fix(frontend): ignore idle/checking in the desktop cache reset

Aikido flagged the offline check as contradicting its own comment. It does,
and the consequence is worse than the mismatch: the monitor has four states,
and treating everything non-offline as reachable inverted the recovery path.

start() sets "checking" and stop() sets "idle". So when the server is down
and the monitor restarts, offline -> checking read as a flip and reset the
cache while routing still pointed at the local fallback, then checking ->
online read as no flip and skipped the reset that mattered. The local
fallback's answers stayed cached after the server came back.

Now only online and offline are considered. Two tests added, both verified
to fail against the previous logic.

Author: ConnorYoh

frontend/editor/src/desktop/components/DesktopQueryCacheReset.test.tsx

@@ -97,4 +97,38 @@ describe("DesktopQueryCacheReset", () => {
 
     expect(queryFn).toHaveBeenCalledTimes(1);
   });
+
+  it("resets on recovery, not on the checking state in between", async () => {
+    const queryFn = vi.fn<() => Promise<string>>().mockResolvedValue("x");
+
+    renderWithConsumer(queryFn);
+    await waitFor(() => expect(queryFn).toHaveBeenCalledTimes(1));
+
+    const emit = (status: string) =>
+      serverListeners.forEach((l) => l({ status }));
+
+    emit("offline");
+    await waitFor(() => expect(queryFn).toHaveBeenCalledTimes(2));
+
+    // A monitor restart while still down must not read as recovery — otherwise
+    // the reset lands here and the real online transition is skipped.
+    emit("checking");
+    expect(queryFn).toHaveBeenCalledTimes(2);
+
+    emit("online");
+    await waitFor(() => expect(queryFn).toHaveBeenCalledTimes(3));
+  });
+
+  it("does not reset when the monitor stops while offline", async () => {
+    const queryFn = vi.fn<() => Promise<string>>().mockResolvedValue("cached");
+
+    renderWithConsumer(queryFn);
+    await waitFor(() => expect(queryFn).toHaveBeenCalledTimes(1));
+
+    serverListeners.forEach((l) => l({ status: "offline" }));
+    await waitFor(() => expect(queryFn).toHaveBeenCalledTimes(2));
+
+    serverListeners.forEach((l) => l({ status: "idle" }));
+    expect(queryFn).toHaveBeenCalledTimes(2);
+  });
 });

frontend/editor/src/desktop/components/DesktopQueryCacheReset.tsx

@@ -17,10 +17,12 @@ export function DesktopQueryCacheReset() {
     const reset = () => void queryClient.resetQueries();
     const unsubscribeMode = connectionModeService.subscribeToModeChanges(reset);
 
-    // Ignore idle/checking, and the state replayed on subscribe.
+    // idle/checking say nothing about reachability — treating them as "not
+    // offline" would reset on offline→checking and then skip the real recovery.
     let wasOffline: boolean | null = null;
     const unsubscribeServer = selfHostedServerMonitor.subscribe(
       ({ status }) => {
+        if (status !== "online" && status !== "offline") return;
         const isOffline = status === "offline";
         if (wasOffline !== null && wasOffline !== isOffline) reset();
         wasOffline = isOffline;