# Platform Service Aggregation Layer

## Module
Platform

## Status
IMPLEMENTED

## Description
Backend Platform Service acting as aggregation layer for health status, quotas, onboarding progress, user preferences, and global search across all modules.

## Implementation Details
- **PlatformEndpoints**: `src/Platform/StellaOps.Platform.WebService/Endpoints/PlatformEndpoints.cs` -- REST API at `/api/v1/platform` with 6 endpoint groups: health (summary/dependencies/incidents/metrics), quotas (summary/tenants/alerts), onboarding (status/complete/skip), preferences (dashboard/profiles), search, metadata; all with tenant-scoped authorization policies
- **PlatformHealthService**: `src/Platform/StellaOps.Platform.WebService/Services/PlatformHealthService.cs` -- aggregates health status from all platform services
- **PlatformQuotaService**: service for quota tracking with alert management (create alert thresholds per tenant)
- **PlatformOnboardingService**: `src/Platform/StellaOps.Platform.WebService/Services/PlatformOnboardingService.cs` -- tracks onboarding progress with step completion and skip support
- **PlatformPreferencesService**: `src/Platform/StellaOps.Platform.WebService/Services/PlatformPreferencesService.cs` -- user dashboard preferences with profile management (CRUD)
- **PlatformSearchService**: global search across all modules with source filtering, pagination
- **PlatformMetadataService**: `src/Platform/StellaOps.Platform.WebService/Services/PlatformMetadataService.cs` -- platform metadata retrieval
- **PlatformCache**: `src/Platform/StellaOps.Platform.WebService/Services/PlatformCache.cs` -- caching layer with TTL and data-as-of timestamps
- **Source**: SPRINT_20251229_043_PLATFORM_platform_service_foundation

## E2E Test Plan
- [ ] Verify health summary endpoint aggregates all service statuses
- [ ] Test quota alerts are created and returned with proper authorization
- [ ] Verify onboarding step completion transitions correctly
- [ ] Test global search returns results from multiple sources with pagination
- [ ] Verify dashboard preferences persist and load per tenant/user