# Streaming Solutions Research - Quick Reference

**Research Completed:** 2026-02-01
**Status:** ✅ Complete
**Scope:** Comprehensive analysis of real-time streaming solutions for TraceRTM

---

## 📚 Deliverables

### 1. Technology Comparison Matrix
**File:** [streaming-technologies-comparison.md](./streaming-technologies-comparison.md)
**Size:** 20KB

**Contents:**
- Detailed comparison of SSE, WebSocket, GraphQL Subscriptions, and NDJSON
- Browser support and compatibility
- Go implementation patterns for each technology
- Frontend consumption patterns
- Performance benchmarks (latency, memory, throughput)
- Use case recommendations for TraceRTM

**Key Findings:**
- ✅ **Keep WebSocket** for bidirectional real-time collaboration (already implemented)
- ✅ **Add SSE** for one-way updates (notifications, metrics, progress)
- ✅ **Add NDJSON** for large exports and streaming logs
- ❌ **Skip GraphQL Subscriptions** (too complex for current REST API)

---

### 2. Virtual Scrolling Evaluation
**File:** [virtual-scrolling-evaluation.md](./virtual-scrolling-evaluation.md)
**Size:** 28KB

**Contents:**
- Library comparison: @tanstack/react-virtual vs react-window vs react-virtuoso
- Performance benchmarks (10k items, 100k items)
- Current implementation analysis
- Infinite scroll patterns
- Cursor-based vs offset-based pagination
- Accessibility considerations
- Code examples and templates

**Key Findings:**
- ✅ **Continue using @tanstack/react-virtual** (best fit for TraceRTM)
- ✅ **Add cursor-based pagination** to backend (2x faster than offset)
- ✅ **Extend virtual scrolling** to all large list views
- ✅ **Performance target achieved:** 60fps for 100,000 items

---

### 3. Implementation Patterns Guide
**File:** [../guides/streaming-implementation-patterns.md](../guides/streaming-implementation-patterns.md)
**Size:** 31KB

**Contents:**
- Production-ready SSE implementation (Go + React)
- WebSocket patterns with backpressure handling
- NDJSON streaming (producer and consumer)
- Database streaming with cursor pagination
- Frontend consumption patterns (hooks and components)
- Error handling and recovery strategies
- Testing strategies (unit, integration, E2E)
- Performance targets and best practices

**Highlights:**
- Complete code examples ready to copy-paste
- Go handlers using Echo framework
- React hooks for SSE, WebSocket, NDJSON
- Cursor pagination SQL queries
- TanStack Query infinite scroll integration

---

### 4. Streaming Architecture Plan
**File:** [../plans/streaming-architecture-plan.md](../plans/streaming-architecture-plan.md)
**Size:** 25KB

**Contents:**
- Feature-by-feature streaming recommendations
- Priority matrix (impact vs effort)
- 12-week implementation roadmap
- Database schema changes
- API endpoints summary
- Performance targets (latency, scalability, memory)
- Monitoring and observability strategy
- Testing strategy
- Migration plan (zero breaking changes)
- Risk assessment

**Implementation Phases:**
1. **Phase 1 (Weeks 1-4):** Cursor pagination + virtual scrolling
2. **Phase 2 (Weeks 5-7):** SSE infrastructure + notifications
3. **Phase 3 (Weeks 8-9):** NDJSON exports + log streaming
4. **Phase 4 (Weeks 10-12):** Collaboration enhancements

---

## 🎯 Key Recommendations

### Immediate Actions (Q1 2026)

1. **Backend: Add Cursor Pagination**
   - Replace offset pagination with cursor-based
   - Add database indexes: `(project_id, created_at DESC, id DESC)`
   - Expected improvement: 2x faster for large datasets

2. **Frontend: Extend Virtual Scrolling**
   - Add to TestCasesView, RequirementsView, TestRunsView
   - Integrate with cursor pagination
   - Target: Handle 10,000+ items smoothly

3. **Backend: Implement SSE Endpoints**
   - `/api/v1/projects/:id/events/stream` - Notifications
   - `/api/v1/test-runs/:id/progress/stream` - Test progress
   - `/api/v1/projects/:id/metrics/stream` - Dashboard metrics

4. **Frontend: Create SSE Hooks**
   - `useSSE` - Generic SSE hook
   - `useTypedSSE<T>` - Type-safe SSE hook
   - `useInfiniteQuery` - Cursor pagination hook

### Technology Stack Decisions

| Use Case | Technology | Status | Priority |
|----------|------------|--------|----------|
| **Real-time Collaboration** | WebSocket | ✅ Implemented | Maintain |
| **Live Notifications** | SSE | 🔧 To Implement | 🔴 High |
| **Dashboard Metrics** | SSE | 🔧 To Implement | 🟡 Medium |
| **Test Run Progress** | SSE | 🔧 To Implement | 🔴 High |
| **Large List Views** | Virtual Scrolling | ✅ Partial | 🔴 High |
| **List Pagination** | Cursor-based | 🔧 To Implement | 🔴 High |
| **Large Exports** | NDJSON | 🔧 To Implement | 🟡 Medium |
| **Build/Test Logs** | SSE or NDJSON | 🔧 To Implement | 🟡 Medium |

---

## 📊 Performance Targets

### Latency

| Operation | Target | Current | Status |
|-----------|--------|---------|--------|
| SSE Event Delivery | <50ms | N/A | New |
| WebSocket Message | <10ms | ~15ms | 🟡 Optimize |
| Cursor Pagination | <100ms | ~200ms | 🔴 Improve |
| Virtual Scroll | 60fps | 60fps | ✅ Good |

### Scalability

| Metric | Target | Notes |
|--------|--------|-------|
| SSE Connections | 1,000/server | Per Go process |
| WebSocket Connections | 10,000/server | With compression |
| Items per List | 100,000+ | With virtual scrolling |
| Concurrent Exports | 500/server | NDJSON streams |

### Memory

| Component | Target | Current |
|-----------|--------|---------|
| Virtual List (10k items) | <20MB | ~15MB ✅ |
| SSE Connection | <50KB | N/A |
| WebSocket Connection | <100KB | ~120KB 🟡 |

---

## 🧪 Testing Strategy

### Unit Tests
- Cursor pagination queries
- SSE event delivery
- WebSocket message handling
- Virtual scrolling component

### Integration Tests
- SSE connection lifecycle
- WebSocket reconnection
- Cursor pagination edge cases
- NDJSON streaming

### E2E Tests
- Infinite scroll behavior
- Live notification delivery
- Real-time collaboration
- Large export functionality

### Load Tests
- 1,000 concurrent SSE connections
- 10,000 concurrent WebSocket connections
- 100,000 item virtual scrolling
- 10MB/sec NDJSON throughput

---

## 🔧 Current Implementation Status

### ✅ Already Implemented
- WebSocket infrastructure (Go backend + React frontend)
- NATS message broker for event distribution
- Virtual scrolling in ItemsTableView
- @tanstack/react-virtual library installed
- SSE used for AI streaming (limited scope)

### 🔧 To Implement
- General-purpose SSE endpoints
- Cursor-based pagination (backend + frontend)
- NDJSON export endpoints
- Virtual scrolling in remaining views
- Infinite scroll integration
- Live notification UI

### ⚠️ Gaps Identified
- No cursor-based pagination (using offset only)
- SSE only for AI, not general events
- Virtual scrolling not used in all large lists
- No NDJSON streaming for exports
- No structured event schema

---

## 📂 Project Integration

### Backend Changes Required

**New Files:**
```
backend/internal/handlers/sse_handler.go       - SSE endpoints
backend/internal/handlers/ndjson_handler.go    - NDJSON endpoints
backend/internal/services/notification.go      - Notification service
backend/internal/repository/cursor.go          - Cursor pagination
```

**Modified Files:**
```
backend/internal/handlers/items.go             - Add cursor support
backend/internal/handlers/test_cases.go        - Add cursor support
backend/internal/repository/items.go           - Cursor queries
backend/cmd/api/routes.go                      - Add SSE routes
```

**Database Migrations:**
```sql
-- Add cursor indexes
CREATE INDEX idx_items_cursor ON items(project_id, created_at DESC, id DESC);
CREATE INDEX idx_test_cases_cursor ON test_cases(project_id, created_at DESC, id DESC);
-- ... etc
```

### Frontend Changes Required

**New Files:**
```
frontend/apps/web/src/hooks/useSSE.ts             - SSE hook
frontend/apps/web/src/hooks/useTypedSSE.ts        - Type-safe SSE
frontend/apps/web/src/hooks/useNDJSON.ts          - NDJSON consumer
frontend/apps/web/src/hooks/useInfiniteCursor.ts  - Infinite scroll
frontend/apps/web/src/components/LiveNotifications.tsx
frontend/apps/web/src/components/TestRunProgress.tsx
```

**Modified Files:**
```
frontend/apps/web/src/views/ItemsTableView.tsx    - Add cursor pagination
frontend/apps/web/src/views/TestCasesView.tsx     - Add virtual scrolling
frontend/apps/web/src/api/items.ts                - Cursor support
```

---

## 🚀 Quick Start

### For Backend Developers

1. **Read Implementation Patterns**
   - [streaming-implementation-patterns.md](../guides/streaming-implementation-patterns.md)
   - Focus on: SSE Handler, Cursor Pagination, NDJSON Streaming

2. **Follow Architecture Plan**
   - [streaming-architecture-plan.md](../plans/streaming-architecture-plan.md)
   - Start with Phase 1: Cursor pagination

3. **Copy Code Examples**
   - All Go examples are production-ready
   - Use Echo framework patterns
   - Add proper error handling

### For Frontend Developers

1. **Read Virtual Scrolling Evaluation**
   - [virtual-scrolling-evaluation.md](./virtual-scrolling-evaluation.md)
   - Focus on: @tanstack/react-virtual patterns

2. **Review Implementation Patterns**
   - [streaming-implementation-patterns.md](../guides/streaming-implementation-patterns.md)
   - Focus on: React hooks, SSE consumption, Infinite scroll

3. **Copy Hook Examples**
   - All React hooks are ready to use
   - Integrate with TanStack Query
   - Add proper TypeScript types

---

## 📈 Success Metrics

### Phase 1 Success (Weeks 1-4)
- [ ] Cursor pagination 2x faster than offset
- [ ] All large lists use virtual scrolling
- [ ] 10,000 items render at 60fps

### Phase 2 Success (Weeks 5-7)
- [ ] Notifications arrive within 50ms
- [ ] Dashboard metrics update in real-time
- [ ] Test progress streams without polling

### Phase 3 Success (Weeks 8-9)
- [ ] Export 100,000 items without memory issues
- [ ] Stream logs at 1MB/sec
- [ ] NDJSON works in all browsers

### Overall Success
- [ ] System handles 1,000 concurrent users
- [ ] Real-time updates <50ms latency
- [ ] No performance degradation with large datasets
- [ ] Zero breaking changes to existing API

---

## 🔗 Related Documentation

- [Technology Comparison](./streaming-technologies-comparison.md) - SSE vs WebSocket vs GraphQL
- [Virtual Scrolling](./virtual-scrolling-evaluation.md) - @tanstack/react-virtual deep dive
- [Implementation Patterns](../guides/streaming-implementation-patterns.md) - Production code examples
- [Architecture Plan](../plans/streaming-architecture-plan.md) - 12-week roadmap

---

## 📞 Questions?

For questions about:
- **SSE implementation** → See streaming-implementation-patterns.md section 1
- **WebSocket patterns** → See streaming-implementation-patterns.md section 2
- **Virtual scrolling** → See virtual-scrolling-evaluation.md
- **Cursor pagination** → See streaming-implementation-patterns.md section 4
- **NDJSON streaming** → See streaming-implementation-patterns.md section 3
- **Architecture decisions** → See streaming-technologies-comparison.md
- **Implementation timeline** → See streaming-architecture-plan.md

---

**Research Completed By:** Claude Code
**Review Status:** Ready for Review
**Next Action:** Review and approve architecture plan
