diff --git a/frontend/src/components/EditorLayout/EditorView.tsx b/frontend/src/components/EditorLayout/EditorView.tsx
index b99aafec..b2340d3b 100644
--- a/frontend/src/components/EditorLayout/EditorView.tsx
+++ b/frontend/src/components/EditorLayout/EditorView.tsx
@@ -876,6 +876,7 @@ export function EditorView({
                         onOpenFiles={canRead ? () => { setEditingCompose(true); setActiveTab('files'); } : undefined}
                         onOpenGitSource={() => setGitSourceOpen(true)}
                         onApplyUpdate={() => { void updateStack(); }}
+                        applying={loadingAction === 'update'}
                         canEdit={can('stack:edit', 'stack', stackName)}
                         notifications={notifications}
                     />
diff --git a/frontend/src/components/StackAnatomyPanel.test.tsx b/frontend/src/components/StackAnatomyPanel.test.tsx
new file mode 100644
index 00000000..e93d57c7
--- /dev/null
+++ b/frontend/src/components/StackAnatomyPanel.test.tsx
@@ -0,0 +1,256 @@
+/**
+ * Covers the "Update available" banner lifecycle: the apply button must reflect
+ * the in-flight update (disabled + progress label), and the banner must clear
+ * itself once the update lands (re-checking the preview) while staying put if
+ * the update did not take effect.
+ */
+import { describe, it, expect, vi, beforeEach } from 'vitest';
+import { render, screen, fireEvent, waitFor } from '@testing-library/react';
+
+vi.mock('@/lib/api', () => ({ apiFetch: vi.fn() }));
+vi.mock('./stack/StackActivityTimeline', () => ({
+  StackActivityTimeline: () => <div data-testid="activity-timeline" />,
+}));
+
+import { apiFetch } from '@/lib/api';
+import StackAnatomyPanel from './StackAnatomyPanel';
+
+const COMPOSE = 'services:\n  web:\n    image: nginx:1.25\n';
+
+function previewBody(hasUpdate: boolean) {
+  return {
+    summary: {
+      has_update: hasUpdate,
+      primary_image: 'nginx',
+      current_tag: '1.25',
+      next_tag: '1.26',
+      semver_bump: 'minor',
+      blocked: false,
+      blocked_reason: null,
+    },
+    changelog: null,
+  };
+}
+
+function jsonRes(body: unknown, ok = true) {
+  return { ok, status: ok ? 200 : 404, json: async () => body, text: async () => '' } as unknown as Response;
+}
+
+let hasUpdate = true;
+
+const updatePreviewCalls = () =>
+  vi.mocked(apiFetch).mock.calls.filter(([input]) => String(input).includes('/update-preview')).length;
+
+beforeEach(() => {
+  hasUpdate = true;
+  vi.mocked(apiFetch).mockReset();
+  vi.mocked(apiFetch).mockImplementation(async (input: RequestInfo | URL) => {
+    const url = String(input);
+    if (url.includes('/update-preview')) return jsonRes(previewBody(hasUpdate));
+    if (url.includes('/scan-status')) return jsonRes({ status: 'ok' });
+    return jsonRes(null, false); // git-source and anything else: nothing to show
+  });
+});
+
+function panel(applying: boolean, onApplyUpdate: () => void = vi.fn(), stackName = 'web') {
+  return (
+    <StackAnatomyPanel
+      stackName={stackName}
+      content={COMPOSE}
+      envContent=""
+      selectedEnvFile=".env"
+      gitSourcePending={false}
+      onEditCompose={vi.fn()}
+      onOpenGitSource={vi.fn()}
+      onApplyUpdate={onApplyUpdate}
+      canEdit
+      applying={applying}
+    />
+  );
+}
+
+describe('StackAnatomyPanel update banner', () => {
+  it('shows the apply button and fires onApplyUpdate when clicked', async () => {
+    const onApply = vi.fn();
+    render(panel(false, onApply));
+
+    expect(await screen.findByTestId('update-available-banner')).toBeInTheDocument();
+    fireEvent.click(screen.getByRole('button', { name: 'apply' }));
+    expect(onApply).toHaveBeenCalledTimes(1);
+  });
+
+  it('disables the apply button and shows progress while applying', async () => {
+    const onApply = vi.fn();
+    const { rerender } = render(panel(false, onApply));
+    await screen.findByTestId('update-available-banner');
+
+    rerender(panel(true, onApply));
+
+    const btn = screen.getByRole('button', { name: /applying/i });
+    expect(btn).toBeDisabled();
+  });
+
+  it('clears the banner after the update lands', async () => {
+    const onApply = vi.fn();
+    const { rerender } = render(panel(false, onApply));
+    await screen.findByTestId('update-available-banner');
+
+    rerender(panel(true, onApply)); // update in flight
+    hasUpdate = false; // backend now reports the stack is current
+    rerender(panel(false, onApply)); // apply finished
+
+    await waitFor(() =>
+      expect(screen.queryByTestId('update-available-banner')).not.toBeInTheDocument(),
+    );
+  });
+
+  it('keeps the banner if the update did not take effect', async () => {
+    const onApply = vi.fn();
+    const { rerender } = render(panel(false, onApply));
+    await screen.findByTestId('update-available-banner');
+
+    const before = updatePreviewCalls();
+    rerender(panel(true, onApply));
+    rerender(panel(false, onApply)); // hasUpdate stays true: still an update pending
+
+    await waitFor(() => expect(updatePreviewCalls()).toBeGreaterThan(before));
+    expect(screen.getByTestId('update-available-banner')).toBeInTheDocument();
+  });
+
+  it('does not re-check the preview while applying stays false', async () => {
+    const onApply = vi.fn();
+    const { rerender } = render(panel(false, onApply));
+    await screen.findByTestId('update-available-banner');
+
+    const before = updatePreviewCalls();
+    rerender(panel(false, onApply));
+    rerender(panel(false, onApply));
+    await Promise.resolve();
+
+    expect(updatePreviewCalls()).toBe(before); // re-check fires only on the true -> false edge
+  });
+
+  it('does not fire onApplyUpdate while the apply button is disabled', async () => {
+    const onApply = vi.fn();
+    const { rerender } = render(panel(false, onApply));
+    await screen.findByTestId('update-available-banner');
+
+    rerender(panel(true, onApply));
+    fireEvent.click(screen.getByRole('button', { name: /applying/i }));
+
+    expect(onApply).not.toHaveBeenCalled();
+  });
+
+  it('keeps the banner when the post-apply re-check returns a non-OK response', async () => {
+    const errSpy = vi.spyOn(console, 'error').mockImplementation(() => {});
+    let updateCalls = 0;
+    vi.mocked(apiFetch).mockImplementation(async (input: RequestInfo | URL) => {
+      const url = String(input);
+      if (url.includes('/update-preview')) {
+        updateCalls += 1;
+        return updateCalls >= 2 ? jsonRes(null, false) : jsonRes(previewBody(true));
+      }
+      if (url.includes('/scan-status')) return jsonRes({ status: 'ok' });
+      return jsonRes(null, false);
+    });
+
+    const onApply = vi.fn();
+    const { rerender } = render(panel(false, onApply));
+    await screen.findByTestId('update-available-banner');
+
+    const before = updatePreviewCalls();
+    rerender(panel(true, onApply));
+    rerender(panel(false, onApply)); // re-check returns not-ok: keep the known banner
+
+    await waitFor(() => expect(updatePreviewCalls()).toBeGreaterThan(before));
+    expect(screen.getByTestId('update-available-banner')).toBeInTheDocument();
+    expect(errSpy).toHaveBeenCalled();
+    errSpy.mockRestore();
+  });
+
+  it('keeps the banner when the post-apply re-check throws', async () => {
+    const errSpy = vi.spyOn(console, 'error').mockImplementation(() => {});
+    let updateCalls = 0;
+    vi.mocked(apiFetch).mockImplementation(async (input: RequestInfo | URL) => {
+      const url = String(input);
+      if (url.includes('/update-preview')) {
+        updateCalls += 1;
+        if (updateCalls >= 2) throw new Error('network down');
+        return jsonRes(previewBody(true));
+      }
+      if (url.includes('/scan-status')) return jsonRes({ status: 'ok' });
+      return jsonRes(null, false);
+    });
+
+    const onApply = vi.fn();
+    const { rerender } = render(panel(false, onApply));
+    await screen.findByTestId('update-available-banner');
+
+    const before = updatePreviewCalls();
+    rerender(panel(true, onApply));
+    rerender(panel(false, onApply)); // re-check throws: keep the known banner
+
+    await waitFor(() => expect(updatePreviewCalls()).toBeGreaterThan(before));
+    expect(screen.getByTestId('update-available-banner')).toBeInTheDocument();
+    expect(errSpy).toHaveBeenCalled();
+    errSpy.mockRestore();
+  });
+
+  it('does not re-check after switching stacks while the first is still applying', async () => {
+    const calls: string[] = [];
+    vi.mocked(apiFetch).mockImplementation(async (input: RequestInfo | URL) => {
+      const url = String(input);
+      if (url.includes('/update-preview')) {
+        calls.push(url);
+        return jsonRes(previewBody(!url.includes('/stacks/other/'))); // web has an update, other does not
+      }
+      if (url.includes('/scan-status')) return jsonRes({ status: 'ok' });
+      return jsonRes(null, false);
+    });
+    const otherCalls = () => calls.filter((u) => u.includes('/stacks/other/update-preview')).length;
+
+    const onApply = vi.fn();
+    const { rerender } = render(panel(false, onApply, 'web'));
+    await screen.findByTestId('update-available-banner');
+
+    rerender(panel(true, onApply, 'web')); // web applying
+    rerender(panel(false, onApply, 'other')); // switch stacks before web's apply finishes
+
+    await waitFor(() => expect(otherCalls()).toBe(1)); // only the stack-change mount fetch
+    await Promise.resolve();
+    expect(otherCalls()).toBe(1); // the apply-completion re-check must not fire for "other"
+  });
+
+  it('ignores a stale re-check that resolves after the stack changed', async () => {
+    let resolveStale!: (r: Response) => void;
+    const stale = new Promise<Response>((r) => { resolveStale = r; });
+    const webResponses: Response[] = [jsonRes(previewBody(true))]; // mount: web has an update
+    vi.mocked(apiFetch).mockImplementation((input: RequestInfo | URL) => {
+      const url = String(input);
+      if (url.includes('/stacks/web/update-preview')) {
+        const next = webResponses.shift();
+        return next ? Promise.resolve(next) : stale; // post-apply re-check for web hangs
+      }
+      if (url.includes('/stacks/other/update-preview')) return Promise.resolve(jsonRes(previewBody(false)));
+      if (url.includes('/scan-status')) return Promise.resolve(jsonRes({ status: 'ok' }));
+      return Promise.resolve(jsonRes(null, false));
+    });
+
+    const onApply = vi.fn();
+    const { rerender } = render(panel(false, onApply, 'web'));
+    await screen.findByTestId('update-available-banner');
+
+    rerender(panel(true, onApply, 'web'));
+    rerender(panel(false, onApply, 'web')); // re-check fires and hangs
+    rerender(panel(false, onApply, 'other')); // switch stacks: cleanup cancels the hung re-check
+
+    await waitFor(() =>
+      expect(screen.queryByTestId('update-available-banner')).not.toBeInTheDocument(),
+    );
+
+    resolveStale(jsonRes(previewBody(true))); // late stale result for web must be dropped
+    await Promise.resolve();
+
+    expect(screen.queryByTestId('update-available-banner')).not.toBeInTheDocument();
+  });
+});
diff --git a/frontend/src/components/StackAnatomyPanel.tsx b/frontend/src/components/StackAnatomyPanel.tsx
index eb27ac17..4d62797b 100644
--- a/frontend/src/components/StackAnatomyPanel.tsx
+++ b/frontend/src/components/StackAnatomyPanel.tsx
@@ -1,4 +1,4 @@
-import { useEffect, useMemo, useState } from 'react';
+import { useEffect, useMemo, useRef, useState } from 'react';
 import { parse as parseYaml } from 'yaml';
 import { GitBranch, Pencil, ExternalLink, Rocket, FolderOpen } from 'lucide-react';
 import { Button } from './ui/button';
@@ -19,6 +19,7 @@ interface StackAnatomyPanelProps {
   onApplyUpdate: () => void;
   onOpenFiles?: () => void;
   canEdit: boolean;
+  applying?: boolean;
   notifications?: NotificationItem[];
 }
 
@@ -236,6 +237,7 @@ export default function StackAnatomyPanel({
   onApplyUpdate,
   onOpenFiles,
   canEdit,
+  applying = false,
   notifications,
 }: StackAnatomyPanelProps) {
   const anatomy = useMemo(() => parseAnatomy(content), [content]);
@@ -295,6 +297,38 @@ export default function StackAnatomyPanel({
     return () => { cancelled = true; };
   }, [stackName]);
 
+  // When an apply for the current stack finishes (applying true -> false on the same
+  // stackName), re-check the preview: a landed update clears has_update so the banner
+  // unmounts; if it did not land, or the re-check itself fails, the banner stays.
+  // Tracking stackName alongside applying avoids treating a stack switch made while the
+  // first stack is still applying as a completion for the newly selected stack.
+  const prevApplyRef = useRef({ applying, stackName });
+  useEffect(() => {
+    const prev = prevApplyRef.current;
+    const finishedApplying = prev.applying && !applying && prev.stackName === stackName;
+    prevApplyRef.current = { applying, stackName };
+    if (!finishedApplying) return;
+    let cancelled = false;
+    const run = async () => {
+      try {
+        const res = await apiFetch(`/stacks/${stackName}/update-preview`);
+        if (cancelled) return;
+        if (!res.ok) {
+          // Re-check failed: keep the banner already shown rather than hiding a
+          // possibly-still-pending update. The apply action reports its own outcome.
+          console.error(`[StackAnatomyPanel] update-preview re-check returned ${res.status}; keeping the existing banner`);
+          return;
+        }
+        const data = await res.json();
+        if (!cancelled) setUpdatePreview(data);
+      } catch (err) {
+        console.error('[StackAnatomyPanel] update-preview re-check failed:', err);
+      }
+    };
+    void run();
+    return () => { cancelled = true; };
+  }, [applying, stackName]);
+
   useEffect(() => {
     let cancelled = false;
     const run = async () => {
@@ -494,7 +528,7 @@ export default function StackAnatomyPanel({
           </>
         )}
         {hasUpdate && updatePreview && (
-          <div className={cn('mt-3 mb-3 rounded-lg border p-3', bannerTone)}>
+          <div data-testid="update-available-banner" className={cn('mt-3 mb-3 rounded-lg border p-3', bannerTone)}>
             <div className="flex items-start justify-between gap-2">
               <div className="min-w-0">
                 <div className="font-mono text-[11px] uppercase tracking-wide">
@@ -524,11 +558,12 @@ export default function StackAnatomyPanel({
                   type="button"
                   size="sm"
                   variant="outline"
+                  disabled={applying}
                   className={cn('shrink-0 h-7 gap-1', applyBtnTone)}
                   onClick={onApplyUpdate}
                 >
-                  <Rocket className="h-3 w-3" strokeWidth={1.5} />
-                  apply
+                  <Rocket className={cn('h-3 w-3', applying && 'animate-pulse')} strokeWidth={1.5} />
+                  {applying ? 'applying...' : 'apply'}
                 </Button>
               )}
             </div>