Extract usePacketDetail and share it across the analyzer and overlay

src/App.tsx

@@ -1,6 +1,6 @@
 import React, { useState, useEffect, useCallback, useRef, lazy, Suspense } from "react";
 import { BrowserRouter, useSearchParams } from "react-router-dom";
-import { QueryClient, QueryClientProvider, useQuery } from "@tanstack/react-query";
+import { QueryClient, QueryClientProvider } from "@tanstack/react-query";
 import { RegionProvider, useRegion, useRegionSelection } from "./hooks/useRegion";
 import {
   ALL_REGIONS,
@@ -27,7 +27,7 @@ import { RouteTable } from "./features/routes/RouteTable";
 import { TraceList } from "./features/traces/TraceList";
 import { ChannelList } from "./features/channels/ChannelList";
 import { EmptyState } from "./components/EmptyState";
-import { getPacketDetail } from "./api/client";
+import { usePacketDetail } from "./features/packets/usePacketDetail";
 import { WsManager } from "./api/ws-manager";
 import { WS_URL, ENABLED_TABS } from "./lib/constants";
 import type { PacketDetail } from "./types/api";
@@ -145,21 +145,8 @@ function AppInner() {
   const [pathMapInitialKey, setPathMapInitialKey] = useState<string | null>(null);
   const pathLinkHandledRef = useRef(false);
 
-  // short staleTime: observations keep accruing, so reopening the analyzer should show them
-  // instead of a snapshot frozen at first open
-  const { data: analyzerDetail, isLoading: analyzerLoading } = useQuery({
-    queryKey: ["packet-detail", analyzerHash],
-    queryFn: () => getPacketDetail(analyzerHash!),
-    enabled: !!analyzerHash,
-    staleTime: 30_000,
-  });
-
-  const { data: overlayPacketDetail, isLoading: overlayPacketLoading } = useQuery({
-    queryKey: ["packet-detail", overlayPacketHash],
-    queryFn: () => getPacketDetail(overlayPacketHash!),
-    enabled: !!overlayPacketHash,
-    staleTime: 30_000,
-  });
+  const { data: analyzerDetail, isLoading: analyzerLoading } = usePacketDetail(analyzerHash);
+  const { data: overlayPacketDetail, isLoading: overlayPacketLoading } = usePacketDetail(overlayPacketHash);
 
   // deep link: ?hash opens the analyzer drawer; ?path then opens the path popup once, pre-selected
   useEffect(() => {

src/features/packets/usePacketDetail.ts

@@ -0,0 +1,14 @@
+import { useQuery } from "@tanstack/react-query";
+import { getPacketDetail } from "../../api/client";
+import type { PacketDetail } from "../../types/api";
+
+// One query per hash shared by the expanded row, the analyzer drawer and the overlay — TanStack
+// dedupes, so a row expanded under an open drawer costs a single request.
+export function usePacketDetail(hash: string | null) {
+  return useQuery<PacketDetail>({
+    queryKey: ["packet-detail", hash],
+    queryFn: () => getPacketDetail(hash!),
+    enabled: !!hash,
+    staleTime: 30_000,
+  });
+}

tests/features/packets/usePacketDetail.test.tsx

@@ -0,0 +1,31 @@
+import { describe, it, expect, vi, beforeEach } from "vitest";
+import { renderHook, waitFor } from "@testing-library/react";
+import { QueryClient, QueryClientProvider } from "@tanstack/react-query";
+import { usePacketDetail } from "../../../src/features/packets/usePacketDetail";
+
+const getPacketDetail = vi.fn();
+vi.mock("../../../src/api/client", () => ({
+  getPacketDetail: (hash: string) => getPacketDetail(hash),
+}));
+
+const wrapper = ({ children }: { children: React.ReactNode }) => (
+  <QueryClientProvider client={new QueryClient({ defaultOptions: { queries: { retry: false } } })}>
+    {children}
+  </QueryClientProvider>
+);
+
+beforeEach(() => getPacketDetail.mockReset());
+
+describe("usePacketDetail", () => {
+  it("does not fetch when hash is null", () => {
+    renderHook(() => usePacketDetail(null), { wrapper });
+    expect(getPacketDetail).not.toHaveBeenCalled();
+  });
+
+  it("fetches the detail for a hash", async () => {
+    getPacketDetail.mockResolvedValue({ packetHash: "AA11", observations: [] });
+    const { result } = renderHook(() => usePacketDetail("AA11"), { wrapper });
+    await waitFor(() => expect(result.current.data?.packetHash).toBe("AA11"));
+    expect(getPacketDetail).toHaveBeenCalledWith("AA11");
+  });
+});