# Policy Version Binding to Reachability Slices (strict/forward/any)

## Module
Scanner

## Status
IMPLEMENTED

## Description
Binds reachability slices to specific policy versions with three validation modes: strict (invalidate on any policy change), forward (valid with newer versions), and any (valid with any version). Production defaults to strict mode.

## Implementation Details
- **Policy Binding**:
  - `src/Scanner/__Libraries/StellaOps.Scanner.Reachability/Slices/PolicyBinding.cs` - `PolicyBinding` binds reachability slices to specific policy versions with three validation modes: strict (invalidate on any policy change), forward (valid with newer versions), and any (valid with any version)
- **Slice Schema**:
  - `src/Scanner/__Libraries/StellaOps.Scanner.Reachability/Slices/SliceSchema.cs` - `SliceSchema` includes policy version binding metadata in slice definitions

## E2E Test Plan
- [ ] Create a reachability slice with strict policy binding and verify it is invalidated when the policy version changes
- [ ] Create a reachability slice with forward binding and verify it remains valid when the policy version is incremented
- [ ] Create a reachability slice with forward binding and verify it is invalidated when the policy version is rolled back
- [ ] Create a reachability slice with "any" binding and verify it remains valid regardless of policy version changes
- [ ] Verify production defaults to strict mode when no binding mode is explicitly specified
- [ ] Verify invalidated slices trigger re-computation of reachability analysis