fix(zone-warm): warm 表 UNIQUE KEY + set() 改 upsert + 原子 increment（B1/B3）

- CREATE TABLE wpdo_warm 的 meta_key varchar(255)→varchar(191)，
  KEY idx_post_meta → UNIQUE KEY ui_post_meta：沒有這個唯一鍵，
  ON DUPLICATE KEY UPDATE 不會觸發，會不斷 INSERT 重複列。
  （既有站台的 ALTER 遷移原本就在 installer:1329，只有 CREATE 落後）
- Zone_Warm::set() 由 SELECT→update/insert 改為 TMDO_DB::upsert()
- 新增 Zone_Warm::increment()：CAST(COALESCE(meta_value,0) AS SIGNED)+N
  原子計數，取代 get()+set() 的 read-modify-write race（A v3.3.3）
- ZoneWarmTest stub 與 ZoneWarmIntegrationTest 建表同步適配

unit 379 / integration 398 GREEN

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01TbG1keQQ7XBa7qMQY16KCY

includes/class-tmdo-installer.php

@@ -1327,12 +1327,12 @@ class TMDO_Installer {
 		$sqls[] = "CREATE TABLE {$p}wpdo_warm (
   id bigint(20) unsigned NOT NULL AUTO_INCREMENT,
   post_id bigint(20) unsigned NOT NULL DEFAULT 0,
-  meta_key varchar(255) NOT NULL DEFAULT '',
+  meta_key varchar(191) NOT NULL DEFAULT '',
   meta_value longtext,
   expires_at datetime NULL DEFAULT NULL,
   created_at datetime NOT NULL DEFAULT '0000-00-00 00:00:00',
   PRIMARY KEY (id),
-  KEY idx_post_meta (post_id, meta_key(191)),
+  UNIQUE KEY ui_post_meta (post_id, meta_key),
   KEY idx_expires_at (expires_at)
 ) {$charset};";
 

includes/zones/class-tmdo-zone-warm.php

@@ -100,35 +100,12 @@ class TMDO_Zone_Warm {
 	 * @param int|null $ttl      TTL in seconds. Null = no expiry.
 	 */
 	public static function set( int $post_id, string $meta_key, string $value, ?int $ttl = null ): void {
-		global $wpdb;
 		$table = self::table();
 		$now   = TMDO_DB::now();
 
-		$expires_at = null;
+		$expires_at = ( $ttl && $ttl > 0 ) ? gmdate( 'Y-m-d H:i:s', time() + $ttl ) : null;
-		if ( $ttl && $ttl > 0 ) {
-			$expires_at = gmdate( 'Y-m-d H:i:s', time() + $ttl );
-		}
 
-		// phpcs:disable WordPress.DB.PreparedSQL.InterpolatedNotPrepared -- Table name from TMDO_Zone_Warm::table() via TMDO_DB::table().
+		TMDO_DB::upsert(
-		$existing = $wpdb->get_var(
-			$wpdb->prepare(
-				"SELECT id FROM `{$table}` WHERE post_id = %d AND meta_key = %s LIMIT 1",
-				$post_id,
-				$meta_key
-			)
-		);
-		// phpcs:enable WordPress.DB.PreparedSQL.InterpolatedNotPrepared
-
-		if ( $existing ) {
-			$update_data   = array( 'meta_value' => $value );
-			$update_format = array( '%s' );
-			if ( null !== $expires_at ) {
-				$update_data['expires_at'] = $expires_at;
-				$update_format[]           = '%s';
-			}
-			$wpdb->update( $table, $update_data, array( 'id' => (int) $existing ), $update_format, array( '%d' ) );
-		} else {
-			$wpdb->insert(
 			$table,
 			array(
 				'post_id'    => $post_id,
@@ -137,9 +114,44 @@ class TMDO_Zone_Warm {
 				'expires_at' => $expires_at,
 				'created_at' => $now,
 			),
-				array( '%d', '%s', '%s', $expires_at ? '%s' : null, '%s' )
+			array( 'meta_value', 'expires_at' ),
+			array( 'post_id', 'meta_key' ),
+			array( '%d', '%s', '%s', '%s', '%s' )
 		);
 	}
+
+	/**
+	 * Atomically increment an integer counter in the warm zone.
+	 *
+	 * Uses INSERT ... ON DUPLICATE KEY UPDATE to avoid the read-then-write race
+	 * condition present in get()+set() patterns.
+	 *
+	 * @param int      $post_id  Post ID.
+	 * @param string   $meta_key Counter key.
+	 * @param int      $by       Amount to increment (default 1).
+	 * @param int|null $ttl      TTL in seconds. Null = no expiry.
+	 */
+	public static function increment( int $post_id, string $meta_key, int $by = 1, ?int $ttl = null ): void {
+		global $wpdb;
+		$table      = self::table();
+		$now        = TMDO_DB::now();
+		$expires_at = ( $ttl && $ttl > 0 ) ? gmdate( 'Y-m-d H:i:s', time() + $ttl ) : null;
+
+		// phpcs:disable WordPress.DB.DirectDatabaseQuery,WordPress.DB.PreparedSQL.InterpolatedNotPrepared -- table from self::table()
+		$wpdb->query(
+			$wpdb->prepare(
+				"INSERT INTO `{$table}` (post_id, meta_key, meta_value, expires_at, created_at)
+				VALUES (%d, %s, %d, %s, %s)
+				ON DUPLICATE KEY UPDATE meta_value = CAST(COALESCE(meta_value, 0) AS SIGNED) + %d",
+				$post_id,
+				$meta_key,
+				$by,
+				$expires_at,
+				$now,
+				$by
+			)
+		);
+		// phpcs:enable WordPress.DB.DirectDatabaseQuery,WordPress.DB.PreparedSQL.InterpolatedNotPrepared
 	}
 
 	/**

tests/integration/ZoneWarmIntegrationTest.php

@@ -28,7 +28,7 @@ class ZoneWarmIntegrationTest extends TestCase {
 				`expires_at` datetime DEFAULT NULL,
 				`created_at` datetime NOT NULL DEFAULT \'0000-00-00 00:00:00\',
 				PRIMARY KEY (`id`),
-				KEY `post_id` (`post_id`),
+				UNIQUE KEY `ui_post_meta` (`post_id`, `meta_key`),
 				KEY `expires_at` (`expires_at`)
 			) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4'
 		);

tests/unit/ZoneWarmTest.php

@@ -102,6 +102,40 @@ class ZoneWarmTest extends TestCase {
 			}
 
 			public function query( string $sql ): int|bool {
+				$store = &ZoneWarmTest::$store;
+				$flat  = preg_replace( '/\s+/', ' ', $sql );
+
+				// INSERT ... ON DUPLICATE KEY UPDATE (from set() via TMDO_DB::upsert())
+				// Pattern: VALUES (post_id, 'meta_key', 'value', expires_or_NULL, 'now') ON DUPLICATE KEY
+				if ( stripos( $flat, 'ON DUPLICATE KEY' ) !== false && stripos( $flat, 'COALESCE' ) === false ) {
+					if ( preg_match( "/VALUES \((\d+), '([^']+)', '([^']*)', (NULL|'[^']+'), '[^']+'\)/i", $flat, $m ) ) {
+						$post_id                        = (int) $m[1];
+						$meta_key                       = $m[2];
+						$meta_value                     = $m[3];
+						$expires_at                     = 'NULL' === $m[4] ? null : strtotime( trim( $m[4], "'" ) );
+						$store[ $post_id ][ $meta_key ] = array(
+							'value'      => $meta_value,
+							'expires_at' => $expires_at,
+						);
+						return 1;
+					}
+				}
+
+				// INSERT ... ON DUPLICATE KEY UPDATE meta_value = CAST(COALESCE...) + N (from increment())
+				if ( stripos( $flat, 'COALESCE' ) !== false ) {
+					if ( preg_match( "/VALUES \((\d+), '([^']+)', (\d+),/i", $flat, $m ) ) {
+						$post_id                        = (int) $m[1];
+						$meta_key                       = $m[2];
+						$by                             = (int) $m[3];
+						$current                        = (int) ( $store[ $post_id ][ $meta_key ]['value'] ?? 0 );
+						$store[ $post_id ][ $meta_key ] = array(
+							'value'      => (string) ( $current + $by ),
+							'expires_at' => null,
+						);
+						return 1;
+					}
+				}
+
 				return 0;
 			}
 		};