Code Review: Implements an expandable lineage trail for superseded decisions, enabling users to view revision history. Ensure the `HistoryTrail` component handles state updates after unmount to prevent potential race conditions during the asynchronous fetch.

1. 💡 Bug: HistoryTrail can setState after unmount during fetch
   Files: desktop/src/apps/DecisionsApp.tsx:337-351

   `toggle()` issues an async `fetch` and then calls `setLoading`, `setChain`, and `setError` in the `try/catch/finally`. If the card unmounts while the request is in flight (e.g. the answered list refreshes via the parent's `load()` polling, or the user switches tabs), these setState calls run on an unmounted component. There is no `AbortController` and no mounted-ref guard, so the in-flight request is neither cancelled nor ignored. Impact is limited to a wasted request and a possible React state-update-on-unmounted-component warning rather than a crash, hence minor. Suggested fix: track mounted state with a ref (or use an AbortController stored per-toggle) and bail out before setting state.

   Fix (Guard state updates with a mounted ref):
   const mounted = useRef(true);
   useEffect(() => () => { mounted.current = false; }, []);
   // ...inside toggle(), wrap each post-await setState:
   if (!mounted.current) return;
   setChain(asDecisionList(await res.json()));