# Graph Indexer Incremental Update Pipeline

## Module
Graph

## Status
IMPLEMENTED

## Description
Change-stream processor for incremental graph updates, consuming SBOM/scan events and applying delta mutations to the indexed graph with idempotency tracking and backfill metrics.

## Implementation Details
- **Change stream processor**: `src/Graph/StellaOps.Graph.Indexer/Incremental/GraphChangeStreamProcessor.cs` -- consumes SBOM/scan events and applies delta mutations to indexed graph
- **Change event model**: `src/Graph/StellaOps.Graph.Indexer/Incremental/GraphChangeEvent.cs` -- event model for graph mutations
- **Stream options**: `src/Graph/StellaOps.Graph.Indexer/Incremental/GraphChangeStreamOptions.cs` -- configurable stream processing parameters
- **Idempotency store**: `src/Graph/StellaOps.Graph.Indexer/Incremental/InMemoryIdempotencyStore.cs` -- in-memory deduplication for event processing
- **Postgres idempotency**: `src/Graph/__Libraries/StellaOps.Graph.Indexer.Persistence/Postgres/Repositories/PostgresIdempotencyStore.cs` -- PostgreSQL-backed idempotency tracking
- **No-op event source**: `src/Graph/StellaOps.Graph.Indexer/Incremental/NoOpGraphChangeEventSource.cs` -- stub event source for testing
- **Backfill metrics**: `src/Graph/StellaOps.Graph.Indexer/Incremental/GraphBackfillMetrics.cs` -- metrics for backfill operations
- **DI extensions**: `src/Graph/StellaOps.Graph.Indexer/Incremental/GraphChangeStreamServiceCollectionExtensions.cs` -- DI registration
- **SBOM ingestion**: `src/Graph/StellaOps.Graph.Indexer/Ingestion/Sbom/SbomIngestProcessor.cs`, `SbomIngestTransformer.cs` -- SBOM event processing and graph transformation
- **Tests**: `src/Graph/__Tests/StellaOps.Graph.Indexer.Tests/GraphChangeStreamProcessorTests.cs`, `GraphIndexerEndToEndTests.cs`
- **Persistence tests**: `src/Graph/__Tests/StellaOps.Graph.Indexer.Persistence.Tests/PostgresIdempotencyStoreTests.cs`
- **Source**: SPRINT_0141_0001_0001_graph_indexer.md

## E2E Test Plan
- [ ] Verify change stream processor applies delta mutations correctly
- [ ] Test idempotency ensures duplicate events are not processed
- [ ] Verify backfill metrics track progress accurately
- [ ] Test SBOM ingestion transforms events into graph updates
- [ ] Verify PostgreSQL idempotency store persists across restarts