diff --git a/src/cli/tui/hooks/__tests__/useDevDeploy.test.tsx b/src/cli/tui/hooks/__tests__/useDevDeploy.test.tsx
index 690055c55..d4130ccd0 100644
--- a/src/cli/tui/hooks/__tests__/useDevDeploy.test.tsx
+++ b/src/cli/tui/hooks/__tests__/useDevDeploy.test.tsx
@@ -36,10 +36,11 @@ vi.mock('../../../operations/deploy/change-detection', () => ({
 }));
 
 function Harness({ skip }: { skip?: boolean }) {
-  const { steps, isComplete, error } = useDevDeploy({ skip });
+  const { steps, isComplete, error, managedMemoryNotice } = useDevDeploy({ skip });
   return (
     <Text>
-      steps:{steps.length} isComplete:{String(isComplete)} error:{error ?? 'null'}
+      steps:{steps.length} isComplete:{String(isComplete)} error:{error ?? 'null'} notice:
+      {managedMemoryNotice ?? 'null'}
     </Text>
   );
 }
@@ -108,6 +109,31 @@ describe('useDevDeploy', () => {
     });
   });
 
+  it('surfaces the managed-memory heads-up from the onNotice callback', async () => {
+    mockHandleDeploy.mockImplementation((opts: { onNotice?: (message: string) => void }) => {
+      opts.onNotice?.('Managed memory: this harness automatically provisions a dedicated AgentCore Memory resource');
+      return Promise.resolve({ success: true });
+    });
+
+    const { lastFrame } = render(<Harness />);
+
+    await vi.waitFor(() => {
+      expect(lastFrame()).toContain('notice:Managed memory:');
+      expect(lastFrame()).toContain('isComplete:true');
+    });
+  });
+
+  it('leaves the managed-memory heads-up null when onNotice is not called', async () => {
+    mockHandleDeploy.mockResolvedValue({ success: true });
+
+    const { lastFrame } = render(<Harness />);
+
+    await vi.waitFor(() => {
+      expect(lastFrame()).toContain('isComplete:true');
+    });
+    expect(lastFrame()).toContain('notice:null');
+  });
+
   it('populates steps from onProgress callback', async () => {
     mockHandleDeploy.mockImplementation((opts: { onProgress?: (step: string, status: string) => void }) => {
       opts.onProgress?.('Validate project', 'start');
diff --git a/src/cli/tui/hooks/useDevDeploy.ts b/src/cli/tui/hooks/useDevDeploy.ts
index a570676f4..d6615f8ee 100644
--- a/src/cli/tui/hooks/useDevDeploy.ts
+++ b/src/cli/tui/hooks/useDevDeploy.ts
@@ -18,6 +18,8 @@ export interface UseDevDeployResult {
   isComplete: boolean;
   error: string | undefined;
   logPath: string | undefined;
+  /** Managed-memory heads-up surfaced by handleDeploy (null when not applicable) */
+  managedMemoryNotice: string | null;
 }
 
 export function useDevDeploy({ skip, ready = true }: UseDevDeployOptions = {}): UseDevDeployResult {
@@ -26,6 +28,7 @@ export function useDevDeploy({ skip, ready = true }: UseDevDeployOptions = {}):
   const [deployDone, setDeployDone] = useState(false);
   const [error, setError] = useState<string | undefined>();
   const [logPath, setLogPath] = useState<string | undefined>();
+  const [managedMemoryNotice, setManagedMemoryNotice] = useState<string | null>(null);
   const hasStarted = useRef(false);
 
   const onProgress = useCallback((stepName: string, status: 'start' | 'success' | 'error') => {
@@ -41,6 +44,10 @@ export function useDevDeploy({ skip, ready = true }: UseDevDeployOptions = {}):
     setDeployMessages(prev => [...prev, msg]);
   }, []);
 
+  const onNotice = useCallback((message: string) => {
+    setManagedMemoryNotice(message);
+  }, []);
+
   useEffect(() => {
     if (skip || !ready || hasStarted.current) return;
     hasStarted.current = true;
@@ -78,6 +85,7 @@ export function useDevDeploy({ skip, ready = true }: UseDevDeployOptions = {}):
           verbose: true,
           onProgress,
           onDeployMessage,
+          onNotice,
         });
 
         if (result.logPath) {
@@ -95,10 +103,10 @@ export function useDevDeploy({ skip, ready = true }: UseDevDeployOptions = {}):
     };
 
     void run();
-  }, [skip, ready, onProgress, onDeployMessage]);
+  }, [skip, ready, onProgress, onDeployMessage, onNotice]);
 
   // eslint-disable-next-line @typescript-eslint/prefer-nullish-coalescing -- skip is boolean, not nullable; || is the correct operator here
   const isComplete = skip || deployDone;
 
-  return { steps, deployMessages, isComplete, error, logPath };
+  return { steps, deployMessages, isComplete, error, logPath, managedMemoryNotice };
 }
diff --git a/src/cli/tui/screens/dev/DevScreen.tsx b/src/cli/tui/screens/dev/DevScreen.tsx
index aa3abd89d..e52280b53 100644
--- a/src/cli/tui/screens/dev/DevScreen.tsx
+++ b/src/cli/tui/screens/dev/DevScreen.tsx
@@ -245,6 +245,7 @@ export function DevScreen(props: DevScreenProps) {
     isComplete: deployComplete,
     error: deployError,
     logPath: deployLogPath,
+    managedMemoryNotice,
   } = useDevDeploy({ skip: props.skipDeploy, ready: mode === 'deploying' });
 
   const hasTransitionedFromDeployRef = useRef(false);
@@ -527,6 +528,11 @@ export function DevScreen(props: DevScreenProps) {
           <Box marginTop={1}>
             <StepProgress steps={displaySteps} />
           </Box>
+          {managedMemoryNotice && !deployComplete && (
+            <Box marginTop={1}>
+              <Text dimColor>Note: {managedMemoryNotice}</Text>
+            </Box>
+          )}
           {hasStartedCfn && (
             <Box marginTop={1}>
               <DeployStatus messages={deployMessages} isComplete={deployComplete} hasError={!!deployError} />
diff --git a/src/cli/tui/screens/harness/AddHarnessScreen.tsx b/src/cli/tui/screens/harness/AddHarnessScreen.tsx
index 3d94b85cb..60941f5f8 100644
--- a/src/cli/tui/screens/harness/AddHarnessScreen.tsx
+++ b/src/cli/tui/screens/harness/AddHarnessScreen.tsx
@@ -1423,7 +1423,10 @@ export function AddHarnessScreen({
             initialValue="/mnt/data/"
             onSubmit={wizard.setSessionStoragePath}
             onCancel={() => wizard.goBack()}
-            customValidation={value => (value.startsWith('/') ? true : 'Must be an absolute path')}
+            customValidation={value => {
+              const r = validateBYOMountPath(value);
+              return r === true ? true : r;
+            }}
           />
         )}