diff --git a/services/api-server/src/api_server/main.py b/services/api-server/src/api_server/main.py
index 226866d..91907a6 100644
--- a/services/api-server/src/api_server/main.py
+++ b/services/api-server/src/api_server/main.py
@@ -8442,7 +8442,11 @@ def _html5_sse_headers() -> dict[str, str]:
 
 
 def _html5_response(fragment: str) -> Response:
-    return Response(fragment, media_type="text/html; charset=utf-8")
+    return Response(
+        fragment,
+        media_type="text/html; charset=utf-8",
+        headers={"Cache-Control": "no-cache, no-transform"},
+    )
 
 
 def _html5_sse_response(content: Any) -> StreamingResponse:
diff --git a/services/api-server/tests/test_api.py b/services/api-server/tests/test_api.py
index ce9235a..98aabd0 100644
--- a/services/api-server/tests/test_api.py
+++ b/services/api-server/tests/test_api.py
@@ -44,6 +44,12 @@ def assert_html5_contract(text: str, *markers: str, full_page: bool = False) ->
         assert marker in text
 
 
+def assert_html5_response_contract(response, *markers: str, full_page: bool = False) -> None:
+    assert "text/html" in response.headers["content-type"]
+    assert response.headers["cache-control"] == "no-cache, no-transform"
+    assert_html5_contract(response.text, *markers, full_page=full_page)
+
+
 def test_cors_allows_lan_panel_origin():
     client = TestClient(app)
     response = client.options(
@@ -301,7 +307,7 @@ def test_html5_contracts_are_server_rendered_and_stable(tmp_path: Path):
     for path, markers in full_pages:
         response = client.get(path)
         assert response.status_code == 200
-        assert_html5_contract(response.text, *markers, full_page=True)
+        assert_html5_response_contract(response, *markers, full_page=True)
 
     partials = [
         (f"/html5/projects/{project_id}/symbols", {"q": "Проверить"}, ("data-html5-symbol",)),
@@ -316,7 +322,7 @@ def test_html5_contracts_are_server_rendered_and_stable(tmp_path: Path):
     for path, params, markers in partials:
         response = client.get(path, params=params)
         assert response.status_code == 200
-        assert_html5_contract(response.text, *markers)
+        assert_html5_response_contract(response, *markers)
 
 
 def test_html5_project_index_creates_project_with_fragment():