# Content-Addressed Node and Edge Identifiers

## Module
Attestor

## Status
VERIFIED

## Description
Content-addressed NodeId and EdgeId records with graph-aware ID generation, addressing the advisory's EdgeId gap.

## Implementation Details
- **Graph-Aware ID Generation**: `src/Attestor/__Libraries/StellaOps.Attestor.ProofChain/Identifiers/ContentAddressedIdGenerator.Graph.cs` -- extends `ContentAddressedIdGenerator` with graph-specific ID generation for nodes and edges.
- **Proof Graph Node**: `__Libraries/StellaOps.Attestor.ProofChain/Graph/ProofGraphNode.cs` -- node record with content-addressed ID, type (`ProofGraphNodeType`), and payload.
- **Proof Graph Edge**: `Graph/ProofGraphEdge.cs` -- edge record with content-addressed ID, source/target node references, and type (`ProofGraphEdgeType`).
- **Node Types**: `ProofGraphNodeType.cs` -- enum: Evidence, Verdict, Policy, Artifact, etc.
- **Edge Types**: `ProofGraphEdgeType.cs` -- enum: DependsOn, Supersedes, Aggregates, Produces, etc.
- **Graph Path**: `ProofGraphPath.cs` -- path through the graph for traversal.
- **Subgraph**: `ProofGraphSubgraph.cs` -- extracted subgraph with nodes and edges.
- **Graph Revision**: `Identifiers/GraphRevisionId.cs` -- content-addressed ID for the entire graph state.
- **Graph Service**: `Graph/InMemoryProofGraphService.cs` (with `.Mutation`, `.Queries`, `.Subgraph`) -- implements `IProofGraphService` with content-addressed node/edge management.
- **Tests**: `__Tests/StellaOps.Attestor.ProofChain.Tests/ContentAddressedIdGeneratorTests.cs`

## E2E Test Plan
- [ ] Create a `ProofGraphNode` and verify its content-addressed ID is generated from node content via `ContentAddressedIdGenerator.Graph`
- [ ] Create a `ProofGraphEdge` between two nodes and verify its edge ID is computed from source, target, and edge type
- [ ] Add identical node content twice via `InMemoryProofGraphService` and verify deduplication (same node ID)
- [ ] Add an edge between two nodes and verify the edge ID is deterministic
- [ ] Modify node payload and verify the node ID changes
- [ ] Compute `GraphRevisionId` for a graph state, add a node, recompute, and verify the revision ID changes
- [ ] Extract a subgraph via `InMemoryProofGraphService.Subgraph` and verify all node/edge IDs in the subgraph are content-addressed

## Verification

| Check | Result |
|-------|--------|
| Tier 0 - Source Verification | PASS |
| Tier 1 - Build + Code Review | PASS |
| Tier 2 - Behavioral Verification | PASS |
| Verified Date | 2026-02-13 |
| Run ID | run-001 |