fix(flows): canvas re-sync after save + Fix with agent on failed runs (B21/B22) (#4823)

app/src/components/flows/FlowRunsSidebar.test.tsx

@@ -0,0 +1,182 @@
+/**
+ * FlowRunsSidebar — the flow canvas's projected run-history sidebar. Asserts
+ * the run list renders, a run row opens the {@link FlowRunInspectorDrawer},
+ * and (issue B22) the drawer's "Fix with agent" action navigates to this same
+ * flow's canvas seeded with a `copilotRepair` state and closes the sidebar's
+ * own drawer — this sidebar is only ever mounted while the user is ALREADY on
+ * the failing run's own `/flows/:id` canvas (`FlowCanvasPage` projects it into
+ * the shell sidebar), so re-navigating to the SAME route with a fresh repair
+ * seed is the fix (see `FlowCanvasPage.tsx`'s `locationKey`-based copilot
+ * panel remount, which reacts to exactly this navigation).
+ */
+import { act, fireEvent, render, screen, waitFor } from '@testing-library/react';
+import { Provider } from 'react-redux';
+import { MemoryRouter, Route, Routes, useLocation } from 'react-router-dom';
+import { beforeEach, describe, expect, it, vi } from 'vitest';
+
+import type { FlowRun } from '../../services/api/flowsApi';
+import { store } from '../../store';
+import FlowRunsSidebar from './FlowRunsSidebar';
+
+const listFlowRuns = vi.hoisted(() => vi.fn());
+vi.mock('../../services/api/flowsApi', () => ({ listFlowRuns }));
+
+// Capture the props handed to the drawer so "Fix with agent" can be invoked
+// directly without standing up the drawer's own run-polling machinery
+// (mirrors `FlowApprovalCard.test.tsx`'s stub pattern).
+const inspectorDrawerProps = vi.hoisted(() => ({
+  current: null as Record<string, unknown> | null,
+}));
+vi.mock('./FlowRunInspectorDrawer', () => ({
+  FLOW_RUN_STATUS_ACCENT: {
+    running: '',
+    completed: '',
+    completed_with_warnings: '',
+    pending_approval: '',
+    failed: '',
+    cancelled: '',
+  },
+  FLOW_RUN_STATUS_DOT: {
+    running: '',
+    completed: '',
+    completed_with_warnings: '',
+    pending_approval: '',
+    failed: '',
+    cancelled: '',
+  },
+  FLOW_RUN_STATUS_KEY: {
+    running: 'flowRuns.status.running',
+    completed: 'flowRuns.status.completed',
+    completed_with_warnings: 'flowRuns.status.completed_with_warnings',
+    pending_approval: 'flowRuns.status.pending_approval',
+    failed: 'flowRuns.status.failed',
+    cancelled: 'flowRuns.status.cancelled',
+  },
+  FlowRunInspectorDrawer: (props: Record<string, unknown>) => {
+    inspectorDrawerProps.current = props;
+    return props.runId ? (
+      <div data-testid="flow-run-inspector-drawer-stub">{props.runId as string}</div>
+    ) : null;
+  },
+}));
+
+function makeRun(overrides: Partial<FlowRun> = {}): FlowRun {
+  return {
+    id: 'run-1',
+    flow_id: 'flow-1',
+    thread_id: 'run-1',
+    status: 'failed',
+    started_at: '2026-07-13T18:23:00Z',
+    finished_at: '2026-07-13T18:23:05Z',
+    steps: [],
+    pending_approvals: [],
+    error: 'GMAIL_SEND_EMAIL: empty body',
+    ...overrides,
+  };
+}
+
+/** Renders whatever `location.state` a navigation landed with, for assertions. */
+function LocationStateProbe() {
+  const location = useLocation();
+  return <div data-testid="location-state-probe">{JSON.stringify(location.state)}</div>;
+}
+
+function renderSidebar(flowId = 'flow-1') {
+  return render(
+    <Provider store={store}>
+      <MemoryRouter initialEntries={[`/flows/${flowId}`]}>
+        <Routes>
+          <Route path="/flows/:id" element={<FlowRunsSidebar flowId={flowId} />} />
+        </Routes>
+      </MemoryRouter>
+    </Provider>
+  );
+}
+
+describe('FlowRunsSidebar', () => {
+  beforeEach(() => {
+    vi.clearAllMocks();
+    inspectorDrawerProps.current = null;
+  });
+
+  it('lists runs and opens the inspector drawer for the clicked run', async () => {
+    listFlowRuns.mockResolvedValue([makeRun()]);
+    renderSidebar();
+
+    const row = await screen.findByTestId('flow-runs-sidebar-run-run-1');
+    expect(screen.queryByTestId('flow-run-inspector-drawer-stub')).not.toBeInTheDocument();
+
+    fireEvent.click(row);
+
+    expect(screen.getByTestId('flow-run-inspector-drawer-stub')).toHaveTextContent('run-1');
+  });
+
+  it('passes onFixWithAgent through to the run inspector drawer', async () => {
+    listFlowRuns.mockResolvedValue([makeRun()]);
+    renderSidebar();
+
+    fireEvent.click(await screen.findByTestId('flow-runs-sidebar-run-run-1'));
+
+    expect(inspectorDrawerProps.current?.onFixWithAgent).toBeInstanceOf(Function);
+  });
+
+  it('"Fix with agent" closes the drawer and navigates to the same flow seeded with the repair context (B22)', async () => {
+    listFlowRuns.mockResolvedValue([makeRun()]);
+    render(
+      <Provider store={store}>
+        <MemoryRouter initialEntries={['/flows/flow-1']}>
+          <Routes>
+            <Route
+              path="/flows/:id"
+              element={
+                <>
+                  <FlowRunsSidebar flowId="flow-1" />
+                  <LocationStateProbe />
+                </>
+              }
+            />
+          </Routes>
+        </MemoryRouter>
+      </Provider>
+    );
+
+    fireEvent.click(await screen.findByTestId('flow-runs-sidebar-run-run-1'));
+    expect(screen.getByTestId('flow-run-inspector-drawer-stub')).toBeInTheDocument();
+
+    act(() => {
+      (
+        inspectorDrawerProps.current?.onFixWithAgent as (request: {
+          flowId: string;
+          runId: string;
+          error?: string | null;
+          failingNodeIds?: string[];
+        }) => void
+      )({
+        flowId: 'flow-1',
+        runId: 'run-1',
+        error: 'GMAIL_SEND_EMAIL: empty body',
+        failingNodeIds: ['send_summary'],
+      });
+    });
+
+    // The sidebar's own run-inspector drawer closes (repair takes over).
+    await waitFor(() =>
+      expect(screen.queryByTestId('flow-run-inspector-drawer-stub')).not.toBeInTheDocument()
+    );
+    const probe = screen.getByTestId('location-state-probe');
+    expect(JSON.parse(probe.textContent ?? 'null')).toEqual({
+      copilotRepair: {
+        runId: 'run-1',
+        error: 'GMAIL_SEND_EMAIL: empty body',
+        failingNodeIds: ['send_summary'],
+      },
+    });
+  });
+
+  it('shows the empty state when there are no runs', async () => {
+    listFlowRuns.mockResolvedValue([]);
+    renderSidebar();
+
+    expect(await screen.findByTestId('flow-runs-sidebar-empty')).toBeInTheDocument();
+  });
+});

app/src/components/flows/FlowRunsSidebar.tsx

@@ -11,6 +11,7 @@
  */
 import createDebug from 'debug';
 import { useCallback, useEffect, useState } from 'react';
+import { useNavigate } from 'react-router-dom';
 
 import { useT } from '../../lib/i18n/I18nContext';
 import { type FlowRun, listFlowRuns } from '../../services/api/flowsApi';
@@ -19,6 +20,7 @@ import {
   FLOW_RUN_STATUS_ACCENT,
   FLOW_RUN_STATUS_DOT,
   FLOW_RUN_STATUS_KEY,
+  type FlowRepairRequest,
   FlowRunInspectorDrawer,
 } from './FlowRunInspectorDrawer';
 
@@ -44,11 +46,38 @@ export interface FlowRunsSidebarProps {
 
 export default function FlowRunsSidebar({ flowId }: FlowRunsSidebarProps) {
   const { t } = useT();
+  const navigate = useNavigate();
   const [runs, setRuns] = useState<FlowRun[]>([]);
   const [loading, setLoading] = useState(true);
   const [error, setError] = useState<string | null>(null);
   const [selectedRunId, setSelectedRunId] = useState<string | null>(null);
 
+  // "Fix with agent" (issue B22) — this sidebar is only ever mounted while
+  // already on the failed run's own `/flows/:id` canvas (`FlowCanvasPage`
+  // projects it into the shell sidebar), so re-navigating to the SAME route
+  // with a fresh `copilotRepair` state is enough to open the canvas copilot
+  // preloaded with the failure — same mechanism `FlowsPage`'s run-history
+  // drawer uses to reach this page from elsewhere. `replace: true` avoids
+  // stacking a new history entry per click on top of the page the user is
+  // already viewing.
+  const handleFixWithAgent = useCallback(
+    (request: FlowRepairRequest) => {
+      log('fix with agent: flow=%s run=%s', request.flowId, request.runId);
+      setSelectedRunId(null);
+      navigate(`/flows/${request.flowId}`, {
+        replace: true,
+        state: {
+          copilotRepair: {
+            runId: request.runId,
+            error: request.error,
+            failingNodeIds: request.failingNodeIds,
+          },
+        },
+      });
+    },
+    [navigate]
+  );
+
   const load = useCallback(async () => {
     log('loading runs for flow=%s', flowId);
     setLoading(true);
@@ -145,7 +174,11 @@ export default function FlowRunsSidebar({ flowId }: FlowRunsSidebarProps) {
         </ul>
       </div>
 
-      <FlowRunInspectorDrawer runId={selectedRunId} onClose={() => setSelectedRunId(null)} />
+      <FlowRunInspectorDrawer
+        runId={selectedRunId}
+        onClose={() => setSelectedRunId(null)}
+        onFixWithAgent={handleFixWithAgent}
+      />
     </div>
   );
 }

app/src/components/notifications/FlowApprovalCard.test.tsx

@@ -1,15 +1,20 @@
 /**
- * Approve/Dismiss/View-run contract for the flow-pending-approval
- * notification card (issues B3a + B3b). Asserts that Approve reads
- * `{ flow_id, thread_id, node_ids }` from the notification's action payload,
- * calls `flowsApi.resumeFlow` with those args, clears the notification on
- * success, surfaces a localized error on failure (including when `node_ids`
- * contains non-string entries — an invalid payload), that Dismiss clears the
- * notification WITHOUT calling any RPC (there is no `flows_deny` endpoint
- * yet), and that "View run" opens the {@link FlowRunInspectorDrawer}.
+ * Approve/Dismiss/View-run/Fix-with-agent contract for the
+ * flow-pending-approval notification card (issues B3a + B3b + B22). Asserts
+ * that Approve reads `{ flow_id, thread_id, node_ids }` from the notification's
+ * action payload, calls `flowsApi.resumeFlow` with those args, clears the
+ * notification on success, surfaces a localized error on failure (including
+ * when `node_ids` contains non-string entries — an invalid payload), that
+ * Dismiss clears the notification WITHOUT calling any RPC (there is no
+ * `flows_deny` endpoint yet), that "View run" opens the
+ * {@link FlowRunInspectorDrawer}, and that the drawer's "Fix with agent"
+ * action navigates to the flow's canvas seeded with a `copilotRepair` state
+ * (issue B22 — this card can render anywhere in the app, so it always
+ * navigates rather than assuming the canvas is already open).
  */
-import { fireEvent, render, screen, waitFor } from '@testing-library/react';
+import { act, fireEvent, render, screen, waitFor } from '@testing-library/react';
 import { Provider } from 'react-redux';
+import { MemoryRouter, Route, Routes, useLocation } from 'react-router-dom';
 import { beforeEach, describe, expect, it, vi } from 'vitest';
 
 import { store } from '../../store';
@@ -19,9 +24,20 @@ import FlowApprovalCard from './FlowApprovalCard';
 const resumeFlow = vi.hoisted(() => vi.fn());
 vi.mock('../../services/api/flowsApi', () => ({ resumeFlow }));
 
+// Capture the props `FlowApprovalCard` hands the drawer (mirrors
+// `FlowCanvasPage.test.tsx`'s copilot-panel stub pattern) so tests can invoke
+// `onFixWithAgent` directly without needing the drawer's own run-polling
+// machinery.
+const inspectorDrawerProps = vi.hoisted(() => ({
+  current: null as Record<string, unknown> | null,
+}));
 vi.mock('../flows/FlowRunInspectorDrawer', () => ({
-  FlowRunInspectorDrawer: ({ runId }: { runId: string | null; onClose: () => void }) =>
-    runId ? <div data-testid="flow-run-inspector-drawer-stub">{runId}</div> : null,
+  FlowRunInspectorDrawer: (props: Record<string, unknown>) => {
+    inspectorDrawerProps.current = props;
+    return props.runId ? (
+      <div data-testid="flow-run-inspector-drawer-stub">{props.runId as string}</div>
+    ) : null;
+  },
 }));
 
 function makeItem(overrides: Partial<NotificationItem> = {}): NotificationItem {
@@ -43,10 +59,21 @@ function makeItem(overrides: Partial<NotificationItem> = {}): NotificationItem {
   };
 }
 
+/** Renders whatever `location.state` a navigation landed with, for assertions. */
+function LocationStateProbe() {
+  const location = useLocation();
+  return <div data-testid="location-state-probe">{JSON.stringify(location.state)}</div>;
+}
+
 function renderCard(item: NotificationItem) {
   return render(
     <Provider store={store}>
-      <FlowApprovalCard notification={item} />
+      <MemoryRouter initialEntries={['/home']}>
+        <Routes>
+          <Route path="/home" element={<FlowApprovalCard notification={item} />} />
+          <Route path="/flows/:id" element={<LocationStateProbe />} />
+        </Routes>
+      </MemoryRouter>
     </Provider>
   );
 }
@@ -55,6 +82,7 @@ describe('FlowApprovalCard', () => {
   beforeEach(() => {
     vi.clearAllMocks();
     store.dispatch({ type: 'notifications/clearAll' });
+    inspectorDrawerProps.current = null;
   });
 
   it('renders both Approve and Dismiss buttons', () => {
@@ -227,4 +255,46 @@ describe('FlowApprovalCard', () => {
     expect(drawer).toBeInTheDocument();
     expect(drawer).toHaveTextContent('thread-1');
   });
+
+  it('passes onFixWithAgent through to the run inspector drawer', () => {
+    renderCard(makeItem());
+    fireEvent.click(screen.getByTestId('flow-approval-view-run'));
+
+    expect(inspectorDrawerProps.current?.onFixWithAgent).toBeInstanceOf(Function);
+  });
+
+  it('"Fix with agent" navigates to the flow canvas seeded with the repair context (B22)', async () => {
+    renderCard(makeItem());
+    fireEvent.click(screen.getByTestId('flow-approval-view-run'));
+    expect(screen.getByTestId('flow-run-inspector-drawer-stub')).toBeInTheDocument();
+
+    act(() => {
+      (
+        inspectorDrawerProps.current?.onFixWithAgent as (request: {
+          flowId: string;
+          runId: string;
+          error?: string | null;
+          failingNodeIds?: string[];
+        }) => void
+      )({
+        flowId: 'flow-1',
+        runId: 'thread-1',
+        error: 'GMAIL_SEND_EMAIL: empty body',
+        failingNodeIds: ['send_summary'],
+      });
+    });
+
+    // Navigated away — the drawer stub (and the whole card) unmounts.
+    await waitFor(() =>
+      expect(screen.queryByTestId('flow-run-inspector-drawer-stub')).not.toBeInTheDocument()
+    );
+    const probe = await screen.findByTestId('location-state-probe');
+    expect(JSON.parse(probe.textContent ?? 'null')).toEqual({
+      copilotRepair: {
+        runId: 'thread-1',
+        error: 'GMAIL_SEND_EMAIL: empty body',
+        failingNodeIds: ['send_summary'],
+      },
+    });
+  });
 });

app/src/components/notifications/FlowApprovalCard.tsx

@@ -28,6 +28,7 @@
  */
 import debug from 'debug';
 import { useState } from 'react';
+import { useNavigate } from 'react-router-dom';
 
 import { useT } from '../../lib/i18n/I18nContext';
 import { resumeFlow } from '../../services/api/flowsApi';
@@ -37,7 +38,7 @@ import {
   markRead,
   type NotificationItem,
 } from '../../store/notificationSlice';
-import { FlowRunInspectorDrawer } from '../flows/FlowRunInspectorDrawer';
+import { type FlowRepairRequest, FlowRunInspectorDrawer } from '../flows/FlowRunInspectorDrawer';
 import Button from '../ui/Button';
 
 const log = debug('notifications:flow-approval-card');
@@ -71,10 +72,31 @@ interface Props {
 const FlowApprovalCard = ({ notification: n }: Props) => {
   const { t } = useT();
   const dispatch = useAppDispatch();
+  const navigate = useNavigate();
   const [pending, setPending] = useState<'approve' | null>(null);
   const [error, setError] = useState<string | null>(null);
   const [inspecting, setInspecting] = useState(false);
 
+  // "Fix with agent" (issue B22) — a run opened from this notification can
+  // fail with the gate never actually reached (or after it), so the same
+  // repair action `FlowsPage`'s run-history drawer offers must be reachable
+  // from here too. This card can render from anywhere in the app (it's a
+  // `CoreNotification` surface), so — unlike `FlowRunsSidebar`, which is
+  // always already on the flow's own canvas — always navigate there first.
+  const handleFixWithAgent = (request: FlowRepairRequest) => {
+    log('fix with agent: notification=%s flow=%s run=%s', n.id, request.flowId, request.runId);
+    setInspecting(false);
+    navigate(`/flows/${request.flowId}`, {
+      state: {
+        copilotRepair: {
+          runId: request.runId,
+          error: request.error,
+          failingNodeIds: request.failingNodeIds,
+        },
+      },
+    });
+  };
+
   const payload = n.actions?.[0]?.payload;
   const parsed = isFlowApprovalPayload(payload) ? payload : null;
 
@@ -204,6 +226,7 @@ const FlowApprovalCard = ({ notification: n }: Props) => {
         <FlowRunInspectorDrawer
           runId={inspecting ? parsed.thread_id : null}
           onClose={() => setInspecting(false)}
+          onFixWithAgent={handleFixWithAgent}
         />
       )}
     </div>

app/src/pages/FlowCanvasPage.tsx

@@ -138,6 +138,7 @@ function FlowEditor({
   initialCopilotSeed = null,
   initialBuildSeed = null,
   onBuildSeedConsumed,
+  locationKey,
 }: {
   editorFlow: EditorFlow;
   initialCopilotSeed?: CopilotRepairSeed | null;
@@ -145,6 +146,16 @@ function FlowEditor({
   initialBuildSeed?: CopilotBuildSeed | null;
   /** Clear the route's build seed once the copilot has dispatched it (#4597). */
   onBuildSeedConsumed?: () => void;
+  /**
+   * The route's `location.key` (issue B22) — react-router mints a fresh one on
+   * every navigation, including a same-path repeat navigation (e.g. the "Fix
+   * with agent" action from {@link FlowRunsSidebar}, which stays on this same
+   * `/flows/:id` route and so does NOT remount `FlowEditor`). Folded into the
+   * copilot panel's `key` below so a repair seed arriving without a page-level
+   * remount still forces a fresh panel mount — required for the panel's
+   * once-per-mount auto-fire guard (`repairSentRef`) to actually fire again.
+   */
+  locationKey: string;
 }) {
   const { t } = useT();
   const navigate = useNavigate();
@@ -206,6 +217,19 @@ function FlowEditor({
   const [copilotOpen, setCopilotOpen] = useState(
     initialCopilotSeed !== null || initialBuildSeed !== null
   );
+  // Issue B22: a repair seed can also arrive WITHOUT a `FlowEditor` remount —
+  // "Fix with agent" clicked from `FlowRunsSidebar` stays on this same
+  // `/flows/:id` route (only `location.state`/`location.key` change), so the
+  // `useState` initializer above (mount-only) won't re-open the panel for it.
+  // Re-assert open whenever a new repair seed prop arrives — done during
+  // render (React's "adjusting state when a prop changes" pattern) rather
+  // than a `useEffect`, so it lands in the same render pass instead of an
+  // extra one.
+  const [seenCopilotSeed, setSeenCopilotSeed] = useState(initialCopilotSeed);
+  if (initialCopilotSeed !== seenCopilotSeed) {
+    setSeenCopilotSeed(initialCopilotSeed);
+    if (initialCopilotSeed) setCopilotOpen(true);
+  }
   // Per-workflow copilot thread: seeded from the session cache so opening/closing
   // the panel (or switching flows and back) resumes the same conversation
   // instead of starting a fresh `workflow_builder` thread each time.
@@ -323,6 +347,14 @@ function FlowEditor({
   // the new flow's canonical `/flows/:id` canvas so further saves update it.
   // Rejections propagate so the canvas surfaces the failure inline (and leaves
   // the draft dirty).
+  //
+  // Issue B21: `flows_update` re-validates/normalizes the graph server-side
+  // (schema migration, id defaults, port normalization, etc.) before
+  // persisting, so the canonical saved shape can differ from what the client
+  // sent. Re-sync the canvas draft from the RESPONSE (not just the just-sent
+  // `next`) and bump `canvasVersion` so the editable canvas re-seeds from the
+  // canonical persisted graph immediately — matching what a navigate-away-
+  // and-back remount would show, without requiring one.
   const handleSave = useCallback(
     async (next: WorkflowGraph) => {
       if (isDraft) {
@@ -338,9 +370,17 @@ function FlowEditor({
         return;
       }
       log('save: flow id=%s nodes=%d edges=%d', flowId, next.nodes.length, next.edges.length);
-      await updateFlow(flowId, { graph: next });
-      persistedGraphRef.current = next;
-      log('save: flow id=%s persisted', flowId);
+      const updated = await updateFlow(flowId, { graph: next });
+      const persisted = updated.graph as WorkflowGraph;
+      persistedGraphRef.current = persisted;
+      setDraftGraph(persisted);
+      setCanvasVersion(v => v + 1);
+      log(
+        'save: flow id=%s persisted — canvas re-synced from response nodes=%d edges=%d',
+        flowId,
+        persisted.nodes.length,
+        persisted.edges.length
+      );
     },
     [isDraft, flowId, name, requireApproval, navigate]
   );
@@ -534,6 +574,14 @@ function FlowEditor({
 
         {copilotOpen && (
           <WorkflowCopilotPanel
+            // Stable ('copilot') across manual open/close and build-seed
+            // navigations (unaffected — those always land on a fresh
+            // `FlowEditor` mount already, see `locationKey`'s doc comment).
+            // Repair seeds fold in `locationKey` so a same-route "Fix with
+            // agent" click (no `FlowEditor` remount) still forces a fresh
+            // panel mount, resetting the once-per-mount `repairSentRef` guard
+            // so the repair turn actually (re)fires (issue B22).
+            key={initialCopilotSeed ? `copilot-repair-${locationKey}` : 'copilot'}
             graph={preview?.base ?? draftGraph}
             flowId={flowId}
             onProposal={handleProposal}
@@ -647,6 +695,7 @@ export default function FlowCanvasPage() {
         initialCopilotSeed={copilotSeed}
         initialBuildSeed={buildSeed}
         onBuildSeedConsumed={clearBuildSeed}
+        locationKey={location.key}
       />
     );
   }
@@ -735,6 +784,7 @@ export function FlowCanvasDraftPage() {
             graph: draft.graph,
             requireApproval: draft.requireApproval,
           }}
+          locationKey={location.key}
         />
         <ToastContainer notifications={toasts} onRemove={removeToast} />
       </>

app/src/pages/__tests__/FlowCanvasPage.test.tsx

@@ -194,6 +194,78 @@ describe('FlowCanvasPage', () => {
     ]);
   });
 
+  // Issue B21: `flows_update` re-validates/normalizes the graph server-side
+  // before persisting, so the canonical response can legitimately differ from
+  // what the client sent (schema migration, id defaults, etc.). Previously the
+  // canvas re-baselined against its OWN pre-save nodes/edges and ignored the
+  // response entirely — the canonical shape only ever appeared after a
+  // navigate-away-and-back remount refetched it via `flows_get`. Assert the
+  // canvas now reflects the SAVE RESPONSE's graph immediately, with no
+  // navigation and no remount of `FlowCanvasPage`.
+  it('re-syncs the canvas from the flows_update response on save, without a remount (B21)', async () => {
+    getFlow.mockResolvedValue(makeFlow());
+    // The server "normalizes" the saved graph: it accepts the client's
+    // trigger+agent nodes but also injects a third node the client never
+    // added (standing in for a server-side migration/default-fill), and
+    // renames the trigger. A stale canvas would keep showing only the two
+    // client-added nodes named "Start"/"New agent".
+    updateFlow.mockResolvedValue(
+      makeFlow({
+        graph: {
+          schema_version: 1,
+          id: 'test-id',
+          name: 'Daily digest',
+          nodes: [
+            {
+              id: 't',
+              kind: 'trigger',
+              name: 'Start (normalized)',
+              config: {},
+              ports: [],
+              position: { x: 0, y: 0 },
+            },
+            {
+              id: 'new-agent-0',
+              kind: 'agent',
+              name: 'New agent',
+              config: {},
+              ports: [],
+              position: { x: 80, y: 80 },
+            },
+            {
+              id: 'server-added',
+              kind: 'transform',
+              name: 'Server-added node',
+              config: {},
+              ports: [],
+              position: { x: 160, y: 160 },
+            },
+          ],
+          edges: [],
+        },
+      })
+    );
+    renderEditor();
+    await waitFor(() => expect(screen.getByTestId('flow-canvas')).toBeInTheDocument());
+
+    fireEvent.click(screen.getByTestId('flow-palette-item-agent'));
+    expect(screen.getAllByTestId('flow-node')).toHaveLength(2);
+
+    fireEvent.click(screen.getByTestId('flow-editor-save'));
+    await waitFor(() => expect(updateFlow).toHaveBeenCalledTimes(1));
+
+    // The canvas now shows the RESPONSE's three nodes (including the one the
+    // client never added and the renamed trigger) — no navigation, no
+    // `flows_get` refetch, no remount required.
+    await waitFor(() => expect(screen.getAllByTestId('flow-node')).toHaveLength(3));
+    expect(screen.getByText('Start (normalized)')).toBeInTheDocument();
+    expect(screen.getByText('Server-added node')).toBeInTheDocument();
+    // Still the same page/component — proving this wasn't a navigate-away
+    // remount refetch in disguise.
+    expect(getFlow).toHaveBeenCalledTimes(1);
+    expect(screen.getByTestId('flow-canvas-page')).toBeInTheDocument();
+  });
+
   it('does not prompt when navigating Back with no unsaved changes', async () => {
     getFlow.mockResolvedValue(makeFlow());
     renderEditor();