diff --git a/ui/src/api/queries/admin/apps.ts b/ui/src/api/queries/admin/apps.ts
index 188f220c..12b0fa25 100644
--- a/ui/src/api/queries/admin/apps.ts
+++ b/ui/src/api/queries/admin/apps.ts
@@ -41,6 +41,11 @@ export interface Deployment {
   deployedAt: string | null;
   stoppedAt: string | null;
   createdAt: string;
+  deployedConfigSnapshot?: {
+    jarVersionId: string;
+    agentConfig: Record<string, unknown> | null;
+    containerConfig: Record<string, unknown>;
+  } | null;
 }
 
 /**
diff --git a/ui/src/pages/AppsTab/AppDeploymentPage/hooks/useUnsavedChangesBlocker.ts b/ui/src/pages/AppsTab/AppDeploymentPage/hooks/useUnsavedChangesBlocker.ts
new file mode 100644
index 00000000..4493981e
--- /dev/null
+++ b/ui/src/pages/AppsTab/AppDeploymentPage/hooks/useUnsavedChangesBlocker.ts
@@ -0,0 +1,26 @@
+import { useState, useEffect } from 'react';
+import { useBlocker } from 'react-router';
+
+export function useUnsavedChangesBlocker(hasUnsavedChanges: boolean) {
+  const blocker = useBlocker(({ currentLocation, nextLocation }) =>
+    hasUnsavedChanges && currentLocation.pathname !== nextLocation.pathname
+  );
+
+  const [dialogOpen, setDialogOpen] = useState(false);
+
+  useEffect(() => {
+    if (blocker.state === 'blocked') setDialogOpen(true);
+  }, [blocker.state]);
+
+  return {
+    dialogOpen,
+    confirm: () => {
+      setDialogOpen(false);
+      blocker.proceed?.();
+    },
+    cancel: () => {
+      setDialogOpen(false);
+      blocker.reset?.();
+    },
+  };
+}
diff --git a/ui/src/pages/AppsTab/AppDeploymentPage/index.tsx b/ui/src/pages/AppsTab/AppDeploymentPage/index.tsx
index 4713b41f..cc39b5d8 100644
--- a/ui/src/pages/AppsTab/AppDeploymentPage/index.tsx
+++ b/ui/src/pages/AppsTab/AppDeploymentPage/index.tsx
@@ -30,6 +30,7 @@ import { DeploymentTab } from './DeploymentTab/DeploymentTab';
 import { PrimaryActionButton, computeMode } from './PrimaryActionButton';
 import { useDeploymentPageState } from './hooks/useDeploymentPageState';
 import { useFormDirty } from './hooks/useFormDirty';
+import { useUnsavedChangesBlocker } from './hooks/useUnsavedChangesBlocker';
 import { deriveAppName } from './utils/deriveAppName';
 import styles from './AppDeploymentPage.module.css';
 
@@ -108,6 +109,8 @@ export default function AppDeploymentPage() {
   // Derived
   const mode = app ? 'deployed' : 'net-new';
   const dirty = useFormDirty(form, serverState, stagedJar);
+  const { dialogOpen: blockerOpen, confirm: blockerConfirm, cancel: blockerCancel } =
+    useUnsavedChangesBlocker(dirty.anyLocalEdit);
   const serverDirtyAgainstDeploy = dirtyState?.dirty ?? false;
   const deploymentInProgress = !!activeDeployment;
   const primaryMode = computeMode({
@@ -302,9 +305,7 @@ export default function AppDeploymentPage() {
   }
 
   function handleRestore(deploymentId: string) {
-    const deployment = deployments.find((d) => d.id === deploymentId) as
-      | (Deployment & { deployedConfigSnapshot?: { agentConfig?: Record<string, unknown>; containerConfig?: Record<string, unknown> } })
-      | undefined;
+    const deployment = deployments.find((d) => d.id === deploymentId);
     if (!deployment) return;
     const snap = deployment.deployedConfigSnapshot;
     if (!snap) return;
@@ -519,6 +520,17 @@ export default function AppDeploymentPage() {
         confirmLabel="Delete"
         variant="danger"
       />
+
+      {/* ── Unsaved changes navigation blocker ── */}
+      <AlertDialog
+        open={blockerOpen}
+        onClose={blockerCancel}
+        onConfirm={blockerConfirm}
+        title="Unsaved changes"
+        description="You have unsaved changes on this page. Discard and leave?"
+        confirmLabel="Discard & Leave"
+        variant="warning"
+      />
     </div>
   );
 }