semi implemented and features implemented save checkpoint

docs/features/unchecked/sbomservice/sbom-lineage-api-backend.md

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+# SBOM Lineage API Backend
+
+## Module
+SbomService
+
+## Status
+IMPLEMENTED
+
+## Description
+REST API endpoints for lineage graph queries, diff computation, and export. Architecture fully documented but backend implementation pending.
+
+## Implementation Details
+- **Lineage controller**: `src/SbomService/StellaOps.SbomService/Controllers/LineageController.cs` -- REST endpoints for lineage queries
+- **Lineage export models**: `src/SbomService/StellaOps.SbomService/Models/LineageExportModels.cs` -- export format models
+- **Path models**: `src/SbomService/StellaOps.SbomService/Models/SbomPathModels.cs` -- graph path traversal models
+- **Projection models**: `src/SbomService/StellaOps.SbomService/Models/SbomProjectionModels.cs` -- lineage projection data
+- **Lineage library**: `src/SbomService/__Libraries/StellaOps.SbomService.Lineage/` -- core lineage logic
+- **VEX delta repository**: `src/SbomService/__Libraries/StellaOps.SbomService.Lineage/Repositories/VexDeltaRepository.cs`
+- **Persistence migrations**: `src/SbomService/__Libraries/StellaOps.SbomService.Lineage/Persistence/Migrations/00001_InitialSchema.sql`
+- **Observability**: `src/SbomService/StellaOps.SbomService/Observability/SbomMetrics.cs`, `SbomTracing.cs`
+- **Source**: Feature matrix scan
+
+## E2E Test Plan
+- [ ] Verify lineage API endpoints return valid graph data
+- [ ] Test diff computation between SBOM versions
+- [ ] Verify export endpoints generate correct lineage exports
+- [ ] Test path traversal queries through lineage graph