error-handler

# Error Handler Observability that makes debugging fast and production predictable. Based on Google SRE (Site Reliability Engineering), OpenTelemetry semantic conventions, and production patterns from Sentry, Honeycomb, and Datadog. ## Sub-Commands | Command | Description | |---------|-------------| | `setup` | Set up OpenTelemetry SDK + instrumentation for a service | | `classify` | Classify errors by HTTP status, severity, and alert priority | | `recover` | Implement recovery patterns: retry with jitter, circuit breaker, timeout | | `slo` | Define error budget, SLO, and burn rate alerts | | `audit` | Audit existing error handling against best practices | ## The 3 Signals (OpenTelemetry) | Signal | Purpose | Example | |--------|---------|---------| | Traces | Follow a request across services | User request ? API Gateway ? Auth ? DB | | Metrics | Aggregate measurements over time | Request count, error rate, latency p50/p95/p99 | | Logs | Discrete events with context | "User login failed: invalid credentials for user_abc123" | All three signals share `trace_id` + `span_id` for correlation. ## Workflow ### Step 1: Classify errors | Category | HTTP | Severity | Log level | SLO impact | Alert? | |----------|------|:--------:|-----------|:----------:|:------:| | Validation (user error) | 400 | Low | info | No | No | | Authentication | 401 | Medium | warn | No | Only if spike detected | | Authorization | 403 | Medium | warn | No | Only if spike detected | | Not Found | 404...