fix(explorer): address edge label review findings

explorer/src/workspaces/GraphWorkspace/GraphCanvas.tsx

@@ -1312,6 +1312,9 @@ export const GraphCanvas = forwardRef<GraphCanvasHandle, GraphCanvasProps>(
     const onEdgeClickRef = useRef(onEdgeClick);
     const onSceneRuntimeChangeRef = useRef(onSceneRuntimeChange);
     const onCameraStateChangeRef = useRef(onCameraStateChange);
+    // #1009: tracked as a ref so the Sigma creation effect always reads the
+    // current value without needing effectsState in its dependency array.
+    const effectsStateRef = useRef(effectsState);
     const [hoveredNodeId, setHoveredNodeId] = useState<string | null>(null);
     const [zoomTier, setZoomTier] = useState<GraphZoomTier>("overview");
     const [analyticsSnapshot, setAnalyticsSnapshot] = useState<GraphAnalyticsSnapshot | null>(null);
@@ -1340,6 +1343,7 @@ export const GraphCanvas = forwardRef<GraphCanvasHandle, GraphCanvasProps>(
     onEdgeClickRef.current = onEdgeClick;
     onSceneRuntimeChangeRef.current = onSceneRuntimeChange;
     onCameraStateChangeRef.current = onCameraStateChange;
+    effectsStateRef.current = effectsState;
 
     const behaviors = useMemo<GraphBehavior[]>(
       () => [
@@ -1852,7 +1856,13 @@ export const GraphCanvas = forwardRef<GraphCanvasHandle, GraphCanvasProps>(
         return;
       }
 
-      const sigma = new Sigma(displayGraphRef.current, containerRef.current, SIGMA_SETTINGS);
+      const sigma = new Sigma(displayGraphRef.current, containerRef.current, {
+        ...SIGMA_SETTINGS,
+        // #1009: initialize with the current toggle value rather than the
+        // static default so that a user who disabled Edge Labels before
+        // graph/Sigma initialization sees the correct state after mount.
+        renderEdgeLabels: effectsStateRef.current.edgeLabelsEnabled,
+      });
       sigmaRef.current = sigma;
       appliedGraphVersionRef.current = graphVersionRef.current;
 

explorer/src/workspaces/GraphWorkspace/graphSceneState.ts

@@ -2099,6 +2099,15 @@ function createCollapsedNeighborhoodGraph(
   return collapsedGraph;
 }
 
+// Normalize an edge relationship type: empty string, null, and undefined all
+// fall back to the project-wide default used consistently across every
+// aggregation path. Keep this local — it exists only to guarantee that the
+// three code paths (single-entry, multi-entry, community-grouped) produce the
+// same semantics and do not diverge again.
+function normalizeEdgeType(value: string | null | undefined): string {
+  return value || "related_to";
+}
+
 function aggregateDisplayGraph(graphRef: GraphRef): Graph<NodeAttributes, EdgeAttributes> {
   const aggregated = new Graph<NodeAttributes, EdgeAttributes>({
     type: "directed",
@@ -2124,10 +2133,13 @@ function aggregateDisplayGraph(graphRef: GraphRef): Graph<NodeAttributes, EdgeAt
       const [{ edgeId, attrs }] = entries;
       aggregated.mergeDirectedEdgeWithKey(edgeId, sourceId, targetId, {
         ...attrs,
+        // #1009: normalize empty/null/undefined edgeType so Sigma's label
+        // renderer never receives a blank string on the single-entry path.
+        edgeType: normalizeEdgeType(attrs.edgeType),
+        dominantEdgeType: normalizeEdgeType(attrs.dominantEdgeType ?? attrs.edgeType),
         rawEdgeIds: collectRawEdgeIds(attrs, edgeId),
         isAggregated: isAggregatedEdgeAttributes(attrs),
         aggregateCount: attrs.aggregateCount ?? collectRawEdgeIds(attrs, edgeId).length,
-        dominantEdgeType: attrs.dominantEdgeType ?? attrs.edgeType,
         representativeWeight: attrs.representativeWeight ?? Number(attrs.weight ?? 1),
       });
       return;
@@ -2150,10 +2162,11 @@ function aggregateDisplayGraph(graphRef: GraphRef): Graph<NodeAttributes, EdgeAt
     const rawEdgeIds = entries.flatMap(({ edgeId, attrs }) => collectRawEdgeIds(attrs, edgeId));
     const typeCounts = new Map<string, number>();
     entries.forEach(({ attrs }) => {
-      const edgeType = String(attrs.edgeType || "related_to");
+      const edgeType = normalizeEdgeType(attrs.edgeType);
       typeCounts.set(edgeType, (typeCounts.get(edgeType) ?? 0) + 1);
     });
-    const dominantEdgeType = [...typeCounts.entries()].sort((left, right) => right[1] - left[1])[0]?.[0] ?? representative.attrs.edgeType ?? "related_to";
+    const dominantEdgeType = [...typeCounts.entries()].sort((left, right) => right[1] - left[1])[0]?.[0]
+      ?? normalizeEdgeType(representative.attrs.edgeType);
     const reverseKey = `${targetId}→${sourceId}`;
     const isBidirectionalBundle = groupedEdges.has(reverseKey);
     const syntheticEdgeId = `${AGGREGATED_EDGE_PREFIX}${sourceId}::${targetId}`;
@@ -2167,10 +2180,10 @@ function aggregateDisplayGraph(graphRef: GraphRef): Graph<NodeAttributes, EdgeAt
       rawEdgeIds,
       isAggregated: true,
       aggregateCount: rawEdgeIds.length,
-      dominantEdgeType: String(dominantEdgeType),
+      dominantEdgeType: dominantEdgeType,
       representativeWeight: Number(representative.attrs.weight ?? 1),
       weight: Number(representative.attrs.weight ?? 1),
-      edgeType: String(representative.attrs.edgeType || dominantEdgeType || "related_to"),
+      edgeType: representative.attrs.edgeType || dominantEdgeType,
       parallelCount: rawEdgeIds.length,
       familySize: rawEdgeIds.length,
       bundleKind: isBidirectionalBundle ? "bidirectional" : "parallel",
@@ -2280,7 +2293,7 @@ function buildCommunityGroupedGraph(): GraphDisplayResult {
     };
     bucket.rawEdgeIds.push(String(edgeId));
     bucket.weight = Math.max(bucket.weight, Number((attrs as EdgeAttributes).weight ?? 1));
-    const edgeType = String((attrs as EdgeAttributes).edgeType || "related_to");
+    const edgeType = normalizeEdgeType((attrs as EdgeAttributes).edgeType);
     bucket.typeCounts.set(edgeType, (bucket.typeCounts.get(edgeType) ?? 0) + 1);
     groupedEdges.set(key, bucket);
   });
@@ -2396,7 +2409,8 @@ function buildCommunityGroupedGraph(): GraphDisplayResult {
     if (!visibleGroupedEdgeKeys.has(key)) {
       return;
     }
-    const dominantEdgeType = [...bundle.typeCounts.entries()].sort((left, right) => right[1] - left[1])[0]?.[0] ?? "related_to";
+    const dominantEdgeType = [...bundle.typeCounts.entries()].sort((left, right) => right[1] - left[1])[0]?.[0]
+      ?? "related_to";
     const reverseKey = `${bundle.targetId}→${bundle.sourceId}`;
     const syntheticEdgeId = `${AGGREGATED_EDGE_PREFIX}${key}`;
     const aggregateCount = bundle.rawEdgeIds.length;

explorer/src/workspaces/GraphWorkspace/plugins/explorationEffectsPlugin.tsx

@@ -1,6 +1,7 @@
 import type { CSSProperties } from "react";
 
 import type {
+  GraphDiagnosticsSnapshot,
   GraphEffectAvailability,
   GraphEffectToggle,
 } from "../types";
@@ -42,6 +43,17 @@ const EFFECT_ROWS: EffectRowConfig[] = [
   },
 ];
 
+// Maps the effect toggle keys rendered by this plugin to their corresponding
+// availability keys in GraphDiagnosticsSnapshot["effectAvailability"]. Kept
+// local because this plugin only renders a subset of all effects.
+const EFFECT_AVAILABILITY_KEYS: Partial<Record<GraphEffectToggle, keyof GraphDiagnosticsSnapshot["effectAvailability"]>> = {
+  pathPulseEnabled: "pathPulse",
+  pathFlowEnabled: "pathFlow",
+  lensEnabled: "lens",
+  edgeLabelsEnabled: "edgeLabels",
+  legendEnabled: "legend",
+};
+
 function renderAvailabilityText(availability: GraphEffectAvailability) {
   if (availability.available) {
     if (typeof availability.visibleSegments === "number" && typeof availability.segmentCap === "number") {
@@ -144,17 +156,9 @@ export const explorationEffectsPlugin: GraphPlugin = {
                 description={row.description}
                 checked={effectsState[row.key]}
                 availability={
-                  availability?.[
-                    row.key === "pathPulseEnabled"
-                      ? "pathPulse"
-                      : row.key === "pathFlowEnabled"
-                        ? "pathFlow"
-                        : row.key === "lensEnabled"
-                          ? "lens"
-                          : row.key === "edgeLabelsEnabled"
-                            ? "edgeLabels"
-                            : "legend"
-                  ] ?? {
+                  (EFFECT_AVAILABILITY_KEYS[row.key] !== undefined
+                    ? availability?.[EFFECT_AVAILABILITY_KEYS[row.key]!]
+                    : undefined) ?? {
                     enabled: effectsState[row.key],
                     available: false,
                     reason: "Waiting for graph runtime",

explorer/tests/graphSceneState.display.test.ts

@@ -1213,3 +1213,46 @@ test("resolveEdgeElementStyle hidden class produces hidden:true for suppressed e
   );
   assert.equal(style.hidden, true);
 });
+
+// ── #1009 maintainer-blocking regression: single-edge empty edgeType ─────────
+
+test("resolveDisplayGraph single-edge normalizes empty-string edgeType to related_to", () => {
+  addNode("a");
+  addNode("b");
+  // One edge only — exercises the entries.length === 1 path in aggregateDisplayGraph.
+  batchMergeEdges([{
+    id: "e-single-empty",
+    source: "a",
+    target: "b",
+    attributes: { edgeType: "", weight: 1, properties: {} },
+  }]);
+
+  const { graph: displayGraph } = resolveDisplayGraph("", [], [], "full", { aggregationEnabled: true });
+  assert.equal(displayGraph.size, 1);
+
+  const edgeId = displayGraph.edges()[0];
+  const attrs = displayGraph.getEdgeAttributes(edgeId) as { edgeType?: string; dominantEdgeType?: string };
+  assert.equal(attrs.edgeType, "related_to",
+    "single-edge path must normalize empty edgeType to the canonical fallback");
+  assert.equal(attrs.dominantEdgeType, "related_to",
+    "single-edge dominantEdgeType must also be normalized");
+});
+
+test("resolveDisplayGraph single-edge preserves a valid non-empty edgeType unchanged", () => {
+  addNode("a");
+  addNode("b");
+  batchMergeEdges([{
+    id: "e-single-valid",
+    source: "a",
+    target: "b",
+    attributes: { edgeType: "works_for", weight: 1, properties: {} },
+  }]);
+
+  const { graph: displayGraph } = resolveDisplayGraph("", [], [], "full", { aggregationEnabled: true });
+  assert.equal(displayGraph.size, 1);
+
+  const edgeId = displayGraph.edges()[0];
+  const attrs = displayGraph.getEdgeAttributes(edgeId) as { edgeType?: string };
+  assert.equal(attrs.edgeType, "works_for",
+    "single-edge path must not alter a valid relationship type");
+});