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.agents/skills/cloudflare-deploy/references/observability/patterns.md

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+# Observability Patterns
+
+## Usage-Based Billing
+
+```typescript
+env.ANALYTICS.writeDataPoint({
+  blobs: [customerId, request.url, request.method],
+  doubles: [1], // request_count
+  indexes: [customerId]
+});
+```
+
+```sql
+SELECT blob1 AS customer_id, SUM(_sample_interval * double1) AS total_calls
+FROM api_usage WHERE timestamp >= DATE_TRUNC('month', NOW())
+GROUP BY customer_id
+```
+
+## Performance Monitoring
+
+```typescript
+const start = Date.now();
+const response = await fetch(url);
+env.ANALYTICS.writeDataPoint({
+  blobs: [url, response.status.toString()],
+  doubles: [Date.now() - start, response.status]
+});
+```
+
+```sql
+SELECT blob1 AS url, AVG(double1) AS avg_ms, percentile(double1, 0.95) AS p95_ms
+FROM fetch_metrics WHERE timestamp >= NOW() - INTERVAL '1' HOUR
+GROUP BY url
+```
+
+## Error Tracking
+
+```typescript
+env.ANALYTICS.writeDataPoint({
+  blobs: [error.name, request.url, request.method],
+  doubles: [1],
+  indexes: [error.name]
+});
+```
+
+## Multi-Tenant Tracking
+
+```typescript
+env.ANALYTICS.writeDataPoint({
+  indexes: [tenantId], // efficient filtering
+  blobs: [tenantId, url.pathname, method, status],
+  doubles: [1, duration, bytesSize]
+});
+```
+
+## Tail Worker Log Filtering
+
+```typescript
+export default {
+  async tail(events, env, ctx) {
+    const critical = events.filter(e => 
+      e.exceptions.length > 0 || e.event.wallTime > 1000000
+    );
+    if (critical.length === 0) return;
+    
+    ctx.waitUntil(
+      fetch('https://logging.example.com/ingest', {
+        method: 'POST',
+        headers: { 'Authorization': `Bearer ${env.API_KEY}` },
+        body: JSON.stringify(critical.map(e => ({
+          outcome: e.event.outcome,
+          cpu_ms: e.event.cpuTime / 1000,
+          errors: e.exceptions
+        })))
+      })
+    );
+  }
+};
+```
+
+## OpenTelemetry Export
+
+```typescript
+export default {
+  async tail(events, env, ctx) {
+    const otelSpans = events.map(e => ({
+      traceId: generateId(32),
+      spanId: generateId(16),
+      name: e.scriptName || 'worker.request',
+      attributes: [
+        { key: 'worker.outcome', value: { stringValue: e.event.outcome } },
+        { key: 'worker.cpu_time_us', value: { intValue: String(e.event.cpuTime) } }
+      ]
+    }));
+    
+    ctx.waitUntil(
+      fetch('https://api.honeycomb.io/v1/traces', {
+        method: 'POST',
+        headers: { 'X-Honeycomb-Team': env.HONEYCOMB_KEY },
+        body: JSON.stringify({ resourceSpans: [{ scopeSpans: [{ spans: otelSpans }] }] })
+      })
+    );
+  }
+};
+```