# 8-State Reachability Lattice

## Module
ReachGraph

## Status
IMPLEMENTED

## Description
Reachability infrastructure exists with triage integration, but the full 8-state lattice model (U/SR/SU/RO/RU/CR/CU/X) with mathematical state transitions as described is not fully implemented as a distinct subsystem.

## What's Implemented
- **LatticeState enum**: `src/__Libraries/StellaOps.Reachability.Core/LatticeState.cs` -- full 8-state model defined: Unknown (U), StaticReachable (SR), StaticUnreachable (SU), RuntimeObserved (RO), RuntimeUnobserved (RU), ConfirmedReachable (CR), ConfirmedUnreachable (CU), Contested (X); includes VEX mapping and confidence ranges per state
- **ReachabilityLattice state machine**: `src/__Libraries/StellaOps.Reachability.Core/ReachabilityLattice.cs` -- `FrozenDictionary` transition table with evidence accumulation; transitions from all states including conflict detection (X state when static and runtime evidence contradict); confidence delta per transition
- **ConfidenceCalculator**: `src/__Libraries/StellaOps.Reachability.Core/ConfidenceCalculator.cs` -- confidence score computation
- **IReachabilityIndex**: `src/__Libraries/StellaOps.Reachability.Core/IReachabilityIndex.cs` -- `QueryHybridAsync` returns `HybridReachabilityResult` with lattice state
- **HybridReachabilityResult**: `src/__Libraries/StellaOps.Reachability.Core/HybridReachabilityResult.cs` -- includes lattice state, confidence, and VEX recommendation

## What's Missing
- The lattice state machine is implemented as a library but not fully integrated as a distinct subsystem with its own API surface for triage workflows
- Triage-specific UI for lattice state visualization and manual state overrides
- Lattice state persistence and audit trail for state transitions

## Implementation Plan
- Expose lattice state transitions as an API for triage integration
- Build UI for lattice state visualization and manual overrides
- Add persistence layer for state transition history and audit trail

## Related Documentation
- Source: See feature catalog