semi implemented and features implemented save checkpoint

docs/features/unchecked/attestor/adaptive-noise-gating-for-vulnerability-graphs.md

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+# Adaptive Noise Gating for Vulnerability Graphs
+
+## Module
+Attestor
+
+## Status
+IMPLEMENTED
+
+## Description
+Four-part noise reduction system: (1) Semantic edge deduplication collapsing redundant edges with provenance sets, (2) Proof Strength hierarchy (Authoritative=100 > BinaryProof=80 > StaticAnalysis=60 > Heuristic=40), (3) Stability damping gate preventing flip-flopping verdicts with hysteresis thresholds, (4) Delta sections categorizing changes as New/Resolved/ConfidenceUp/ConfidenceDown/PolicyImpact.
+
+## Implementation Details
+- **ProofChain Graph**: `src/Attestor/__Libraries/StellaOps.Attestor.ProofChain/Graph/` -- `InMemoryProofGraphService` (with `.Mutation`, `.Queries`, `.Subgraph` partials) provides the in-memory graph with node/edge deduplication. `ProofGraphEdge` and `ProofGraphEdgeType` define edge semantics including provenance sets. `ProofGraphNode` and `ProofGraphNodeType` classify node types with strength levels.
+- **Delta Verdict System**: `src/Attestor/__Libraries/StellaOps.Attestor.ProofChain/Predicates/DeltaVerdictPredicate.cs` and `DeltaVerdictPredicate.Budget.cs` implement delta categorization (New/Resolved/ConfidenceUp/ConfidenceDown). `DeltaVerdictChange.cs` and `VerdictDeltaSummary.cs` track per-finding changes.
+- **Evidence Confidence**: `src/Attestor/__Libraries/StellaOps.Attestor.ProofChain/Generators/BackportProofGenerator.Confidence.cs` computes confidence scores using proof-strength hierarchy. `EvidenceSummary.cs` aggregates evidence with strength weighting.
+- **Change Trace**: `src/Attestor/__Libraries/StellaOps.Attestor.ProofChain/ChangeTrace/ChangeTraceAttestationService.cs` (with `.Helpers` and `.Mapping` partials) tracks changes over time for stability damping.
+- **Verdict Delta Predicates**: `VerdictFindingChange.cs`, `VerdictRuleChange.cs` categorize changes by policy impact.
+- **Tests**: `__Tests/StellaOps.Attestor.ProofChain.Tests/Statements/DeltaVerdictStatementTests.cs`, `ChangeTrace/ChangeTracePredicateTests.cs`
+
+## E2E Test Plan
+- [ ] Create a proof graph with redundant edges (same source/target, different provenance) and verify that `InMemoryProofGraphService` deduplicates them into a single edge with merged provenance sets
+- [ ] Submit evidence at different proof-strength tiers (Authoritative, BinaryProof, StaticAnalysis, Heuristic) and verify the `BackportProofGenerator.Confidence` produces correct weighted confidence scores
+- [ ] Generate two consecutive verdict snapshots with minor score fluctuations below the hysteresis threshold and verify that `ChangeTraceAttestationService` suppresses the flip-flop delta
+- [ ] Generate a delta verdict where findings are added, resolved, and confidence-changed, then verify `DeltaVerdictPredicate` categorizes each change correctly (New/Resolved/ConfidenceUp/ConfidenceDown/PolicyImpact)
+- [ ] Query a subgraph via `InMemoryProofGraphService.Subgraph` and verify only reachable nodes from the root are included, with correct edge types