fix(communities): canonicalize projection order

gitnexus/src/core/ingestion/community-processor.ts

@@ -302,21 +302,28 @@ export const buildCommunityProjection = (knowledgeGraph: KnowledgeGraph): Commun
 
   const nodes: CommunityProjectionNode[] = [];
   const nodeIndexById = new Map<string, number>();
+  const eligibleNodes: GraphNode[] = [];
 
   knowledgeGraph.forEachNode((node) => {
     if (!isCommunitySymbol(node) || !connectedNodes.has(node.id)) return;
     // For large graphs, skip degree-1 nodes — they just become singletons or
     // get absorbed into their single neighbor's community, but cost iteration time.
     if (isLarge && (nodeDegree.get(node.id) || 0) < 2) return;
 
+    eligibleNodes.push(node);
+  });
+
+  eligibleNodes.sort((left, right) => (left.id < right.id ? -1 : left.id > right.id ? 1 : 0));
+
+  for (const node of eligibleNodes) {
     nodeIndexById.set(node.id, nodes.length);
     nodes.push({
       id: node.id,
       name: node.properties.name,
       filePath: node.properties.filePath,
       type: node.label,
     });
-  });
+  }
 
   const seenEdges = new Set<string>();
   const edges: Array<readonly [number, number]> = [];
@@ -338,6 +345,7 @@ export const buildCommunityProjection = (knowledgeGraph: KnowledgeGraph): Commun
     seenEdges.add(edgeKey);
     edges.push([a, b]);
   });
+  edges.sort(([leftA, leftB], [rightA, rightB]) => leftA - rightA || leftB - rightB);
 
   return { nodes, edges, symbolCount, isLarge };
 };

gitnexus/test/fixtures/pipeline-golden/mini-repo/expected-graph.json

@@ -24,5 +24,5 @@
     "MEMBER_OF": 12,
     "STEP_IN_PROCESS": 12
   },
-  "edgeDigest": "1e80aba78cb1784276d387e9debd006ae4e82e60ce33c59e338aac4886d98f61"
+  "edgeDigest": "02858462a2acca13f09b7ae2a81d56fe858e67064552ea966cd9ca242371e029"
 }

gitnexus/test/integration/cfg/__snapshots__/pipeline-pdg.test.ts.snap

@@ -18,7 +18,7 @@ exports[`U7 — C-family worker-mode --pdg pipeline > C#: --pdg off is byte-iden
     "Namespace": 1,
     "Process": 1,
   },
-  "edgeDigest": "2271af66531e4fb54afb2d6e0a024abc536e2109f445e0ecff9868c01661ebfa",
+  "edgeDigest": "0497d26dbe060d36426bf10cde5db490a6d82c013e0835296723a4c00ef7442a",
   "relationships": 38,
   "symbols": 24,
 }
@@ -66,7 +66,7 @@ exports[`U7 — C-family worker-mode --pdg pipeline > Go: --pdg off is byte-iden
     "File": 1,
     "Function": 28,
   },
-  "edgeDigest": "731ee1aa406fe7a96c5747dc2e5059f9079fd883dfca70a1933d49ce7f161a99",
+  "edgeDigest": "33164ebef537538cce43ab1a518d8a5d4944d6d9ad059973b974d3b0fea7caaa",
   "relationships": 64,
   "symbols": 37,
 }
@@ -86,7 +86,7 @@ exports[`U7 — C-family worker-mode --pdg pipeline > Java: --pdg off is byte-id
     "File": 1,
     "Method": 21,
   },
-  "edgeDigest": "b5e4c1459c59f385949964c3e4e479e67c98a2eaa7e102f4acacb108a9ccec29",
+  "edgeDigest": "488a3f80683f3e2fd0160847f22537cdd1d48f1e8f34c929562854459abfe03a",
   "relationships": 46,
   "symbols": 27,
 }

gitnexus/test/unit/community-processor.test.ts

@@ -102,6 +102,26 @@ describe('community-processor', () => {
       expect(projection.symbolCount).toBe(3);
     });
 
+    it('produces the same projection regardless of graph insertion order', () => {
+      const first = createKnowledgeGraph();
+      for (const id of ['fn:c', 'fn:a', 'fn:b']) {
+        first.addNode(makeNode(id, id.slice(3)));
+      }
+      first.addRelationship(makeRel('rel:ac', 'fn:a', 'fn:c'));
+      first.addRelationship(makeRel('rel:ab', 'fn:a', 'fn:b'));
+      first.addRelationship(makeRel('rel:bc', 'fn:b', 'fn:c'));
+
+      const second = createKnowledgeGraph();
+      for (const id of ['fn:b', 'fn:c', 'fn:a']) {
+        second.addNode(makeNode(id, id.slice(3)));
+      }
+      second.addRelationship(makeRel('rel:bc', 'fn:c', 'fn:b'));
+      second.addRelationship(makeRel('rel:ab', 'fn:b', 'fn:a'));
+      second.addRelationship(makeRel('rel:ac', 'fn:c', 'fn:a'));
+
+      expect(buildCommunityProjection(second)).toEqual(buildCommunityProjection(first));
+    });
+
     it('exports a deterministic undirected CSR adjacency', () => {
       const projection = {
         nodes: [