# SBOM-to-symbol component reachability mapping

## Module
Signals

## Status
VERIFIED

## Description
SBOM correlation and function-level proof linking services map symbols to SBOM components and generate reachability facts.

## Implementation Details
- **Modules**: `src/Signals/StellaOps.Signals/Services/`
- **Key Classes**:
  - `SbomCorrelationService` (`src/Signals/StellaOps.Signals/Services/ISbomCorrelationService.cs`) - correlates call-graph symbols with SBOM component identifiers
  - `FuncProofLinkingService` (`src/Signals/StellaOps.Signals/Services/IFuncProofLinkingService.cs`) - links function-level evidence to SBOM components for reachability proof
  - `HotSymbolsController` (`src/Signals/StellaOps.Signals/Api/HotSymbolsController.cs`) - API for querying hot (reachable) symbols mapped to SBOM components
  - `HotSymbolIndex` (`src/Signals/StellaOps.Signals/Models/HotSymbolIndex.cs`) - index of frequently called/reachable symbols
- **Interfaces**: `ISbomCorrelationService`, `IFuncProofLinkingService`
- **Source**: Feature matrix scan

## E2E Test Plan
- [ ] Ingest a call graph and an SBOM, then verify `SbomCorrelationService` maps symbols to their SBOM components
- [ ] Verify `FuncProofLinkingService` generates function-level reachability proof linking symbols to components
- [ ] Query hot symbols via `HotSymbolsController` and verify reachable symbols are returned with their SBOM component references
- [ ] Verify mapping accuracy: submit a known symbol and confirm it maps to the correct SBOM package
- [ ] Verify unmapped symbols are flagged as unknown components