diff --git a/tests/backend/test_auto_propagation.py b/tests/backend/test_auto_propagation.py
index bc1dcc9..035c254 100644
--- a/tests/backend/test_auto_propagation.py
+++ b/tests/backend/test_auto_propagation.py
@@ -93,8 +93,8 @@ async def test_auto_propagation_logic():
         # announce1 is 1 hop, but probe fails
         # announce3 is 2 hops, probe succeeds
         mock_hops.side_effect = lambda dh: 1 if dh == bytes.fromhex("aaaa1111") else 2
-        mock_probe.side_effect = (
-            lambda dh: False if dh == bytes.fromhex("aaaa1111") else True
+        mock_probe.side_effect = lambda dh: (
+            False if dh == bytes.fromhex("aaaa1111") else True
         )
 
         await manager.check_and_update_propagation_node()
diff --git a/tests/backend/test_fuzzing_extended.py b/tests/backend/test_fuzzing_extended.py
index b5b58b9..27c38b7 100644
--- a/tests/backend/test_fuzzing_extended.py
+++ b/tests/backend/test_fuzzing_extended.py
@@ -353,17 +353,19 @@ def test_markdown_renderer_fuzzing(text):
 @given(
     text=st.one_of(
         st.text(min_size=0, max_size=5000),
-        st.sampled_from([
-            "<script>alert(1)</script>",
-            "[x](javascript:alert(1))",
-            "[x](data:text/html,<script>alert(1)</script>)",
-            "**" * 2000,
-            "#" * 2000,
-            "`" * 2000,
-            "[](" * 500 + ")" * 500,
-            "\x00\x01\x02\n\t",
-            "\ufffd" * 100,
-        ]),
+        st.sampled_from(
+            [
+                "<script>alert(1)</script>",
+                "[x](javascript:alert(1))",
+                "[x](data:text/html,<script>alert(1)</script>)",
+                "**" * 2000,
+                "#" * 2000,
+                "`" * 2000,
+                "[](" * 500 + ")" * 500,
+                "\x00\x01\x02\n\t",
+                "\ufffd" * 100,
+            ]
+        ),
     ),
 )
 def test_markdown_renderer_dangerous_patterns(text):
diff --git a/tests/backend/test_lxmf_sync.py b/tests/backend/test_lxmf_sync.py
index bccb4fa..f9a5010 100644
--- a/tests/backend/test_lxmf_sync.py
+++ b/tests/backend/test_lxmf_sync.py
@@ -157,9 +157,7 @@ async def test_status_includes_sync_storage_and_confirmation_metrics(mock_app):
         if r.path == "/api/v1/lxmf/propagation-node/sync"
     )
 
-    mock_app.current_context.message_router.get_outbound_propagation_node.return_value = (
-        b"somehash"
-    )
+    mock_app.current_context.message_router.get_outbound_propagation_node.return_value = b"somehash"
     mock_app.current_context.message_router.propagation_transfer_last_result = 8
 
     with (
@@ -213,9 +211,7 @@ async def test_status_hidden_metric_is_clamped_to_zero(mock_app):
         if r.path == "/api/v1/lxmf/propagation-node/sync"
     )
 
-    mock_app.current_context.message_router.get_outbound_propagation_node.return_value = (
-        b"somehash"
-    )
+    mock_app.current_context.message_router.get_outbound_propagation_node.return_value = b"somehash"
     mock_app.current_context.message_router.propagation_transfer_last_result = 1
 
     with (
diff --git a/tests/backend/test_markdown_renderer.py b/tests/backend/test_markdown_renderer.py
index ddacae0..f62987d 100644
--- a/tests/backend/test_markdown_renderer.py
+++ b/tests/backend/test_markdown_renderer.py
@@ -77,7 +77,7 @@ class TestMarkdownRenderer(unittest.TestCase):
         cases = [
             "<script>alert(1)</script>",
             "<SCRIPT>alert(1)</SCRIPT>",
-            "<script src=\"evil.js\"></script>",
+            '<script src="evil.js"></script>',
             "</script><script>alert(1)</script>",
         ]
         for s in cases:
diff --git a/tests/backend/test_meshchat_coverage.py b/tests/backend/test_meshchat_coverage.py
index fcb5c12..4753be4 100644
--- a/tests/backend/test_meshchat_coverage.py
+++ b/tests/backend/test_meshchat_coverage.py
@@ -290,4 +290,6 @@ def test_on_lxmf_sending_failed_no_propagation(mock_app):
     mock_app.on_lxmf_sending_state_updated = MagicMock()
 
     mock_app.on_lxmf_sending_failed(mock_msg)
-    mock_app.on_lxmf_sending_state_updated.assert_called_once_with(mock_msg, context=None)
+    mock_app.on_lxmf_sending_state_updated.assert_called_once_with(
+        mock_msg, context=None
+    )
diff --git a/tests/backend/test_risky_inputs.py b/tests/backend/test_risky_inputs.py
index bbff2a4..5cc090b 100644
--- a/tests/backend/test_risky_inputs.py
+++ b/tests/backend/test_risky_inputs.py
@@ -9,7 +9,16 @@ class TestBase64DecodeRisky(unittest.TestCase):
             from meshchatx.src.backend.meshchat_utils import parse_lxmf_display_name
         except ImportError:
             self.skipTest("meshchat_utils not importable")
-        for bad in ["!!!", "\x00\x01", "a" * 10000, " ", "=", "===", "a\nb\tc", "\xff\xfe"]:
+        for bad in [
+            "!!!",
+            "\x00\x01",
+            "a" * 10000,
+            " ",
+            "=",
+            "===",
+            "a\nb\tc",
+            "\xff\xfe",
+        ]:
             result = parse_lxmf_display_name(bad, default_value="Fallback")
             self.assertIsInstance(result, str)