diff --git a/tests/backend/conftest.py b/tests/backend/conftest.py
index 9fe7e1d..fa28b61 100644
--- a/tests/backend/conftest.py
+++ b/tests/backend/conftest.py
@@ -43,9 +43,6 @@ def global_mocks():
 @pytest.fixture(autouse=True)
 def cleanup_sqlite_connections():
     yield
-    # After each test, try to close any lingering sqlite connections if possible
-    # This is a bit hard globally without tracking them, but we can at least
-    # trigger GC which often helps with ResourceWarnings.
     import gc
 
     gc.collect()
diff --git a/tests/backend/test_database_snapshots.py b/tests/backend/test_database_snapshots.py
index 49f29ca..bdcd0fd 100644
--- a/tests/backend/test_database_snapshots.py
+++ b/tests/backend/test_database_snapshots.py
@@ -65,7 +65,6 @@ def test_database_snapshot_restoration(temp_dir):
 
 
 def test_database_auto_backup_logic(temp_dir):
-    # This test verifies the loop logic if possible, or just the backup method
     db_path = os.path.join(temp_dir, "test.db")
     db = Database(db_path)
     db.initialize()
diff --git a/tests/backend/test_display_name_fuzzing.py b/tests/backend/test_display_name_fuzzing.py
index 5b13ab6..e69cd84 100644
--- a/tests/backend/test_display_name_fuzzing.py
+++ b/tests/backend/test_display_name_fuzzing.py
@@ -66,7 +66,6 @@ def test_parse_nomadnetwork_node_display_name_property_based(name):
 def test_parse_lxmf_display_name_invalid_base64(data):
     # Generate something that is NOT valid base64 (by adding invalid chars)
     invalid_b64 = base64.b64encode(data).decode("utf-8") + "!!!"
-    # This should not crash, it should just return the default value or fail gracefully
     result = parse_lxmf_display_name(invalid_b64)
     assert isinstance(result, str)
 
diff --git a/tests/backend/test_docs_manager.py b/tests/backend/test_docs_manager.py
index 9044cef..b1ba6c7 100644
--- a/tests/backend/test_docs_manager.py
+++ b/tests/backend/test_docs_manager.py
@@ -52,7 +52,6 @@ def test_docs_manager_storage_dir_fallback(tmp_path):
 
 
 def test_docs_manager_readonly_public_dir_handling(tmp_path):
-    # This test simulates a read-only public dir without storage_dir
     public_dir = tmp_path / "readonly_public"
     public_dir.mkdir()
 
@@ -189,7 +188,6 @@ def test_extract_docs_malformed_zip(docs_manager, temp_dirs):
     # 1. Zip with no folders at all
     create_mock_zip(zip_path, ["file_at_root.txt"])
     try:
-        # This might fail with IndexError at namelist()[0].split('/')[0] if no slash
         docs_manager._extract_docs(zip_path)
     except (IndexError, Exception):
         pass  # Expected or at least handled by not crashing the whole app
diff --git a/tests/backend/test_fuzzing.py b/tests/backend/test_fuzzing.py
index 97d7f46..de9799b 100644
--- a/tests/backend/test_fuzzing.py
+++ b/tests/backend/test_fuzzing.py
@@ -33,7 +33,6 @@ from meshchatx.src.backend.telemetry_utils import Telemeter
 def test_telemetry_unpack_fuzzing(data):
     """Fuzz the telemetry unpacking logic with random binary data."""
     try:
-        # This should not raise unhandled exceptions
         Telemeter.from_packed(data)
     except Exception:
         # We expect some failures for invalid packed data, but no crashes
@@ -113,7 +112,6 @@ def test_display_name_parsing_fuzzing(app_data_base64):
 def test_lxmf_fields_parsing_fuzzing(fields_data):
     """Fuzz the parsing of LXMF message fields."""
     try:
-        # This simulates how meshchat.py processes fields in on_lxmf_delivery
         for field_id, field_data in fields_data.items():
             if field_id == 0x01:  # FIELD_COMMANDS
                 try:
@@ -514,10 +512,7 @@ def test_malformed_announce_data(mock_app):
 def test_malformed_message_data(mock_app):
     """Test handling of malformed LXMF messages."""
     mock_message = MagicMock()
-    # Simulate missing attributes or methods
     del mock_message.source_hash
-
-    # This should be caught by the try-except in on_lxmf_delivery
     mock_app.on_lxmf_delivery(mock_message)
 
 
diff --git a/tests/backend/test_fuzzing_extended.py b/tests/backend/test_fuzzing_extended.py
index 1d8850b..b5b58b9 100644
--- a/tests/backend/test_fuzzing_extended.py
+++ b/tests/backend/test_fuzzing_extended.py
@@ -246,7 +246,6 @@ def test_lxmf_message_construction_fuzzing(mock_app, content, title, fields):
 )
 def test_database_record_fuzzing(mock_app, table_name, data):
     """Fuzz database record insertion logic (simulated)."""
-    # This tests the DAO layer's resilience to weird data types if they aren't properly sanitized
     try:
         dao = None
         if table_name == "messages" and hasattr(mock_app.database, "messages"):
@@ -350,6 +349,36 @@ def test_markdown_renderer_fuzzing(text):
         pytest.fail(f"MarkdownRenderer crashed: {e}")
 
 
+@settings(suppress_health_check=[HealthCheck.function_scoped_fixture], deadline=None)
+@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,
+        ]),
+    ),
+)
+def test_markdown_renderer_dangerous_patterns(text):
+    """Fuzz markdown renderer with known risky patterns (XSS, ReDoS, control chars)."""
+    from meshchatx.src.backend.markdown_renderer import MarkdownRenderer
+
+    try:
+        html_out = MarkdownRenderer.render(text)
+        assert isinstance(html_out, str)
+        assert "<script>" not in html_out
+        assert "javascript:" not in html_out
+    except Exception as e:
+        pytest.fail(f"MarkdownRenderer crashed on dangerous pattern: {e}")
+
+
 # LXMF Message Dictionary Conversion Fuzzing
 @settings(suppress_health_check=[HealthCheck.function_scoped_fixture], deadline=None)
 @given(
diff --git a/tests/backend/test_fuzzing_telemetry.py b/tests/backend/test_fuzzing_telemetry.py
index 3ca6627..8eca4c2 100644
--- a/tests/backend/test_fuzzing_telemetry.py
+++ b/tests/backend/test_fuzzing_telemetry.py
@@ -62,7 +62,6 @@ def test_fuzz_full_telemetry_packing(charge, charging, rssi, snr, q):
 @settings(deadline=None)
 @given(data=st.binary(min_size=0, max_size=2000))
 def test_fuzz_from_packed_random_bytes(data):
-    # This should never crash
     try:
         Telemeter.from_packed(data)
     except Exception:
@@ -97,5 +96,4 @@ def test_fuzz_command_parsing(commands):
                 new_cmd[k] = v
         processed_commands.append(new_cmd)
 
-    # Just ensure no crash
     assert len(processed_commands) == len(commands)
diff --git a/tests/backend/test_interface_config_parser.py b/tests/backend/test_interface_config_parser.py
index eb34f05..af3290f 100644
--- a/tests/backend/test_interface_config_parser.py
+++ b/tests/backend/test_interface_config_parser.py
@@ -37,8 +37,6 @@ def test_parse_best_effort_on_failure():
 [[Fixed Interface]]
   type = fixed
 """
-    # Note: ConfigObj might still parse [[Broken Interface] as a key if not careful,
-    # but the parser should return something.
     interfaces = InterfaceConfigParser.parse(config_text)
     assert len(interfaces) >= 1
     names = [i["name"] for i in interfaces]
diff --git a/tests/backend/test_lxmf_sync.py b/tests/backend/test_lxmf_sync.py
index d449475..bccb4fa 100644
--- a/tests/backend/test_lxmf_sync.py
+++ b/tests/backend/test_lxmf_sync.py
@@ -142,3 +142,107 @@ async def test_specific_node_hash_validation(mock_app):
 
     await sync_handler(None)
     mock_app.current_context.message_router.request_messages_from_propagation_node.assert_called_once()
+
+
+@pytest.mark.asyncio
+async def test_status_includes_sync_storage_and_confirmation_metrics(mock_app):
+    status_handler = next(
+        r.handler
+        for r in mock_app.get_routes()
+        if r.path == "/api/v1/lxmf/propagation-node/status"
+    )
+    sync_handler = next(
+        r.handler
+        for r in mock_app.get_routes()
+        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.propagation_transfer_last_result = 8
+
+    with (
+        patch.object(
+            mock_app.current_context.database.messages,
+            "count_lxmf_messages",
+            side_effect=[10, 13],
+        ),
+        patch.object(
+            mock_app.current_context.database.messages,
+            "count_lxmf_messages_by_state",
+            side_effect=[2, 4],
+        ),
+    ):
+        await sync_handler(None)
+        response = await status_handler(None)
+
+    data = json.loads(response.body)["propagation_node_status"]
+    assert data["messages_received"] == 8
+    assert data["messages_stored"] == 3
+    assert data["delivery_confirmations"] == 2
+    assert data["messages_hidden"] == 3
+
+
+@pytest.mark.asyncio
+async def test_status_metrics_default_to_zero_before_any_sync(mock_app):
+    status_handler = next(
+        r.handler
+        for r in mock_app.get_routes()
+        if r.path == "/api/v1/lxmf/propagation-node/status"
+    )
+    response = await status_handler(None)
+    data = json.loads(response.body)["propagation_node_status"]
+
+    assert data["messages_received"] == 0
+    assert data["messages_stored"] == 0
+    assert data["delivery_confirmations"] == 0
+    assert data["messages_hidden"] == 0
+
+
+@pytest.mark.asyncio
+async def test_status_hidden_metric_is_clamped_to_zero(mock_app):
+    status_handler = next(
+        r.handler
+        for r in mock_app.get_routes()
+        if r.path == "/api/v1/lxmf/propagation-node/status"
+    )
+    sync_handler = next(
+        r.handler
+        for r in mock_app.get_routes()
+        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.propagation_transfer_last_result = 1
+
+    with (
+        patch.object(
+            mock_app.current_context.database.messages,
+            "count_lxmf_messages",
+            side_effect=[10, 20],
+        ),
+        patch.object(
+            mock_app.current_context.database.messages,
+            "count_lxmf_messages_by_state",
+            side_effect=[2, 8],
+        ),
+    ):
+        await sync_handler(None)
+        response = await status_handler(None)
+
+    data = json.loads(response.body)["propagation_node_status"]
+    assert data["messages_hidden"] == 0
+
+
+def test_on_lxmf_sending_failed_forwards_context_to_state_update(mock_app):
+    msg = MagicMock(spec=LXMF.LXMessage)
+    msg.state = LXMF.LXMessage.FAILED
+    msg.try_propagation_on_fail = False
+
+    with patch.object(mock_app, "on_lxmf_sending_state_updated") as state_update_mock:
+        mock_app.on_lxmf_sending_failed(msg, context=mock_app.current_context)
+
+    state_update_mock.assert_called_once_with(msg, context=mock_app.current_context)
diff --git a/tests/backend/test_markdown_renderer.py b/tests/backend/test_markdown_renderer.py
index 4f69aae..ddacae0 100644
--- a/tests/backend/test_markdown_renderer.py
+++ b/tests/backend/test_markdown_renderer.py
@@ -1,4 +1,5 @@
 import unittest
+import time
 
 from meshchatx.src.backend.markdown_renderer import MarkdownRenderer
 
@@ -22,7 +23,6 @@ class TestMarkdownRenderer(unittest.TestCase):
         self.assertIn("<pre", rendered)
         self.assertIn("<code", rendered)
         self.assertIn("language-python", rendered)
-        # Check for escaped characters
         self.assertTrue(
             "print(&#x27;hello&#x27;)" in rendered
             or "print(&#039;hello&#039;)" in rendered,
@@ -67,6 +67,123 @@ class TestMarkdownRenderer(unittest.TestCase):
         self.assertIn("Para 1", rendered)
         self.assertIn("Para 2", rendered)
 
+    def test_render_none_and_empty(self):
+        self.assertEqual(MarkdownRenderer.render(None), "")
+        self.assertEqual(MarkdownRenderer.render(""), "")
+        r = MarkdownRenderer.render("   ")
+        self.assertIsInstance(r, str)
 
-if __name__ == "__main__":
-    unittest.main()
+    def test_xss_script_tags(self):
+        cases = [
+            "<script>alert(1)</script>",
+            "<SCRIPT>alert(1)</SCRIPT>",
+            "<script src=\"evil.js\"></script>",
+            "</script><script>alert(1)</script>",
+        ]
+        for s in cases:
+            r = MarkdownRenderer.render(s)
+            self.assertNotIn("<script>", r, msg=s)
+            self.assertNotIn("</script>", r, msg=s)
+            self.assertIn("&lt;", r, msg=s)
+
+    def test_xss_event_handlers(self):
+        cases = [
+            '<img src="x" onerror="alert(1)">',
+            '<body onload="alert(1)">',
+            '<a href="x" onmouseover="alert(1)">x</a>',
+            '<svg onload="alert(1)">',
+        ]
+        for s in cases:
+            r = MarkdownRenderer.render(s)
+            self.assertNotIn("<img", r, msg=s)
+            self.assertNotIn("<body", r, msg=s)
+            self.assertNotIn("<svg", r, msg=s)
+            self.assertNotIn("<a ", r, msg=s)
+            self.assertIn("&lt;", r, msg=s)
+
+    def test_xss_link_href_javascript(self):
+        r = MarkdownRenderer.render("[click](javascript:alert(1))")
+        self.assertNotIn("javascript:", r)
+        self.assertIn('href="#"', r)
+
+    def test_xss_link_href_data(self):
+        r = MarkdownRenderer.render("[click](data:text/html,<script>alert(1)</script>)")
+        self.assertNotIn("data:", r)
+        self.assertIn('href="#"', r)
+
+    def test_xss_link_href_vbscript(self):
+        r = MarkdownRenderer.render("[click](vbscript:msgbox(1))")
+        self.assertNotIn("vbscript:", r)
+        self.assertIn('href="#"', r)
+
+    def test_safe_links_preserved(self):
+        r = MarkdownRenderer.render("[link](https://example.com/path)")
+        self.assertIn('href="https://example.com/path"', r)
+        r = MarkdownRenderer.render("[link](/relative)")
+        self.assertIn('href="/relative"', r)
+        r = MarkdownRenderer.render("[link](#anchor)")
+        self.assertIn('href="#anchor"', r)
+
+    def test_redos_safe_repeated_markers(self):
+        t0 = time.perf_counter()
+        MarkdownRenderer.render("*" * 8000)
+        MarkdownRenderer.render("#" * 8000)
+        MarkdownRenderer.render("`" * 8000)
+        MarkdownRenderer.render("[](" * 2000 + "x" * 2000 + ")" * 2000)
+        elapsed = time.perf_counter() - t0
+        self.assertLess(elapsed, 2.0, "ReDoS or excessive backtracking suspected")
+
+    def test_malformed_unclosed_markdown(self):
+        cases = [
+            "**bold no close",
+            "```\ncode no close",
+            "*italic",
+            "`code",
+            "___under",
+            "[unclosed link](url",
+            "![unclosed img](src",
+        ]
+        for s in cases:
+            r = MarkdownRenderer.render(s)
+            self.assertIsInstance(r, str)
+            self.assertNotIn("<script>", r)
+
+    def test_very_long_input(self):
+        big = "x" * (1024 * 1024)
+        r = MarkdownRenderer.render(big)
+        self.assertIsInstance(r, str)
+        self.assertIn("x", r)
+
+    def test_unicode_and_control_chars(self):
+        cases = [
+            "\x00hello",
+            "hello\x07world",
+            "\u202eRTL",
+            "\ufffd replacement",
+            "# header \n normal",
+        ]
+        for s in cases:
+            r = MarkdownRenderer.render(s)
+            self.assertIsInstance(r, str)
+
+    def test_render_returns_string(self):
+        r = MarkdownRenderer.render("Hello **world**")
+        self.assertIsInstance(r, str)
+        self.assertIn("Hello", r)
+        self.assertIn("strong", r)
+
+    def test_message_content_style_input_safe(self):
+        """Simulate message body (e.g. decoded from LXMF) passed to render; must not crash or emit script."""
+        cases = [
+            b"Hello world".decode("utf-8"),
+            ("Hi \ufffd replacement char " * 10).strip(),
+            "\x00\x01\n\t\r",
+            "<script>alert(1)</script> normal text",
+            "**bold** and [link](javascript:x) end",
+            "\u202eRTL override",
+        ]
+        for s in cases:
+            r = MarkdownRenderer.render(s)
+            self.assertIsInstance(r, str)
+            self.assertNotIn("<script>", r)
+            self.assertNotIn("javascript:", r)
diff --git a/tests/backend/test_meshchat_coverage.py b/tests/backend/test_meshchat_coverage.py
index 28d3aaf..fcb5c12 100644
--- a/tests/backend/test_meshchat_coverage.py
+++ b/tests/backend/test_meshchat_coverage.py
@@ -290,4 +290,4 @@ 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)
+    mock_app.on_lxmf_sending_state_updated.assert_called_once_with(mock_msg, context=None)
diff --git a/tests/backend/test_notifications.py b/tests/backend/test_notifications.py
index ca57f04..d1df2c5 100644
--- a/tests/backend/test_notifications.py
+++ b/tests/backend/test_notifications.py
@@ -264,9 +264,6 @@ async def test_notifications_api(mock_app):
     # But it's defined as a nested function.
     # Alternatively, we can test the DAOs and meshchat.py logic that the handler uses.
 
-    # For now, let's verify that system notifications are correctly combined with LXMF messages.
-    # This is done in notifications_get.
-
     # Let's test a spike of notifications
     for i in range(100):
         mock_app.database.misc.add_notification(
diff --git a/tests/backend/test_performance_bottlenecks.py b/tests/backend/test_performance_bottlenecks.py
index 89f1081..909a1a8 100644
--- a/tests/backend/test_performance_bottlenecks.py
+++ b/tests/backend/test_performance_bottlenecks.py
@@ -90,7 +90,6 @@ class TestPerformanceBottlenecks(unittest.TestCase):
                 app_data = b"app_data"
                 packet_hash = b"packet_hash"
 
-                # This is the synchronous part that could be a bottleneck
                 self.announce_manager.upsert_announce(
                     self.reticulum_mock,
                     identities[i],
diff --git a/tests/backend/test_property_based.py b/tests/backend/test_property_based.py
index 677d18c..3882796 100644
--- a/tests/backend/test_property_based.py
+++ b/tests/backend/test_property_based.py
@@ -171,7 +171,6 @@ def test_parse_bool_query_param(val):
 
 @given(data=st.binary())
 def test_parse_lxmf_display_name_robustness(data):
-    # This should never crash
     try:
         parse_lxmf_display_name(data)
     except Exception as e:
@@ -180,7 +179,6 @@ def test_parse_lxmf_display_name_robustness(data):
 
 @given(data=st.binary())
 def test_parse_lxmf_propagation_node_app_data_robustness(data):
-    # This should never crash
     try:
         result = parse_lxmf_propagation_node_app_data(data)
         if result is not None:
@@ -226,7 +224,6 @@ def test_interface_config_parser_best_effort_property(names, keys, values):
 
 @given(data=st.binary())
 def test_parse_lxmf_stamp_cost_robustness(data):
-    # This should never crash
     try:
         parse_lxmf_stamp_cost(data)
     except Exception as e:
@@ -235,7 +232,6 @@ def test_parse_lxmf_stamp_cost_robustness(data):
 
 @given(name=st.text())
 def test_parse_nomadnetwork_node_display_name_robustness(name):
-    # This should never crash
     try:
         parse_nomadnetwork_node_display_name(name)
     except Exception as e:
@@ -244,7 +240,6 @@ def test_parse_nomadnetwork_node_display_name_robustness(name):
 
 @given(packed=st.binary())
 def test_telemeter_from_packed_robustness(packed):
-    # This should never crash
     try:
         Telemeter.from_packed(packed)
     except Exception as e:
@@ -444,8 +439,6 @@ def test_markdown_renderer_headers(content):
     assert result.startswith("<h1")
     assert result.endswith("</h1>")
 
-    # If the content doesn't contain markdown special chars, we can expect it to be there escaped
-    # This is a safer assertion for property-based testing
     if not any(c in content for c in "*_~`[]()"):
         assert html.escape(content) in result
 
@@ -852,13 +845,11 @@ def test_lxmf_utils_conversions_robustness(
     hex_str=st.from_regex(r"^[0-9a-fA-F]*$"),
 )
 def test_identity_recall_logic_robustness(hex_str):
-    # This tests the kind of logic used in meshchat.py for recalling identities
     import RNS
 
     try:
         if len(hex_str) % 2 == 0:
             hash_bytes = bytes.fromhex(hex_str)
-            # Just ensure RNS doesn't crash on random bytes
             RNS.Identity.recall(hash_bytes)
     except Exception:
         pass
diff --git a/tests/backend/test_reply_detection.py b/tests/backend/test_reply_detection.py
index 1408e2f..0f70427 100644
--- a/tests/backend/test_reply_detection.py
+++ b/tests/backend/test_reply_detection.py
@@ -31,7 +31,6 @@ def test_fuzz_reply_detection_no_crash(content):
     mock_msg.snr = 0
     mock_msg.q = 0
 
-    # This will trigger the detection logic
     mesh_chat.db_upsert_lxmf_message(mock_msg)
 
 
diff --git a/tests/backend/test_risky_inputs.py b/tests/backend/test_risky_inputs.py
new file mode 100644
index 0000000..bbff2a4
--- /dev/null
+++ b/tests/backend/test_risky_inputs.py
@@ -0,0 +1,205 @@
+import base64
+import json
+import unittest
+
+
+class TestBase64DecodeRisky(unittest.TestCase):
+    def test_invalid_base64_does_not_crash_display_name(self):
+        try:
+            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"]:
+            result = parse_lxmf_display_name(bad, default_value="Fallback")
+            self.assertIsInstance(result, str)
+
+    def test_invalid_base64_does_not_crash_propagation_node_app_data(self):
+        try:
+            from meshchatx.src.backend.meshchat_utils import (
+                parse_lxmf_propagation_node_app_data,
+            )
+        except ImportError:
+            self.skipTest("meshchat_utils not importable")
+        for bad in ["!!!", "", "a" * 5000]:
+            try:
+                parse_lxmf_propagation_node_app_data(bad)
+            except Exception:
+                pass
+
+    def test_invalid_base64_does_not_crash_stamp_cost(self):
+        try:
+            from meshchatx.src.backend.meshchat_utils import parse_lxmf_stamp_cost
+        except ImportError:
+            self.skipTest("meshchat_utils not importable")
+        for bad in ["!!!", "", "x" * 10000]:
+            try:
+                parse_lxmf_stamp_cost(bad)
+            except Exception:
+                pass
+
+    def test_base64_decode_direct_invalid_chars(self):
+        for s in ["a\x00b", "a--b", "a/b+c", " " * 1000]:
+            try:
+                base64.b64decode(s, validate=False)
+            except Exception:
+                pass
+        try:
+            base64.b64decode("!!!", validate=True)
+        except Exception:
+            pass
+
+
+class TestJsonLoadsRisky(unittest.TestCase):
+    def test_deeply_nested_json_does_not_crash_message_dict(self):
+        try:
+            from meshchatx.src.backend.lxmf_utils import convert_db_lxmf_message_to_dict
+        except ImportError:
+            self.skipTest("lxmf_utils not importable")
+        deep = "x"
+        for _ in range(200):
+            deep = '{"a":' + deep + "}"
+        db_msg = {
+            "id": 1,
+            "hash": "h",
+            "source_hash": "s",
+            "destination_hash": "d",
+            "is_incoming": True,
+            "state": "delivered",
+            "progress": 100.0,
+            "method": "direct",
+            "delivery_attempts": 0,
+            "next_delivery_attempt_at": None,
+            "title": "t",
+            "content": "c",
+            "fields": deep,
+            "timestamp": 123.0,
+            "rssi": -50,
+            "snr": 10,
+            "quality": 100,
+            "is_spam": False,
+            "created_at": "2024-01-01T00:00:00Z",
+            "updated_at": "2024-01-01T00:00:00Z",
+        }
+        try:
+            convert_db_lxmf_message_to_dict(db_msg)
+        except (RecursionError, OverflowError):
+            pass
+
+    def test_prototype_pollution_keys_in_fields_do_not_crash(self):
+        try:
+            from meshchatx.src.backend.lxmf_utils import convert_db_lxmf_message_to_dict
+        except ImportError:
+            self.skipTest("lxmf_utils not importable")
+        db_msg = {
+            "id": 1,
+            "hash": "h",
+            "source_hash": "s",
+            "destination_hash": "d",
+            "is_incoming": True,
+            "state": "delivered",
+            "progress": 100.0,
+            "method": "direct",
+            "delivery_attempts": 0,
+            "next_delivery_attempt_at": None,
+            "title": "t",
+            "content": "c",
+            "fields": '{"__proto__":{"x":1},"constructor":{"prototype":{"y":1}}}',
+            "timestamp": 123.0,
+            "rssi": -50,
+            "snr": 10,
+            "quality": 100,
+            "is_spam": False,
+            "created_at": "2024-01-01T00:00:00Z",
+            "updated_at": "2024-01-01T00:00:00Z",
+        }
+        result = convert_db_lxmf_message_to_dict(db_msg)
+        self.assertIsInstance(result, dict)
+
+    def test_huge_fields_string_does_not_hang(self):
+        try:
+            from meshchatx.src.backend.lxmf_utils import convert_db_lxmf_message_to_dict
+        except ImportError:
+            self.skipTest("lxmf_utils not importable")
+        db_msg = {
+            "id": 1,
+            "hash": "h",
+            "source_hash": "s",
+            "destination_hash": "d",
+            "is_incoming": True,
+            "state": "delivered",
+            "progress": 100.0,
+            "method": "direct",
+            "delivery_attempts": 0,
+            "next_delivery_attempt_at": None,
+            "title": "t",
+            "content": "c",
+            "fields": '{"k":"' + "v" * 50000 + '"}',
+            "timestamp": 123.0,
+            "rssi": -50,
+            "snr": 10,
+            "quality": 100,
+            "is_spam": False,
+            "created_at": "2024-01-01T00:00:00Z",
+            "updated_at": "2024-01-01T00:00:00Z",
+        }
+        try:
+            convert_db_lxmf_message_to_dict(db_msg)
+        except (MemoryError, json.JSONDecodeError):
+            pass
+
+    def test_invalid_json_fields_returns_safe_dict(self):
+        try:
+            from meshchatx.src.backend.lxmf_utils import convert_db_lxmf_message_to_dict
+        except ImportError:
+            self.skipTest("lxmf_utils not importable")
+        db_msg = {
+            "id": 1,
+            "hash": "h",
+            "source_hash": "s",
+            "destination_hash": "d",
+            "is_incoming": True,
+            "state": "delivered",
+            "progress": 100.0,
+            "method": "direct",
+            "delivery_attempts": 0,
+            "next_delivery_attempt_at": None,
+            "title": "t",
+            "content": "c",
+            "fields": "not json at all {{{",
+            "timestamp": 123.0,
+            "rssi": -50,
+            "snr": 10,
+            "quality": 100,
+            "is_spam": False,
+            "created_at": "2024-01-01T00:00:00Z",
+            "updated_at": "2024-01-01T00:00:00Z",
+        }
+        result = convert_db_lxmf_message_to_dict(db_msg)
+        self.assertIsInstance(result, dict)
+        self.assertIn("fields", result)
+
+
+class TestPathAndStringRisky(unittest.TestCase):
+    def test_interface_config_with_null_byte(self):
+        try:
+            from meshchatx.src.backend.interface_config_parser import (
+                InterfaceConfigParser,
+            )
+        except ImportError:
+            self.skipTest("interface_config_parser not importable")
+        try:
+            InterfaceConfigParser.parse("[section]\nname\x00=value")
+        except Exception:
+            pass
+
+    def test_interface_config_very_long_line(self):
+        try:
+            from meshchatx.src.backend.interface_config_parser import (
+                InterfaceConfigParser,
+            )
+        except ImportError:
+            self.skipTest("interface_config_parser not importable")
+        try:
+            InterfaceConfigParser.parse("[x]\nkey=" + "v" * 100000)
+        except Exception:
+            pass
diff --git a/tests/backend/test_security_fuzzing.py b/tests/backend/test_security_fuzzing.py
index b3d4630..6dedd90 100644
--- a/tests/backend/test_security_fuzzing.py
+++ b/tests/backend/test_security_fuzzing.py
@@ -355,7 +355,6 @@ def test_telephone_callback_fuzzing(mock_app, caller_id_bytes):
 )
 def test_message_dao_upsert_fuzzing(mock_app, data):
     """Fuzz MessageDAO.upsert_lxmf_message with varied dictionary data."""
-    # This should not raise SQL errors or crash
     mock_app.database.messages.upsert_lxmf_message(data)
 
 
diff --git a/tests/backend/test_telemetry_extended.py b/tests/backend/test_telemetry_extended.py
index 5550149..9342a31 100644
--- a/tests/backend/test_telemetry_extended.py
+++ b/tests/backend/test_telemetry_extended.py
@@ -40,9 +40,4 @@ def test_telemeter_unpack_location_robustness():
 
 
 def test_sideband_request_format_compatibility():
-    # Sideband telemetry request command is 0x01
-    # It can be a simple int 0x01 or a dict {0x01: timebase}
-
-    # This test is more about the logic in on_lxmf_delivery,
-    # but we can verify our assumptions about command structure here if needed.
     pass
diff --git a/tests/backend/test_telemetry_integration.py b/tests/backend/test_telemetry_integration.py
index 12e6911..8dbbefd 100644
--- a/tests/backend/test_telemetry_integration.py
+++ b/tests/backend/test_telemetry_integration.py
@@ -65,7 +65,6 @@ async def test_process_incoming_telemetry_single(mock_app):
 
 @pytest.mark.asyncio
 async def test_process_incoming_telemetry_stream(mock_app):
-    # This simulates receiving a telemetry stream (e.g. from Sideband collector)
     entries = [
         (
             "peer1",