Resend Email Skill

Purpose

This skill enforces the project Resend email conventions automatically during email implementation. It ensures consistent patterns for service architecture, email sending operations, template management, broadcast handling, error handling, and Sentry integration.

Activation

This skill activates when:

• Creating or modifying src/lib/services/resend*.ts files
• Working with email template files in src/lib/email-templates/
• Implementing email sending operations via Resend
• Creating broadcast or newsletter functionality
• Any code that imports from resend package
• Files containing email-related operations (send, batch, broadcast)

Workflow

1. Detect Resend email work (imports from resend or uses ResendService patterns)
2. Load references/Resend-Email-Conventions.md
3. Generate/modify code following all conventions
4. Scan for violations of email patterns
5. Auto-fix all violations (no permission needed)
6. Report fixes applied

Key Patterns

Service Architecture

• Use ResendService static class pattern
• Methods must have Async suffix for async operations
• Apply circuit breaker protection via circuitBreakers.externalService()
• Implement retry logic via withDatabaseRetry()
• Add Sentry breadcrumbs on success, capture exceptions on failure

Email Sending

| Operation | Method | Limit | | ------------ | --------------------------------------- | ------------------ | | Single email | resend.emails.send() | 1 per call | | Batch emails | resend.batch.send() | Up to 100 per call | | Broadcast | resend.broadcasts.create() + send() | Audience-based |

Template Patterns

| Type | Use Case | Location | | -------------------- | ----------------------------------- | -------------------------- | | Inline HTML | Simple confirmations, notifications | Private static methods | | React Email | Complex newsletters, rich content | src/lib/email-templates/ | | Resend API Templates | Variable-based templates | Resend dashboard/API |

Error Handling

• Return { failedEmails, sentCount } for bulk operations
• Return boolean for single operations
• Use level: 'warning' for non-critical failures
• Never fail entire operation for partial failures

Broadcasts & Audiences

• Always include {{{RESEND_UNSUBSCRIBE_URL}}} in broadcasts
• Use variable syntax: {{{VARIABLE|fallback}}}
• Support scheduled sending via scheduledAt parameter

Anti-Patterns to Avoid

1. Never include PII in Sentry context
2. Never skip circuit breaker protection
3. Never exceed 100 emails per batch call
4. Never hardcode email addresses
5. Never send broadcasts without unsubscribe link
6. Never use external CSS in email templates (inline only)
7. Never skip retry logic for email operations

Usage Pattern Reference

| Use Case | Method | Skills Needed | | --------------------- | ------------------------------- | ------------------------------- | | Waitlist confirmation | sendWaitlistConfirmationAsync | resend-email | | Welcome email | sendNewsletterWelcomeAsync | resend-email | | Bulk notifications | sendLaunchNotificationsAsync | resend-email | | Newsletter broadcast | sendBroadcastAsync | resend-email, sentry-monitoring | | React template email | sendWithTemplateAsync | resend-email |

References

• references/Resend-Email-Conventions.md - Complete Resend email conventions