# Story 5.4: Email Notification System

## Metadata
- **Story ID**: 5.4
- **Title**: Email Notification System
- **Epic**: 5 - Infrastructure Adapters
- **Status**: Pending
- **Priority**: High
- **Estimated Time**: 5-6 hours
- **Dependencies**: 1.1, 2.2

## Goal
Implement a complete email notification system with SMTP support, HTML email templates, and integration with identity management.

## Description
This story implements email notifications using SMTP with support for HTML emails and templates. It integrates with the identity service to send verification and password reset emails.

## Deliverables

### 1. Notification Interface (`pkg/notification/notification.go`)
- `Notifier` interface with:
  - `SendEmail(ctx context.Context, to, subject, body string) error`
  - `SendHTMLEmail(ctx context.Context, to, subject, htmlBody, textBody string) error`
  - `SendSMS(ctx context.Context, to, message string) error` (placeholder)

### 2. SMTP Implementation (`internal/infra/email/smtp_notifier.go`)
- SMTP client setup
- HTML email support
- Email templates for:
  - Email verification
  - Password reset
  - Welcome email

### 3. Integration with Identity Service
- Send verification email on registration
- Send password reset email
- Send welcome email

### 4. Configuration
- Email config in `config/default.yaml`:
  - SMTP server
  - Port
  - Username/password
  - From address

### 5. DI Integration
- Provider function for Notifier
- Register in DI container

## Acceptance Criteria
- [ ] Notification interface is defined
- [ ] SMTP implementation works correctly
- [ ] HTML emails are sent successfully
- [ ] Email templates work
- [ ] Verification emails are sent on registration
- [ ] Password reset emails are sent
- [ ] Configuration is loaded from config
- [ ] Notifier is injectable via DI

## Files to Create/Modify
- `pkg/notification/notification.go` - Notification interface
- `internal/infra/email/smtp_notifier.go` - SMTP implementation
- `internal/infra/email/templates.go` - Email templates
- `internal/identity/user_service.go` - Integrate email sending
- `internal/di/providers.go` - Add notifier provider
- `config/default.yaml` - Add email config