# Runtime Reachability Collection

## Module
Signals

## Status
IMPLEMENTED

## Description
Runtime collection via .NET EventPipe agent with method-level tracing and facts ingestion is implemented.

## Implementation Details
- **Modules**: `src/Signals/StellaOps.Signals.RuntimeAgent/`, `src/Signals/StellaOps.Signals/Services/`
- **Key Classes**:
  - `DotNetEventPipeAgent` (`src/Signals/StellaOps.Signals.RuntimeAgent/DotNetEventPipeAgent.cs`) - .NET EventPipe agent for method-level runtime tracing
  - `RuntimeFactsIngestService` (`src/Signals/StellaOps.Signals.RuntimeAgent/RuntimeFactsIngestService.cs`) - ingests runtime method events into the signals store
  - `RuntimeMethodEvent` (`src/Signals/StellaOps.Signals.RuntimeAgent/RuntimeMethodEvent.cs`) - event model for captured runtime method calls
  - `ReachabilityFactEventBuilder` (`src/Signals/StellaOps.Signals/Services/ReachabilityFactEventBuilder.cs`) - builds reachability fact events from runtime data
  - `ReachabilityFactCacheDecorator` (`src/Signals/StellaOps.Signals/Services/ReachabilityFactCacheDecorator.cs`) - caching layer for reachability fact lookups
- **Interfaces**: `IRuntimeAgent`, `IRuntimeFactsIngest`, `IReachabilityFactRepository`
- **Source**: Feature matrix scan

## E2E Test Plan
- [ ] Start `DotNetEventPipeAgent` against a target .NET process and verify method-level events are captured
- [ ] Verify `RuntimeFactsIngestService` processes runtime method events and stores reachability facts
- [ ] Verify runtime facts include method names, call stacks, and timestamps
- [ ] Verify `ReachabilityFactCacheDecorator` caches frequently queried facts
- [ ] Verify runtime facts are correlated with static call-graph data to produce combined reachability evidence