diff --git a/tests/Feature/Ai/AutofillBrandTest.php b/tests/Feature/Ai/AutofillBrandTest.php
index e4be9ded..fd5469c0 100644
--- a/tests/Feature/Ai/AutofillBrandTest.php
+++ b/tests/Feature/Ai/AutofillBrandTest.php
@@ -100,13 +100,29 @@
 
     expect($result->language)->toBe($expected);
 })->with([
+    // Every supported language, detected from its primary subtag.
+    ['en', 'en'],
     ['pt', 'pt-BR'],
+    ['es', 'es'],
+    ['fr', 'fr'],
+    ['de', 'de'],
+    ['it', 'it'],
+    ['nl', 'nl'],
+    ['pl', 'pl'],
+    ['el', 'el'],
+    ['ja', 'ja'],
+    ['ko', 'ko'],
+    ['zh', 'zh'],
+    ['ru', 'ru'],
+    ['tr', 'tr'],
+    ['ar', 'ar'],
+    // Region/script subtags still resolve to the supported language.
     ['pt-PT', 'pt-BR'],
     ['en-US', 'en'],
     ['es-MX', 'es'],
-    ['fr', 'fr'],
     ['ja-JP', 'ja'],
     ['zh-Hans', 'zh'],
+    // Unsupported languages stay null.
     ['sv', null],
 ]);
 
diff --git a/tests/Unit/Enums/Workspace/ContentLanguageTest.php b/tests/Unit/Enums/Workspace/ContentLanguageTest.php
index 525d66d1..58db5692 100644
--- a/tests/Unit/Enums/Workspace/ContentLanguageTest.php
+++ b/tests/Unit/Enums/Workspace/ContentLanguageTest.php
@@ -44,4 +44,7 @@
     ['sv', null],
     ['e', null],
     ['', null],
+    // A malformed tag is matched on its whole primary subtag, never a
+    // two-letter prefix — "english" must not resolve to English via "en".
+    ['english', null],
 ]);