includes/class-tmdo-core.php

@@ -296,6 +296,9 @@ class TMDO_Core {
 		// v2.3.0 M6: daily health probe cron.
 		add_action( 'wpdo_daily_health_check', array( 'TMDO_Health_Cron', 'run' ) );
 
+		// 1.2.0: daily flat-vs-native drift sample (read by the post query router).
+		add_action( 'wpdo_daily_health_check', array( 'TMDO_Drift_Check', 'cron_tick' ) );
+
 		// v2.3.0 M6: daily snapshot prune cron (paired with health check).
 		add_action( 'wpdo_snapshot_prune_daily', array( 'TMDO_Snapshot_Pruner', 'cron_run' ) );
 

includes/diagnostic/class-tmdo-drift-check.php

@@ -40,6 +40,11 @@ final class TMDO_Drift_Check {
 	 */
 	public const OPTION = 'wpdo_drift_status';
 
+	/**
+	 * Entities per group sampled by the daily check.
+	 */
+	public const CRON_SAMPLE = 500;
+
 	/**
 	 * MySQL regex for a plain decimal number, used to skip rows that obviously match.
 	 * Exact matches compare BINARY: meta and flat tables may differ in collation,
@@ -97,6 +102,24 @@ final class TMDO_Drift_Check {
 		return $report;
 	}
 
+	/**
+	 * Daily check (wpdo_daily_health_check): sample every entity type whose
+	 * flat tables are written (mode dual_write or higher). The outcome replaces
+	 * the recorded status, so a group found drifting leaves the router at once.
+	 */
+	public static function cron_tick(): void {
+		foreach ( TMDO_Entity_Registry::VALID_ENTITY_TYPES as $entity_type ) {
+			if ( ! TMDO_Mode_Manager::writes_to_flat( $entity_type ) ) {
+				continue;
+			}
+			try {
+				self::run( $entity_type, '', self::CRON_SAMPLE );
+			} catch ( InvalidArgumentException $e ) {
+				continue; // No adapter for this entity type on this site.
+			}
+		}
+	}
+
 	/**
 	 * Rebuild drifted flat rows from native meta, then check again.
 	 *

tests/integration/DriftCheckTest.php

@@ -181,6 +181,45 @@ class DriftCheckTest extends TestCase {
 		$this->assertFalse( TMDO_Cache_Orchestrator::get_row( 'user', 2, 'dc_grp' ) );
 	}
 
+	// ── cron_tick() (2.2 PR-073) ────────────────────────────────────────────
+
+	private static function set_modes( ?array $modes ): void {
+		$cache = ( new ReflectionClass( WPDO_Mode_Manager::class ) )->getProperty( 'cache' );
+		$cache->setAccessible( true );
+		$cache->setValue( null, $modes );
+	}
+
+	public function test_the_daily_tick_samples_entities_that_write_to_flat(): void {
+		self::set_modes( array( 'post' => 'disabled', 'user' => 'dual_write', 'term' => 'disabled', 'comment' => 'disabled' ) );
+		try {
+			TMDO_Drift_Check::cron_tick();
+		} finally {
+			self::set_modes( null );
+		}
+
+		$status = get_option( TMDO_Drift_Check::OPTION );
+		$this->assertSame( TMDO_Drift_Check::CRON_SAMPLE, $status['user']['dc_grp']['sample'] );
+		$this->assertSame( 2, $status['user']['dc_grp']['diff'], 'the sample covers all 7 fixture users' );
+		$this->assertArrayNotHasKey( 'post', $status );
+	}
+
+	public function test_the_daily_tick_skips_entities_that_do_not_write_to_flat(): void {
+		self::set_modes( array( 'post' => 'disabled', 'user' => 'disabled', 'term' => 'disabled', 'comment' => 'disabled' ) );
+		try {
+			TMDO_Drift_Check::cron_tick();
+		} finally {
+			self::set_modes( null );
+		}
+
+		$this->assertFalse( get_option( TMDO_Drift_Check::OPTION ) );
+	}
+
+	public function test_the_daily_tick_runs_on_the_daily_health_check_hook(): void {
+		$source = (string) file_get_contents( WPDO_PLUGIN_DIR . 'includes/class-tmdo-core.php' );
+
+		$this->assertStringContainsString( "add_action( 'wpdo_daily_health_check', array( 'TMDO_Drift_Check', 'cron_tick' ) );", $source );
+	}
+
 	public function test_rejects_an_unknown_group(): void {
 		$this->expectException( InvalidArgumentException::class );
 		TMDO_Drift_Check::run( 'user', 'no_such_group' );