diff --git a/tests/test_streaming_markdown.py b/tests/test_streaming_markdown.py
index e86d4872..76e1db7d 100644
--- a/tests/test_streaming_markdown.py
+++ b/tests/test_streaming_markdown.py
@@ -108,9 +108,21 @@ class TestIndexHtmlSmdScript:
         )
 
     def test_smd_vendor_import_is_mount_agnostic(self):
-        assert "static/vendor/smd.min.js" in INDEX_HTML, (
-            "index.html must load the vendored streaming-markdown module"
+        """Import must resolve relative to current document, not a bare
+        specifier (rejected by ES module spec, #1849) and not root-absolute
+        (escapes /hermes/-style subpath mounts). The `./` form is the only
+        shape that satisfies both: ES-spec-valid AND mount-agnostic.
+        """
+        assert "from './static/vendor/smd.min.js'" in INDEX_HTML, (
+            "index.html must use the './static/vendor/smd.min.js' form — "
+            "bare specifiers are rejected by the ES module spec (#1849) and "
+            "leading-/ paths break subpath deployments such as /hermes/"
         )
+        # Forbid the bare form (#1849 broke streaming-markdown silently)
+        assert "import * as smd from 'static/vendor/smd.min.js'" not in INDEX_HTML, (
+            "bare specifier is rejected by the ES module spec — use './static/...'"
+        )
+        # Forbid the root-absolute form (subpath deployments escape the mount)
         assert "from '/static/vendor/smd.min.js'" not in INDEX_HTML, (
             "streaming-markdown import must not be root-absolute; root-absolute "
             "static paths break subpath deployments such as /hermes/"
diff --git a/tests/test_subpath_frontend_routes.py b/tests/test_subpath_frontend_routes.py
index 8bb15b78..c04e8914 100644
--- a/tests/test_subpath_frontend_routes.py
+++ b/tests/test_subpath_frontend_routes.py
@@ -56,6 +56,15 @@ def test_direct_frontend_event_sources_are_relative_to_current_mount():
 
 
 def test_static_vendor_import_is_relative_to_current_mount():
+    """Import must use `./static/vendor/smd.min.js` form so the URL resolves
+    relative to the document URL. Bare specifier (no leading `./` or `/`)
+    is invalid per ES module spec and breaks markdown streaming silently
+    (#1849). Root-absolute (`/static/...`) escapes subpath mounts like
+    `/hermes/`. The `./` form satisfies both constraints.
+    """
     src = read("static/index.html")
-    assert "import * as smd from 'static/vendor/smd.min.js'" in src
+    assert "import * as smd from './static/vendor/smd.min.js'" in src
+    # Bare specifier — broken per ES module spec (#1849)
+    assert "import * as smd from 'static/vendor/smd.min.js'" not in src
+    # Root-absolute — breaks /hermes/ subpath mounts
     assert "import * as smd from '/static/vendor/smd.min.js'" not in src