diff --git a/apps/desktop/src/app/settings/model-settings.test.tsx b/apps/desktop/src/app/settings/model-settings.test.tsx
index 93c43972d3..ce5f7546f3 100644
--- a/apps/desktop/src/app/settings/model-settings.test.tsx
+++ b/apps/desktop/src/app/settings/model-settings.test.tsx
@@ -781,6 +781,65 @@ describe('ModelSettings MoA preset editor', () => {
   })
 })
 
+describe('ModelSettings stale-aux banner dismissal', () => {
+  beforeEach(() => {
+    window.localStorage.clear()
+  })
+
+  afterEach(() => {
+    window.localStorage.clear()
+  })
+
+  const staleAux = {
+    main: { provider: 'nous', model: 'hermes-4' },
+    tasks: [{ task: 'vision', provider: 'alibaba', model: 'qwen3.6-flash', base_url: '' }]
+  }
+
+  it('hides the persistent stale-aux banner after acknowledging it, and re-arms when the main provider changes', async () => {
+    getAuxiliaryModels.mockResolvedValue(staleAux)
+
+    // First visit: the deliberate cross-provider pin surfaces the banner.
+    renderModelSettings()
+    expect(await screen.findByText(/still run on/)).toBeTruthy()
+    fireEvent.click(await screen.findByRole('button', { name: TRANSLATIONS.en.settings.model.staleAuxDismiss }))
+
+    await waitFor(() => expect(screen.queryByText(/still run on/)).toBeNull())
+
+    // Second visit (fresh mount): the acknowledgement persists.
+    cleanup()
+    renderModelSettings()
+    await waitFor(() => expect(getAuxiliaryModels).toHaveBeenCalled())
+    await waitFor(() => expect(screen.queryByText(/still run on/)).toBeNull())
+
+    // A main-provider switch re-arms the banner: the acknowledged
+    // configuration no longer matches what is running.
+    cleanup()
+    getGlobalModelInfo.mockResolvedValue({ provider: 'openrouter', model: 'hermes-4' })
+    renderModelSettings()
+    expect(await screen.findByText(/still run on/)).toBeTruthy()
+    // The dismiss affordance is offered again for the new configuration.
+    expect(screen.getByRole('button', { name: TRANSLATIONS.en.settings.model.staleAuxDismiss })).toBeTruthy()
+  })
+
+  it('keeps the post-switch notice undismissable — it announces a change that just happened', async () => {
+    setModelAssignment.mockResolvedValueOnce({
+      ok: true,
+      provider: 'openrouter',
+      model: 'anthropic/claude-opus-4.7',
+      gateway_tools: [],
+      stale_aux: [{ task: 'compression', provider: 'nous', model: 'hermes-4' }]
+    })
+
+    renderModelSettings()
+    await waitFor(() => expect(getGlobalModelInfo).toHaveBeenCalled())
+
+    fireEvent.click(await screen.findByRole('button', { name: 'Apply' }))
+
+    expect(await screen.findByText(/still run on/)).toBeTruthy()
+    expect(screen.queryByRole('button', { name: TRANSLATIONS.en.settings.model.staleAuxDismiss })).toBeNull()
+  })
+})
+
 describe('ModelSettings code-skew 503', () => {
   const skewError = new Error(
     'Error invoking remote method \'hermes:api\': Error: 503: {"detail":"Restart required: This process is running code from 08b4875f4a but the checkout on disk is now 48d2528066. The model picker would risk a stale-module crash — restart the Desktop-owned backend to load the new code (use Restart backend in Hermes Desktop, or quit and reopen the app)"}'
diff --git a/apps/desktop/src/app/settings/model-settings.tsx b/apps/desktop/src/app/settings/model-settings.tsx
index 5b396afcdb..1c6d7ebe45 100644
--- a/apps/desktop/src/app/settings/model-settings.tsx
+++ b/apps/desktop/src/app/settings/model-settings.tsx
@@ -45,6 +45,7 @@ import { CONTROL_TEXT } from './constants'
 import { getNested, setNested } from './helpers'
 import { ModelSelect, withActive } from './model-select'
 import { ListRow, ListRowSkeleton, Pill, SectionHeading, SectionHeadingSkeleton } from './primitives'
+import { dismissStaleAux, readStaleAuxDismissal, staleAuxFingerprint } from './stale-aux-dismissal'
 import { useDeepLinkHighlight } from './use-deep-link-highlight'
 
 // Skeleton mirror of the Model settings DOM so the page keeps its shape while
@@ -166,11 +167,17 @@ export function staleAuxAssignments(
       // (auxiliary_client._normalize_aux_provider), so it can never be a stale pin.
       return p && p !== 'auto' && p !== 'main' && p !== main && !entry.local_endpoint
     })
-    .map(entry => ({ task: entry.task, provider: entry.provider, model: entry.model }))
+    // base_url rides along for the dismissal fingerprint (see
+    // stale-aux-dismissal.ts): repointing a pin at a different endpoint changes
+    // the billing surface and must re-arm an acknowledged banner.
+    .map(entry => ({ base_url: entry.base_url, task: entry.task, provider: entry.provider, model: entry.model }))
 }
 
 interface StaleAuxWarningProps {
   applying: boolean
+  /** Offered only on the persistent variant — the post-switch notice announces
+   *  a change that just happened and must not be silenced. */
+  onDismiss?: () => void
   onReset: () => void
   slots: readonly StaleAuxAssignment[]
   taskLabel: (key: string) => string
@@ -180,7 +187,9 @@ interface StaleAuxWarningProps {
 // current main. Surfaces the silent credit-burn path (e.g. aux pinned to a
 // $0-balance provider after switching main away from it) and offers the
 // existing one-click reset rather than auto-clearing legitimate pins.
-function StaleAuxWarning({ applying, onReset, slots, taskLabel }: StaleAuxWarningProps) {
+// Sized to be read at a glance (#66740) with the theme-aware amber text the
+// app's warn badges use, so light mode keeps its contrast.
+function StaleAuxWarning({ applying, onDismiss, onReset, slots, taskLabel }: StaleAuxWarningProps) {
   const { t } = useI18n()
   const m = t.settings.model
 
@@ -193,9 +202,9 @@ function StaleAuxWarning({ applying, onReset, slots, taskLabel }: StaleAuxWarnin
   const names = slots.map(slot => taskLabel(slot.task)).join(', ')
 
   return (
-    <div className="flex flex-wrap items-center gap-2 rounded-md border border-amber-500/40 bg-amber-500/10 px-3 py-2 text-xs text-amber-200">
-      <AlertTriangle className="size-3.5 shrink-0" />
-      <span className="grow">
+    <div className="flex flex-wrap items-center gap-2 rounded-md border border-amber-400/60 bg-amber-500/15 px-3 py-2.5 text-sm text-amber-600 dark:text-amber-300">
+      <AlertTriangle className="size-4 shrink-0" />
+      <span className="grow font-medium">
         {m.staleAuxBefore(slots.length, names)}
         <span className="font-mono">{allSameProvider ? provider : m.staleAuxOtherProviders}</span>
         {m.staleAuxAfter}
@@ -203,6 +212,11 @@ function StaleAuxWarning({ applying, onReset, slots, taskLabel }: StaleAuxWarnin
       <Button disabled={applying} onClick={onReset} size="sm" variant="textStrong">
         {m.resetAllToMain}
       </Button>
+      {onDismiss && (
+        <Button disabled={applying} onClick={onDismiss} size="sm" variant="textStrong">
+          {m.staleAuxDismiss}
+        </Button>
+      )}
     </div>
   )
 }
@@ -582,6 +596,24 @@ export function ModelSettings({ onMainModelChanged, scopeProfile, subpage }: Mod
     [auxiliary, mainModel]
   )
 
+  // Acknowledgement of the persistent stale-aux banner (#66740): a dismissal
+  // is bound to the exact pin configuration it acknowledged, so any slot edit,
+  // main switch, or endpoint repoint produces a different fingerprint and
+  // re-arms the warning. Seeded lazily at first render (before the data can
+  // paint, so an acknowledged banner never flashes); the panel stays mounted
+  // across profile switches, so re-read when the scope changes.
+  const [dismissedStaleAux, setDismissedStaleAux] = useState<null | string>(() =>
+    readStaleAuxDismissal(scopeProfile)
+  )
+
+  useEffect(() => {
+    setDismissedStaleAux(readStaleAuxDismissal(scopeProfile))
+  }, [scopeProfile])
+
+  const staleAuxDismissed =
+    persistentStaleAux.length > 0 &&
+    dismissedStaleAux === staleAuxFingerprint(mainModel?.provider ?? '', persistentStaleAux)
+
   // Capabilities of the APPLIED main model — gates the profile-default
   // reasoning/speed controls the same way the composer picker gates per-model
   // edits (reasoning defaults on, fast defaults off when unreported).
@@ -1052,16 +1084,24 @@ export function ModelSettings({ onMainModelChanged, scopeProfile, subpage }: Mod
             </Button>
           </div>
           <p className="mb-2 text-xs text-muted-foreground">{m.auxiliaryDesc}</p>
-          {(switchStaleAux.length === 0 || !showMain) && persistentStaleAux.length > 0 && (
-            <div className="mb-2.5">
-              <StaleAuxWarning
-                applying={applying}
-                onReset={() => void resetAuxiliaryModels()}
-                slots={persistentStaleAux}
-                taskLabel={auxiliaryTaskLabel}
-              />
-            </div>
-          )}
+          {(switchStaleAux.length === 0 || !showMain) &&
+            persistentStaleAux.length > 0 &&
+            !staleAuxDismissed && (
+              <div className="mb-2.5">
+                <StaleAuxWarning
+                  applying={applying}
+                  onDismiss={() => {
+                    const mainProvider = mainModel?.provider ?? ''
+
+                    dismissStaleAux(scopeProfile, mainProvider, persistentStaleAux)
+                    setDismissedStaleAux(staleAuxFingerprint(mainProvider, persistentStaleAux))
+                  }}
+                  onReset={() => void resetAuxiliaryModels()}
+                  slots={persistentStaleAux}
+                  taskLabel={auxiliaryTaskLabel}
+                />
+              </div>
+            )}
           <div className="grid gap-1">
             {AUX_TASKS.map(meta => {
               const copy = m.tasks[meta.key] ?? { label: meta.key, hint: meta.key }