diff --git a/admin/class-tmdo-admin.php b/admin/class-tmdo-admin.php
index fb916b2..9f11387 100644
--- a/admin/class-tmdo-admin.php
+++ b/admin/class-tmdo-admin.php
@@ -2721,6 +2721,14 @@ wpdo.getListings({ per_page: 3 }).then(r => console.log(r));'
 	 * HPCT Import tab: preview and execute import.
 	 */
 	private static function render_hpct_import(): void {
+		// HPCT is a HivePress-family plugin; the importer ships in that AddOn.
+		if ( ! class_exists( 'TMDO_HPCT_Import' ) ) {
+			echo '<div class="notice notice-warning"><p>'
+				. esc_html__( 'HPCT 匯入需要啟用 2meet-data-optimizer-hivepress-addon。', '2meet-data-optimizer' )
+				. '</p></div>';
+			return;
+		}
+
 		// Handle import action.
 		if ( isset( $_POST['wpdo_run_import'] ) && check_admin_referer( 'wpdo_hpct_import' ) ) {
 			$result = TMDO_HPCT_Import::run();
diff --git a/cli/class-tmdo-cli.php b/cli/class-tmdo-cli.php
index 9048b53..e227736 100644
--- a/cli/class-tmdo-cli.php
+++ b/cli/class-tmdo-cli.php
@@ -648,6 +648,11 @@ class TMDO_CLI {
 	 * @subcommand import-hpct
 	 */
 	public function import_hpct( $args, $assoc_args ): void { // phpcs:ignore Generic.CodeAnalysis.UnusedFunctionParameter.FoundAfterLastUsed
+		// HPCT is a HivePress-family plugin; the importer ships in that AddOn.
+		if ( ! class_exists( 'TMDO_HPCT_Import' ) ) {
+			WP_CLI::error( 'import-hpct needs 2meet-data-optimizer-hivepress-addon to be active.' );
+		}
+
 		if ( TMDO_HPCT_Import::is_imported() ) {
 			WP_CLI::warning( 'HPCT settings have already been imported.' );
 			return;
diff --git a/tests/bootstrap.php b/tests/bootstrap.php
index 54988f4..f10be06 100644
--- a/tests/bootstrap.php
+++ b/tests/bootstrap.php
@@ -253,6 +253,15 @@ if ( ! function_exists( 'update_post_meta' ) ) {
 		return true;
 	}
 }
+if ( ! function_exists( 'add_post_meta' ) ) {
+	function add_post_meta( int $post_id, string $key, $value, bool $unique = false ): int|bool {
+		if ( $unique && isset( $GLOBALS['_wp_postmeta'][ $post_id ][ $key ] ) ) {
+			return false;
+		}
+		$GLOBALS['_wp_postmeta'][ $post_id ][ $key ] = $value;
+		return 1;
+	}
+}
 if ( ! function_exists( 'get_user_meta' ) ) {
 	function get_user_meta( int $uid, string $key = '', bool $single = false ) {
 		return $GLOBALS['_wp_usermeta'][ $uid ][ $key ] ?? ( $single ? '' : [] );
@@ -661,7 +670,9 @@ add_filter( 'wpdo/fsm_guard/bypass', '__return_true' );
 
 // TMDO_Listing_Stats → 2meet-data-optimizer-hivepress-addon.
 // Tests that hit REST endpoints using listing stats receive stub responses.
-if ( ! class_exists( 'TMDO_Listing_Stats' ) ) {
+// The HivePress AddOn's own suite defines TMDO_TEST_SKIP_LISTING_STATS_STUB so
+// it can load the real class instead of this stub.
+if ( ! defined( 'TMDO_TEST_SKIP_LISTING_STATS_STUB' ) && ! class_exists( 'TMDO_Listing_Stats' ) ) {
 	class TMDO_Listing_Stats {
 		public static function register(): void {}
 		public static function get_view_count( int $post_id ): int { return 0; }
diff --git a/tests/unit/CoreBoundaryTest.php b/tests/unit/CoreBoundaryTest.php
new file mode 100644
index 0000000..a1a3381
--- /dev/null
+++ b/tests/unit/CoreBoundaryTest.php
@@ -0,0 +1,152 @@
+<?php
+declare(strict_types=1);
+
+use PHPUnit\Framework\TestCase;
+
+/**
+ * Architectural guard: core must never hard-depend on an AddOn's classes.
+ *
+ * The 11 AddOns are optional. A site can run this plugin alone, so every
+ * reference core makes to an AddOn-owned class has to sit behind a
+ * class_exists() check — otherwise that code path fatals.
+ *
+ * This caught a real defect: the admin Dashboard tab and two public REST
+ * endpoints called TMDO_Listing_Stats (which ships in the HivePress AddOn)
+ * unconditionally, so they died with "Class not found" on any plain install.
+ *
+ * Static analysis on purpose — the alternative, booting core once per AddOn
+ * combination, is far more machinery for a weaker signal.
+ */
+class CoreBoundaryTest extends TestCase {
+
+	/**
+	 * Classes that are declared by an AddOn, never by core.
+	 *
+	 * Kept as prefixes so a newly added TMDO_HivePress_* adapter is covered
+	 * without touching this list.
+	 *
+	 * @var string[]
+	 */
+	private const ADDON_CLASS_PREFIXES = array(
+		'TMDO_HivePress',
+		'TMDO_Hivepress',
+		'TMDO_HP_',
+		'TMDO_HPCT_',
+		'TMDO_Listing_',
+		'TMDO_Favorites_',
+		'TMDO_Messages_',
+		'TMDO_Memberships_',
+		'TMDO_Requests_',
+		'TMDO_Reviews_',
+		'TMDO_Statistics_',
+		'TMDO_WooCommerce',
+		'TMDO_Woocommerce',
+		'TMDO_WC_',
+		'TMDO_LatePoint',
+		'TMDO_Latepoint',
+		'TMDO_Infocards',
+		'TMDO_Bookings',
+		'TMDO_Collab',
+		'TMDO_Playlist',
+		'TMDO_Quotation',
+		'TMDO_Mobile_Bridge',
+		'TMDO_Hub_',
+		'TMDO_Spoke_',
+		'TMDO_Admin_HivePress',
+		'TMDO_Admin_WC',
+		'TMDO_CLI_HivePress',
+	);
+
+	/**
+	 * Every core production file, excluding vendor and the test suite itself.
+	 *
+	 * @return array<string, array{string}>
+	 */
+	public static function coreFileProvider(): array {
+		$root  = dirname( __DIR__, 2 );
+		$files = array();
+		foreach ( array( 'includes', 'admin', 'cli', 'modules' ) as $dir ) {
+			$iterator = new RecursiveIteratorIterator(
+				new RecursiveDirectoryIterator( $root . '/' . $dir, FilesystemIterator::SKIP_DOTS )
+			);
+			foreach ( $iterator as $file ) {
+				if ( 'php' === $file->getExtension() ) {
+					$rel           = substr( $file->getPathname(), strlen( $root ) + 1 );
+					$files[ $rel ] = array( $file->getPathname() );
+				}
+			}
+		}
+		ksort( $files );
+		return $files;
+	}
+
+	/**
+	 * @dataProvider coreFileProvider
+	 *
+	 * @param string $path Absolute path to a core production file.
+	 */
+	public function test_addon_classes_are_only_used_behind_a_guard( string $path ): void {
+		$source = file_get_contents( $path );
+		$this->assertIsString( $source, "Unreadable: {$path}" );
+
+		$lines    = explode( "\n", $source );
+		$offences = array();
+
+		foreach ( $lines as $i => $line ) {
+			$code = $this->strip_comments_and_strings( $line );
+			foreach ( self::ADDON_CLASS_PREFIXES as $prefix ) {
+				// Only static calls / constant reads bind at runtime; a bare
+				// mention (e.g. inside an array of names to probe) does not.
+				if ( ! preg_match( '/\b(' . preg_quote( $prefix, '/' ) . '\w*)::/', $code, $m ) ) {
+					continue;
+				}
+				if ( $this->is_guarded( $lines, $i, $m[1] ) ) {
+					continue;
+				}
+				$offences[] = sprintf( '%s:%d — %s', basename( $path ), $i + 1, trim( $line ) );
+			}
+		}
+
+		$this->assertSame(
+			array(),
+			$offences,
+			"Core calls an AddOn class without a class_exists() guard:\n" . implode( "\n", $offences )
+		);
+	}
+
+	/**
+	 * Remove line comments and string literals so mentions inside them are ignored.
+	 */
+	private function strip_comments_and_strings( string $line ): string {
+		$line = preg_replace( '#(//|\*|\#).*$#', '', $line ) ?? $line;
+		$line = preg_replace( "/'[^']*'/", "''", $line ) ?? $line;
+		return preg_replace( '/"[^"]*"/', '""', $line ) ?? $line;
+	}
+
+	/**
+	 * A guard counts if class_exists() for the same class appears earlier in
+	 * the same function (or, for top-level code, earlier in the file).
+	 *
+	 * Function scope rather than a fixed line window: an early-return guard at
+	 * the top of a 60-line CLI command legitimately protects every call below
+	 * it, and a window tight enough to be meaningful would reject that.
+	 *
+	 * @param string[] $lines Whole file, split on newlines.
+	 * @param int      $index Zero-based line index of the call site.
+	 * @param string   $class Class name being called.
+	 */
+	private function is_guarded( array $lines, int $index, string $class ): bool {
+		$from = 0;
+		for ( $i = $index; $i >= 0; $i-- ) {
+			if ( preg_match( '/^\t{1,2}(?:(?:public|private|protected|static|final|abstract)\s+)*function\s/', $lines[ $i ] ) ) {
+				$from = $i;
+				break;
+			}
+		}
+		$slice = implode( "\n", array_slice( $lines, $from, $index - $from + 1 ) );
+		return (bool) preg_match(
+			'/class_exists\(\s*[\'"]' . preg_quote( $class, '/' ) . '[\'"]/',
+			$slice
+		);
+	}
+}
diff --git a/tests/unit/StandardPostInterceptorTest.php b/tests/unit/StandardPostInterceptorTest.php
new file mode 100644
index 0000000..7bea9d5
--- /dev/null
+++ b/tests/unit/StandardPostInterceptorTest.php
@@ -0,0 +1,219 @@
+<?php
+declare(strict_types=1);
+
+use PHPUnit\Framework\TestCase;
+
+if ( ! class_exists( 'WP_Post' ) ) {
+	class WP_Post {
+		public int    $ID           = 0;
+		public string $post_type    = '';
+		public string $post_status  = 'publish';
+		public string $post_title   = '';
+		public string $post_content = '';
+		public int    $post_author  = 0;
+		public int    $post_parent  = 0;
+		public function __construct( object $data ) {
+			foreach ( (array) $data as $k => $v ) {
+				$this->$k = $v;
+			}
+		}
+	}
+}
+
+/**
+ * Concrete test double for TMDO_Standard_Post_Interceptor.
+ */
+class TMDO_Test_Post_Interceptor extends TMDO_Standard_Post_Interceptor {
+
+	protected string $module = 'test_module';
+
+	public const FIELD_MAP = array(
+		'test_meta' => 'test_col',
+		'other_meta' => 'other_col',
+	);
+
+	protected function get_post_type(): string {
+		return 'test_post';
+	}
+
+	protected function get_table_key(): string {
+		return 'test_table';
+	}
+
+	protected function build_insert_data( int $post_id, \WP_Post $post, string $now ): array {
+		return array(
+			'values'  => array(
+				'post_id'    => $post_id,
+				'status'     => $post->post_status,
+				'created_at' => $now,
+				'updated_at' => $now,
+			),
+			'formats' => array( '%d', '%s', '%s', '%s' ),
+		);
+	}
+}
+
+/**
+ * Unit tests for TMDO_Standard_Post_Interceptor abstract base.
+ *
+ * Exercises the three shared hook methods (action_delete_post,
+ * filter_update_meta, action_insert_post) via the TMDO_Test_Post_Interceptor
+ * concrete subclass, which never needs to live outside this test file.
+ */
+class StandardPostInterceptorTest extends TestCase {
+
+	private TMDO_Test_Post_Interceptor $interceptor;
+
+	/** Last $wpdb->delete() call: [table, where, formats]. */
+	public static array $last_delete = [];
+
+	/** Last SQL passed to $wpdb->query(). */
+	public static string $last_query = '';
+
+	/** Last $wpdb->insert() call: [table, data, formats]. */
+	public static array $last_insert = [];
+
+	protected function setUp(): void {
+		self::$last_delete = [];
+		self::$last_query  = '';
+		self::$last_insert = [];
+
+		$this->interceptor = new TMDO_Test_Post_Interceptor();
+
+		// Reset Feature Flags request cache.
+		$ff = new ReflectionClass( TMDO_Feature_Flags::class );
+		$ff->getProperty( 'cache' )->setValue( null, null );
+		$GLOBALS['_wp_options'] = [];
+
+		$this->setup_wpdb_mock();
+	}
+
+	private function setup_wpdb_mock(): void {
+		global $wpdb;
+		$wpdb = new class {
+			public string $prefix = 'wp_';
+			public function prepare( string $sql, mixed ...$args ): string {
+				$i = 0;
+				return preg_replace_callback( '/%([sd])/', static function ( $m ) use ( &$i, $args ) {
+					$val = $args[ $i++ ] ?? '';
+					return $m[1] === 'd' ? (string) (int) $val : "'" . addslashes( (string) $val ) . "'";
+				}, $sql );
+			}
+			public function query( string $sql ): int|bool {
+				StandardPostInterceptorTest::$last_query = $sql;
+				return 1;
+			}
+			public function delete( string $table, array $where, array $formats ): int|false {
+				StandardPostInterceptorTest::$last_delete = [ $table, $where, $formats ];
+				return 1;
+			}
+			public function insert( string $table, array $data, array $formats ): int|false {
+				StandardPostInterceptorTest::$last_insert = [ $table, $data, $formats ];
+				return 1;
+			}
+		};
+	}
+
+	private function make_post( string $type = 'test_post', int $id = 1 ): WP_Post {
+		$post             = new WP_Post( (object) [] );
+		$post->ID         = $id;
+		$post->post_type  = $type;
+		$post->post_status = 'publish';
+		$post->post_title  = 'Test';
+		$post->post_content = '';
+		$post->post_author  = 0;
+		$post->post_parent  = 0;
+		return $post;
+	}
+
+	// ── action_delete_post ────────────────────────────────────────────────────
+
+	public function test_delete_post_calls_wpdb_delete_for_correct_type(): void {
+		TMDO_Feature_Flags::set( 'test_module', 'complete' );
+		$post = $this->make_post( 'test_post', 99 );
+		$this->interceptor->action_delete_post( 99, $post );
+		$this->assertStringContainsString( 'wp_test_table', self::$last_delete[0] ?? '' );
+		$this->assertSame( [ 'post_id' => 99 ], self::$last_delete[1] );
+	}
+
+	public function test_delete_post_skips_wrong_post_type(): void {
+		TMDO_Feature_Flags::set( 'test_module', 'complete' );
+		$post = $this->make_post( 'other_type', 99 );
+		$this->interceptor->action_delete_post( 99, $post );
+		$this->assertSame( [], self::$last_delete );
+	}
+
+	public function test_delete_post_skips_when_not_active(): void {
+		TMDO_Feature_Flags::set( 'test_module', 'idle' );
+		$post = $this->make_post( 'test_post', 99 );
+		$this->interceptor->action_delete_post( 99, $post );
+		$this->assertSame( [], self::$last_delete );
+	}
+
+	// ── filter_update_meta ────────────────────────────────────────────────────
+
+	public function test_update_meta_issues_sql_update_for_known_key(): void {
+		TMDO_Feature_Flags::set( 'test_module', 'complete' );
+		// get_post_type() stub returns 'test_post' for post ID 5.
+		$GLOBALS['_wp_post_types'][5] = 'test_post';
+
+		$result = $this->interceptor->filter_update_meta( null, 5, 'test_meta', 'newval', '' );
+
+		$this->assertNull( $result );
+		$this->assertStringContainsString( 'UPDATE', self::$last_query );
+		$this->assertStringContainsString( 'test_col', self::$last_query );
+		$this->assertStringContainsString( 'newval', self::$last_query );
+	}
+
+	public function test_update_meta_skips_unregistered_key(): void {
+		TMDO_Feature_Flags::set( 'test_module', 'complete' );
+		$GLOBALS['_wp_post_types'][5] = 'test_post';
+
+		$this->interceptor->filter_update_meta( null, 5, 'unknown_key', 'val', '' );
+
+		$this->assertSame( '', self::$last_query );
+	}
+
+	public function test_update_meta_skips_wrong_post_type(): void {
+		TMDO_Feature_Flags::set( 'test_module', 'complete' );
+		$GLOBALS['_wp_post_types'][5] = 'other_type';
+
+		$this->interceptor->filter_update_meta( null, 5, 'test_meta', 'val', '' );
+
+		$this->assertSame( '', self::$last_query );
+	}
+
+	public function test_update_meta_passes_through_check_unchanged(): void {
+		TMDO_Feature_Flags::set( 'test_module', 'complete' );
+		$GLOBALS['_wp_post_types'][5] = 'test_post';
+		$sentinel = 'original_check';
+
+		$result = $this->interceptor->filter_update_meta( $sentinel, 5, 'test_meta', 'v', '' );
+
+		$this->assertSame( $sentinel, $result );
+	}
+
+	// ── action_insert_post ────────────────────────────────────────────────────
+
+	public function test_insert_post_calls_wpdb_insert_for_new_post(): void {
+		TMDO_Feature_Flags::set( 'test_module', 'complete' );
+		$post = $this->make_post( 'test_post', 42 );
+		$this->interceptor->action_insert_post( 42, $post, false );
+		$this->assertStringContainsString( 'wp_test_table', self::$last_insert[0] ?? '' );
+		$this->assertSame( 42, self::$last_insert[1]['post_id'] ?? 0 );
+	}
+
+	public function test_insert_post_skips_updates(): void {
+		TMDO_Feature_Flags::set( 'test_module', 'complete' );
+		$post = $this->make_post( 'test_post', 42 );
+		$this->interceptor->action_insert_post( 42, $post, true );
+		$this->assertSame( [], self::$last_insert );
+	}
+
+	public function test_insert_post_skips_wrong_post_type(): void {
+		TMDO_Feature_Flags::set( 'test_module', 'complete' );
+		$post = $this->make_post( 'other_type', 42 );
+		$this->interceptor->action_insert_post( 42, $post, false );
+		$this->assertSame( [], self::$last_insert );
+	}
+}