refactor: single dependency probe in capability detection; real test coverage

detect_mode_availability accepts a pre-computed dep_status so the agent
probes once; interface and fallback paths now have content-level tests.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

tests/test_capabilities.py

@@ -1,6 +1,6 @@
 """Tests for shared capability detection."""
 
-from unittest.mock import patch
+from unittest.mock import MagicMock, patch
 
 from utils.capabilities import detect_interfaces, detect_mode_availability
 
@@ -34,10 +34,90 @@ class TestModeAvailability:
             modes = detect_mode_availability()
         assert modes.get("sensor") is False
 
+    def test_pre_computed_dep_status_skips_probe(self):
+        """Passing dep_status must not trigger a second check_all_dependencies call."""
+        pre_computed = {
+            key: {"ready": True}
+            for key in (
+                "pager",
+                "sensor",
+                "aircraft",
+                "ais",
+                "acars",
+                "aprs",
+                "wifi",
+                "bluetooth",
+                "tscm",
+                "satellite",
+            )
+        }
+        with patch("utils.capabilities.check_all_dependencies") as mock_deps:
+            modes = detect_mode_availability(dep_status=pre_computed)
+        mock_deps.assert_not_called()
+        assert modes.get("sensor") is True
+        assert modes.get("adsb") is True
+
 
 class TestInterfaceDetection:
-    def test_returns_expected_shape(self, fake_process):
-        with patch("subprocess.Popen", return_value=fake_process()):
+    def test_darwin_wifi_parsing(self):
+        """The Darwin branch must parse a Wi-Fi device out of networksetup output."""
+        networksetup_output = (
+            "Hardware Port: Wi-Fi\n"
+            "Device: en0\n"
+            "Ethernet Address: aa:bb:cc:dd:ee:ff\n"
+            "\n"
+            "Hardware Port: Thunderbolt Bridge\n"
+            "Device: bridge0\n"
+        )
+
+        def fake_run(cmd, **kwargs):
+            result = MagicMock()
+            result.stdout = networksetup_output
+            result.stderr = ""
+            result.returncode = 0
+            return result
+
+        with (
+            patch("utils.capabilities.platform.system", return_value="Darwin"),
+            patch("subprocess.run", side_effect=fake_run),
+        ):
             interfaces = detect_interfaces()
-        assert set(interfaces) == {"wifi_interfaces", "bt_adapters", "sdr_devices"}
-        assert isinstance(interfaces["wifi_interfaces"], list)
+
+        names = [i["name"] for i in interfaces["wifi_interfaces"]]
+        assert "en0" in names
+        # Verify the full shape of the parsed entry
+        en0 = next(i for i in interfaces["wifi_interfaces"] if i["name"] == "en0")
+        assert "display_name" in en0
+        assert "type" in en0
+        assert "monitor_capable" in en0
+        # Thunderbolt Bridge must not appear — it has no Wi-Fi/AirPort keyword
+        assert "bridge0" not in names
+
+
+class TestFallback:
+    def test_fallback_uses_check_tool(self):
+        """When check_all_dependencies raises, fall back to per-tool checks."""
+        with (
+            patch(
+                "utils.capabilities.check_all_dependencies",
+                side_effect=RuntimeError("module unavailable"),
+            ),
+            patch("utils.capabilities.check_tool", return_value=False) as mock_check,
+        ):
+            modes = detect_mode_availability()
+        assert modes.get("sensor") is False
+        assert mock_check.called
+
+    def test_fallback_extra_mode_tools(self):
+        """EXTRA_MODE_TOOLS modes (dsc, rtlamr, listening_post) reflect check_tool's return."""
+        with (
+            patch(
+                "utils.capabilities.check_all_dependencies",
+                side_effect=RuntimeError("module unavailable"),
+            ),
+            patch("utils.capabilities.check_tool", return_value=False),
+        ):
+            modes = detect_mode_availability()
+        assert modes.get("dsc") is False
+        assert modes.get("rtlamr") is False
+        assert modes.get("listening_post") is False