Notification Service#

The notification service handles sending messages to users across multiple channels.

Delivery Channels#

• The service must support email delivery via SMTP
• The service must support push notifications
• The service must support in-app notification storage
• Channel preference must be configurable per user

Templates#

• Notifications must be rendered from named templates
• Templates must support variable interpolation
• Missing template variables must produce a clear error, not silent blanks
• Template rendering must be locale-aware

Retry Logic#

• Failed deliveries must be retried up to 3 times with exponential backoff
• Permanently failed deliveries must be marked and archived
• Retry status must be queryable per notification

Security Constraints#

• Email content must never include raw user passwords
• Push notification payloads must be limited to 4KB
• All notification content must be sanitized against XSS