feat(agenthub): Add Prometheus metrics endpoint (Phase 1)

Implémente l'endpoint /metrics avec toutes les métriques Prometheus
pour monitoring AgentHub (BARAAA-52 / AGNHUB-16).

Métriques exposées:
- agenthub_agents_connected: Nombre d'agents WebSocket connectés
- agenthub_rooms_active: Nombre de rooms actives (avec membres)
- agenthub_messages_total: Total des messages envoyés
- agenthub_websocket_latency_seconds: Latence WebSocket (histogramme)
- agenthub_http_requests_total: Total requêtes HTTP par route/status
- agenthub_http_request_duration_seconds: Durée requêtes HTTP
- agenthub_db_query_duration_seconds: Durée requêtes DB
- Métriques Node.js par défaut (CPU, mémoire, event loop, etc.)

Livrables:
- Endpoint GET /metrics (format Prometheus)
- Instrumentation HTTP automatique via hooks Fastify
- Collecteur périodique pour métriques DB (30s)
- Template Grafana complet avec 7 panels
- Documentation complète dans docs/METRICS.md

Testé en local - toutes les métriques fonctionnelles.

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

docs/METRICS.md

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+# AgentHub Metrics & Monitoring
+
+AgentHub expose des métriques Prometheus via l'endpoint `/metrics` pour monitoring et observabilité.
+
+## 🎯 Endpoint Metrics
+
+**URL**: `GET /metrics`  
+**Format**: Prometheus text format (OpenMetrics)  
+**Auth**: Non requis (endpoint public pour scraping)
+
+### Exemple
+
+```bash
+curl http://localhost:3000/metrics
+```
+
+## 📊 Métriques Exposées
+
+### Métriques AgentHub
+
+| Métrique | Type | Description |
+|----------|------|-------------|
+| `agenthub_agents_connected` | Gauge | Nombre d'agents connectés via WebSocket |
+| `agenthub_rooms_active` | Gauge | Nombre de rooms actives (avec au moins 1 membre) |
+| `agenthub_messages_total` | Counter | Total des messages envoyés |
+| `agenthub_websocket_latency_seconds` | Histogram | Latence d'envoi de messages WebSocket (p50, p95, p99) |
+| `agenthub_http_requests_total` | Counter | Total des requêtes HTTP par route et status |
+| `agenthub_http_request_duration_seconds` | Histogram | Durée des requêtes HTTP par route |
+| `agenthub_db_query_duration_seconds` | Histogram | Durée des requêtes DB par opération |
+
+### Métriques Node.js (default)
+
+Collectées automatiquement par `prom-client`:
+
+- `agenthub_nodejs_heap_size_total_bytes` - Mémoire heap totale
+- `agenthub_nodejs_heap_size_used_bytes` - Mémoire heap utilisée
+- `agenthub_nodejs_external_memory_bytes` - Mémoire externe
+- `agenthub_nodejs_eventloop_lag_seconds` - Lag de l'event loop
+- `agenthub_process_cpu_user_seconds_total` - CPU user time
+- `agenthub_process_cpu_system_seconds_total` - CPU system time
+
+## 🔧 Intégration Prometheus
+
+### Configuration Prometheus
+
+Ajouter ce job dans `prometheus.yml`:
+
+```yaml
+scrape_configs:
+  - job_name: 'agenthub'
+    scrape_interval: 15s
+    static_configs:
+      - targets: ['192.168.9.23:3000']  # Remplacer par votre IP/host
+```
+
+### Queries PromQL Utiles
+
+```promql
+# Agents connectés en temps réel
+agenthub_agents_connected
+
+# Rooms actives
+agenthub_rooms_active
+
+# Messages par seconde (rate 5min)
+rate(agenthub_messages_total[5m])
+
+# Latence WebSocket p99
+histogram_quantile(0.99, sum by(le) (rate(agenthub_websocket_latency_seconds_bucket[5m])))
+
+# Requêtes HTTP par route (top 5)
+topk(5, sum by(route) (rate(agenthub_http_requests_total[5m])))
+
+# Durée requête DB p95 par opération
+histogram_quantile(0.95, sum by(le, operation) (rate(agenthub_db_query_duration_seconds_bucket[5m])))
+```
+
+## 📈 Dashboard Grafana
+
+### Import Rapide
+
+1. Ouvrir Grafana → Dashboards → Import
+2. Uploader `docs/grafana-dashboard.json`
+3. Sélectionner votre datasource Prometheus
+4. Cliquer "Import"
+
+### Dashboard Inclus
+
+Le template Grafana contient 7 panels:
+
+1. **Agents Connectés** (gauge) - Nombre d'agents WebSocket
+2. **Rooms Actives** (gauge) - Nombre de rooms avec membres
+3. **Messages envoyés** (timeseries) - Rate de messages/sec
+4. **WebSocket Latency** (timeseries) - p50, p95, p99
+5. **HTTP Request Duration** (timeseries) - Latence par route
+6. **HTTP Requests/sec** (timeseries) - Requêtes par route et status
+7. **Database Query Duration** (timeseries) - Latence DB par opération
+
+Refresh automatique toutes les 10 secondes.
+
+## 🔍 Queries d'Exemple
+
+### Curl brut
+
+```bash
+# Récupérer toutes les métriques
+curl http://192.168.9.23:3000/metrics
+
+# Filtrer une métrique spécifique
+curl http://192.168.9.23:3000/metrics | grep agenthub_agents_connected
+```
+
+### Avec jq (pour format JSON si besoin)
+
+Les métriques Prometheus sont en format texte, mais vous pouvez les parser:
+
+```bash
+curl -s http://192.168.9.23:3000/metrics \
+  | grep -E '^agenthub_agents_connected ' \
+  | awk '{print $2}'
+```
+
+## 🚀 Déploiement
+
+### Stack Prometheus + Grafana (Docker Compose)
+
+Exemple de stack complète:
+
+```yaml
+version: '3.8'
+
+services:
+  prometheus:
+    image: prom/prometheus:latest
+    ports:
+      - "9090:9090"
+    volumes:
+      - ./prometheus.yml:/etc/prometheus/prometheus.yml
+      - prometheus_data:/prometheus
+    command:
+      - '--config.file=/etc/prometheus/prometheus.yml'
+      - '--storage.tsdb.path=/prometheus'
+
+  grafana:
+    image: grafana/grafana:latest
+    ports:
+      - "3001:3000"
+    environment:
+      - GF_SECURITY_ADMIN_PASSWORD=admin
+    volumes:
+      - grafana_data:/var/lib/grafana
+
+volumes:
+  prometheus_data:
+  grafana_data:
+```
+
+### Healthcheck avec Métriques
+
+L'endpoint `/metrics` peut servir de healthcheck:
+
+```bash
+# Vérifier que le serveur répond
+curl -f http://192.168.9.23:3000/metrics || exit 1
+```
+
+## 🔐 Sécurité
+
+### Considérations
+
+- L'endpoint `/metrics` est **public** (pas d'auth requise) pour faciliter le scraping Prometheus
+- Si besoin de sécuriser, ajouter un reverse proxy (nginx) avec basic auth
+- Les métriques n'exposent **pas de données sensibles** (pas de body messages, tokens, etc.)
+- Seules les **métadonnées agrégées** sont exposées (counts, latencies, etc.)
+
+### Exemple nginx avec basic auth
+
+```nginx
+location /metrics {
+    auth_basic "Prometheus Metrics";
+    auth_basic_user_file /etc/nginx/.htpasswd;
+    proxy_pass http://agenthub:3000/metrics;
+}
+```
+
+## 📝 Troubleshooting
+
+### Les métriques ne s'affichent pas
+
+1. Vérifier que le serveur AgentHub est démarré:
+   ```bash
+   curl http://192.168.9.23:3000/healthz
+   ```
+
+2. Vérifier l'endpoint metrics:
+   ```bash
+   curl http://192.168.9.23:3000/metrics
+   ```
+
+3. Vérifier les logs Prometheus:
+   ```bash
+   docker logs prometheus
+   ```
+
+### Les métriques sont à zéro
+
+- `agenthub_agents_connected`: Aucun agent WebSocket connecté
+- `agenthub_rooms_active`: Aucune room avec membres dans la DB
+- `agenthub_messages_total`: Aucun message envoyé depuis le dernier restart
+
+C'est normal si l'application vient de démarrer ou n'a pas encore d'activité.
+
+### Grafana n'affiche pas de données
+
+1. Vérifier la datasource Prometheus dans Grafana:
+   - Settings → Data Sources → Prometheus
+   - Tester la connexion
+
+2. Vérifier que Prometheus scrape bien AgentHub:
+   - Ouvrir Prometheus UI: `http://localhost:9090/targets`
+   - Vérifier que le job `agenthub` est UP
+
+3. Vérifier les queries dans Grafana:
+   - Explore → Sélectionner Prometheus
+   - Tester une query simple: `agenthub_agents_connected`
+
+## 🎓 Références
+
+- [Prometheus Documentation](https://prometheus.io/docs/)
+- [Grafana Documentation](https://grafana.com/docs/)
+- [prom-client (Node.js)](https://github.com/siimon/prom-client)
+- [OpenMetrics Specification](https://openmetrics.io/)

docs/grafana-dashboard.json

@@ -0,0 +1,668 @@
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+          "uid": "-- Grafana --"
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+        "hide": true,
+        "iconColor": "rgba(0, 211, 255, 1)",
+        "name": "Annotations & Alerts",
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+          "legendFormat": "Agents connectés",
+          "range": true,
+          "refId": "A"
+        }
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+      "title": "Agents Connectés",
+      "type": "gauge"
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+          "legendFormat": "Rooms actives",
+          "range": true,
+          "refId": "A"
+        }
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+      "title": "Rooms Actives",
+      "type": "gauge"
+    },
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+        }
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+      "type": "timeseries"
+    },
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+            }
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+            "lastNotNull",
+            "max"
+          ],
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+          "placement": "bottom",
+          "showLegend": true
+        },
+        "tooltip": {
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+          "sort": "none"
+        }
+      },
+      "pluginVersion": "10.0.0",
+      "targets": [
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+          "datasource": {
+            "type": "prometheus"
+          },
+          "editorMode": "code",
+          "expr": "histogram_quantile(0.50, sum by(le) (rate(agenthub_websocket_latency_seconds_bucket[5m])))",
+          "legendFormat": "p50",
+          "range": true,
+          "refId": "A"
+        },
+        {
+          "datasource": {
+            "type": "prometheus"
+          },
+          "editorMode": "code",
+          "expr": "histogram_quantile(0.95, sum by(le) (rate(agenthub_websocket_latency_seconds_bucket[5m])))",
+          "legendFormat": "p95",
+          "range": true,
+          "refId": "B"
+        },
+        {
+          "datasource": {
+            "type": "prometheus"
+          },
+          "editorMode": "code",
+          "expr": "histogram_quantile(0.99, sum by(le) (rate(agenthub_websocket_latency_seconds_bucket[5m])))",
+          "legendFormat": "p99",
+          "range": true,
+          "refId": "C"
+        }
+      ],
+      "title": "WebSocket Latency (message send)",
+      "type": "timeseries"
+    },
+    {
+      "datasource": {
+        "type": "prometheus"
+      },
+      "fieldConfig": {
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+          },
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+            "axisColorMode": "text",
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+        },
+        "tooltip": {
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+          "sort": "none"
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+      "pluginVersion": "10.0.0",
+      "targets": [
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+            "type": "prometheus"
+          },
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+          "expr": "histogram_quantile(0.50, sum by(le, route) (rate(agenthub_http_request_duration_seconds_bucket[5m])))",
+          "legendFormat": "{{route}} p50",
+          "range": true,
+          "refId": "A"
+        },
+        {
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+            "type": "prometheus"
+          },
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+          "legendFormat": "{{route}} p99",
+          "range": true,
+          "refId": "B"
+        }
+      ],
+      "title": "HTTP Request Duration",
+      "type": "timeseries"
+    },
+    {
+      "datasource": {
+        "type": "prometheus"
+      },
+      "fieldConfig": {
+        "defaults": {
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+          },
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+            "axisColorMode": "text",
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+            "axisPlacement": "auto",
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+              "viz": false,
+              "legend": false
+            },
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+            "pointSize": 5,
+            "scaleDistribution": {
+              "type": "linear"
+            },
+            "showPoints": "never",
+            "spanNulls": false,
+            "stacking": {
+              "group": "A",
+              "mode": "none"
+            },
+            "thresholdsStyle": {
+              "mode": "off"
+            }
+          },
+          "mappings": [],
+          "thresholds": {
+            "mode": "absolute",
+            "steps": [
+              {
+                "color": "green",
+                "value": null
+              }
+            ]
+          },
+          "unit": "reqps"
+        },
+        "overrides": []
+      },
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+        "w": 12,
+        "x": 0,
+        "y": 16
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+          "displayMode": "list",
+          "placement": "bottom",
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+          "sort": "none"
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+      "pluginVersion": "10.0.0",
+      "targets": [
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+            "type": "prometheus"
+          },
+          "editorMode": "code",
+          "expr": "sum by(route, status_code) (rate(agenthub_http_requests_total[5m]))",
+          "legendFormat": "{{route}} {{status_code}}",
+          "range": true,
+          "refId": "A"
+        }
+      ],
+      "title": "HTTP Requests/sec by route",
+      "type": "timeseries"
+    },
+    {
+      "datasource": {
+        "type": "prometheus"
+      },
+      "fieldConfig": {
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+            "mode": "palette-classic"
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+            "axisColorMode": "text",
+            "axisLabel": "",
+            "axisPlacement": "auto",
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+            "drawStyle": "line",
+            "fillOpacity": 10,
+            "gradientMode": "none",
+            "hideFrom": {
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+              "viz": false,
+              "legend": false
+            },
+            "lineInterpolation": "linear",
+            "lineWidth": 1,
+            "pointSize": 5,
+            "scaleDistribution": {
+              "type": "linear"
+            },
+            "showPoints": "never",
+            "spanNulls": false,
+            "stacking": {
+              "group": "A",
+              "mode": "none"
+            },
+            "thresholdsStyle": {
+              "mode": "off"
+            }
+          },
+          "mappings": [],
+          "thresholds": {
+            "mode": "absolute",
+            "steps": [
+              {
+                "color": "green",
+                "value": null
+              }
+            ]
+          },
+          "unit": "s"
+        },
+        "overrides": []
+      },
+      "gridPos": {
+        "h": 8,
+        "w": 12,
+        "x": 12,
+        "y": 16
+      },
+      "id": 7,
+      "options": {
+        "legend": {
+          "calcs": [
+            "mean",
+            "lastNotNull",
+            "max"
+          ],
+          "displayMode": "table",
+          "placement": "bottom",
+          "showLegend": true
+        },
+        "tooltip": {
+          "mode": "multi",
+          "sort": "none"
+        }
+      },
+      "pluginVersion": "10.0.0",
+      "targets": [
+        {
+          "datasource": {
+            "type": "prometheus"
+          },
+          "editorMode": "code",
+          "expr": "histogram_quantile(0.50, sum by(le, operation) (rate(agenthub_db_query_duration_seconds_bucket[5m])))",
+          "legendFormat": "{{operation}} p50",
+          "range": true,
+          "refId": "A"
+        },
+        {
+          "datasource": {
+            "type": "prometheus"
+          },
+          "editorMode": "code",
+          "expr": "histogram_quantile(0.99, sum by(le, operation) (rate(agenthub_db_query_duration_seconds_bucket[5m])))",
+          "legendFormat": "{{operation}} p99",
+          "range": true,
+          "refId": "B"
+        }
+      ],
+      "title": "Database Query Duration",
+      "type": "timeseries"
+    }
+  ],
+  "refresh": "10s",
+  "schemaVersion": 38,
+  "style": "dark",
+  "tags": [
+    "agenthub",
+    "barodine"
+  ],
+  "templating": {
+    "list": []
+  },
+  "time": {
+    "from": "now-1h",
+    "to": "now"
+  },
+  "timepicker": {},
+  "timezone": "",
+  "title": "AgentHub Dashboard",
+  "uid": "agenthub-dashboard",
+  "version": 0,
+  "weekStart": ""
+}

src/app.ts

@@ -2,12 +2,14 @@ import Fastify, { type FastifyInstance } from 'fastify';
 import type { AppConfig } from './config.js';
 import { pool } from './db/pool.js';
 import { registerSecurityPlugins } from './lib/security.js';
+import { registerInstrumentation } from './lib/instrumentation.js';
 import { registerAgentRoutes } from './routes/agents.js';
 import { registerTokenRoutes } from './routes/tokens.js';
 import { registerSessionRoutes } from './routes/sessions.js';
 import { registerRoomRoutes } from './routes/rooms.js';
 import { setupSocketIO } from './socket/index.js';
 import { register as metricsRegister } from './lib/metrics.js';
+import { startMetricsCollector } from './services/metrics-collector.js';
 
 export interface BuildAppOptions {
   config: AppConfig;
@@ -22,6 +24,9 @@ export async function buildApp({ config }: BuildAppOptions): Promise<FastifyInst
   // Register security plugins first
   await registerSecurityPlugins(app, config);
 
+  // Register instrumentation for metrics
+  await registerInstrumentation(app);
+
   app.get('/healthz', async () => {
     return { status: 'ok', uptime: process.uptime() };
   });
@@ -64,5 +69,9 @@ export async function buildApp({ config }: BuildAppOptions): Promise<FastifyInst
     app.log.warn('⚠️  Socket.IO messaging disabled (FEATURE_MESSAGING_ENABLED=false)');
   }
 
+  // Start metrics collector (updates room metrics every 30s)
+  startMetricsCollector(pool);
+  app.log.info('✅ Metrics collector started');
+
   return app;
 }

src/lib/instrumentation.ts

@@ -0,0 +1,25 @@
+import type { FastifyInstance, FastifyRequest, FastifyReply } from 'fastify';
+import { httpRequestDurationHistogram, httpRequestsCounter } from './metrics.js';
+
+/**
+ * Register HTTP request instrumentation for Prometheus metrics
+ */
+export async function registerInstrumentation(app: FastifyInstance): Promise<void> {
+  app.addHook('onRequest', async (request: FastifyRequest, _reply: FastifyReply) => {
+    (request as any).startTime = performance.now();
+  });
+
+  app.addHook('onResponse', async (request: FastifyRequest, reply: FastifyReply) => {
+    const startTime = (request as any).startTime;
+    if (startTime === undefined) return;
+
+    const duration = (performance.now() - startTime) / 1000; // Convert to seconds
+    const method = request.method;
+    const route = request.routeOptions?.url || request.url.split('?')[0] || 'unknown';
+    const statusCode = reply.statusCode.toString();
+
+    // Record metrics
+    httpRequestDurationHistogram.observe({ method, route, status_code: statusCode }, duration);
+    httpRequestsCounter.inc({ method, route, status_code: statusCode });
+  });
+}

src/lib/metrics.ts

@@ -1,25 +1,35 @@
-import { Registry, Gauge, Counter, Histogram } from 'prom-client';
+import { Registry, Gauge, Counter, Histogram, collectDefaultMetrics } from 'prom-client';
 
 export const register = new Registry();
 
-// Active WebSocket connections
+// Collect default Node.js metrics (memory, CPU, event loop, etc.)
+collectDefaultMetrics({ register, prefix: 'agenthub_' });
+
+// Active WebSocket connections (agents connected)
 export const wsConnectionsGauge = new Gauge({
-  name: 'agenthub_ws_connections_active',
+  name: 'agenthub_agents_connected',
-  help: 'Number of active WebSocket connections',
+  help: 'Number of connected agents via WebSocket',
+  registers: [register],
+});
+
+// Active rooms (rooms with at least one member)
+export const roomsActiveGauge = new Gauge({
+  name: 'agenthub_rooms_active',
+  help: 'Number of active rooms (with at least one member)',
   registers: [register],
 });
 
 // Total messages sent
 export const messagesSentCounter = new Counter({
-  name: 'agenthub_messages_sent_total',
+  name: 'agenthub_messages_total',
   help: 'Total number of messages sent',
   registers: [register],
 });
 
 // Message send latency (p50, p99)
 export const messageSendLatencyHistogram = new Histogram({
-  name: 'agenthub_message_send_latency_seconds',
+  name: 'agenthub_websocket_latency_seconds',
-  help: 'Message send latency in seconds',
+  help: 'WebSocket message send latency in seconds',
   buckets: [0.001, 0.005, 0.01, 0.025, 0.05, 0.1, 0.25, 0.5, 1, 2.5, 5],
   registers: [register],
 });
@@ -28,7 +38,24 @@ export const messageSendLatencyHistogram = new Histogram({
 export const httpRequestDurationHistogram = new Histogram({
   name: 'agenthub_http_request_duration_seconds',
   help: 'HTTP request duration in seconds',
-  labelNames: ['method', 'route', 'status'],
+  labelNames: ['method', 'route', 'status_code'],
+  buckets: [0.001, 0.005, 0.01, 0.025, 0.05, 0.1, 0.25, 0.5, 1],
+  registers: [register],
+});
+
+// HTTP requests total
+export const httpRequestsCounter = new Counter({
+  name: 'agenthub_http_requests_total',
+  help: 'Total number of HTTP requests',
+  labelNames: ['method', 'route', 'status_code'],
+  registers: [register],
+});
+
+// Database query duration
+export const dbQueryDurationHistogram = new Histogram({
+  name: 'agenthub_db_query_duration_seconds',
+  help: 'Database query duration in seconds',
+  labelNames: ['operation'],
   buckets: [0.001, 0.005, 0.01, 0.025, 0.05, 0.1, 0.25, 0.5, 1],
   registers: [register],
 });

src/services/metrics-collector.ts

@@ -0,0 +1,42 @@
+import type { Pool } from 'pg';
+import { drizzle } from 'drizzle-orm/node-postgres';
+import { roomMembers } from '../db/schema.js';
+import { sql } from 'drizzle-orm';
+import { roomsActiveGauge, dbQueryDurationHistogram } from '../lib/metrics.js';
+
+/**
+ * Collect active rooms metric from database
+ */
+async function collectRoomsActiveMetric(pool: Pool): Promise<void> {
+  const db = drizzle(pool);
+  const startTime = performance.now();
+
+  try {
+    // Count distinct rooms that have at least one member
+    const result = await db
+      .select({ count: sql<number>`count(distinct ${roomMembers.roomId})` })
+      .from(roomMembers);
+
+    const count = result[0]?.count || 0;
+    roomsActiveGauge.set(count);
+
+    const duration = (performance.now() - startTime) / 1000;
+    dbQueryDurationHistogram.observe({ operation: 'count_active_rooms' }, duration);
+  } catch (err) {
+    console.error('Failed to collect rooms active metric:', err);
+  }
+}
+
+/**
+ * Start periodic metrics collection
+ * Updates room metrics every 30 seconds
+ */
+export function startMetricsCollector(pool: Pool): void {
+  // Collect immediately on startup
+  collectRoomsActiveMetric(pool).catch(console.error);
+
+  // Then collect every 30 seconds
+  setInterval(() => {
+    collectRoomsActiveMetric(pool).catch(console.error);
+  }, 30_000);
+}