diff --git a/tests/backend/test_user_guidance_autointerface.py b/tests/backend/test_user_guidance_autointerface.py
new file mode 100644
index 0000000..cedcb00
--- /dev/null
+++ b/tests/backend/test_user_guidance_autointerface.py
@@ -0,0 +1,158 @@
+# SPDX-License-Identifier: 0BSD
+
+"""Tests for AutoInterface bind-failure detection in user guidance.
+"""
+
+from __future__ import annotations
+
+from types import SimpleNamespace
+from unittest.mock import MagicMock, patch
+
+import pytest
+
+from meshchatx.meshchat import ReticulumMeshChat
+
+
+def _make_app(config_interfaces):
+    """Build a minimal app stub exposing only what the helpers touch."""
+    app = SimpleNamespace()
+    app.reticulum = SimpleNamespace(
+        config={"interfaces": dict(config_interfaces)},
+        transport_enabled=lambda: True,
+    )
+    app._get_interfaces_section = (
+        ReticulumMeshChat._get_interfaces_section.__get__(app)
+    )
+    app._detect_failed_autointerfaces = (
+        ReticulumMeshChat._detect_failed_autointerfaces.__get__(app)
+    )
+    return app
+
+
+class _FakeAutoInterface:
+    pass
+
+
+_FakeAutoInterface.__name__ = "AutoInterface"
+
+
+class _FakeTCPClientInterface:
+    pass
+
+
+_FakeTCPClientInterface.__name__ = "TCPClientInterface"
+
+
+def test_detects_enabled_autointerface_that_failed_to_start():
+    app = _make_app(
+        {
+            "Default Interface": {"type": "AutoInterface", "enabled": "yes"},
+        },
+    )
+    with patch("meshchatx.meshchat.RNS.Transport") as transport:
+        transport.interfaces = []
+        assert app._detect_failed_autointerfaces() == ["Default Interface"]
+
+
+def test_running_autointerface_is_not_reported():
+    app = _make_app(
+        {
+            "Default Interface": {"type": "AutoInterface", "enabled": "yes"},
+        },
+    )
+    with patch("meshchatx.meshchat.RNS.Transport") as transport:
+        transport.interfaces = [_FakeAutoInterface()]
+        assert app._detect_failed_autointerfaces() == []
+
+
+def test_disabled_autointerface_is_ignored():
+    app = _make_app(
+        {
+            "Default Interface": {"type": "AutoInterface", "enabled": "no"},
+        },
+    )
+    with patch("meshchatx.meshchat.RNS.Transport") as transport:
+        transport.interfaces = []
+        assert app._detect_failed_autointerfaces() == []
+
+
+def test_non_auto_interface_does_not_trigger_warning():
+    app = _make_app(
+        {
+            "Hub": {
+                "type": "TCPClientInterface",
+                "enabled": "yes",
+                "target_host": "127.0.0.1",
+                "target_port": "4242",
+            },
+        },
+    )
+    with patch("meshchatx.meshchat.RNS.Transport") as transport:
+        transport.interfaces = [_FakeTCPClientInterface()]
+        assert app._detect_failed_autointerfaces() == []
+
+
+def test_empty_interfaces_section_is_safe():
+    app = _make_app({})
+    with patch("meshchatx.meshchat.RNS.Transport") as transport:
+        transport.interfaces = []
+        assert app._detect_failed_autointerfaces() == []
+
+
+def test_guidance_message_emitted_for_failed_autointerface():
+    app = _make_app(
+        {
+            "Default Interface": {"type": "AutoInterface", "enabled": "yes"},
+        },
+    )
+    app.config = MagicMock()
+    app.config.auto_announce_enabled.get.return_value = True
+    app.build_user_guidance_messages = (
+        ReticulumMeshChat.build_user_guidance_messages.__get__(app)
+    )
+
+    with patch("meshchatx.meshchat.RNS.Transport") as transport:
+        transport.interfaces = []
+        guidance = app.build_user_guidance_messages()
+
+    autointerface_msgs = [g for g in guidance if g["id"] == "autointerface_bind_failed"]
+    assert len(autointerface_msgs) == 1
+    msg = autointerface_msgs[0]
+    assert msg["severity"] == "warning"
+    assert msg["action_route"] == "/interfaces"
+    assert "Default Interface" in msg["description"]
+    assert "Sideband" in msg["description"]
+
+
+def test_guidance_message_absent_when_autointerface_running():
+    app = _make_app(
+        {
+            "Default Interface": {"type": "AutoInterface", "enabled": "yes"},
+        },
+    )
+    app.config = MagicMock()
+    app.config.auto_announce_enabled.get.return_value = True
+    app.build_user_guidance_messages = (
+        ReticulumMeshChat.build_user_guidance_messages.__get__(app)
+    )
+
+    with patch("meshchatx.meshchat.RNS.Transport") as transport:
+        transport.interfaces = [_FakeAutoInterface()]
+        guidance = app.build_user_guidance_messages()
+
+    assert not any(g["id"] == "autointerface_bind_failed" for g in guidance)
+
+
+@pytest.mark.parametrize("enabled_value", ["yes", "true", "1", "Yes", "TRUE"])
+def test_truthy_enabled_values_are_recognised(enabled_value):
+    app = _make_app(
+        {
+            "Default Interface": {
+                "type": "AutoInterface",
+                "enabled": enabled_value,
+            },
+        },
+    )
+    with patch("meshchatx.meshchat.RNS.Transport") as transport:
+        transport.interfaces = []
+        assert app._detect_failed_autointerfaces() == ["Default Interface"]