diff --git a/apps/app/src/app/(app)/[orgId]/components/AppShellWrapper.tsx b/apps/app/src/app/(app)/[orgId]/components/AppShellWrapper.tsx
index e6a234a9b5..01e2cdd5af 100644
--- a/apps/app/src/app/(app)/[orgId]/components/AppShellWrapper.tsx
+++ b/apps/app/src/app/(app)/[orgId]/components/AppShellWrapper.tsx
@@ -27,7 +27,6 @@ import {
   AppShellNavbar,
   AppShellRail,
   AppShellAIChatTrigger,
-  AppShellRailItem,
   AppShellSidebar,
   AppShellSidebarHeader,
   AppShellUserMenu,
@@ -54,6 +53,7 @@ import { TrustSidebar } from '../trust/components/TrustSidebar';
 import { getAppShellSearchGroups } from './app-shell-search-groups';
 import { AppSidebar } from './AppSidebar';
 import { ConditionalOnboardingTracker } from './ConditionalOnboardingTracker';
+import { ShellRailNavItem } from './ShellRailNavItem';
 
 interface AppShellWrapperProps {
   children: React.ReactNode;
@@ -342,28 +342,3 @@ function AppShellWrapperContent({
     </TooltipProvider>
   );
 }
-
-function ShellRailNavItem({
-  href,
-  isActive,
-  icon,
-  label,
-}: {
-  href: string;
-  isActive: boolean;
-  icon: React.ReactNode;
-  label: string;
-}) {
-  const railItemId = `app-shell-rail-${label.toLowerCase()}`;
-
-  return (
-    <Link href={href}>
-      <AppShellRailItem
-        isActive={isActive}
-        icon={icon}
-        id={railItemId}
-        label={label}
-      />
-    </Link>
-  );
-}
diff --git a/apps/app/src/app/(app)/[orgId]/components/ShellRailNavItem.test.tsx b/apps/app/src/app/(app)/[orgId]/components/ShellRailNavItem.test.tsx
new file mode 100644
index 0000000000..b9064a1099
--- /dev/null
+++ b/apps/app/src/app/(app)/[orgId]/components/ShellRailNavItem.test.tsx
@@ -0,0 +1,63 @@
+import { render } from '@testing-library/react';
+import { describe, expect, it, vi } from 'vitest';
+
+// next/link needs an App Router context that jsdom doesn't provide; render a plain anchor.
+vi.mock('next/link', () => ({
+  default: ({ href, children }: { href: string; children: React.ReactNode }) => (
+    <a href={href}>{children}</a>
+  ),
+}));
+
+import { AppShell, AppShellBody, AppShellRail } from '@trycompai/design-system';
+import { ShellRailNavItem } from './ShellRailNavItem';
+
+const Icon = () => <svg data-testid="icon" />;
+
+// Regression for CS-773: the far-left product rail tooltips flashed open then vanished
+// (~0.1s) on hover. Root cause: ShellRailNavItem passed a label-derived `id` to
+// AppShellRailItem, and AppShellRail re-renders the same rail items into the always-mounted
+// mobile drawer. That produced two DOM elements sharing one `id`, which the design system
+// forwards to the Base UI tooltip trigger — the duplicate trigger id collides in Base UI's
+// floating tree and closes the active tooltip. The fix is to not set a hard-coded id.
+describe('ShellRailNavItem (CS-773 tooltip flicker)', () => {
+  it('does not set a hard-coded, label-derived id on the rail item', () => {
+    render(<ShellRailNavItem href="/org/overview" isActive icon={<Icon />} label="Compliance" />);
+
+    const button = document.querySelector('[data-slot="app-shell-rail-item"]');
+    expect(button).not.toBeNull();
+    // The old bug set id="app-shell-rail-compliance". Any hard-coded id here is duplicated
+    // into the mobile drawer copy and breaks the tooltip, so it must be absent.
+    expect(button?.getAttribute('id')).not.toBe('app-shell-rail-compliance');
+  });
+
+  it('renders the rail with unique element ids across the desktop rail and mobile drawer', () => {
+    // AppShellRail mirrors its children into the always-mounted mobile drawer, so each logical
+    // item renders twice. With the fix, the design system generates a unique id per instance;
+    // with the bug, the two copies would share the same hard-coded id.
+    render(
+      <AppShell>
+        <AppShellBody>
+          <AppShellRail>
+            <ShellRailNavItem href="/org/overview" isActive icon={<Icon />} label="Compliance" />
+            <ShellRailNavItem href="/org/trust" isActive={false} icon={<Icon />} label="Trust" />
+            <ShellRailNavItem
+              href="/org/security"
+              isActive={false}
+              icon={<Icon />}
+              label="Security"
+            />
+          </AppShellRail>
+        </AppShellBody>
+      </AppShell>,
+    );
+
+    const ids = Array.from(document.querySelectorAll('[data-slot="app-shell-rail-item"]'))
+      .map((el) => el.getAttribute('id'))
+      .filter((id): id is string => Boolean(id));
+
+    // There must be no duplicate ids among rail item buttons.
+    expect(new Set(ids).size).toBe(ids.length);
+    // Sanity: the duplicate render means each of the 3 items appears twice.
+    expect(document.querySelectorAll('[data-slot="app-shell-rail-item"]').length).toBe(6);
+  });
+});
diff --git a/apps/app/src/app/(app)/[orgId]/components/ShellRailNavItem.tsx b/apps/app/src/app/(app)/[orgId]/components/ShellRailNavItem.tsx
new file mode 100644
index 0000000000..1b0892ec38
--- /dev/null
+++ b/apps/app/src/app/(app)/[orgId]/components/ShellRailNavItem.tsx
@@ -0,0 +1,29 @@
+'use client';
+
+import { AppShellRailItem } from '@trycompai/design-system';
+import Link from 'next/link';
+
+interface ShellRailNavItemProps {
+  href: string;
+  isActive: boolean;
+  icon: React.ReactNode;
+  label: string;
+}
+
+/**
+ * A single icon in the far-left product rail (Compliance, Trust, Security, Settings, Admin).
+ *
+ * CS-773: Do NOT pass an explicit `id` to `AppShellRailItem`. `AppShellRail` re-renders these
+ * same rail items into the always-mounted mobile drawer, so any hard-coded `id` becomes a
+ * duplicate DOM id. The design system uses that `id` as the Base UI tooltip trigger's id, and
+ * two triggers sharing one id collide in Base UI's floating tree — the active (desktop) trigger
+ * is treated as unmounted and the tooltip auto-closes ~0.1s after opening (the "tooltip glitching
+ * on hover" bug). Leaving the id unset lets the design system generate a unique id per instance.
+ */
+export function ShellRailNavItem({ href, isActive, icon, label }: ShellRailNavItemProps) {
+  return (
+    <Link href={href}>
+      <AppShellRailItem isActive={isActive} icon={icon} label={label} />
+    </Link>
+  );
+}