Phase 06 Tier 1: Complete Backend Implementation - Recovery Tracking & Swap System

COMPLETED TASKS:
✅ 06-01: Workout Swap System
   - Added swapped_from_id to workout_logs
   - Created workout_swaps table for history
   - POST /api/workouts/:id/swap endpoint
   - GET /api/workouts/available endpoint
   - Reversible swaps with audit trail

✅ 06-02: Muscle Group Recovery Tracking
   - Created muscle_group_recovery table
   - Implemented calculateRecoveryScore() function
   - GET /api/recovery/muscle-groups endpoint
   - GET /api/recovery/most-recovered endpoint
   - Auto-tracking on workout log completion

✅ 06-03: Smart Workout Recommendations
   - GET /api/recommendations/smart-workout endpoint
   - 7-day workout analysis algorithm
   - Recovery-based filtering (>30% threshold)
   - Top 3 recommendations with context
   - Context-aware reasoning messages

DATABASE CHANGES:
- Added 4 new tables: muscle_group_recovery, workout_swaps, custom_workouts, custom_workout_exercises
- Extended workout_logs with: swapped_from_id, source_type, custom_workout_id, custom_workout_exercise_id
- Created 7 new indexes for performance

IMPLEMENTATION:
- Recovery service with 4 core functions
- 2 new route handlers (recovery, smartRecommendations)
- Updated workouts router with swap endpoints
- Integrated recovery tracking into POST /api/logs
- Full error handling and logging

TESTING:
- Test file created: /backend/test/phase-06-tests.js
- Ready for E2E and staging validation

STATUS: Ready for frontend integration and production review
Branch: feature/06-phase-06

k8s/production/load-test.js

@@ -0,0 +1,76 @@
+import http from 'k6/http';
+import { check, sleep } from 'k6';
+import { Rate, Trend, Counter, Gauge } from 'k6/metrics';
+
+// Custom metrics
+const errorRate = new Rate('errors');
+const requestDuration = new Trend('request_duration');
+const requestCount = new Counter('requests');
+const activeConnections = new Gauge('active_connections');
+
+// Test configuration
+export const options = {
+  vus: 10,           // Virtual users
+  duration: '5m',    // Test duration
+  thresholds: {
+    'http_req_duration': ['p(95)<200', 'p(99)<500'],  // p95 <200ms, p99 <500ms
+    'http_req_failed': ['rate<0.1'],                   // <0.1% error rate
+    'errors': ['rate<0.01'],                           // <1% custom errors
+  },
+};
+
+// Test target (update with production domain)
+const BASE_URL = __ENV.GRAVL_API_URL || 'https://gravl.example.com';
+
+export default function () {
+  // Simulate active connection count
+  activeConnections.add(1);
+
+  // Test 1: Health check
+  {
+    let response = http.get(`${BASE_URL}/api/health`);
+    check(response, {
+      'health check status is 200': (r) => r.status === 200,
+      'health check has status field': (r) => r.body.includes('status'),
+    });
+    errorRate.add(response.status !== 200);
+    requestDuration.add(response.timings.duration);
+    requestCount.add(1);
+  }
+
+  sleep(1);
+
+  // Test 2: List exercises (unauthenticated or with test token)
+  {
+    let response = http.get(`${BASE_URL}/api/exercises`);
+    check(response, {
+      'exercises endpoint status is 200': (r) => r.status === 200,
+      'exercises returns array': (r) => r.body.includes('['),
+    });
+    errorRate.add(response.status !== 200);
+    requestDuration.add(response.timings.duration);
+    requestCount.add(1);
+  }
+
+  sleep(1);
+
+  // Test 3: Metrics endpoint (for monitoring)
+  {
+    let response = http.get(`${BASE_URL}:3001/metrics`);
+    check(response, {
+      'metrics endpoint status is 200': (r) => r.status === 200 || r.status === 404, // Optional endpoint
+    });
+    requestDuration.add(response.timings.duration);
+    requestCount.add(1);
+  }
+
+  sleep(1);
+
+  activeConnections.add(-1);
+}
+
+export function teardown(data) {
+  console.log(`\n=== Load Test Summary ===`);
+  console.log(`Total requests: ${requestCount.value}`);
+  console.log(`Error rate: ${(errorRate.value * 100).toFixed(2)}%`);
+}