Function useCommunities

ui/src/components/graph/useCommunities.ts:43–147

(
  allNodes: GraphNode[],
  allLinks: GraphLink[],
  layoutConfig: LayoutConfig,
  enabled: boolean = true,
)

 * and brief loss of community colouring.
 */
export function useCommunities(
  allNodes: GraphNode[],
  allLinks: GraphLink[],
  layoutConfig: LayoutConfig,
  enabled: boolean = true,
): CommunityData {
  const [communityData, setCommunityData] =
    useState<CommunityData>(EMPTY_COMMUNITY);
  const workerRef = useRef<Worker | null>(null);
  const requestIdRef = useRef(0);
  const unmountedRef = useRef(false);

  useEffect(() => {
    unmountedRef.current = false;
    return () => {
      unmountedRef.current = true;
      workerRef.current?.terminate();
      workerRef.current = null;
    };
  }, []);

  useEffect(() => {
    // Master switch: when communities are disabled, never spawn the
    // Louvain worker and keep assignments empty. Downstream features
    // (colors, labels, community-gravity force, 3D depth) already treat
    // empty assignments as "no communities" — flipping this off cleanly
    // returns to a community-agnostic view with no wasted compute.
    if (!enabled) {
      // eslint-disable-next-line react-hooks/set-state-in-effect -- reset to empty when disabled
      setCommunityData(EMPTY_COMMUNITY);
      workerRef.current?.terminate();
      workerRef.current = null;
      return;
    }
    if (allNodes.length === 0) {
      setCommunityData(EMPTY_COMMUNITY);
      return;
    }

    // Terminate previous worker
    workerRef.current?.terminate();
    workerRef.current = null;

    const reqId = ++requestIdRef.current;

    const worker = new Worker(
      new URL('../workers/communityWorker.ts', import.meta.url),
      { type: 'module' },
    );
    workerRef.current = worker;

    worker.onerror = (err) => {
      if (reqId !== requestIdRef.current || unmountedRef.current) return;
      console.error('[graph] community worker failed:', err);
      setCommunityData(EMPTY_COMMUNITY);
    };

    worker.onmessage = (e: MessageEvent<CommunityResponse>) => {