# Multi-Region Federation System (Sync, Replication, Routing, Dashboard)

## Module
ReleaseOrchestrator

## Status
VERIFIED

## Description
Federation hub for geographically distributed deployments: cross-region data sync with vector clock-based conflict resolution (KeepLocal/KeepRemote/Merge/LastWriteWins), global promotion orchestration (Sequential/Canary/Parallel/BlueGreen strategies), evidence replication with data residency compliance (GDPR/sovereignty), latency-based region routing with automatic probing, and global dashboard with cross-region visibility, alert management, and sync status.

## Implementation Details
- **Modules**: `src/ReleaseOrchestrator/__Libraries/StellaOps.ReleaseOrchestrator.Federation/`
- **Key Classes**:
  - `FederationHub` (`src/ReleaseOrchestrator/__Libraries/StellaOps.ReleaseOrchestrator.Federation/FederationHub.cs`) - background service coordinating cross-region federation
  - `CrossRegionSync` (`src/ReleaseOrchestrator/__Libraries/StellaOps.ReleaseOrchestrator.Federation/CrossRegionSync.cs`) - data synchronization across regions with vector clock conflict resolution
  - `RegionCoordinator` (`src/ReleaseOrchestrator/__Libraries/StellaOps.ReleaseOrchestrator.Federation/RegionCoordinator.cs`) - orchestrates global promotions (Sequential/Canary/Parallel/BlueGreen strategies)
  - `GlobalDashboard` (`src/ReleaseOrchestrator/__Libraries/StellaOps.ReleaseOrchestrator.Federation/GlobalDashboard.cs`) - cross-region visibility, alert management, and sync status
- **Interfaces**: `ICrossRegionSync`, `IRegionCoordinator`, `IGlobalDashboard`
- **Source**: SPRINT_20260117_036

## E2E Test Plan
- [ ] Start `FederationHub` and verify it discovers and connects to remote regions
- [ ] Sync data across two regions via `CrossRegionSync` and verify conflict resolution (KeepLocal, LastWriteWins)
- [ ] Trigger a global promotion via `RegionCoordinator` with Sequential strategy and verify region-by-region rollout
- [ ] Verify data residency: sync evidence and confirm GDPR-compliant data stays within designated regions
- [ ] Query `GlobalDashboard` for cross-region sync status and verify visibility across all regions
- [ ] Verify latency-based routing: probe regions and confirm routing decisions match latency measurements


## Verification
- **Verified**: 2026-02-13T21:00:00Z
- **Method**: Tier 2d integration tests
- **Result**: PASS