Collaboration: Bump db_version and add deprecated route test

Increment $wp_db_version from 61833 to 61834 so the upgrade_700()
routine triggers dbDelta() for the new collaboration table. Add a
PHPUnit test covering the backward-compatible wp-sync/v1 route alias,
including a $_namespace parameter on the dispatch_collaboration helper.

Author: josephfusco

src/wp-includes/version.php

@@ -23,7 +23,7 @@
  *
  * @global int $wp_db_version
  */
-$wp_db_version = 61833;
+$wp_db_version = 61834;
 
 /**
  * Holds the TinyMCE version.

tests/phpunit/tests/rest-api/rest-collaboration-server.php

@@ -61,11 +61,12 @@ private function build_room( $room, $client_id = '1', $cursor = 0, $awareness =
 	/**
 	 * Dispatches a collaboration request with the given rooms.
 	 *
-	 * @param array $rooms Array of room request data.
+	 * @param array  $rooms      Array of room request data.
+	 * @param string $_namespace REST namespace to dispatch against.
 	 * @return WP_REST_Response Response object.
 	 */
-	private function dispatch_collaboration( $rooms ) {
-		$request = new WP_REST_Request( 'POST', '/wp-collaboration/v1/updates' );
+	private function dispatch_collaboration( $rooms, $_namespace = 'wp-collaboration/v1' ) {
+		$request = new WP_REST_Request( 'POST', '/' . $_namespace . '/updates' );
 		$request->set_body_params( array( 'rooms' => $rooms ) );
 		return rest_get_server()->dispatch( $request );
 	}
@@ -1674,6 +1675,53 @@ public function test_collaboration_null_awareness_skips_write() {
 	 * Query count tests.
 	 */
 
+	/*
+	 * Deprecated route tests.
+	 */
+
+	/**
+	 * Verifies the deprecated wp-sync/v1 route alias works identically to
+	 * the canonical wp-collaboration/v1 namespace.
+	 *
+	 * @ticket 64696
+	 */
+	public function test_collaboration_deprecated_sync_route() {
+		wp_set_current_user( self::$editor_id );
+
+		$room   = $this->get_post_room();
+		$update = array(
+			'type' => 'update',
+			'data' => 'c3luYyByb3V0ZQ==',
+		);
+
+		// Send an update via the deprecated namespace.
+		$response = $this->dispatch_collaboration(
+			array(
+				$this->build_room( $room, '1', 0, array( 'user' => 'client1' ), array( $update ) ),
+			),
+			'wp-sync/v1'
+		);
+
+		$this->assertSame( 200, $response->get_status(), 'Deprecated wp-sync/v1 route should return 200.' );
+
+		$data = $response->get_data();
+		$this->assertArrayHasKey( 'rooms', $data, 'Response should contain rooms key.' );
+		$this->assertSame( $room, $data['rooms'][0]['room'], 'Room identifier should match.' );
+
+		// Verify the update is retrievable via the canonical namespace.
+		$response2 = $this->dispatch_collaboration(
+			array(
+				$this->build_room( $room, '2', 0 ),
+			)
+		);
+
+		$updates = $response2->get_data()['rooms'][0]['updates'];
+		$this->assertNotEmpty( $updates, 'Update sent via deprecated route should be retrievable via canonical route.' );
+
+		$update_data = wp_list_pluck( $updates, 'data' );
+		$this->assertContains( 'c3luYyByb3V0ZQ==', $update_data );
+	}
+
 	/**
 	 * An idle poll (no new updates) should use at most 4 queries per room:
 	 * 1. SELECT … FROM collaboration WHERE type = 'awareness' (read + ownership check)