diff --git a/cli/class-tmdo-cli.php b/cli/class-tmdo-cli.php
index b44bd5b..304f173 100644
--- a/cli/class-tmdo-cli.php
+++ b/cli/class-tmdo-cli.php
@@ -142,6 +142,10 @@ class TMDO_CLI {
 		foreach ( $violations as $entity_type => $integrations ) {
 			WP_CLI::warning( "  [GUARD] {$entity_type} is aeav_only while " . implode( ', ', $integrations ) . " reads native meta — write flat back with `wp tmdo bridge-restore-native {$entity_type} --demote`." );
 		}
+		$deferred = array_keys( (array) get_option( TMDO_Schema_Manager::DEFERRED_OPTION, array() ) );
+		if ( $deferred ) {
+			WP_CLI::warning( '  [SCHEMA] table upgrades not done yet (these groups use native meta meanwhile): ' . implode( ', ', $deferred ) . ' — see the error log if this run did not finish them.' );
+		}
 		$pending = TMDO_Schema_Manager::pending_indexes();
 		if ( $pending ) {
 			WP_CLI::warning( '  [INDEX] declared indexes not added yet: ' . implode( ', ', $pending ) . ' — still missing after this run: another process is adding them, or the ALTER failed (see the `schema.index_failed` log).' );
diff --git a/includes/engine/class-tmdo-hook-bus.php b/includes/engine/class-tmdo-hook-bus.php
index 7b0d4ea..ce6be65 100644
--- a/includes/engine/class-tmdo-hook-bus.php
+++ b/includes/engine/class-tmdo-hook-bus.php
@@ -948,10 +948,11 @@ final class TMDO_Hook_Bus {
 	 */
 	private static function field_for( string $type, int $object_id, string $meta_key ): ?array {
 		$field_def = TMDO_Entity_Registry::get_field( $type, $meta_key );
-		if ( null === $field_def || 'post' !== $type ) {
-			return $field_def;
+		if ( null !== $field_def && 'post' === $type ) {
+			$field_def = TMDO_Entity_Registry::get_field( $type, $meta_key, (string) get_post_type( $object_id ) );
 		}
-		return TMDO_Entity_Registry::get_field( $type, $meta_key, (string) get_post_type( $object_id ) );
+		// A group whose table upgrade waits for WP-CLI / WP-Cron stays native.
+		return null !== $field_def && TMDO_Schema_Manager::is_deferred( $type, (string) $field_def['group'] ) ? null : $field_def;
 	}
 
 	/**
diff --git a/includes/engine/class-tmdo-schema-manager.php b/includes/engine/class-tmdo-schema-manager.php
index 88ee68b..527c9da 100644
--- a/includes/engine/class-tmdo-schema-manager.php
+++ b/includes/engine/class-tmdo-schema-manager.php
@@ -26,6 +26,9 @@ final class TMDO_Schema_Manager {
 	/** Single cron event that adds declared indexes a visitor request had to leave out. */
 	public const INDEXES_HOOK = 'tmdo_ensure_group_indexes';
 
+	/** Option: "entity/group" → time an existing table's upgrade was left to WP-CLI / WP-Cron. */
+	public const DEFERRED_OPTION = 'tmdo_schema_deferred';
+
 	/** Request-scoped cache for table_exists() — prevents repeated SHOW TABLES per request. */
 	private static array $table_exists_cache = array();
 
@@ -95,7 +98,12 @@ final class TMDO_Schema_Manager {
 			return false;
 		}
 
-		$table   = self::get_table_name( $entity_type, $group_name );
+		$table = self::get_table_name( $entity_type, $group_name );
+		if ( self::upgrade_waits( $entity_type, $table ) ) {
+			self::defer_upgrade( "{$entity_type}/{$group_name}" );
+			return false;
+		}
+
 		$charset = $wpdb->get_charset_collate();
 		$id_col  = $adapter->get_entity_id_column();
 
@@ -167,6 +175,7 @@ final class TMDO_Schema_Manager {
 
 		// 記錄 Schema 版本與定義
 		self::store_schema_metadata( $entity_type, $group_name, $schema_hash, $field_definitions );
+		self::end_deferral( $entity_type, $group_name );
 
 		/**
 		 * Action: 表建立／升級完成
@@ -269,6 +278,73 @@ final class TMDO_Schema_Manager {
 		}
 	}
 
+	/**
+	 * Whether the group's table upgrade is waiting for WP-CLI / WP-Cron; its
+	 * keys then stay native (Hook Bus, query router).
+	 *
+	 * @param string $entity_type Entity type.
+	 * @param string $group_name  Group name.
+	 * @return bool
+	 */
+	public static function is_deferred( string $entity_type, string $group_name ): bool {
+		$deferred = get_option( self::DEFERRED_OPTION, array() );
+		return is_array( $deferred ) && isset( $deferred[ "{$entity_type}/{$group_name}" ] );
+	}
+
+	/**
+	 * Whether an existing table's upgrade waits for WP-CLI / WP-Cron: altering
+	 * a large table takes seconds to minutes, as for indexes. Until then the
+	 * group reads and writes native meta (is_deferred()). Not in aeav_only,
+	 * where the flat table is the only copy: that upgrade runs at once.
+	 *
+	 * @param string $entity_type Entity type.
+	 * @param string $table       Flat table name.
+	 * @return bool
+	 */
+	public static function upgrade_waits( string $entity_type, string $table ): bool {
+		return self::table_exists( $table )
+			&& ! self::ddl_allowed()
+			&& TMDO_Mode_Manager::MODE_AEAV_ONLY !== TMDO_Mode_Manager::get( $entity_type );
+	}
+
+	/**
+	 * Record a deferred table upgrade and have WP-Cron run it.
+	 *
+	 * @param string $id "entity/group".
+	 * @return void
+	 */
+	private static function defer_upgrade( string $id ): void {
+		$deferred = get_option( self::DEFERRED_OPTION, array() );
+		$deferred = is_array( $deferred ) ? $deferred : array();
+		if ( ! isset( $deferred[ $id ] ) ) {
+			$deferred[ $id ] = time();
+			update_option( self::DEFERRED_OPTION, $deferred, true );
+		}
+		if ( ! wp_next_scheduled( self::INDEXES_HOOK ) ) {
+			wp_schedule_single_event( time(), self::INDEXES_HOOK ); // Its request's init runs the upgrade.
+		}
+	}
+
+	/**
+	 * A deferred upgrade is done: writes made meanwhile skipped the flat table,
+	 * so rebuild it from native (drift fix) a minute later.
+	 *
+	 * @param string $entity_type Entity type.
+	 * @param string $group_name  Group name.
+	 * @return void
+	 */
+	private static function end_deferral( string $entity_type, string $group_name ): void {
+		if ( ! self::is_deferred( $entity_type, $group_name ) ) {
+			return;
+		}
+		$deferred = (array) get_option( self::DEFERRED_OPTION, array() );
+		unset( $deferred[ "{$entity_type}/{$group_name}" ] );
+		update_option( self::DEFERRED_OPTION, $deferred, true );
+		if ( TMDO_Mode_Manager::writes_to_flat( $entity_type ) && ! wp_next_scheduled( TMDO_Drift_Check::RESYNC_HOOK, array( $entity_type ) ) ) {
+			wp_schedule_single_event( time() + MINUTE_IN_SECONDS, TMDO_Drift_Check::RESYNC_HOOK, array( $entity_type ) );
+		}
+	}
+
 	/**
 	 * Key of the MySQL lock held while indexes are added. Lock names are
 	 * server-wide, so SQL hashes it with DATABASE() to keep sites apart.
diff --git a/includes/query/class-tmdo-post-query-router.php b/includes/query/class-tmdo-post-query-router.php
index 161b6b4..acdb148 100644
--- a/includes/query/class-tmdo-post-query-router.php
+++ b/includes/query/class-tmdo-post-query-router.php
@@ -634,6 +634,9 @@ class TMDO_Post_Query_Router {
 		if ( TMDO_Mode_Manager::MODE_AEAV_ONLY === TMDO_Mode_Manager::get( 'post' ) ) {
 			return false;
 		}
+		if ( TMDO_Schema_Manager::is_deferred( 'post', $group ) ) {
+			return true; // Table upgrade waiting for WP-CLI / WP-Cron.
+		}
 		$status = get_option( TMDO_Drift_Check::OPTION, array() );
 		$last   = is_array( $status ) ? ( $status['post'][ $group ] ?? null ) : null;
 		return is_array( $last ) && (int) ( $last['miss'] ?? 0 ) + (int) ( $last['diff'] ?? 0 ) + (int) ( $last['extra'] ?? 0 ) > 0;
diff --git a/tests/integration/HookBusIntegrationTest.php b/tests/integration/HookBusIntegrationTest.php
index b4e4fec..5d60c23 100644
--- a/tests/integration/HookBusIntegrationTest.php
+++ b/tests/integration/HookBusIntegrationTest.php
@@ -227,6 +227,29 @@ class HookBusIntegrationTest extends TestCase {
 		);
 	}
 
+	/**
+	 * A group whose table upgrade waits for WP-CLI / WP-Cron (2.3 PR-107)
+	 * stays native: its table may lack the new columns.
+	 */
+	public function test_a_group_waiting_for_its_table_upgrade_stays_native(): void {
+		global $wpdb;
+		self::set_user_mode( WPDO_Mode_Manager::MODE_DUAL_WRITE );
+		update_option( TMDO_Schema_Manager::DEFERRED_OPTION, array( 'user/core_profile' => time() ) );
+		try {
+			$this->with_usermeta(
+				function () use ( $wpdb ) {
+					$wpdb->insert( $wpdb->usermeta, array( 'user_id' => 4, 'meta_key' => 'first_name', 'meta_value' => 'Dora' ) );
+
+					WPDO_Hook_Bus::sync_from_native( 'user', 4, 'first_name', 'Dora', 'update' );
+
+					$this->assertNull( $this->read_flat_first_name( 4 ) );
+				}
+			);
+		} finally {
+			delete_option( TMDO_Schema_Manager::DEFERRED_OPTION );
+		}
+	}
+
 	/**
 	 * delete_all passes object ID 0: the delete_ action records the touched
 	 * users from the meta IDs, the deleted_ action re-syncs each to NULL.
diff --git a/tests/integration/PostQueryRouterFoundRowsTest.php b/tests/integration/PostQueryRouterFoundRowsTest.php
index f66e4cc..a374e91 100644
--- a/tests/integration/PostQueryRouterFoundRowsTest.php
+++ b/tests/integration/PostQueryRouterFoundRowsTest.php
@@ -90,6 +90,17 @@ class PostQueryRouterFoundRowsTest extends TestCase {
 		return array( $router, $query, $request );
 	}
 
+	public function test_a_group_waiting_for_its_table_upgrade_is_not_routed(): void {
+		$mode = new ReflectionProperty( WPDO_Mode_Manager::class, 'cache' );
+		$mode->setAccessible( true );
+		$mode->setValue( null, array( 'post' => 'shadow_read', 'user' => 'disabled', 'term' => 'disabled', 'comment' => 'disabled' ) );
+		update_option( TMDO_Schema_Manager::DEFERRED_OPTION, array( 'post/fr_core' => time() ) );
+
+		list( , $query ) = $this->routed();
+
+		$this->assertEmpty( $query->get( 'wpdo_post_clauses' ), 'kept native' );
+	}
+
 	public function test_routed_request_drops_sql_calc_found_rows(): void {
 		list( $router, $query, $request ) = $this->routed();
 
diff --git a/tests/integration/SchemaUpgradeDeferralTest.php b/tests/integration/SchemaUpgradeDeferralTest.php
new file mode 100644
index 0000000..979bc02
--- /dev/null
+++ b/tests/integration/SchemaUpgradeDeferralTest.php
@@ -0,0 +1,91 @@
+<?php
+declare(strict_types=1);
+
+use PHPUnit\Framework\TestCase;
+
+/**
+ * An existing flat table whose definition changed is upgraded from WP-CLI /
+ * WP-Cron only (2.3 PR-107); web requests record the group as deferred.
+ */
+class SchemaUpgradeDeferralTest extends TestCase {
+
+	private const TABLE = 'wp_itest_wpdo_user_sd_core';
+
+	public static function setUpBeforeClass(): void {
+		$base = WPDO_PLUGIN_DIR;
+		foreach ( array(
+			'includes/adapters/interface-entity-adapter.php',
+			'includes/engine/class-tmdo-type-caster.php',
+			'includes/engine/class-tmdo-schema-manager.php',
+			'includes/engine/class-tmdo-entity-registry.php',
+			'includes/engine/class-tmdo-mode-manager.php',
+			'includes/adapters/class-tmdo-adapter-user.php',
+		) as $file ) {
+			require_once $base . $file;
+		}
+		WPDO_Installer::install_v2_tables();
+	}
+
+	protected function setUp(): void {
+		global $wpdb;
+		$wpdb->query( 'DROP TABLE IF EXISTS `' . self::TABLE . '`' );
+		$wpdb->query( 'CREATE TABLE `' . self::TABLE . '` ( id BIGINT NOT NULL AUTO_INCREMENT, user_id BIGINT NOT NULL, sd_a VARCHAR(255) DEFAULT NULL, PRIMARY KEY (id), UNIQUE KEY uk_entity (user_id) ) ENGINE=InnoDB' );
+		$wpdb->delete( $wpdb->prefix . 'wpdo_registry_meta', array( 'entity_type' => 'user', 'group_name' => 'sd_core' ) );
+		$wpdb->insert( $wpdb->prefix . 'wpdo_registry_meta', array( 'entity_type' => 'user', 'group_name' => 'sd_core', 'schema_hash' => 'old', 'field_definitions' => '[]' ) );
+
+		$GLOBALS['_wp_options']                                     = array();
+		$GLOBALS['_wp_scheduled_single']                            = array();
+		$GLOBALS['_wp_filter_callbacks']['tmdo_schema_ddl_allowed'] = array(); // A web request.
+		$ref = new ReflectionProperty( WPDO_Schema_Manager::class, 'table_exists_cache' );
+		$ref->setAccessible( true );
+		$ref->setValue( null, array() );
+		self::set_user_mode( 'dual_write' );
+
+		WPDO_Entity_Registry::init();
+		WPDO_Entity_Registry::register_adapter( 'user', new WPDO_Adapter_User() );
+		WPDO_Entity_Registry::register_group( 'user', 'sd_core', array( array( 'key' => 'sd_a', 'type' => 'text' ), array( 'key' => 'sd_b', 'type' => 'integer' ) ) );
+	}
+
+	protected function tearDown(): void {
+		global $wpdb;
+		$wpdb->query( 'DROP TABLE IF EXISTS `' . self::TABLE . '`' );
+		$wpdb->delete( $wpdb->prefix . 'wpdo_registry_meta', array( 'entity_type' => 'user', 'group_name' => 'sd_core' ) );
+		WPDO_Entity_Registry::init();
+		self::set_user_mode( null );
+		unset( $GLOBALS['_wp_scheduled_single'] );
+	}
+
+	private static function set_user_mode( ?string $mode ): void {
+		$ref = new ReflectionProperty( WPDO_Mode_Manager::class, 'cache' );
+		$ref->setAccessible( true );
+		$ref->setValue( null, null === $mode ? null : array( 'post' => 'disabled', 'user' => $mode, 'term' => 'disabled', 'comment' => 'disabled' ) );
+	}
+
+	private function upgrade(): bool {
+		return TMDO_Schema_Manager::create_or_upgrade_table( 'user', 'sd_core', WPDO_Entity_Registry::get_group_fields( 'user', 'sd_core' ) );
+	}
+
+	public function test_a_web_request_leaves_the_upgrade_to_wp_cron_and_the_group_native(): void {
+		global $wpdb;
+
+		$this->assertFalse( $this->upgrade() );
+
+		$this->assertTrue( TMDO_Schema_Manager::is_deferred( 'user', 'sd_core' ) );
+		$this->assertContains( TMDO_Schema_Manager::INDEXES_HOOK, $GLOBALS['_wp_scheduled_single'] );
+		$this->assertSame( array( 'id', 'user_id', 'sd_a' ), $wpdb->get_col( 'SHOW COLUMNS FROM `' . self::TABLE . '`' ), 'no ALTER' );
+		$this->assertSame( 'old', TMDO_Schema_Manager::get_stored_schema_hash( 'user', 'sd_core' ) );
+	}
+
+	public function test_only_existing_tables_outside_aeav_only_and_outside_cli_or_cron_wait(): void {
+		$this->assertTrue( TMDO_Schema_Manager::upgrade_waits( 'user', self::TABLE ) );
+		$this->assertFalse( TMDO_Schema_Manager::upgrade_waits( 'user', 'wp_itest_wpdo_user_sd_missing' ), 'a new table is created at once' );
+
+		self::set_user_mode( 'aeav_only' );
+		$this->assertFalse( TMDO_Schema_Manager::upgrade_waits( 'user', self::TABLE ), 'aeav_only: the flat table is the only copy' );
+
+		self::set_user_mode( 'dual_write' );
+		add_filter( 'tmdo_schema_ddl_allowed', static fn() => true ); // WP-CLI / WP-Cron.
+		$this->assertFalse( TMDO_Schema_Manager::upgrade_waits( 'user', self::TABLE ) );
+		$GLOBALS['_wp_filter_callbacks']['tmdo_schema_ddl_allowed'] = array();
+	}
+}