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Build Log – 2025-12-20

Build Log – 2025-12-20

📅 Daily Log — December 20, 2025

🧠 Context / Focus for Today

Complete Training API V2 implementation with workout templates, creation endpoints, and training schedules. Finish Garmin integration roadmap with backfill, intelligent matching, and auto-sync. Enhance AI integration to generate structured workout data compatible with Garmin devices.

✔️ Things I Got Done Today

Training API V2 (Priorities 10-12)

  • Implemented structured workout steps with workout template library containing 10 professional templates:
    • Yasso 800s, tempo runs, VO2max intervals, threshold repeats
    • Mile repeats, pyramid workouts, progressive long runs
    • Easy runs and recovery runs with proper pace zones
  • Enhanced AI system prompt with detailed structured_data documentation:
    • Pace zone reference table (8 zones with seconds per mile)
    • Full workout examples and common patterns
    • Duration mode consistency rules for Garmin compatibility
  • Added Garmin step limit validation (max 50 steps, 20 repeat blocks).
  • Created workout creation endpoint (/api/garmin/workout) for direct workout creation:
    • Single and batch workout creation (up to 10 workouts)
    • Rate limiting (500ms delays between requests)
    • Permission checking and automatic token refresh
    • Comprehensive error handling
  • Implemented training schedules with /api/garmin/schedule/sync for bulk schedule synchronization:
    • Sync entire training plans to Garmin calendar
    • Smart rescheduling when workout dates change
    • Detailed sync results with per-workout status
  • Created training_plans database table with proper relationships:
    • Plan phases (base, build, peak, taper)
    • Goal race date tracking and status management
    • RLS policies for user isolation
  • Added training plan templates (4 complete periodized plans):
    • 5K beginner (8 weeks), 5K intermediate (10 weeks)
    • Half Marathon intermediate (12 weeks)
    • Marathon intermediate (16 weeks)
  • Created TrainingPlanBuilder component:
    • Template selection with goal date picker
    • Plan generation and preview
    • One-click save to calendar and Garmin sync

Garmin Integration Roadmap (Priorities 2-5)

  • Implemented backfill on connection with automatic 90-day historical backfill trigger in OAuth callback.
  • Created /api/garmin/backfill/status endpoint for progress tracking.
  • Implemented non-blocking backfill initiation for better UX.
  • Created training history table for workout-activity relationships.
  • Added sync_status, match_status fields to workouts table.
  • Implemented confidence-based matching algorithm with 5 strategies:
    • Export link match (1.0 confidence)
    • Sport + date + duration (0.9 confidence)
    • Sport + date only (0.7 confidence)
    • Fuzzy title match (0.5-0.7 confidence)
    • Time window match (0.6 confidence)
  • Updated activity upsert to use new matching with training_history.
  • Created auto-sync infrastructure (lib/garmin/auto-sync.ts) with intelligent sync logic.
  • Added /api/garmin/auto-sync endpoint for manual/batch syncs.
  • Implemented automatic workout rescheduling handling.
  • Added sync status tracking with error reporting.
  • Implemented rate limiting for Garmin API calls.
  • Enhanced AI integration with structured data generation:
    • Updated AI system prompt to generate structured_data field
    • Enhanced all training engine workout creators:
      • createEasyRun() with structured steps
      • createRecoveryRun() with recovery phase
      • createTempoRun() with warmup/tempo/cooldown
      • createIntervalWorkout() with full interval structure
      • createLongRun() with optional marathon pace finish
    • Updated Workout type interface with structured_data
    • Enabled seamless export of AI-generated workouts to Garmin

Database Changes

  • Created training_history table for workout-activity linking.
  • Added columns: linked_activity_id, match_status, sync_status, sync_error, last_synced_at.
  • Created views: weekly_training_load, match_quality_metrics.

Debugging / Fixes

  • Fixed phase value: changed 'active' to valid 'base' value in plan templates.
  • Corrected import paths in schedule/sync route.
  • Fixed WorkoutStep type to match Workout interface exactly.
  • Added explicit WorkoutStep type to fix TypeScript array inference.
  • Updated history route to use new MatchResult type with confidence scoring.
  • Exported createTrainingAPISchedule function for auto-sync module.

🚧 In Progress

  • Testing training plan synchronization with Garmin calendar.
  • Validating workout matching algorithm accuracy.
  • Performance optimization for bulk workout creation.

🎯 Targets for Tomorrow

  1. Implement Phase 3 multi-sport support (Priority 15) — extend to swim, strength, and other sports.
  2. Add advanced step complexity (Priority 16) — HR, power, and cadence targets.
  3. Begin Phase 4 production readiness — error handling, rate limiting, branding compliance.
  4. Create production key application documentation.

🤔 Notes / Observations

  • Training API V2 completes the full workout creation and scheduling pipeline.
  • Confidence-based matching significantly improves workout-activity linking accuracy.
  • Auto-sync infrastructure enables seamless two-way synchronization with Garmin.
  • Structured workout data from AI makes workouts immediately usable on Garmin devices.
  • Training plan templates provide professional periodized plans out of the box.
  • Batch operations require careful rate limiting to avoid Garmin API throttling.

📈 Momentum Score: 9.5 / 10

Outstanding day completing major feature sets. Training API V2 fully implemented with professional templates and seamless Garmin integration. Garmin integration roadmap complete with intelligent matching and auto-sync. AI now generates Garmin-compatible structured workouts. Ready for multi-sport expansion and production hardening.