diff --git a/api/Window.json b/api/Window.json
index d2276436837307..4f6dedd870a1fa 100644
--- a/api/Window.json
+++ b/api/Window.json
@@ -4314,7 +4314,9 @@
             "opera": "mirror",
             "opera_android": "mirror",
             "safari": {
-              "version_added": "18.2"
+              "version_added": "18.2",
+              "partial_implementation": true,
+              "notes": "Cross-origin navigation does not fire `pageswap`. See [bug 306447](https://webkit.org/b/306447)."
             },
             "safari_ios": "mirror",
             "samsunginternet_android": "mirror",