# Compositional Library-Aware Call-Graph Reachability

## Module
Scanner

## Status
VERIFIED

## Description
Multi-layer reachability analysis combining call-graph extraction, dependency-aware analysis, surface-aware analysis, and conditional reachability with ReachGraph integration.

## Implementation Details
- **Dependency-Aware Reachability**:
  - `src/Scanner/__Libraries/StellaOps.Scanner.Reachability/Dependencies/ConditionalReachabilityAnalyzer.cs` - Conditional reachability analysis considering library dependencies
  - `src/Scanner/__Libraries/StellaOps.Scanner.Reachability/Dependencies/DependencyReachabilityModels.cs` - Models for dependency-aware reachability
  - `src/Scanner/__Libraries/StellaOps.Scanner.Reachability/Dependencies/ReachGraphReachabilityCombiner.cs` - Combines ReachGraph data with local reachability analysis
- **Dependency Reporting**:
  - `src/Scanner/__Libraries/StellaOps.Scanner.Reachability/Dependencies/Reporting/DependencyReachabilityReporter.cs` - Generates dependency reachability reports
  - `src/Scanner/__Libraries/StellaOps.Scanner.Reachability/Dependencies/Reporting/DependencyReachabilityReport.cs` - Report model
- **Surface-Aware Analysis**:
  - `src/Scanner/__Libraries/StellaOps.Scanner.Reachability/Surfaces/SurfaceAwareReachabilityAnalyzer.cs` - Surface-aware reachability analysis combining attack surface with call graph
- **Call Graph Extraction** (multi-language):
  - `src/Scanner/__Libraries/StellaOps.Scanner.CallGraph/` - Multi-language call graph extractors
- **Worker Integration**:
  - `src/Scanner/StellaOps.Scanner.Worker/Processing/Reachability/ReachabilityBuildStageExecutor.cs` - Builds reachability during scan
  - `src/Scanner/StellaOps.Scanner.Worker/Processing/Reachability/SbomReachabilityStageExecutor.cs` - SBOM-level reachability analysis
- **API**:
  - `src/Scanner/StellaOps.Scanner.WebService/Endpoints/ReachabilityEndpoints.cs` - `ReachabilityEndpoints` for querying reachability results

## E2E Test Plan
- [ ] Scan an image with a multi-library application and verify call graph extraction captures inter-library calls
- [ ] Verify `ConditionalReachabilityAnalyzer` considers conditional dependencies (optional/feature-flagged)
- [ ] Verify `SurfaceAwareReachabilityAnalyzer` combines attack surface data with call graph to produce accurate reachability verdicts
- [ ] Verify `ReachGraphReachabilityCombiner` integrates external ReachGraph data with local analysis
- [ ] Query reachability results via `GET /api/v1/scans/{scanId}/reachability` and verify library-aware paths are included
- [ ] Verify the dependency reachability report includes per-library reachability status

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## Verification

| Check | Result |
|-------|--------|
| Tier 0 - Source files exist | PASS |
| Tier 1 - Build + code review | PASS |
| Tier 2 - Integration tests | PASS |
| Verified | 2026-02-13T18:10:00Z |