app/tui/useLaneSnapshots.ts

 // Polls `listLanes` across a set of repos on an interval -- the one data

 // source both `zz work`'s default view and `zz top` render from. Polling

 // instead of a real subscription because the underlying state is still

 // flat JSON files (and later, a Backend read) -- there's nothing to

 // subscribe to yet, only something to re-read.

 import { useEffect, useState } from "react";

 import { listLanes } from "../engine/store.js";

 import { callRemoteTool } from "../cli/lib/remoteTools.js";

 import type { Lane } from "../engine/types.js";

 import type { LaneSnapshot } from "./types.js";

 export function useLaneSnapshots(repos: { repo: string; stateDir: string }[], intervalMs = 500, remote = false): LaneSnapshot[] {

  const [snapshots, setSnapshots] = useState<LaneSnapshot[]>([]);

  // repos' CONTENTS, not its identity -- a growing watch store (see

  // cli/lib/watchedRepos.ts) gives WorkApp a fresh array reference every

  // render regardless of whether the set actually changed, so keying off

  // the array itself would restart polling every 500ms for no reason.

  const reposKey = repos.map((r) => r.repo).join(",");

  useEffect(() => {

  let cancelled = false;

  const read = async () => {

  // Parallel across repos, not sequential -- in remote mode each

  // one is its own HTTP round trip (callRemoteTool), and nothing

  // here depends on another repo's result. Watching more than one

  // repo used to pay those round trips one after another, which is

  // the real reason this ever felt slow to load.

  const perRepo = await Promise.all(

  repos.map(async ({ repo, stateDir }): Promise<LaneSnapshot[]> => {

  if (remote) {

  try {

  // allowAnonymous: zz top's "not logged in" mode (Explore's

  // whole point) still needs to watch a public repo it just

  // tracked -- the server already allows this tool with no

  // auth for a public repo (webApp.ts's ANON_READ_TOOLS).

  const lanes = (await callRemoteTool(repo, "lane_list", {}, true)) as Lane[];

  return lanes.map((lane) => ({ repo, lane }));

  } catch {

  return []; // repo not reachable/onboarded yet -- skip rather than crash the view

  }

  }

  return listLanes(stateDir).map((lane) => ({ repo, lane }));

  }),

  );

  if (!cancelled) setSnapshots(perRepo.flat());

  };

  read();

  const id = setInterval(read, intervalMs);

  return () => {

  cancelled = true;

  clearInterval(id);

  };

  // eslint-disable-next-line react-hooks/exhaustive-deps

  }, [intervalMs, remote, reposKey]);

  return snapshots;

 }