diff --git a/services/api-server/src/api_server/html5.py b/services/api-server/src/api_server/html5.py
index e0eac52..2c3af4a 100644
--- a/services/api-server/src/api_server/html5.py
+++ b/services/api-server/src/api_server/html5.py
@@ -978,6 +978,7 @@ def render_html5_authoring_change_detail(project_id: str, preview: object | None
         <span>{escape(original_version_id)} -> {escape(rollback_version_id)}</span>
         <small>{escape(change_id)}</small>
       </article>
+      {_authoring_detail_summary(diff, checks, apply_available)}
       <div class="check-list">{check_rows}</div>
       <div class="diff-list">{diff_rows}</div>
       {apply_form}
@@ -1718,6 +1719,23 @@ def _authoring_changes_summary(changes: Iterable[object]) -> str:
     """
 
 
+def _authoring_detail_summary(diff: Iterable[object], checks: Iterable[object], apply_available: bool) -> str:
+    diff_list = list(diff)
+    check_list = list(checks)
+    diff_kinds = Counter(str(getattr(line, "kind", "") or "CHANGE") for line in diff_list)
+    check_statuses = Counter(str(getattr(check, "status", "") or "UNKNOWN") for check in check_list)
+    added = sum(1 for line in diff_list if str(getattr(line, "kind", "")) == "ADD")
+    removed = sum(1 for line in diff_list if str(getattr(line, "kind", "")) == "REMOVE")
+    diff_text = ", ".join(f"{name}: {count}" for name, count in sorted(diff_kinds.items())) or "empty diff"
+    check_text = ", ".join(f"{name}: {count}" for name, count in sorted(check_statuses.items())) or "no checks"
+    state = "rollback ready" if apply_available else "rollback blocked"
+    return f"""
+    <p class="authoring-summary" data-html5-authoring-detail-summary>
+      {escape(state)} · {escape(str(len(diff_list)))} diff lines · +{escape(str(added))} / -{escape(str(removed))} · {escape(diff_text)} · {escape(check_text)}
+    </p>
+    """
+
+
 def _named_node_item(label: str, node: object) -> str:
     name = getattr(node, "qualified_name", None) or getattr(node, "name", "")
     kind = getattr(node, "kind", label)
diff --git a/services/api-server/tests/test_api.py b/services/api-server/tests/test_api.py
index 0bb2622..45f6509 100644
--- a/services/api-server/tests/test_api.py
+++ b/services/api-server/tests/test_api.py
@@ -2700,6 +2700,9 @@ def test_authoring_context_and_completion_preview(tmp_path: Path):
     assert html5_detail.status_code == 200
     assert "text/html" in html5_detail.headers["content-type"]
     assert "data-html5-authoring-detail" in html5_detail.text
+    assert "data-html5-authoring-detail-summary" in html5_detail.text
+    assert "rollback ready" in html5_detail.text
+    assert "diff lines" in html5_detail.text
     assert "Rollback preview" in html5_detail.text
     assert "data-html5-authoring-rollback-form" in html5_detail.text
     assert f'hx-post="/html5/projects/{project_id}/authoring/changes/{apply_payload["change_id"]}/apply-rollback"' in html5_detail.text