fix(2meet-data-optimizer): serve native meta in shadow_read and compare flat values

- In shadow_read, TMDO_Hook_Bus::intercept_get() returned the flat value.
  update_metadata() reads the old value through that filter after the Hook
  Bus has upserted the new one, so WP saw old === new and never wrote native
  meta: every update in shadow_read was lost on demotion (dev36 2026-09-26).
  shadow_read now returns $check (native) and compares flat on a sample of
  reads (filter tmdo_shadow_compare_sample_rate, default 0.1). aeav_only is
  unchanged; the post query router still routes in shadow_read.
- Live suite shadow_write: xfail markers removed, HivePress listing case
  added (new int key hp_rating_count); fixtures gain post() and a
  post_type-scoped field()/flat().
- Verify: live shadow_write + serialized 8/8 PASS (old code: 4 FAIL);
  unit 685 OK, integration 484 OK, phpcs (phpcs.xml) 0, stan OK
- PR: PR-056

includes/engine/class-tmdo-hook-bus.php

@@ -388,12 +388,20 @@ final class TMDO_Hook_Bus {
 		// ── Mode-aware dispatch ──────────────────────────────
 		// disabled    : 完全不攔截,回傳 $check 讓 WP 走原生 EAV
 		// dual_write  : 讀取仍走 EAV(flat 可能還沒有資料),回傳 $check
-		// shadow_read : 讀取走 UAE flat,同時與 EAV 比對記錄 diff
+		// shadow_read : 讀取仍走 EAV,抽樣與 flat 比對記錄 diff
 		// aeav_only   : 讀取走 UAE flat,不讀 EAV
 		if ( ! TMDO_Mode_Manager::reads_from_flat( $type ) ) {
 			return $check;  // disabled / dual_write
 		}
 
+		// shadow_read serves native: update_metadata() reads the old value
+		// through this filter, and serving the just-upserted flat value made
+		// WP see old === new and skip the native write (dev36, 2026-09-26).
+		if ( TMDO_Mode_Manager::does_shadow_compare( $type ) ) {
+			self::maybe_shadow_compare( $type, (int) $object_id, $meta_key, $field_def );
+			return $check;
+		}
+
 		$group = $field_def['group'];
 		$row   = self::get_or_load_row( $type, (int) $object_id, $group );
 
@@ -401,22 +409,6 @@ final class TMDO_Hook_Bus {
 		$has_value = is_array( $row ) && array_key_exists( $col, $row );
 		$value     = $has_value ? TMDO_Type_Caster::from_db( $row[ $col ], $field_def ) : null;
 
-		// Shadow-read:與 EAV 比對,記錄差異
-		if ( TMDO_Mode_Manager::does_shadow_compare( $type ) ) {
-			try {
-				TMDO_Shadow_Diff_Logger::compare_and_log(
-					$type,
-					(int) $object_id,
-					$meta_key,
-					$value,
-					$field_def
-				);
-			} catch ( \Throwable $e ) {
-				// 比對失敗不該影響讀取
-				TMDO_Logger::error( 'entity_bridge', 'shadow_compare_exception', $e->getMessage() );
-			}
-		}
-
 		// 值為空 → 回 WP 原生慣例
 		if ( empty( $row ) || $value === null || $value === '' ) {
 			return $single ? '' : array();
@@ -426,6 +418,36 @@ final class TMDO_Hook_Bus {
 		return $single ? array( $value ) : array( $value );
 	}
 
+	/**
+	 * shadow_read: compare the flat value with native meta for a sample of reads.
+	 *
+	 * Each compare costs a flat row read and a native SQL read, so only a share
+	 * of reads is checked (filter `tmdo_shadow_compare_sample_rate`, 0..1,
+	 * default 0.1). The logger rate-limits repeated diffs itself.
+	 *
+	 * @param string               $type      Entity type.
+	 * @param int                  $object_id Entity ID.
+	 * @param string               $meta_key  Meta key.
+	 * @param array<string, mixed> $field_def Field definition.
+	 */
+	private static function maybe_shadow_compare( string $type, int $object_id, string $meta_key, array $field_def ): void {
+		$rate = (float) apply_filters( 'tmdo_shadow_compare_sample_rate', 0.1, $type, $meta_key );
+		if ( $rate <= 0 || ( $rate < 1 && wp_rand( 1, 1000 ) > $rate * 1000 ) ) {
+			return;
+		}
+
+		$row   = self::get_or_load_row( $type, $object_id, $field_def['group'] );
+		$col   = TMDO_Schema_Manager::sanitize_column_name( $meta_key );
+		$value = array_key_exists( $col, $row ) ? TMDO_Type_Caster::from_db( $row[ $col ], $field_def ) : null;
+
+		try {
+			TMDO_Shadow_Diff_Logger::compare_and_log( $type, $object_id, $meta_key, $value, $field_def );
+		} catch ( \Throwable $e ) {
+			// 比對失敗不該影響讀取
+			TMDO_Logger::error( 'entity_bridge', 'shadow_compare_exception', $e->getMessage() );
+		}
+	}
+
 	/**
 	 * 取得（或載入）完整列資料，並快取
 	 */

tests/integration/HookBusIntegrationTest.php

@@ -268,6 +268,30 @@ class HookBusIntegrationTest extends TestCase {
 		$this->assertNull( $result, 'dual_write does not read from flat — must return $check' );
 	}
 
+	/**
+	 * shadow_read serves native meta: update_metadata() reads the old value
+	 * through this filter, and serving the just-written flat value made WP
+	 * skip the native write (dev36, 2026-09-26). Flat is only compared.
+	 */
+	public function test_get_serves_native_in_shadow_read_mode_even_with_a_flat_value(): void {
+		global $wpdb;
+		$wpdb->insert( self::FLAT_TABLE, array( 'user_id' => 12, 'first_name' => 'Flat' ) );
+		self::set_user_mode( WPDO_Mode_Manager::MODE_SHADOW_READ );
+
+		foreach ( array( 0.0, 1.0 ) as $rate ) {
+			$GLOBALS['_wp_filter_callbacks']['tmdo_shadow_compare_sample_rate'] = array(
+				static function () use ( $rate ) {
+					return $rate;
+				},
+			);
+
+			$result = WPDO_Hook_Bus::intercept_get( null, 12, 'first_name', true, 'user' );
+
+			$this->assertNull( $result, "shadow_read must return \$check (sample rate {$rate})" );
+		}
+		unset( $GLOBALS['_wp_filter_callbacks']['tmdo_shadow_compare_sample_rate'] );
+	}
+
 	public function test_get_returns_empty_string_when_column_is_null(): void {
 		global $wpdb;
 		$wpdb->query(

tests/live/README.md

@@ -36,7 +36,8 @@ Exit code 0 when every test passed, 1 otherwise. Output per test:
 
 | Suite | Covers |
 |---|---|
-| `shadow_write` | writes in shadow_read reach native meta (xfail until PR-056) |
+| `shadow_write` | writes in shadow_read reach native meta (user, term, HivePress listing) |
+| `serialized` | array meta values are stored serialized in flat tables, never "Array" |
 
 ## Tools (`tools/`)
 

tests/live/lib/fixtures.php

@@ -89,6 +89,30 @@ final class TMDO_Live_Fixtures {
 		return (int) $t['term_id'];
 	}
 
+	/**
+	 * Create a throwaway post.
+	 *
+	 * @param string $post_type Post type.
+	 */
+	public static function post( string $post_type ): int {
+		if ( ! post_type_exists( $post_type ) ) {
+			throw new TMDO_Live_Skip( "post type {$post_type} not registered on this site" );
+		}
+		$id = wp_insert_post(
+			array(
+				'post_type'   => $post_type,
+				'post_title'  => 'tmdo-live-' . wp_generate_password( 6, false, false ),
+				'post_status' => 'draft',
+			),
+			true
+		);
+		if ( is_wp_error( $id ) ) {
+			throw new TMDO_Live_Failure( 'fixture post: ' . $id->get_error_message() );
+		}
+		self::$created[] = array( 'post', (int) $id );
+		return (int) $id;
+	}
+
 	/**
 	 * Native meta values for a key, read with SQL (no filters, no cache).
 	 *
@@ -112,11 +136,12 @@ final class TMDO_Live_Fixtures {
 	 * @param string $type      Entity type.
 	 * @param int    $id        Entity ID.
 	 * @param string $key       Meta key.
+	 * @param string $post_type For posts: the post type whose group owns the key.
 	 * @return string|null
 	 */
-	public static function flat( string $type, int $id, string $key ) {
+	public static function flat( string $type, int $id, string $key, string $post_type = '' ) {
 		global $wpdb;
-		$field = self::field( $type, $key );
+		$field = self::field( $type, $key, $post_type );
 		$table = TMDO_Schema_Manager::get_table_name( $type, $field['group'] );
 		$col   = TMDO_Schema_Manager::sanitize_column_name( $key );
 		// phpcs:ignore WordPress.DB.PreparedSQL.InterpolatedNotPrepared -- table/column come from the registry.
@@ -127,11 +152,24 @@ final class TMDO_Live_Fixtures {
 	/**
 	 * Registry field for a key, or skip the test when the site does not register it.
 	 *
+	 * A key can live in several post groups (hp_rating in listing and vendor
+	 * groups); pass the post type to pick the group scoped to it.
+	 *
 	 * @param string $type      Entity type.
 	 * @param string $key       Meta key.
+	 * @param string $post_type For posts: the post type whose group owns the key.
 	 */
-	public static function field( string $type, string $key ): array {
+	public static function field( string $type, string $key, string $post_type = '' ): array {
 		$field = TMDO_Entity_Registry::get_field( $type, $key );
+		if ( '' !== $post_type ) {
+			foreach ( TMDO_Entity_Registry::get_groups_for_type( $type ) as $group ) {
+				if ( in_array( $post_type, TMDO_Entity_Registry::get_group_post_types( $type, $group ), true )
+					&& in_array( $key, TMDO_Entity_Registry::get_group_keys( $type, $group ), true ) ) {
+					$field = array( 'group' => $group ) + (array) $field;
+					break;
+				}
+			}
+		}
 		if ( ! $field ) {
 			throw new TMDO_Live_Skip( "{$type} key {$key} is not registered on this site" );
 		}
@@ -151,6 +189,8 @@ final class TMDO_Live_Fixtures {
 				wp_delete_user( $c[1] );
 			} elseif ( 'term' === $c[0] ) {
 				wp_delete_term( $c[1], $c[2] );
+			} elseif ( 'post' === $c[0] ) {
+				wp_delete_post( $c[1], true );
 			}
 		}
 		self::$created = array();

tests/live/suites/shadow_write.php

@@ -41,8 +41,7 @@ TMDO_Live::test(
 
 		tmdo_live_assert_true( false !== $ret, 'update_user_meta returned false' );
 		tmdo_live_assert_same( array( 'After' ), TMDO_Live_Fixtures::native( 'user', $uid, 'first_name' ), 'native first_name' );
-	},
-	array( 'xfail' => 'PR-056' )
+	}
 );
 
 TMDO_Live::test(
@@ -59,8 +58,7 @@ TMDO_Live::test(
 		wp_cache_delete( $uid, 'user_meta' );
 
 		tmdo_live_assert_same( 'After', get_user_meta( $uid, 'last_name', true ), 'last_name after demotion' );
-	},
-	array( 'xfail' => 'PR-056' )
+	}
 );
 
 TMDO_Live::test(
@@ -76,6 +74,23 @@ TMDO_Live::test(
 
 		tmdo_live_assert_true( false !== $ret, 'update_term_meta returned false' );
 		tmdo_live_assert_same( array( 'heart' ), TMDO_Live_Fixtures::native( 'term', $tid, 'hp_icon' ), 'native hp_icon' );
-	},
-	array( 'xfail' => 'PR-056' )
+	}
+);
+
+TMDO_Live::test(
+	'shadow_read: HivePress listing hp_rating_count (new int key) reaches native',
+	static function () {
+		TMDO_Live_Fixtures::field( 'post', 'hp_rating_count', 'hp_listing' );
+		TMDO_Live_Fixtures::use_modes( array( 'post' => 'dual_write' ) );
+		$lid = TMDO_Live_Fixtures::post( 'hp_listing' );
+		TMDO_Live_Fixtures::use_modes( array( 'post' => 'shadow_read' ) );
+
+		// HivePress writes the recomputed count as an int; the flat read cast it
+		// to the same int, so the old code skipped the native write.
+		$ret = update_post_meta( $lid, 'hp_rating_count', 1 );
+
+		tmdo_live_assert_true( false !== $ret, 'update_post_meta returned false' );
+		tmdo_live_assert_same( array( '1' ), TMDO_Live_Fixtures::native( 'post', $lid, 'hp_rating_count' ), 'native hp_rating_count' );
+		tmdo_live_assert_same( '1', TMDO_Live_Fixtures::flat( 'post', $lid, 'hp_rating_count', 'hp_listing' ), 'flat hp_rating_count' );
+	}
 );