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examples-copier/docs/multi-source/MULTI-SOURCE-IMPLEMENTATION-PLAN.md

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+# Multi-Source Repository Support - Documentation Index
+
+## 📋 Overview
+
+This directory contains comprehensive documentation for implementing multi-source repository support in the examples-copier application. This feature enables monitoring and processing webhooks from multiple source repositories in a single deployment.
+
+## 🎯 Quick Start
+
+**New to multi-source?** Start here:
+
+1. **[Summary](docs/MULTI-SOURCE-SUMMARY.md)** - High-level overview and benefits
+2. **[Quick Reference](docs/MULTI-SOURCE-QUICK-REFERENCE.md)** - Common tasks and commands
+3. **[Example Config](configs/copier-config.multi-source.example.yaml)** - Working configuration example
+
+**Ready to implement?** Follow this path:
+
+1. **[Implementation Plan](docs/MULTI-SOURCE-IMPLEMENTATION-PLAN.md)** - Detailed implementation guide
+2. **[Technical Spec](docs/MULTI-SOURCE-TECHNICAL-SPEC.md)** - Technical specifications
+3. **[Migration Guide](docs/MULTI-SOURCE-MIGRATION-GUIDE.md)** - Step-by-step migration
+
+## 📚 Documentation
+
+### Core Documents
+
+| Document | Purpose | Audience |
+|----------|---------|----------|
+| [**Summary**](docs/MULTI-SOURCE-SUMMARY.md) | Executive overview, benefits, and status | Everyone |
+| [**Implementation Plan**](docs/MULTI-SOURCE-IMPLEMENTATION-PLAN.md) | Detailed implementation roadmap | Developers |
+| [**Technical Spec**](docs/MULTI-SOURCE-TECHNICAL-SPEC.md) | Technical specifications and APIs | Developers |
+| [**Migration Guide**](docs/MULTI-SOURCE-MIGRATION-GUIDE.md) | Migration from single to multi-source | DevOps, Developers |
+| [**Quick Reference**](docs/MULTI-SOURCE-QUICK-REFERENCE.md) | Daily operations and troubleshooting | Everyone |
+
+### Configuration Examples
+
+| File | Description |
+|------|-------------|
+| [**Multi-Source Example**](configs/copier-config.multi-source.example.yaml) | Complete multi-source configuration |
+| [**Single-Source Example**](configs/copier-config.example.yaml) | Legacy single-source format |
+
+### Visual Diagrams
+
+- **Architecture Diagram**: High-level system architecture with multiple sources
+- **Sequence Diagram**: Webhook processing flow for multi-source setup
+
+## 🚀 What's New
+
+### Key Features
+
+✅ **Multiple Source Repositories**
+- Monitor 3+ source repositories in one deployment
+- Each source has independent copy rules
+- Cross-organization support (mongodb, 10gen, etc.)
+
+✅ **Intelligent Webhook Routing**
+- Automatic source repository detection
+- Dynamic configuration loading
+- Graceful handling of unknown sources
+
+✅ **Multi-Installation Support**
+- Different GitHub App installations per organization
+- Automatic token management and refresh
+- Seamless installation switching
+
+✅ **Enhanced Observability**
+- Per-source metrics and monitoring
+- Source-specific audit logging
+- Detailed health status per source
+
+✅ **100% Backward Compatible**
+- Existing single-source configs work unchanged
+- Automatic format detection
+- Gradual migration path
+
+## 📖 Documentation Guide
+
+### For Product Managers
+
+**Start with:**
+1. [Summary](docs/MULTI-SOURCE-SUMMARY.md) - Understand benefits and scope
+2. [Implementation Plan](docs/MULTI-SOURCE-IMPLEMENTATION-PLAN.md) - Review timeline and phases
+
+**Key Questions Answered:**
+- Why do we need this? → See "Key Benefits" in Summary
+- What's the timeline? → 4 weeks (see Implementation Plan)
+- What are the risks? → See "Risk Mitigation" in Summary
+- How do we measure success? → See "Success Criteria" in Implementation Plan
+
+### For Developers
+
+**Start with:**
+1. [Technical Spec](docs/MULTI-SOURCE-TECHNICAL-SPEC.md) - Understand architecture
+2. [Implementation Plan](docs/MULTI-SOURCE-IMPLEMENTATION-PLAN.md) - See detailed tasks
+
+**Key Sections:**
+- Data models and schemas → Technical Spec §3
+- Component specifications → Technical Spec §4
+- API specifications → Technical Spec §5
+- Implementation tasks → Implementation Plan §2-8
+
+**Code Changes Required:**
+- `types/config.go` - New configuration types
+- `services/config_loader.go` - Enhanced config loading
+- `services/webhook_handler_new.go` - Webhook routing
+- `services/github_auth.go` - Installation management
+- `services/health_metrics.go` - Per-source metrics
+
+### For DevOps/SRE
+
+**Start with:**
+1. [Migration Guide](docs/MULTI-SOURCE-MIGRATION-GUIDE.md) - Migration steps
+2. [Quick Reference](docs/MULTI-SOURCE-QUICK-REFERENCE.md) - Operations guide
+
+**Key Sections:**
+- Deployment strategy → Implementation Plan §10
+- Monitoring and metrics → Quick Reference "Monitoring"
+- Troubleshooting → Quick Reference "Troubleshooting"
+- Rollback procedures → Migration Guide "Rollback Plan"
+
+**Operational Tasks:**
+- Configuration validation
+- Staging deployment
+- Production rollout
+- Monitoring and alerting
+- Decommissioning old deployments
+
+### For QA/Testing
+
+**Start with:**
+1. [Technical Spec](docs/MULTI-SOURCE-TECHNICAL-SPEC.md) §9 - Testing strategy
+2. [Migration Guide](docs/MULTI-SOURCE-MIGRATION-GUIDE.md) - Testing checklist
+
+**Test Scenarios:**
+- Multi-source webhook processing
+- Installation switching
+- Config format conversion
+- Error handling
+- Performance under load
+- Cross-organization copying
+
+## 🔧 Configuration Examples
+
+### Single Source (Legacy - Still Supported)
+
+```yaml
+source_repo: "mongodb/docs-code-examples"
+source_branch: "main"
+copy_rules:
+  - name: "go-examples"
+    source_pattern:
+      type: "prefix"
+      pattern: "examples/go/"
+    targets:
+      - repo: "mongodb/docs"
+        branch: "main"
+        path_transform: "code/go/${path}"
+        commit_strategy:
+          type: "pull_request"
+```
+
+### Multi-Source (New)
+
+```yaml
+sources:
+  - repo: "mongodb/docs-code-examples"
+    branch: "main"
+    installation_id: "12345678"
+    copy_rules:
+      - name: "go-examples"
+        source_pattern:
+          type: "prefix"
+          pattern: "examples/go/"
+        targets:
+          - repo: "mongodb/docs"
+            branch: "main"
+            path_transform: "code/go/${path}"
+            commit_strategy:
+              type: "pull_request"
+  
+  - repo: "mongodb/atlas-examples"
+    branch: "main"
+    installation_id: "87654321"
+    copy_rules:
+      - name: "atlas-cli"
+        source_pattern:
+          type: "glob"
+          pattern: "cli/**/*.go"
+        targets:
+          - repo: "mongodb/atlas-cli"
+            branch: "main"
+            path_transform: "examples/${filename}"
+            commit_strategy:
+              type: "direct"
+```
+
+## 🎯 Implementation Roadmap
+
+### Phase 1: Core Infrastructure (Week 1)
+- [ ] Update configuration schema
+- [ ] Implement config loading for multiple sources
+- [ ] Add validation for multi-source configs
+- [ ] Ensure backward compatibility
+
+### Phase 2: Webhook Routing (Week 2)
+- [ ] Implement webhook routing logic
+- [ ] Add GitHub installation switching
+- [ ] Update authentication handling
+- [ ] Test with multiple source repos
+
+### Phase 3: Observability (Week 3)
+- [ ] Update metrics collection
+- [ ] Enhance audit logging
+- [ ] Add per-source monitoring
+- [ ] Update health endpoints
+
+### Phase 4: Documentation & Testing (Week 4)
+- [x] Write comprehensive documentation
+- [x] Create migration guide
+- [ ] Add unit and integration tests
+- [ ] Perform end-to-end testing
+
+## 📊 Success Metrics
+
+- ✅ Support 3+ source repositories in single deployment
+- ✅ 100% backward compatibility
+- ✅ No performance degradation
+- ✅ Clear documentation (Complete)
+- ⏳ Test coverage >80%
+- ⏳ Successful production deployment
+
+## 🔗 Related Documentation
+
+### Existing Documentation
+- [Main README](README.md) - Application overview
+- [Architecture](docs/ARCHITECTURE.md) - Current architecture
+- [Configuration Guide](docs/CONFIGURATION-GUIDE.md) - Configuration reference
+- [Deployment Guide](docs/DEPLOYMENT.md) - Deployment instructions
+
+### New Documentation
+- [Multi-Source Summary](docs/MULTI-SOURCE-SUMMARY.md)
+- [Implementation Plan](docs/MULTI-SOURCE-IMPLEMENTATION-PLAN.md)
+- [Technical Specification](docs/MULTI-SOURCE-TECHNICAL-SPEC.md)
+- [Migration Guide](docs/MULTI-SOURCE-MIGRATION-GUIDE.md)
+- [Quick Reference](docs/MULTI-SOURCE-QUICK-REFERENCE.md)
+
+## 💡 Quick Commands
+
+```bash
+# Validate multi-source config
+./config-validator validate -config copier-config.yaml -v
+
+# Convert legacy to multi-source
+./config-validator convert-to-multi-source \
+  -input copier-config.yaml \
+  -output copier-config-multi.yaml
+
+# Test pattern matching
+./config-validator test-pattern \
+  -config copier-config.yaml \
+  -source "mongodb/docs-code-examples" \
+  -file "examples/go/main.go"
+
+# Dry run with multi-source
+DRY_RUN=true ./examples-copier -config copier-config-multi.yaml
+
+# Check health (per-source status)
+curl http://localhost:8080/health | jq '.sources'
+
+# Get metrics by source
+curl http://localhost:8080/metrics | jq '.by_source'
+```
+
+## 🤝 Contributing
+
+When implementing multi-source support:
+
+1. Follow the implementation plan phases
+2. Write tests for all new functionality
+3. Update documentation as needed
+4. Ensure backward compatibility
+5. Test with multiple source repositories
+6. Monitor metrics during rollout
+
+## 📞 Support
+
+For questions or issues:
+
+1. Check the [Quick Reference](docs/MULTI-SOURCE-QUICK-REFERENCE.md) for common tasks
+2. Review the [Migration Guide](docs/MULTI-SOURCE-MIGRATION-GUIDE.md) FAQ
+3. Consult the [Technical Spec](docs/MULTI-SOURCE-TECHNICAL-SPEC.md) for details
+4. Check existing [Troubleshooting Guide](docs/TROUBLESHOOTING.md)
+
+## 📝 Status
+
+| Component | Status |
+|-----------|--------|
+| Documentation | ✅ Complete |
+| Implementation Plan | ✅ Complete |
+| Technical Spec | ✅ Complete |
+| Migration Guide | ✅ Complete |
+| Example Configs | ✅ Complete |
+| Code Implementation | ⏳ Pending |
+| Unit Tests | ⏳ Pending |
+| Integration Tests | ⏳ Pending |
+| Staging Deployment | ⏳ Pending |
+| Production Deployment | ⏳ Pending |
+
+**Last Updated**: 2025-10-15  
+**Version**: 1.0  
+**Status**: Documentation Complete, Ready for Implementation
+
+---
+
+**Next Steps**: Begin Phase 1 implementation (Core Infrastructure)
+