spacedrive/docs/core/sync-roadmap.md

Sync System Implementation Roadmap

Quick Reference: Full Roadmap | Network Integration Status

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📊 Current Status

Overall Progress: 75% Complete (25/34 files) Architecture Grade: 7.5/10 Status: Mid-migration from leader-based to leaderless architecture

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🚀 Quick Start: Priority Actions

🔥 This Week (Critical Path)

1. Implement SyncProtocolHandler (~6 hours)

   • File: core/src/service/network/protocol/sync/handler.rs
   • Status: Currently stubbed, blocks all inbound sync
   • Impact: HIGH - Without this, devices can't receive sync messages

2. Fix Broadcast Error Handling (~2 hours)

   • File: core/src/service/sync/peer.rs
   • Issues: Sequential sends, silent failures
   • Fix: Use futures::join_all for parallel broadcasts

3. Complete TransactionManager (~4 hours)

   • File: core/src/infra/sync/transaction.rs
   • Status: Methods stubbed
   • Impact: HIGH - Need auto-broadcast on commit

4. Clean Up Legacy Files (~30 minutes)

   • Delete: service/sync/applier.rs
   • Delete: service/network/protocol/sync/transport.rs (duplicate)
   • Delete: service/network/core/sync_transport.rs (moved)

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📈 Component Status

Component	Files	Status	Priority
Core Infrastructure	9	✅ 100%	-
Network Integration	5	🚧 80%	P1
Sync Service	5	✅ 80%	P1
Database Models	7	⚠️ 29%	P2
Testing	-	❌ 0%	P2
Architecture	-	🚧 Workarounds	P3

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🎯 Success Metrics

MVP Targets (Week 4)

• All message types handled
• 7/7 models can sync
• Integration tests pass
• < 1% message loss
• Basic error handling

Production Targets (Month 3)

• Zero data corruption
• < 100ms broadcast latency (10 peers)
• < 5s sync time (1000 changes)
• > 70% test coverage
• Monitoring dashboards

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🏗️ Architecture Highlights

✅ What's Good

1. Layered Architecture - Clean separation of concerns
2. Hybrid Sync Model - State-based + log-based with HLC
3. Trait Abstraction - NetworkTransport breaks circular deps
4. Documentation - Excellent inline docs and examples

⚠️ Needs Improvement

1. Circular Dependency Workaround - Trait abstraction is a Band-Aid
2. Registry Pattern Complexity - Function pointers hard to debug
3. Incomplete Migration - Legacy code still present
4. No Retry Mechanism - Failed broadcasts are lost

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📋 Detailed Tracking

For comprehensive implementation details, see:

📁 SYNC_IMPLEMENTATION_ROADMAP.md

Contains:

• Detailed task breakdowns with effort estimates
• Code examples for each improvement
• Architecture decision records
• Success metrics and timeline
• Learning resources

📁 NETWORK_INTEGRATION_STATUS.md

Contains:

• Phase-by-phase completion status
• What works right now
• How to test current implementation
• Files modified and line counts

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🎓 Key Architectural Decisions

ADR-001: Hybrid Sync Model

Decision: State-based for device-owned, log-based with HLC for shared Status: ✅ Implemented

ADR-002: NetworkTransport Trait

Decision: Use trait to break circular dependency Status: ✅ Implemented (may refactor in P3)

ADR-003: Leaderless Architecture

Decision: All devices are peers, no leader election Status: ✅ Implemented

ADR-004: Per-Device Sync.db

Decision: Each device maintains its own peer log Status: ✅ Implemented

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📞 Questions & Discussions

Open Questions

1. Protocol Versioning: Should we add envelope pattern now?

   • Recommendation: Yes (P2) - Future-proof

2. Conflict Resolution: Auto-resolve or show UI?

   • Recommendation: Auto for MVP, UI later

3. Message Compression: Add zstd for large batches?

   • Recommendation: Not for MVP, revisit P3

4. End-to-End Encryption: Per-library keys?

   • Recommendation: Design with it in mind, implement later

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🐛 Known Critical Issues

1. ⚠️ SyncProtocolHandler stubbed - Blocks inbound messages
2. ⚠️ TransactionManager incomplete - No auto-broadcast
3. ⚠️ Sequential broadcasts - Slow for many peers
4. ⚠️ Silent error handling - .unwrap_or_default() hides issues
5. ⚠️ No retry mechanism - Lost messages not recovered
6. ⚠️ Only 2/7 models implemented - Most data can't sync

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📅 Timeline

Week 1 (Current)

Focus: Critical path to MVP

• Implement SyncProtocolHandler
• Fix broadcast error handling
• Complete TransactionManager
• Clean up legacy code

Weeks 2-4

Focus: Complete model coverage

• Implement all 7 model apply functions
• Add retry queue
• Write integration tests
• Add message envelope pattern

Months 2-3

Focus: Production hardening

• Refactor circular dependency
• Simplify registry pattern
• Add observability (metrics, traces)
• Performance testing (1000+ devices)

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🚀 Getting Started

For Implementers

1. Read SYNC_IMPLEMENTATION_ROADMAP.md
2. Pick a task from Priority 1 section
3. Check the "Checklist" items in the roadmap
4. Implement, test, update roadmap status

For Reviewers

1. Check Architecture Quality section
2. Review specific refactoring recommendations in full roadmap
3. Validate against success metrics
4. Update status matrix after review

For QA

1. See Testing section
2. Run integration tests (when implemented)
3. Test failure scenarios (network partition, device offline)
4. Validate data consistency across devices

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📚 Additional Resources

• Daemon Architecture
• Hybrid Logical Clocks Paper
• CRDT Research
• Automerge CRDT Library

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Last Updated: October 9, 2025 Maintained By: Spacedrive Core Team Status: Living Document