fix: keep the schedule's stack selected on prefill and edit (#1496)

Opening the New Schedule modal from a stack's Schedule action, or editing
a stack-targeted task, set the node and the stack, but the node-change
effect then ran and cleared the stack, forcing the user to reselect it.

Move the stack-clear out of that effect into the Node picker's change
handler so it only fires on a user-driven node change. A programmatic node
set from prefill or edit now preserves the stack.

frontend/src/components/ScheduledOperationsView.tsx

@@ -201,12 +201,13 @@ export default function ScheduledOperationsView({ filterNodeId, onClearFilter, p
     return () => { cancelled = true; };
   }, [formAction, formTargetId, formNodeId]);
 
-  // Re-fetch stacks when node changes
+  // Re-fetch stacks when the node changes. Clearing a stale stack selection is
+  // done in the Node picker's onValueChange (a user-driven change), not here, so
+  // a prefilled or edited node keeps its stack instead of being wiped on open.
   useEffect(() => {
     if (!dialogOpen) return;
     if (formNodeId) {
       fetchStacks(formNodeId);
-      setFormTargetId('');
     } else {
       setStacks([]);
     }
@@ -790,7 +791,7 @@ export default function ScheduledOperationsView({ filterNodeId, onClearFilter, p
                   <Combobox
                     options={nodeOptions}
                     value={formNodeId}
-                    onValueChange={setFormNodeId}
+                    onValueChange={(val) => { setFormNodeId(val); setFormTargetId(''); }}
                     placeholder="Select node..."
                   />
                 </div>

frontend/src/components/__tests__/ScheduledOperationsView.test.tsx

@@ -125,6 +125,39 @@ describe('ScheduledOperationsView', () => {
     expect(onPrefillConsumed).toHaveBeenCalledTimes(1);
     // The prefilled stack drives a node-scoped stack fetch through the proxy.
     await waitFor(() => expect(mockedFetchForNode).toHaveBeenCalledWith('/stacks', 1));
+    // The prefilled stack stays selected; the node-change effect must not wipe it.
+    // Comboboxes render in order: action, node, stack.
+    await waitFor(() => expect(screen.getAllByRole('combobox')[2]).toHaveTextContent('web'));
+  });
+
+  it('keeps the stack selected when editing a stack-targeted task', async () => {
+    tasksFixture = [makeTask({
+      id: 9, name: 'restart-web', action: 'restart', target_type: 'stack', target_id: 'web', node_id: 1,
+    })];
+    render(<ScheduledOperationsView />);
+
+    await userEvent.click(await screen.findByRole('button', { name: /All tasks/ }));
+    await userEvent.click(await screen.findByTitle('Edit'));
+    await waitFor(() => expect(screen.getAllByRole('combobox')[2]).toHaveTextContent('web'));
+  });
+
+  it('clears the stale stack when the user changes the node', async () => {
+    render(<ScheduledOperationsView />);
+
+    await userEvent.click(await screen.findByRole('button', { name: /New Schedule/ }));
+    // Default action Restart Stack: choose a node, then a stack on it.
+    await userEvent.click(screen.getAllByRole('combobox')[1]);
+    await userEvent.click(await screen.findByRole('button', { name: 'hub' }));
+    await userEvent.click(screen.getAllByRole('combobox')[2]);
+    await userEvent.click(await screen.findByRole('button', { name: 'web' }));
+    expect(screen.getAllByRole('combobox')[2]).toHaveTextContent('web');
+
+    // Switching node is a user-driven change, so the now-stale stack clears
+    // and the user must re-pick one before the schedule can be saved.
+    await userEvent.click(screen.getAllByRole('combobox')[1]);
+    await userEvent.click(await screen.findByRole('button', { name: 'edge' }));
+    expect(screen.getAllByRole('combobox')[2]).toHaveTextContent('Select stack...');
+    expect(screen.getByRole('button', { name: 'Create' })).toBeDisabled();
   });
 
   it('filters the table to the selected node and clears the filter', async () => {