[Fleet] Fix missing Alerting tab for pre-installed integrations (elastic#270646)

# Summary

Closes elastic#256826

Pre-installed (bundled) integrations such as Fleet Server and Elastic
Synthetics were not showing the Alerting tab even when they had rule
templates installed. The tab visibility logic only checked
`packageInfo.assets.kibana` (the archive manifest), but for bundled
packages, alerting assets are recorded in
`installationInfo.installed_kibana` after installation — not in the
archive manifest. This adds a second check against `installed_kibana` so
the tab appears whenever alerting assets are actually installed,
regardless of install source. Also adds test coverage to future-proof
against regressions.

  ## Testing

1. Navigate to Data Management → Integrations → Installed integrations.
2. Open a pre-installed integration (e.g. Fleet Server or Elastic
Synthetics).
3. Verify the Alerting tab is now visible in the integration detail
navigation.
4. As a sanity check, confirm the rule templates shown in the Alerting
tab match those available under Stack Management → Rules → Create rule →
Template for that integration.
  
<img width="1706" height="1274" alt="image"
src="https://github.com/user-attachments/assets/c9da3850-cd03-41e7-bce4-af021ba71732"
/>


  ## Checklist

- [ ] Any text added follows [EUI's writing
guidelines](https://elastic.github.io/eui/#/guidelines/writing), uses
sentence case text and includes [i18n
support](https://github.com/elastic/kibana/blob/main/src/platform/packages/shared/kbn-i18n/README.md)
- [ ] [Documentation
](https://www.elastic.co/guide/en/kibana/master/development-documentation.html)was
added for features that require explanation or tutorials
- [ ] [Unit or functional tests
](https://www.elastic.co/guide/en/kibana/master/development-tests.html)were
updated or added to match the most common scenarios
- [ ] If a plugin configuration key changed, check if it needs to be
allowlisted in the cloud and added to the [docker
list](https://github.com/elastic/kibana/blob/main/src/dev/build/tasks/os_packages/docker_generator/resources/base/bin/kibana-docker)
- [ ] This was checked for breaking HTTP API changes, and any breaking
changes have been approved by the breaking-change committee. The
release_note:breaking label should be applied in these situations.
- [ ] [Flaky Test Runner
](https://ci-stats.kibana.dev/trigger_flaky_test_runner/1)was used on
any tests changed
- [ ] The PR description includes the appropriate Release Notes section,
and the correct release_note:* label is applied per the
[guidelines](https://www.elastic.co/guide/en/kibana/master/contributing.html#kibana-release-notes-process)
- [ ] Review the [backport guidelines
](https://docs.google.com/document/d/1VyN5k91e5OVumlc0Gb9RPa3h1ewuPE705nRtioPiTvY/edit?usp=sharing)and
apply applicable backport:* labels.

  ## Identify risks
N/A

Co-authored-by: Elastic Machine <elasticmachine@users.noreply.github.com>

Author: Supplementing

x-pack/platform/plugins/shared/fleet/public/applications/integrations/sections/epm/screens/detail/index.test.tsx

@@ -21,6 +21,7 @@ import type {
   GetVerificationKeyIdResponse,
 } from '../../../../../../../common/types/rest_spec';
 import type { KibanaAssetType } from '../../../../../../../common/types/models';
+import { KibanaSavedObjectType } from '../../../../../../../common/types/models';
 import {
   agentPolicyRouteService,
   appRoutesService,
@@ -189,6 +190,42 @@ describe('When on integration detail', () => {
       // Reset to default
       ExperimentalFeaturesService.init(allowedExperimentalValues);
     });
+
+    it('should show Alerting tab for pre-installed packages with alerting assets in installationInfo', async () => {
+      const baseResponse = mockedApi.responseProvider.epmGetInfo('nginx');
+      const kibanaAssets = baseResponse.item.assets?.kibana as Record<string, unknown> | undefined;
+      const itemWithInstalledAlertingAssets = {
+        ...baseResponse.item,
+        assets: {
+          ...baseResponse.item.assets,
+          kibana: {
+            dashboard: kibanaAssets?.dashboard ?? [],
+            search: kibanaAssets?.search ?? [],
+            visualization: kibanaAssets?.visualization ?? [],
+          },
+        },
+        installationInfo: {
+          install_source: 'bundled' as const,
+          installed_kibana: [
+            {
+              id: 'nginx-inactivity-rule',
+              type: KibanaSavedObjectType.alertingRuleTemplate,
+            },
+          ],
+        },
+      };
+      mockedApi.responseProvider.epmGetInfo.mockReturnValue({
+        ...baseResponse,
+        item: itemWithInstalledAlertingAssets as typeof baseResponse.item,
+      });
+      await render();
+      await act(() => mockedApi.waitForApi());
+      await act(() => mockedApi.waitForApi());
+      await act(() => mockedApi.waitForApi());
+      await act(() => mockedApi.waitForApi());
+
+      expect(await renderResult.findByTestId('tab-alerting')).not.toBeNull();
+    });
   });
 
   function mockGAAndPrereleaseVersions(pkgVersion: string) {

x-pack/platform/plugins/shared/fleet/public/applications/integrations/sections/epm/screens/detail/index.tsx

@@ -323,8 +323,14 @@ export function Detail() {
   const hasArchiveAlertingAssets = Object.keys(packageInfo?.assets?.kibana ?? {}).some((type) =>
     (ALERTING_ASSET_TYPES as string[]).includes(type)
   );
+  const pkgInstallationInfo =
+    packageInfo && 'installationInfo' in packageInfo ? packageInfo.installationInfo : undefined;
+  const hasInstalledAlertingAssets = (pkgInstallationInfo?.installed_kibana ?? []).some((asset) =>
+    (ALERTING_ASSET_TYPES as string[]).includes(asset.type)
+  );
   const showAlertingTab =
     hasArchiveAlertingAssets ||
+    hasInstalledAlertingAssets ||
     (isInstalled && packageInfo?.type === 'integration' && enableIntegrationInactivityAlerting);
 
   // Track install status state