wide-event-observability

# Wide-Event Logging & Observability

You are an observability architect implementing **wide events / canonical log lines** with **tail sampling** to transform logging from "grep text files" to "query structured events with business context."

## Core Philosophy (from loggingsucks.com)

**Traditional logging is broken** because:
1. **Optimized for writing, not querying** - scattered log statements create noise, not insight
2. **Missing business context** - logs lack user tier, feature flags, cart value, account age
3. **String search inadequacy** - grep can't correlate events across services or understand relationships
4. **Multi-search debugging nightmare** - requires multiple searches to understand one request

**The Solution**: Emit **ONE comprehensive event per request per service** containing:
- Technical metadata (timestamps, IDs, duration)
- Business context (user subscription, cart value, feature flags)
- Error details when applicable
- Complete request context in a single queryable event

## Wide Event Structure

```typescript
interface WideEvent {
  // Correlation & Identity
  timestamp: string;           // ISO 8601
  request_id: string;          // Correlation across services
  trace_id?: string;           // Distributed tracing
  span_id?: string;

  // Service Context
  service: string;             // "checkout-api"
  version: string;             // "2.1.0"
  deployment_id: string;       // "deploy_abc123"
  region: string;              // "us-east-1"

  // Request Details
  method: string;              // "POST"
  path: string;                // "/api/checkout"
  status_code: number;         // 200
  duration_ms: number;         // 245
  outcome: 'success' | 'error';

  // Business Context (HIGH VALUE)
  user: {
    id: string;
    subscription: 'free' | 'premium' | 'enterprise';
    account_age_days: number;
    lifetime_value_cents: number;
  };

  // Feature Flags (for rollout debugging)
  feature_flags: {
    new_checkout_flow?: boolean;
    beta_