name: error-tracking description: Add Sentry error tracking and performance monitoring to .NET services. Use this skill when adding error handling, creating new controllers, or tracking performance. ALL ERRORS MUST BE CAPTURED - no exceptions. type: guardrail enforcement: suggest priority: high

Error Tracking & Observability Guidelines

Project-Agnostic Error Tracking Patterns

Placeholders use {Placeholder} syntax - see docs/TEMPLATE_GLOSSARY.md.

Purpose

This skill provides guidelines for implementing robust error tracking and performance monitoring across .NET services (API, Blazor). It outlines patterns for centralized exception handling, logging, tracing, and Sentry integration.

When This Skill Activates

Triggered by:

• Keywords: "error handling", "exception", "sentry", "logging", "performance", "tracing", "problem details", "observability"
• Intent patterns: "add error logging", "implement try-catch", "monitor API performance", "handle UI errors"
• File patterns: **/Program.cs, **/*Controller.cs, **/*Handler.cs, **/*Repository.cs, **/*.razor

CRITICAL RULE: Do Not Swallow Exceptions!

All errors MUST be handled gracefully. Use structured logging (ILogger) and centralized exception handling. When Sentry is integrated, capture all exceptions.

Resources

For detailed implementation examples, refer to the resources/ folder within this skill.

Quick Reference

1. Centralized API Exception Handling

API unhandled exceptions are caught and transformed into RFC 7807 ProblemDetails responses.

// {Project}.API/Program.cs (Simplified)
app.UseExceptionHandler(exceptionHandlerApp => { /* ... */ });

For complete code, see api-exception-handling.md.

2. MediatR Handler Logging & Error Capturing

A LoggingBehavior in the MediatR pipeline ensures all requests are logged and exceptions are captured.

// {Project}.Application/Behaviors/LoggingBehavior.cs (Simplified)
public sealed class LoggingBehavior<TRequest, TResponse>(ILogger<LoggingBehavior<TRequest, TResponse>> logger)
    : IPipelineBehavior<TRequest, TResponse>
{ /* ... */ }

For complete code, see mediatr-logging-behavior.md.

3. Database Performance Monitoring

Use ActivitySource for custom spans to trace database operations, integrating with OpenTelemetry.

// {Project}.Persistence/Repositories/{Entity}Repository.cs (Simplified)
using System.Diagnostics;
public class {Entity}Repository : I{Entity}Repository
{
    public async Task<List<{Entity}>> Get{Entities}WithDetails()
    {
        using var activity = ActivitySourceProvider.PersistenceActivitySource.StartActivity("...");
        // ... EF Core query ...
    }
}

For complete code, see db-performance-monitoring.md.

4. Blazor UI Error Boundary

Gracefully handle unhandled UI errors in Blazor components, displaying a fallback UI and logging the error.

<!-- {Project}.Blazor/Components/Pages/{Entities}.razor (Simplified) -->
<ErrorBoundary>
    <ChildContent> <!-- Potentially error-prone content --> </ChildContent>
    <ErrorContent Context="ex"> <!-- Fallback UI --> </ErrorContent>
</ErrorBoundary>

For complete code, see blazor-error-boundary.md.

5. Sentry Integration (Conceptual)

When Sentry is integrated, UseSentry and app.UseSentryTracing() provide automatic error and performance tracking.

// {Project}.API/Program.cs (Simplified)
builder.WebHost.UseSentry(options => { /* ... */ });
app.UseSentryTracing();

For complete conceptual configuration and usage, see sentry-middleware-config.md.

6. Testing Sentry Integration (Conceptual)

Dedicated endpoints can be used to verify Sentry's error and performance capturing capabilities.

// {Project}.API/Controllers/{Entity}Controller.cs (Simplified)
[HttpGet("sentry/test-error")]
public IActionResult TestSentryError() { /* ... */ }
[HttpGet("sentry/test-performance")]
public async Task<IActionResult> TestPerformance() { /* ... */ }

For complete test endpoint examples, see sentry-testing-endpoints.md.

Key Principles

• No Uncaught Exceptions: All exceptions, whether from API, MediatR handlers, or Blazor UI, should be caught and logged.
• Structured Logging: Use ILogger for all logging, leveraging structured logging capabilities.
• Contextual Information: When reporting errors, always include relevant context (user ID, tenant ID, request data, tags) to aid in debugging.
• Performance First: Monitor critical paths (database, external API calls) for performance bottlenecks.
• RFC 7807 Compliance: Ensure API error responses are standardized using ProblemDetails.

Related Skills:

• clean-architecture-rules - For proper error handling layer placement.
• cqrs-mediatr-guidelines - For error handling patterns within MediatR handlers.
• dotnet-efcore-guidelines - For database error handling and performance considerations.
• blazor-ui-conventions - For UI error handling patterns.