fix: handle undirected graph neighbors correctly in graph adapter

Author: Mearman

src/algorithms/extraction/path.unit.test.ts

@@ -178,10 +178,7 @@ describe("findShortestPath", () => {
 			}
 		});
 
-		// Note: Backward traversal in undirected graphs has a known limitation
-		// in GraphAdapter.getNeighbors - it always maps to edge.target instead
-		// of handling the case where the node is the edge's target (should return source).
-		it.skip("should find path in reverse direction for undirected graph", () => {
+		it("should find path in reverse direction for undirected graph", () => {
 			const graph = new Graph<TestNode, TestEdge>(false);
 			graph.addNode(createNode("A"));
 			graph.addNode(createNode("B"));

src/algorithms/graph/graph-adapter.ts

@@ -42,7 +42,9 @@ export class GraphAdapter<N extends Node, E extends Edge> implements ReadableGra
 		if (!result.ok) {
 			return [];
 		}
-		return result.value.map(edge => edge.target);
+		// For undirected graphs, getOutgoingEdges returns edges where node is
+		// either source or target. We need to return the "other" node in each edge.
+		return result.value.map(edge => edge.source === id ? edge.target : edge.source);
 	}
 
 	getAllNodes(): N[] {