvalidDataException("LanguageCode is required.");
+
+        string lang = languageCode.Trim().ToLowerInvariant();
+        EmailTemplate? template = await _templateRepository.GetAsync(
+            serviceName,
+            templateKey,
+            lang,
+            cancellationToken);
+
+        return template
+            ?? throw new InvalidOperationException(
+                $"Template not found: service='{serviceName}' key='{templateKey}' language='{lang}'.");
+    }
+}

HrynCo.NotificationService.Worker.Services/EmailProcessing/IEmailTemplateRenderingService.cs

@@ -0,0 +1,9 @@
+using HrynCo.NotificationService.Contracts.Messages;
+using HrynCo.NotificationService.DAL.Abstract.Templates;
+
+namespace HrynCo.NotificationService.Worker.Services.EmailProcessing;
+
+public interface IEmailTemplateRenderingService
+{
+    RenderedEmail Render(EmailTemplate template, SendEmailMessageData data);
+}

HrynCo.NotificationService.Worker.Services/EmailProcessing/IEmailTemplateService.cs

@@ -0,0 +1,12 @@
+using HrynCo.NotificationService.DAL.Abstract.Templates;
+
+namespace HrynCo.NotificationService.Worker.Services.EmailProcessing;
+
+public interface IEmailTemplateService
+{
+    Task<EmailTemplate> GetAsync(
+        string serviceName,
+        string templateKey,
+        string? languageCode,
+        CancellationToken cancellationToken);
+}

HrynCo.NotificationService.Worker.Services/EmailProcessing/INotificationResultPublisher.cs

@@ -0,0 +1,11 @@
+namespace HrynCo.NotificationService.Worker.Services.EmailProcessing;
+
+using HrynCo.NotificationService.Contracts.Messages;
+
+public interface INotificationResultPublisher
+{
+    Task PublishAsync(
+        SendEmailMessage message,
+        string? deliveryError,
+        CancellationToken cancellationToken);
+}

HrynCo.NotificationService.Worker.Services/EmailProcessing/ISendEmailService.cs

@@ -0,0 +1,8 @@
+using HrynCo.NotificationService.Contracts.Messages;
+
+namespace HrynCo.NotificationService.Worker.Services.EmailProcessing;
+
+public interface ISendEmailService
+{
+    Task ProcessAsync(SendEmailMessage message, CancellationToken cancellationToken);
+}

HrynCo.NotificationService.Worker.Services/EmailProcessing/ISmtpEmailSender.cs

@@ -0,0 +1,13 @@
+namespace HrynCo.NotificationService.Worker.Services.EmailProcessing;
+
+using HrynCo.NotificationService.DAL.Abstract.Providers;
+
+internal interface ISmtpEmailSender
+{
+    Task SendAsync(
+        SmtpChannelSettings settings,
+        RenderedEmail email,
+        string recipientEmail,
+        string recipientName,
+        CancellationToken cancellationToken);
+}

HrynCo.NotificationService.Worker.Services/EmailProcessing/NotificationDeliveryErrorFormatter.cs

@@ -0,0 +1,80 @@
+namespace HrynCo.NotificationService.Worker.Services.EmailProcessing;
+
+using System.Net.Mail;
+using System.Net.Sockets;
+
+public static class NotificationDeliveryErrorFormatter
+{
+    private const int MaximumErrorLength = 2000;
+    private const string FallbackError = "Notification delivery failed after all retry attempts.";
+
+    public static string Format(Exception exception)
+    {
+        string technicalMessage = Normalize(exception.GetBaseException().Message);
+        if (string.IsNullOrWhiteSpace(technicalMessage))
+        {
+            return FallbackError;
+        }
+
+        string contextualMessage = CreateContextualMessage(exception, technicalMessage);
+        return contextualMessage.Length <= MaximumErrorLength
+            ? contextualMessage
+            : contextualMessage[..MaximumErrorLength];
+    }
+
+    private static string CreateContextualMessage(Exception exception, string technicalMessage)
+    {
+        if (FindException<SmtpFailedRecipientException>(exception) is not null)
+        {
+            return "SMTP delivery failed after all retry attempts: " +
+                   "the SMTP server rejected the recipient address.";
+        }
+
+        SocketException? socketException = FindException<SocketException>(exception);
+        if (socketException is not null)
+        {
+            string reason = socketException.SocketErrorCode switch
+            {
+                SocketError.HostNotFound or SocketError.NoData =>
+                    "the configured SMTP server host could not be resolved",
+                SocketError.ConnectionRefused =>
+                    "the configured SMTP server refused the connection",
+                SocketError.TimedOut =>
+                    "the connection to the configured SMTP server timed out",
+                _ when technicalMessage.Contains(
+                    "Name or service not known",
+                    StringComparison.OrdinalIgnoreCase) =>
+                    "the configured SMTP server host could not be resolved",
+                _ => "the configured SMTP server could not be reached"
+            };
+
+            return $"SMTP delivery failed after all retry attempts: {reason} ({technicalMessage}).";
+        }
+
+        if (FindException<SmtpException>(exception) is not null)
+        {
+            return $"SMTP delivery failed after all retry attempts ({technicalMessage}).";
+        }
+
+        return $"Notification delivery failed after all retry attempts ({technicalMessage}).";
+    }
+
+    private static TException? FindException<TException>(Exception exception)
+        where TException : Exception
+    {
+        for (Exception? current = exception; current is not null; current = current.InnerException)
+        {
+            if (current is TException typedException)
+            {
+                return typedException;
+            }
+        }
+
+        return null;
+    }
+
+    private static string Normalize(string message)
+    {
+        return message.ReplaceLineEndings(" ").Trim();
+    }
+}

HrynCo.NotificationService.Worker.Services/EmailProcessing/NotificationResultPublisher.cs

@@ -0,0 +1,63 @@
+namespace HrynCo.NotificationService.Worker.Services.EmailProcessing;
+
+using HrynCo.NotificationService.Contracts.Messages;
+using Hrynco.RabbitMq;
+using Microsoft.Extensions.Logging;
+
+internal sealed class NotificationResultPublisher : INotificationResultPublisher
+{
+    private readonly ILogger<NotificationResultPublisher> _logger;
+    private readonly IRabbitMqPublisher _publisher;
+
+    public NotificationResultPublisher(
+        IRabbitMqPublisher publisher,
+        ILogger<NotificationResultPublisher> logger)
+    {
+        _publisher = publisher;
+        _logger = logger;
+    }
+
+    public async Task PublishAsync(
+        SendEmailMessage message,
+        string? deliveryError,
+        CancellationToken cancellationToken)
+    {
+        CorrelationContext correlationContext = message.CorrelationContext;
+        string? replyTo = correlationContext.ReplyTo;
+        if (string.IsNullOrWhiteSpace(replyTo))
+        {
+            return;
+        }
+
+        try
+        {
+            var result = new NotificationResultMessage
+            {
+                CorrelationContext = correlationContext with { ReplyTo = null },
+                Data = new NotificationResultData
+                {
+                    ServiceName = message.Data.ServiceName,
+                    RecipientEmail = message.Data.RecipientEmail,
+                    TemplateKey = message.Data.TemplateKey,
+                    Timestamp = DateTimeOffset.UtcNow,
+                    ErrorMessage = deliveryError
+                }
+            };
+
+            await _publisher.PublishAsync(replyTo, result, cancellationToken);
+
+            _logger.LogDebug(
+                "Notification result published to reply queue {Queue} [CorrelationId={CorrelationId}]",
+                replyTo,
+                correlationContext.CorrelationId);
+        }
+        catch (Exception exception)
+        {
+            _logger.LogWarning(
+                exception,
+                "Failed to publish notification result to reply queue {Queue} [CorrelationId={CorrelationId}]",
+                replyTo,
+                correlationContext.CorrelationId);
+        }
+    }
+}

HrynCo.NotificationService.Worker.Services/EmailProcessing/RecipientAddressRedactor.cs

@@ -0,0 +1,22 @@
+namespace HrynCo.NotificationService.Worker.Services.EmailProcessing;
+
+public static class RecipientAddressRedactor
+{
+    public static string Redact(string? address)
+    {
+        if (string.IsNullOrWhiteSpace(address))
+            return "<missing>";
+
+        int separator = address.LastIndexOf('@');
+        if (separator <= 0 || separator == address.Length - 1)
+            return "***";
+
+        string local = address[..separator];
+        string domain = address[(separator + 1)..];
+        int dot = domain.LastIndexOf('.');
+        string domainName = dot > 0 ? domain[..dot] : domain;
+        string suffix = dot > 0 ? domain[dot..] : string.Empty;
+
+        return $"{local[0]}***@{domainName[0]}***{suffix}";
+    }
+}

HrynCo.NotificationService.Worker.Services/EmailProcessing/RenderedEmail.cs

@@ -1,3 +1,3 @@
-namespace HrynCo.NotificationService.Worker;
+namespace HrynCo.NotificationService.Worker.Services.EmailProcessing;
 
 public record RenderedEmail(string Subject, string HtmlBody, string TextBody);

HrynCo.NotificationService.Worker.Services/EmailProcessing/SendEmailMessageValidator.cs

@@ -0,0 +1,36 @@
+namespace HrynCo.NotificationService.Worker.Services.EmailProcessing;
+
+using System.Net.Mail;
+using HrynCo.NotificationService.Contracts.Messages;
+
+public static class SendEmailMessageValidator
+{
+    public static void Validate(SendEmailMessage message)
+    {
+        ArgumentNullException.ThrowIfNull(message);
+
+        if (message.CorrelationContext is null)
+            throw new InvalidDataException("CorrelationContext is required.");
+        if (string.IsNullOrWhiteSpace(message.CorrelationContext.CorrelationId))
+            throw new InvalidDataException("CorrelationContext.CorrelationId is required.");
+        if (message.Data is null)
+            throw new InvalidDataException("Data is required.");
+
+        Require(message.Data.ServiceName, nameof(message.Data.ServiceName));
+        Require(message.Data.TemplateKey, nameof(message.Data.TemplateKey));
+        Require(message.Data.RecipientEmail, nameof(message.Data.RecipientEmail));
+        Require(message.Data.RecipientName, nameof(message.Data.RecipientName));
+        Require(message.Data.LanguageCode, nameof(message.Data.LanguageCode));
+
+        if (!MailAddress.TryCreate(message.Data.RecipientEmail, out _))
+            throw new InvalidDataException("RecipientEmail is not a valid email address.");
+        if (message.Data.Variables is null)
+            throw new InvalidDataException("Variables is required.");
+    }
+
+    private static void Require(string? value, string fieldName)
+    {
+        if (string.IsNullOrWhiteSpace(value))
+            throw new InvalidDataException($"{fieldName} is required.");
+    }
+}

HrynCo.NotificationService.Worker.Services/EmailProcessing/SendEmailService.cs

@@ -0,0 +1,133 @@
+namespace HrynCo.NotificationService.Worker.Services.EmailProcessing;
+
+using HrynCo.NotificationService.Contracts.Messages;
+using HrynCo.NotificationService.DAL.Abstract.Providers;
+using HrynCo.NotificationService.DAL.Abstract.Repositories;
+using HrynCo.NotificationService.DAL.Abstract.Templates;
+using Microsoft.Extensions.Logging;
+
+internal sealed class SendEmailService : ISendEmailService
+{
+    private readonly IEmailChannelRepository _channelRepository;
+    private readonly IEmailChannelUsageRepository _usageRepository;
+    private readonly IEmailTemplateService _templateService;
+    private readonly IEmailTemplateRenderingService _templateRenderingService;
+    private readonly ISmtpEmailSender _smtpEmailSender;
+    private readonly INotificationResultPublisher _resultPublisher;
+    private readonly ILogger<SendEmailService> _logger;
+
+    public SendEmailService(
+        IEmailChannelRepository channelRepository,
+        IEmailChannelUsageRepository usageRepository,
+        IEmailTemplateService templateService,
+        IEmailTemplateRenderingService templateRenderingService,
+        ISmtpEmailSender smtpEmailSender,
+        INotificationResultPublisher resultPublisher,
+        ILogger<SendEmailService> logger)
+    {
+        _channelRepository = channelRepository;
+        _usageRepository = usageRepository;
+        _templateService = templateService;
+        _templateRenderingService = templateRenderingService;
+        _smtpEmailSender = smtpEmailSender;
+        _resultPublisher = resultPublisher;
+        _logger = logger;
+    }
+
+    public async Task ProcessAsync(SendEmailMessage message, CancellationToken cancellationToken)
+    {
+        SendEmailMessageValidator.Validate(message);
+        SendEmailMessageData data = message.Data;
+        string redactedRecipient = RecipientAddressRedactor.Redact(data.RecipientEmail);
+
+        _logger.LogInformation(
+            "Processing SendEmail for service={Service} template={Template} recipient={Recipient} [CorrelationId={CorrelationId}]",
+            data.ServiceName, data.TemplateKey, redactedRecipient, message.CorrelationContext?.CorrelationId);
+
+        EmailChannel channel = await ResolveChannelAsync(data.ServiceName, cancellationToken);
+        EmailTemplate template = await GetTemplateAsync(data, cancellationToken);
+
+        await EnforceLimitsAsync(channel, cancellationToken);
+
+        RenderedEmail rendered = _templateRenderingService.Render(template, data);
+
+        SmtpChannelSettings smtpChannel = channel.Settings as SmtpChannelSettings
+                                          ?? throw new InvalidOperationException(
+                                              $"Channel type '{channel.EmailChannelType}' is not supported for sending.");
+
+        try
+        {
+            await _smtpEmailSender.SendAsync(
+                smtpChannel,
+                rendered,
+                data.RecipientEmail,
+                data.RecipientName,
+                cancellationToken);
+        }
+        catch (Exception ex)
+        {
+            _logger.LogError(ex, "SMTP send failed for channel {ChannelId}", channel.Id);
+            throw;
+        }
+
+        await _usageRepository.IncrementUsageAsync(
+            channel.Id,
+            DateOnly.FromDateTime(DateTime.UtcNow),
+            cancellationToken);
+
+        _logger.LogInformation(
+            "Email sent successfully service={Service} template={Template} recipient={Recipient}",
+            data.ServiceName, data.TemplateKey, redactedRecipient);
+
+        await _resultPublisher.PublishAsync(message, null, cancellationToken);
+    }
+
+    private async Task<EmailTemplate> GetTemplateAsync(SendEmailMessageData data, CancellationToken cancellationToken)
+    {
+        return await _templateService.GetAsync(
+            data.ServiceName,
+            data.TemplateKey,
+            data.LanguageCode,
+            cancellationToken);
+    }
+
+    private async Task<EmailChannel> ResolveChannelAsync(string serviceName, CancellationToken ct)
+    {
+        var channels = await _channelRepository.GetByServiceAsync(serviceName, ct);
+
+        return channels
+                   .Where(c => c.IsActive)
+                   .OrderBy(c => c.Priority)
+                   .FirstOrDefault()
+               ?? throw new InvalidOperationException(
+                   $"No active email channel found for service '{serviceName}'.");
+    }
+
+    private async Task EnforceLimitsAsync(EmailChannel channel, CancellationToken ct)
+    {
+        DateOnly today = DateOnly.FromDateTime(DateTime.UtcNow);
+
+        if (channel.DailyLimit.HasValue)
+        {
+            int daily = await _usageRepository.GetDailyCountAsync(channel.Id, today, ct);
+
+            if (daily >= channel.DailyLimit.Value)
+            {
+                throw new InvalidOperationException(
+                    $"Channel '{channel.Id}' daily limit of {channel.DailyLimit.Value} reached ({daily} sent today).");
+            }
+        }
+
+        if (channel.MonthlyLimit.HasValue)
+        {
+            int monthly = await _usageRepository.GetMonthlyCountAsync(channel.Id, today.Year, today.Month, ct);
+
+            if (monthly >= channel.MonthlyLimit.Value)
+            {
+                throw new InvalidOperationException(
+                    $"Channel '{channel.Id}' monthly limit of {channel.MonthlyLimit.Value} reached ({monthly} sent this month).");
+            }
+        }
+    }
+
+}

HrynCo.NotificationService.Worker.Services/EmailProcessing/SmtpEmailSender.cs

@@ -0,0 +1,47 @@
+namespace HrynCo.NotificationService.Worker.Services.EmailProcessing;
+
+using System.Net;
+using System.Net.Mail;
+using System.Text;
+using HrynCo.NotificationService.DAL.Abstract.Providers;
+
+internal sealed class SmtpEmailSender : ISmtpEmailSender
+{
+    public async Task SendAsync(
+        SmtpChannelSettings settings,
+        RenderedEmail email,
+        string recipientEmail,
+        string recipientName,
+        CancellationToken cancellationToken)
+    {
+        using var client = new SmtpClient(settings.Host, settings.Port)
+        {
+            EnableSsl = settings.UseSsl,
+            Credentials = string.IsNullOrWhiteSpace(settings.Username)
+                ? null
+                : new NetworkCredential(settings.Username, settings.Password)
+        };
+
+        using var mail = new MailMessage
+        {
+            From = new MailAddress(settings.FromEmail, settings.FromName),
+            Subject = email.Subject,
+            Body = email.TextBody,
+            IsBodyHtml = false,
+            BodyEncoding = Encoding.UTF8,
+            SubjectEncoding = Encoding.UTF8
+        };
+
+        if (!string.IsNullOrWhiteSpace(email.HtmlBody))
+        {
+            AlternateView html = AlternateView.CreateAlternateViewFromString(
+                email.HtmlBody,
+                Encoding.UTF8,
+                "text/html");
+            mail.AlternateViews.Add(html);
+        }
+
+        mail.To.Add(new MailAddress(recipientEmail, recipientName));
+        await client.SendMailAsync(mail, cancellationToken);
+    }
+}

HrynCo.NotificationService.Worker.Services/HrynCo.NotificationService.Worker.Services.csproj

@@ -0,0 +1,21 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <TargetFramework>net10.0</TargetFramework>
+    <ImplicitUsings>enable</ImplicitUsings>
+    <Nullable>enable</Nullable>
+    <RootNamespace>HrynCo.NotificationService.Worker.Services</RootNamespace>
+  </PropertyGroup>
+
+  <ItemGroup>
+    <PackageReference Include="HrynCo.RabbitMq" />
+    <PackageReference Include="Microsoft.Extensions.DependencyInjection.Abstractions" />
+    <PackageReference Include="Microsoft.Extensions.Logging.Abstractions" />
+  </ItemGroup>
+
+  <ItemGroup>
+    <ProjectReference Include="..\HrynCo.NotificationService.Contracts\HrynCo.NotificationService.Contracts.csproj" />
+    <ProjectReference Include="..\HrynCo.NotificationService.DAL.Abstract\HrynCo.NotificationService.DAL.Abstract.csproj" />
+  </ItemGroup>
+
+</Project>

HrynCo.NotificationService.Worker.Services/Properties/AssemblyInfo.cs

@@ -0,0 +1,3 @@
+using System.Runtime.CompilerServices;
+
+[assembly: InternalsVisibleTo("HrynCo.NotificationService.Services.Tests")]

HrynCo.NotificationService.Worker.Services/ServiceCollectionExtensions.cs

@@ -0,0 +1,19 @@
+using HrynCo.NotificationService.Worker.Services.EmailProcessing;
+using Hrynco.RabbitMq;
+using Microsoft.Extensions.DependencyInjection;
+
+namespace HrynCo.NotificationService.Worker.Services;
+
+public static class ServiceCollectionExtensions
+{
+    public static IServiceCollection AddNotificationWorkerServices(this IServiceCollection services)
+    {
+        services.AddSingleton<IRabbitMqPublisher, RabbitMqPublisher>();
+        services.AddScoped<IEmailTemplateService, EmailTemplateService>();
+        services.AddScoped<IEmailTemplateRenderingService, EmailTemplateRenderingService>();
+        services.AddScoped<ISmtpEmailSender, SmtpEmailSender>();
+        services.AddScoped<INotificationResultPublisher, NotificationResultPublisher>();
+        services.AddScoped<ISendEmailService, SendEmailService>();
+        return services;
+    }
+}

HrynCo.NotificationService.Worker/AppSettings.cs

@@ -8,4 +8,4 @@ public sealed class AppSettings
 
     public string ConnectionString { get; init; } = string.Empty;
     public RabbitMqSettings RabbitMq { get; init; } = null!;
-}
+}

HrynCo.NotificationService.Worker/Dockerfile

@@ -11,7 +11,7 @@ COPY ["Directory.Build.props", "."]
 COPY ["Directory.Packages.props", "."]
 COPY ["HrynCo.NotificationService.DAL.Abstract/HrynCo.NotificationService.DAL.Abstract.csproj", "HrynCo.NotificationService.DAL.Abstract/"]
 COPY ["HrynCo.NotificationService.DAL.EF/HrynCo.NotificationService.DAL.EF.csproj", "HrynCo.NotificationService.DAL.EF/"]
-COPY ["HrynCo.NotificationService.Services/HrynCo.NotificationService.Services.csproj", "HrynCo.NotificationService.Services/"]
+COPY ["HrynCo.NotificationService.Worker.Services/HrynCo.NotificationService.Worker.Services.csproj", "HrynCo.NotificationService.Worker.Services/"]
 COPY ["HrynCo.NotificationService.Worker/HrynCo.NotificationService.Worker.csproj", "HrynCo.NotificationService.Worker/"]
 
 RUN dotnet restore "HrynCo.NotificationService.Worker/HrynCo.NotificationService.Worker.csproj"
@@ -28,4 +28,4 @@ RUN dotnet publish "./HrynCo.NotificationService.Worker.csproj" -c $BUILD_CONFIG
 FROM base AS final
 WORKDIR /app
 COPY --from=publish /app/publish .
-ENTRYPOINT ["dotnet", "HrynCo.NotificationService.Worker.dll"]
+ENTRYPOINT ["dotnet", "HrynCo.NotificationService.Worker.dll"]

HrynCo.NotificationService.Worker/HrynCo.NotificationService.Worker.csproj

@@ -10,7 +10,6 @@
   <ItemGroup>
     <PackageReference Include="Microsoft.Extensions.Hosting" />
     <PackageReference Include="HrynCo.RabbitMq" />
-    <PackageReference Include="MediatR" />
     <PackageReference Include="Serilog.Extensions.Hosting" />
     <PackageReference Include="Serilog.Settings.Configuration" />
     <PackageReference Include="Serilog.Sinks.Console" />
@@ -19,7 +18,7 @@
 
   <ItemGroup>
     <ProjectReference Include="..\HrynCo.NotificationService.Contracts\HrynCo.NotificationService.Contracts.csproj" />
-    <ProjectReference Include="..\HrynCo.NotificationService.Services\HrynCo.NotificationService.Services.csproj" />
     <ProjectReference Include="..\HrynCo.NotificationService.DAL.EF\HrynCo.NotificationService.DAL.EF.csproj" />
+    <ProjectReference Include="..\HrynCo.NotificationService.Worker.Services\HrynCo.NotificationService.Worker.Services.csproj" />
   </ItemGroup>
 </Project>

HrynCo.NotificationService.Worker/Program.cs

@@ -1,8 +1,7 @@
 using HrynCo.NotificationService.DAL.EF;
-using HrynCo.NotificationService.Services;
 using HrynCo.NotificationService.Worker;
+using HrynCo.NotificationService.Worker.Services;
 using Hrynco.RabbitMq;
-using Microsoft.Extensions.Options;
 
 var builder = Host.CreateApplicationBuilder(args);
 
@@ -14,7 +13,7 @@ var appSettings = builder.Configuration
 
 builder.Services.AddSingleton(appSettings);
 builder.Services.AddNotificationDataAccess(appSettings.ConnectionString);
-builder.Services.AddNotificationServices();
+builder.Services.AddNotificationWorkerServices();
 
 builder.Services.Configure<RabbitMqSettings>(
     builder.Configuration.GetSection($"{AppSettings.SectionName}:RabbitMq"));
@@ -22,4 +21,4 @@ builder.Services.Configure<RabbitMqSettings>(
 builder.Services.AddHostedService<SendEmailConsumer>();
 
 var host = builder.Build();
-host.Run();
+host.Run();

HrynCo.NotificationService.Worker/Properties/AssemblyInfo.cs

@@ -0,0 +1,3 @@
+using System.Runtime.CompilerServices;
+
+[assembly: InternalsVisibleTo("HrynCo.NotificationService.Services.Tests")]

HrynCo.NotificationService.Worker/SendEmailConsumer.cs

@@ -1,174 +1,70 @@
 namespace HrynCo.NotificationService.Worker;
 
-using System.Text;
-using System.Text.Json;
 using HrynCo.NotificationService.Contracts.Messages;
-using HrynCo.NotificationService.DAL.Abstract.Providers;
-using HrynCo.NotificationService.DAL.Abstract.Repositories;
-using HrynCo.NotificationService.DAL.Abstract.Templates;
-using HrynCo.NotificationService.Services.EmailChannels.Send;
+using HrynCo.NotificationService.Worker.Services.EmailProcessing;
 using Hrynco.RabbitMq;
-using MediatR;
 using Microsoft.Extensions.Options;
-using RabbitMQ.Client;
 
-public sealed class SendEmailConsumer(
-    IOptionsMonitor<RabbitMqSettings> options,
-    IEmailChannelRepository channelRepository,
-    IEmailTemplateRepository templateRepository,
-    IEmailChannelUsageRepository usageRepository,
-    IMediator mediator,
-    AppSettings appSettings,
-    ILogger<SendEmailConsumer> logger)
-    : RabbitMqConsumerBase<SendEmailMessage, SendEmailMessageData>(options, logger)
+public sealed class SendEmailConsumer : RabbitMqConsumerBase<SendEmailMessage, SendEmailMessageData>
 {
-    private const string IncomingQueue = "notification.send-email";
+    internal const string IncomingQueue = "notification.send-email";
+    internal const string SupportedMessageType = "Notification.SendEmail.v1";
+
+    private readonly IServiceScopeFactory _scopeFactory;
+    private readonly ILogger<SendEmailConsumer> _logger;
+
+    public SendEmailConsumer(
+        IOptionsMonitor<RabbitMqSettings> options,
+        IServiceScopeFactory scopeFactory,
+        ILogger<SendEmailConsumer> logger)
+        : base(options, logger)
+    {
+        _scopeFactory = scopeFactory;
+        _logger = logger;
+    }
 
     protected override string QueueName => IncomingQueue;
 
-    protected override async Task HandleMessageAsync(SendEmailMessage message, CancellationToken cancellationToken)
+    protected override bool TryValidateMessage(
+        SendEmailMessage message,
+        RabbitMqMessageContext context,
+        out string? validationError)
     {
-        var data = message.Data;
-
-        logger.LogInformation(
-            "Processing SendEmail for service={Service} template={Template} recipient={Recipient} [CorrelationId={CorrelationId}]",
-            data.ServiceName, data.TemplateKey, data.RecipientEmail, message.CorrelationContext?.CorrelationId);
-
-        var channel = await ResolveChannelAsync(data.ServiceName, cancellationToken);
-        var template = await ResolveTemplateAsync(data.ServiceName, data.TemplateKey, data.LanguageCode, cancellationToken);
-
-        await EnforceLimitsAsync(channel, cancellationToken);
-
-        var rendered = RenderTemplate(template, data);
-
-        var sendResult = await mediator.Send(
-            new SendEmailCommand(channel.Id, data.RecipientEmail, data.RecipientName,
-                rendered.Subject, rendered.HtmlBody, rendered.TextBody),
-            cancellationToken);
-
-        if (!sendResult.IsSuccess)
-            throw new InvalidOperationException(sendResult.Error?.Message ?? "Send failed.");
-
-        logger.LogInformation(
-            "Email sent successfully service={Service} template={Template} recipient={Recipient}",
-            data.ServiceName, data.TemplateKey, data.RecipientEmail);
-
-        await PublishResultAsync(message.CorrelationContext, data, errorMessage: null, cancellationToken);
+        validationError = SendEmailDeliveryValidator.GetValidationError(
+            message,
+            context,
+            SupportedMessageType);
+        return validationError is null;
     }
 
-    private async Task<EmailChannel> ResolveChannelAsync(string serviceName, CancellationToken ct)
+    protected override async Task HandleMessageAsync(
+        SendEmailMessage message,
+        RabbitMqMessageContext context,
+        CancellationToken cancellationToken)
     {
-        var channels = await channelRepository.GetByServiceAsync(serviceName, ct);
-
-        return channels
-            .Where(c => c.IsActive)
-            .OrderBy(c => c.Priority)
-            .FirstOrDefault()
-            ?? throw new InvalidOperationException(
-                $"No active email channel found for service '{serviceName}'.");
-    }
-
-    private async Task<EmailTemplate> ResolveTemplateAsync(
-        string serviceName, string templateKey, string? languageCode, CancellationToken ct)
-    {
-        var lang = string.IsNullOrWhiteSpace(languageCode) ? "en" : languageCode;
-        var template = await templateRepository.GetAsync(serviceName, templateKey, lang, ct);
-
-        if (template is null && lang != "en")
-            template = await templateRepository.GetAsync(serviceName, templateKey, "en", ct);
-
-        return template
-            ?? throw new InvalidOperationException(
-                $"Template not found: service='{serviceName}' key='{templateKey}' language='{lang}'.");
-    }
-
-    private async Task EnforceLimitsAsync(EmailChannel channel, CancellationToken ct)
-    {
-        var today = DateOnly.FromDateTime(DateTime.UtcNow);
-
-        if (channel.DailyLimit.HasValue)
+        string payloadCorrelationId = message.CorrelationContext.CorrelationId;
+        if (!string.IsNullOrWhiteSpace(context.CorrelationId) &&
+            !string.Equals(context.CorrelationId, payloadCorrelationId, StringComparison.Ordinal))
         {
-            var daily = await usageRepository.GetDailyCountAsync(channel.Id, today, ct);
-            if (daily >= channel.DailyLimit.Value)
-                throw new InvalidOperationException(
-                    $"Channel '{channel.Id}' daily limit of {channel.DailyLimit.Value} reached ({daily} sent today).");
+            _logger.LogWarning(
+                "Broker and payload correlation IDs differ; payload correlation ID will be used");
         }
 
-        if (channel.MonthlyLimit.HasValue)
-        {
-            var monthly = await usageRepository.GetMonthlyCountAsync(channel.Id, today.Year, today.Month, ct);
-            if (monthly >= channel.MonthlyLimit.Value)
-                throw new InvalidOperationException(
-                    $"Channel '{channel.Id}' monthly limit of {channel.MonthlyLimit.Value} reached ({monthly} sent this month).");
-        }
+        await using AsyncServiceScope scope = _scopeFactory.CreateAsyncScope();
+        ISendEmailService service = scope.ServiceProvider.GetRequiredService<ISendEmailService>();
+        await service.ProcessAsync(message, cancellationToken);
     }
 
-    private static RenderedEmail RenderTemplate(EmailTemplate template, SendEmailMessageData data)
+    protected override async Task HandleMessageRetriesExhaustedAsync(
+        SendEmailMessage message,
+        RabbitMqMessageContext context,
+        Exception exception,
+        CancellationToken cancellationToken)
     {
-        return new RenderedEmail(
-            Interpolate(template.Subject, data.Variables),
-            Interpolate(template.HtmlBody, data.Variables),
-            Interpolate(template.TextBody, data.Variables));
-    }
-
-    private static string Interpolate(string text, IReadOnlyDictionary<string, string> variables)
-    {
-        var sb = new StringBuilder(text);
-        foreach (var (key, value) in variables)
-            sb.Replace($"{{{{{key}}}}}", value);
-        return sb.ToString();
-    }
-
-    private async Task PublishResultAsync(
-        CorrelationContext? correlationContext,
-        SendEmailMessageData data,
-        string? errorMessage,
-        CancellationToken ct)
-    {
-        var replyTo = correlationContext?.ReplyTo;
-        if (string.IsNullOrWhiteSpace(replyTo))
-            return;
-
-        try
-        {
-            var result = new NotificationResultMessage
-            {
-                CorrelationContext = (correlationContext ?? new CorrelationContext { CorrelationId = Guid.NewGuid().ToString() }) with { ReplyTo = null },
-                Data = new NotificationResultData
-                {
-                    ServiceName = data.ServiceName,
-                    RecipientEmail = data.RecipientEmail,
-                    TemplateKey = data.TemplateKey,
-                    Timestamp = DateTimeOffset.UtcNow,
-                    ErrorMessage = errorMessage
-                }
-            };
-
-            byte[] body = Encoding.UTF8.GetBytes(JsonSerializer.Serialize(result));
-
-            var factory = new ConnectionFactory
-            {
-                HostName = appSettings.RabbitMq.Host,
-                Port = appSettings.RabbitMq.Port,
-                UserName = appSettings.RabbitMq.User,
-                Password = appSettings.RabbitMq.Password,
-                VirtualHost = appSettings.RabbitMq.VirtualHost
-            };
-
-            await using var conn = await factory.CreateConnectionAsync(ct);
-            await using var ch = await conn.CreateChannelAsync(cancellationToken: ct);
-
-            await ch.QueueDeclareAsync(replyTo, durable: true, exclusive: false, autoDelete: false,
-                cancellationToken: ct);
-            await ch.BasicPublishAsync(exchange: string.Empty, routingKey: replyTo, body: body,
-                cancellationToken: ct);
-
-            logger.LogDebug("Result published to reply queue '{Queue}' [CorrelationId={CorrelationId}]",
-                replyTo, correlationContext?.CorrelationId);
-        }
-        catch (Exception ex)
-        {
-            logger.LogWarning(ex, "Failed to publish notification result to reply queue '{Queue}'", replyTo);
-        }
+        string deliveryError = NotificationDeliveryErrorFormatter.Format(exception);
+        await using AsyncServiceScope scope = _scopeFactory.CreateAsyncScope();
+        INotificationResultPublisher resultPublisher =
+            scope.ServiceProvider.GetRequiredService<INotificationResultPublisher>();
+        await resultPublisher.PublishAsync(message, deliveryError, cancellationToken);
     }
 }

HrynCo.NotificationService.Worker/SendEmailDeliveryValidator.cs

@@ -0,0 +1,30 @@
+namespace HrynCo.NotificationService.Worker;
+
+using HrynCo.NotificationService.Contracts.Messages;
+using HrynCo.NotificationService.Worker.Services.EmailProcessing;
+using Hrynco.RabbitMq;
+
+internal static class SendEmailDeliveryValidator
+{
+    public static string? GetValidationError(
+        SendEmailMessage message,
+        RabbitMqMessageContext context,
+        string supportedMessageType)
+    {
+        if (string.IsNullOrWhiteSpace(context.MessageId))
+            return "AMQP MessageId is required.";
+
+        if (!string.Equals(context.MessageType, supportedMessageType, StringComparison.Ordinal))
+            return $"Unsupported AMQP message type '{context.MessageType ?? "<missing>"}'.";
+
+        try
+        {
+            SendEmailMessageValidator.Validate(message);
+            return null;
+        }
+        catch (InvalidDataException exception)
+        {
+            return exception.Message;
+        }
+    }
+}

HrynCo.NotificationService.Worker/appsettings.Development.json

@@ -1,4 +1,14 @@
 {
+  "App": {
+    "ConnectionString": "Host=192.168.2.121;Port=55435;Database=hrynco_ns_prod;Username=ns_user;Password=HAwS0c4A1QmH",
+    "RabbitMq": {
+      "Host": "192.168.2.121",
+      "Port": 5675,
+      "User": "ns_user",
+      "Password": "LN22mEWYdfCy",
+      "VirtualHost": "/"
+    }
+  },
   "Serilog": {
     "MinimumLevel": {
       "Default": "Debug",
@@ -7,6 +17,20 @@
         "Microsoft.EntityFrameworkCore": "Information",
         "Microsoft.AspNetCore": "Information"
       }
+    },
+    "WriteTo": [
+      { "Name": "Console" },
+      {
+        "Name": "Seq",
+        "Args": {
+          "serverUrl": "http://192.168.2.121:5341"
+        }
+      }
+    ],
+    "Enrich": [ "FromLogContext" ],
+    "Properties": {
+      "Application": "hrynco-notification-service-worker",
+      "Environment": "Development"
     }
   }
 }

HrynCo.NotificationService.slnx

@@ -20,5 +20,6 @@
   <Project Path="HrynCo.NotificationService.DAL.EF/HrynCo.NotificationService.DAL.EF.csproj" />
   <Project Path="HrynCo.NotificationService.Services.Tests/HrynCo.NotificationService.Services.Tests.csproj" />
   <Project Path="HrynCo.NotificationService.Services/HrynCo.NotificationService.Services.csproj" />
+  <Project Path="HrynCo.NotificationService.Worker.Services/HrynCo.NotificationService.Worker.Services.csproj" />
   <Project Path="HrynCo.NotificationService.Worker/HrynCo.NotificationService.Worker.csproj" />
 </Solution>

NuGet.Config

@@ -1,8 +1,5 @@
 <?xml version="1.0" encoding="utf-8"?>
 <configuration>
-  <config>
-    <add key="globalPackagesFolder" value="%USERPROFILE%\.nuget\packages" />
-  </config>
   <packageSources>
     <add key="nuget.org" value="https://api.nuget.org/v3/index.json" protocolVersion="3" />
   </packageSources>

README.md

@@ -1 +1,118 @@
 # hrynco-notification-service
+
+## Documentation
+
+- [ItemTracker outbox email consumer](docs/itemtracker-outbox-email-consumer.md)
+
+## Development environment
+
+The development Docker Compose stack runs PostgreSQL, RabbitMQ, database migrations,
+the Notification Service Web and Worker applications, Seq, and Mailpit.
+
+Prerequisite: install and start Docker Desktop. Then run the installation script from
+the repository root:
+
+```powershell
+.\docker\environments\install-development.cmd
+```
+
+The script validates Docker and the Compose configuration, builds the application
+images, starts the complete stack in the background, and prints container status and
+the main development URLs. It can also be launched directly from File Explorer or
+from another working directory.
+
+To validate the setup without building images or creating containers, run:
+
+```powershell
+.\docker\environments\install-development.cmd --validate-only
+```
+
+By default, the script uses the tracked `docker/environments/.env.Development` file:
+
+```dotenv
+DB_NAME=notification_service
+DB_USER=postgres
+DB_PASS=postgres
+VOLUME_PREFIX=ns-dev
+RABBITMQ_USER=guest
+RABBITMQ_PASSWORD=guest
+RABBITMQ_AMQP_PORT=5672
+RABBITMQ_MANAGEMENT_PORT=15672
+WEB_PORT=5200
+DEVELOPMENT_EMAIL_SERVICE_NAME=TestService
+```
+
+To use personal values, copy it to the Git-ignored
+`docker/environments/.env.local`, adjust the values, and run Docker Compose manually:
+
+```powershell
+docker compose --env-file docker/environments/.env.local `
+  -f docker/environments/docker-compose.yml `
+  -f docker/environments/docker-compose.Development.yml `
+  up --build -d
+```
+
+After startup, the main development endpoints are:
+
+- Notification Service admin: `http://localhost:5200/admin/channels`
+- Notification templates: `http://localhost:5200/admin/templates`
+- RabbitMQ management: `http://localhost:15672` (`guest` / `guest`)
+- Mailpit inbox: `http://localhost:8025`
+- Seq logs: `http://localhost:5342`
+- PostgreSQL: `localhost:5433`
+
+During development migrations, the stack idempotently creates an active Mailpit SMTP
+channel and a neutral English `TestEmail` template for
+`DEVELOPMENT_EMAIL_SERVICE_NAME`. Existing channels and templates are never
+overwritten. Change that environment value when the publisher uses another service
+name.
+
+Check container status and follow Worker logs:
+
+```powershell
+docker compose --env-file docker/environments/.env.local `
+  -f docker/environments/docker-compose.yml `
+  -f docker/environments/docker-compose.Development.yml `
+  ps
+
+docker compose --env-file docker/environments/.env.local `
+  -f docker/environments/docker-compose.yml `
+  -f docker/environments/docker-compose.Development.yml `
+  logs -f worker
+```
+
+Stop the environment without deleting its database and RabbitMQ volumes:
+
+```powershell
+docker compose --env-file docker/environments/.env.local `
+  -f docker/environments/docker-compose.yml `
+  -f docker/environments/docker-compose.Development.yml `
+  down
+```
+
+See the [ItemTracker consumer guide](docs/itemtracker-outbox-email-consumer.md#local-end-to-end-setup)
+for the complete end-to-end setup.
+
+## Notification worker flow
+
+```mermaid
+flowchart TD
+    A[Worker host starts] --> B[Load config and register services]
+    B --> C[Start SendEmailConsumer]
+    C --> D[Receive message from notification.send-email]
+    D --> E[Validate Notification.SendEmail.v1 metadata and payload]
+    E --> F[Resolve SendEmailService]
+    F --> G[Pick channel and exact-language template]
+    G --> H[Validate variables and render email content]
+    H --> I[Send via SMTP]
+    I --> J[Update usage counters]
+    J --> K[Optionally publish result to reply queue]
+    K --> L[Acknowledge RabbitMQ delivery]
+    I -. failure .-> M[Log and retry]
+    M -->|retries exhausted| N[Publish terminal failure result]
+    N --> O[Nack original delivery without requeue]
+```
+
+Template variables are treated as plain text. The worker HTML-encodes every variable while
+rendering `HtmlBody`; subject and plain-text body interpolation preserve the original value.
+Templates must express markup in `body.html` instead of supplying HTML through variables.

docker/environments/.env.Development

@@ -0,0 +1,10 @@
+DB_NAME=notification_service
+DB_USER=postgres
+DB_PASS=postgres
+VOLUME_PREFIX=ns-dev
+RABBITMQ_USER=guest
+RABBITMQ_PASSWORD=guest
+RABBITMQ_AMQP_PORT=5672
+RABBITMQ_MANAGEMENT_PORT=15672
+WEB_PORT=5200
+DEVELOPMENT_EMAIL_SERVICE_NAME=TestService

docker/environments/docker-compose.Development.yml

@@ -3,7 +3,9 @@ name: hrynco-notification-service
 services:
   migrator:
     environment:
+      - DOTNET_ENVIRONMENT=Development
       - App__ConnectionString=Host=db;Port=5432;Database=notification_service;Username=postgres;Password=postgres
+      - DevelopmentSeed__ServiceName=${DEVELOPMENT_EMAIL_SERVICE_NAME:-TestService}
 
   web:
     environment:
@@ -29,9 +31,6 @@ services:
     environment:
       RABBITMQ_DEFAULT_USER: guest
       RABBITMQ_DEFAULT_PASS: guest
-    ports:
-      - "5672:5672"
-      - "15672:15672"
     networks:
       - internal
 
@@ -55,10 +54,17 @@ services:
     networks:
       - internal
 
+  mailpit:
+    image: axllent/mailpit:v1.30.0
+    ports:
+      - "8025:8025"
+    networks:
+      - internal
+
 volumes:
   pgdata:
     name: ns-dev-pgdata
   rabbitmq_data:
     name: ns-dev-rabbitmq-data
   seq_data:
-    name: ns-dev-seq
+    name: ns-dev-seq