fix(ui): stop stale PR status leaking across cloud task switches

packages/ui/src/features/sidebar/useTaskPrStatus.test.ts

@@ -108,4 +108,18 @@ describe("useTaskPrStatus", () => {
     );
     expect(lastQueryOptions?.enabled).toBe(true);
   });
+
+  it("ignores leftover placeholder data from a previous task when the query is disabled", () => {
+    // Simulates switching from a cloud task with a PR (query data populated)
+    // to a fresh cloud task with no PR yet — TanStack's `placeholderData`
+    // would otherwise keep serving the previous task's resolved data since
+    // the disabled query never fetches to overwrite it.
+    queryData = { prState: "open", hasDiff: true };
+    const { result } = renderHook(() =>
+      useTaskPrStatus(
+        makeTask({ taskRunEnvironment: "cloud", cloudPrUrl: null }),
+      ),
+    );
+    expect(result.current).toEqual({ prState: null, hasDiff: false });
+  });
 });

packages/ui/src/features/sidebar/useTaskPrStatus.ts

@@ -35,6 +35,11 @@ export function useTaskPrStatus(task: {
     ),
   );
 
-  if (!data || (!data.prState && !data.hasDiff)) return EMPTY;
+  // When the query is disabled, `data` can still be populated:
+  // `placeholderData: (prev) => prev` carries over whatever the previous
+  // task's query resolved to, and a disabled query never fetches to replace
+  // it. Without this guard, switching from a task with a PR to one without
+  // (e.g. a fresh cloud task) would keep showing the old task's PR status.
+  if (skipQuery || !data || (!data.prState && !data.hasDiff)) return EMPTY;
   return data;
 }