fix: honest install success for MokoSuiteSupport package installer

The package postflight showed the "license key required" next-steps
message even when a bundled child extension failed to install. Joomla
only logs a failed sub-install but still runs postflight.

Add missingChildExtensions(): verify every <file> declared in the
package manifest actually landed in #__extensions (plugins match on
element+type+folder with plg_<group>_ prefix stripping; component
matches element+type). Gate the license message on it and enqueue an
error listing any missing children. Fails open so a query/IO glitch
never turns a good install into a false failure.

Claude-Session: https://claude.ai/code/session_01B9aZHSWbiiZykJD88pYx8R

CHANGELOG.md

@@ -27,6 +27,7 @@
 - **CLAUDE.md** — repo-specific with channels, key patterns
 
 ### Fixed
+- **Installer** — honest install success: the package postflight now verifies every bundled child extension (component + system plugin) actually landed in `#__extensions` before showing the license/next-steps message, and enqueues an error listing any missing ones instead. Fails open so a transient query/IO glitch never fakes a failure.
 - **WebhookChannelHelper** — conversation race condition on concurrent webhooks (FOR UPDATE transaction)
 
 ### Removed

source/script.php

@@ -16,9 +16,113 @@ class Pkg_MokoSuiteSupportInstallerScript
 {
 	public function postflight(string $type, InstallerAdapter $adapter): void
 	{
+		// Be honest about success. Joomla's package installer only LOGS a failed child
+		// sub-install but still runs this postflight, so don't show the license /
+		// next-steps message if a bundled extension is actually missing. Fails open
+		// (see missingChildExtensions) so a query/IO glitch never fakes a failure.
+		$missing = $this->missingChildExtensions($adapter);
+
+		if (!empty($missing))
+		{
+			Factory::getApplication()->enqueueMessage(
+				'<h4>MokoSuiteSupport did not install correctly.</h4>'
+				. '<p>The following bundled extensions are missing: '
+				. htmlspecialchars(implode(', ', $missing), ENT_QUOTES) . '</p>'
+				. '<p>Please uninstall MokoSuiteSupport and reinstall the full package.</p>',
+				'error'
+			);
+
+			return;
+		}
+
+		// Warn if no license key is configured (success / next-steps path)
 		$this->warnMissingLicenseKey();
 	}
 
+	/**
+	 * Verify every child extension declared in the package manifest actually landed
+	 * in #__extensions. Returns readable labels of any that are missing.
+	 *
+	 * Matching per Joomla's #__extensions uniqueness:
+	 *   - type    = the <file> "type" attribute
+	 *   - element = the <file> "id" attribute, EXCEPT for plugins the manifest often
+	 *               declares the full `plg_<group>_<element>` id, so strip a leading
+	 *               `plg_<group>_` to get the real element; components/modules use id as-is
+	 *   - plugins ALSO match folder = the <file> "group" attribute
+	 *
+	 * FAILS OPEN: any error (unreadable manifest, query failure) returns [] so a
+	 * transient glitch never turns a good install into a false failure.
+	 *
+	 * @param   InstallerAdapter  $adapter  The package installer adapter.
+	 *
+	 * @return  string[]
+	 */
+	private function missingChildExtensions(InstallerAdapter $adapter): array
+	{
+		try
+		{
+			$manifest = $adapter->getParent()->getManifest();
+
+			if (!$manifest || !isset($manifest->files) || !isset($manifest->files->file))
+			{
+				return [];
+			}
+
+			$db      = Factory::getDbo();
+			$missing = [];
+
+			foreach ($manifest->files->file as $file)
+			{
+				$attrs  = $file->attributes();
+				$id     = isset($attrs['id']) ? (string) $attrs['id'] : '';
+				$exType = isset($attrs['type']) ? (string) $attrs['type'] : '';
+
+				if ($id === '' || $exType === '')
+				{
+					continue;
+				}
+
+				$group   = isset($attrs['group']) ? (string) $attrs['group'] : '';
+				$element = $id;
+
+				// Plugin element in #__extensions is the id minus any leading plg_<group>_.
+				if ($exType === 'plugin' && $group !== '')
+				{
+					$prefix = 'plg_' . $group . '_';
+
+					if (strpos($element, $prefix) === 0)
+					{
+						$element = substr($element, \strlen($prefix));
+					}
+				}
+
+				$query = $db->getQuery(true)
+					->select('COUNT(*)')
+					->from($db->quoteName('#__extensions'))
+					->where($db->quoteName('element') . ' = ' . $db->quote($element))
+					->where($db->quoteName('type') . ' = ' . $db->quote($exType));
+
+				if ($exType === 'plugin' && $group !== '')
+				{
+					$query->where($db->quoteName('folder') . ' = ' . $db->quote($group));
+				}
+
+				if ((int) $db->setQuery($query)->loadResult() === 0)
+				{
+					$label     = trim((string) $file);
+					$missing[] = $label !== '' ? preg_replace('/\.zip$/i', '', $label) : $id;
+				}
+			}
+
+			return $missing;
+		}
+		catch (\Throwable $e)
+		{
+			// Fail open — never fake a failure on a glitch.
+			return [];
+		}
+	}
+
 	private function warnMissingLicenseKey(): void
 	{
 		try