diff --git a/app/console/admin_ui.py b/app/console/admin_ui.py
index 4dbdaf3..9863445 100644
--- a/app/console/admin_ui.py
+++ b/app/console/admin_ui.py
@@ -56,8 +56,9 @@ def _fmt_meta_detail(m: object, a: str) -> Markup:
             payload = json.dumps(val, sort_keys=True, default=str)
             blocks.append(
                 Markup(
-                    '<div><strong>{}</strong></div>'
-                    '<json-viewer data="{}" expanded="1" show-toolbar="true"></json-viewer>'
+                    "<div><strong>{}</strong></div>"
+                    '<andypf-json-viewer data="{}" expanded="1" show-copy="true">'
+                    "</andypf-json-viewer>"
                 ).format(label, payload)
             )
         else:
diff --git a/tests/test_admin_ui.py b/tests/test_admin_ui.py
index 467aeca..6e3713e 100644
--- a/tests/test_admin_ui.py
+++ b/tests/test_admin_ui.py
@@ -1,5 +1,7 @@
 import base64
 import os
+import re
+from pathlib import Path
 
 import pytest
 from fastapi import FastAPI
@@ -95,13 +97,31 @@ class Row:
     # Dict values become a collapsible json-viewer component fed escaped JSON.
     assert isinstance(rendered, Markup)
     assert "/console/static/json_viewer.js" in rendered
-    assert "<json-viewer data=" in rendered
+    assert "<andypf-json-viewer data=" in rendered
     assert "Generation Snapshot" in rendered
     assert "&#34;provider&#34;: &#34;bedrock&#34;" in rendered
     # Scalar values stay as plain labelled lines.
     assert "Moderation Score:</strong> 0.42" in rendered
 
 
+def test_meta_formatter_tag_matches_vendored_custom_element() -> None:
+    """The emitted tag must be the one the vendored bundle registers — an
+    unknown tag silently renders as an empty element (prod regression)."""
+    bundle = (
+        Path(__file__).parent.parent / "app" / "console" / "static" / "json_viewer.js"
+    ).read_text()
+    match = re.search(r'customElements\.define\("([^"]+)"', bundle)
+    assert match, "vendored bundle no longer registers a custom element?"
+    tag = match.group(1)
+
+    class Row:
+        meta = {"texet_generation": {"query": "hi"}}
+
+    rendered = _fmt_meta_detail(Row(), "meta")
+    assert f"<{tag} " in rendered
+    assert f"</{tag}>" in rendered
+
+
 def test_meta_formatter_escapes_user_content() -> None:
     class Row:
         meta = {"texet_generation": {"query": '<script>alert("xss")</script>'}}